Add traces page to UI

the worker plan function had some skipping logic missing, leading to
double-submitting tasks.

.github/actions/typecheck/action.yml

@@ -1,12 +0,0 @@
-name: Type Check
-
-description: "Run type checker"
-
-runs:
-  using: "composite"
-  steps:
-    - name: Run type checker
-      run: |
-        nix --extra-experimental-features nix-command --extra-experimental-features flakes develop -c just sync
-        nix --extra-experimental-features nix-command --extra-experimental-features flakes develop -c just check
-      shell: bash

.github/workflows/pipeline.yml

@@ -26,73 +26,14 @@ jobs:
           name: exo
           authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
 
-      - name: Configure git user
-        run: |
-          git config --local user.email "github-actions@users.noreply.github.com"
-          git config --local user.name  "github-actions bot"
-        shell: bash
+      - name: Load nix develop environment
+        run: nix run github:nicknovitski/nix-develop/v1
 
-      - name: Pull LFS files
-        run: |
-          echo "Pulling Git LFS files..."
-          git lfs pull
-        shell: bash
+      - name: Sync dependencies
+        run: uv sync --all-packages
 
-      - name: Setup Nix Environment
-        run: |
-          echo "Checking for nix installation..."
-          
-          # Check if nix binary exists directly
-          if [ -f /nix/var/nix/profiles/default/bin/nix ]; then
-            echo "Found nix binary at /nix/var/nix/profiles/default/bin/nix"
-            export PATH="/nix/var/nix/profiles/default/bin:$PATH"
-            echo "PATH=$PATH" >> $GITHUB_ENV
-            nix --version
-          elif [ -f /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh ]; then
-            echo "Found nix profile script, sourcing..."
-            source /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh
-            nix --version
-          elif command -v nix >/dev/null 2>&1; then
-            echo "Nix already in PATH"
-            nix --version
-          else
-            echo "Nix not found. Debugging info:"
-            echo "Contents of /nix/var/nix/profiles/default/:"
-            ls -la /nix/var/nix/profiles/default/ 2>/dev/null || echo "Directory not found"
-            echo "Contents of /nix/var/nix/profiles/default/bin/:"
-            ls -la /nix/var/nix/profiles/default/bin/ 2>/dev/null || echo "Directory not found"
-            exit 1
-          fi
-        shell: bash
-
-      - name: Configure basedpyright include for local MLX
-        run: |
-          RUNNER_LABELS='${{ toJSON(runner.labels) }}'
-          if echo "$RUNNER_LABELS" | grep -q "local_mlx"; then
-            if [ -d "/Users/Shared/mlx" ]; then
-              echo "Updating [tool.basedpyright].include to use /Users/Shared/mlx"
-              awk '
-                BEGIN { in=0 }
-                /^\[tool\.basedpyright\]/ { in=1; print; next }
-                in && /^\[/ { in=0 }  # next section
-                in && /^[ \t]*include[ \t]*=/ {
-                  print "include = [\"/Users/Shared/mlx\"]"
-                  next
-                }
-                { print }
-              ' pyproject.toml > pyproject.toml.tmp && mv pyproject.toml.tmp pyproject.toml
-
-              echo "New [tool.basedpyright] section:"
-              sed -n '/^\[tool\.basedpyright\]/,/^\[/p' pyproject.toml | sed '$d' || true
-            else
-              echo "local_mlx tag present but /Users/Shared/mlx not found; leaving pyproject unchanged."
-            fi
-          else
-            echo "Runner does not have 'local_mlx' tag; leaving pyproject unchanged."
-          fi
-        shell: bash
-
-      - uses: ./.github/actions/typecheck
+      - name: Run type checker
+        run: uv run basedpyright --project pyproject.toml
 
   nix:
     name: Build and check (${{ matrix.system }})
@@ -123,6 +64,63 @@ jobs:
           name: exo
           authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
 
+      - name: Build Metal packages (macOS only)
+        if: runner.os == 'macOS'
+        run: |
+          # Try to build metal-toolchain first (may succeed via cachix cache hit)
+          if nix build .#metal-toolchain 2>/dev/null; then
+            echo "metal-toolchain built successfully (likely cache hit)"
+          else
+            echo "metal-toolchain build failed, extracting from Xcode..."
+
+            NAR_HASH="sha256-ayR5mXN4sZAddwKEG2OszGRF93k9ZFc7H0yi2xbylQw="
+            NAR_NAME="metal-toolchain-17C48.nar"
+
+            # Use RUNNER_TEMP to avoid /tmp symlink issues on macOS
+            WORK_DIR="${RUNNER_TEMP}/metal-work"
+            mkdir -p "$WORK_DIR"
+
+            # Download the Metal toolchain component
+            xcodebuild -downloadComponent MetalToolchain
+
+            # Find and mount the DMG
+            DMG_PATH=$(find /System/Library/AssetsV2/com_apple_MobileAsset_MetalToolchain -name '*.dmg' 2>/dev/null | head -1)
+            if [ -z "$DMG_PATH" ]; then
+              echo "Error: Could not find Metal toolchain DMG"
+              exit 1
+            fi
+
+            echo "Found DMG at: $DMG_PATH"
+            hdiutil attach "$DMG_PATH" -mountpoint "${WORK_DIR}/metal-dmg"
+
+            # Copy the toolchain
+            cp -R "${WORK_DIR}/metal-dmg/Metal.xctoolchain" "${WORK_DIR}/metal-export"
+            hdiutil detach "${WORK_DIR}/metal-dmg"
+
+            # Create NAR and add to store
+            nix nar pack "${WORK_DIR}/metal-export" > "${WORK_DIR}/${NAR_NAME}"
+            STORE_PATH=$(nix store add --mode flat "${WORK_DIR}/${NAR_NAME}")
+            echo "Added NAR to store: $STORE_PATH"
+
+            # Verify the hash matches
+            ACTUAL_HASH=$(nix hash file "${WORK_DIR}/${NAR_NAME}")
+            if [ "$ACTUAL_HASH" != "$NAR_HASH" ]; then
+              echo "Warning: NAR hash mismatch!"
+              echo "Expected: $NAR_HASH"
+              echo "Actual:   $ACTUAL_HASH"
+              echo "The metal-toolchain.nix may need updating"
+            fi
+
+            # Clean up
+            rm -rf "$WORK_DIR"
+
+            # Retry the build now that NAR is in store
+            nix build .#metal-toolchain
+          fi
+
+          # Build mlx (depends on metal-toolchain)
+          nix build .#mlx
+
       - name: Build all Nix outputs
         run: |
           nix flake show --json | jq -r '
@@ -134,3 +132,14 @@ jobs:
 
       - name: Run nix flake check
         run: nix flake check
+
+      - name: Run pytest (macOS only)
+        if: runner.os == 'macOS'
+        run: |
+          # Build the test environment (requires relaxed sandbox for uv2nix on macOS)
+          TEST_ENV=$(nix build '.#exo-test-env' --option sandbox relaxed --print-out-paths)
+
+          # Run pytest outside sandbox (needs GPU access for MLX)
+          export HOME="$RUNNER_TEMP"
+          export EXO_TESTS=1
+          $TEST_ENV/bin/python -m pytest src -m "not slow" --import-mode=importlib

README.md

@@ -5,7 +5,7 @@
   <img alt="exo logo" src="/docs/imgs/exo-logo-transparent.png" width="50%" height="50%">
 </picture>
 
-exo: Run your own AI cluster at home with everyday devices. Maintained by [exo labs](https://x.com/exolabs).
+exo: Run frontier AI locally. Maintained by [exo labs](https://x.com/exolabs).
 
 <p align="center">
   <a href="https://discord.gg/TJ4P57arEm" target="_blank" rel="noopener noreferrer"><img src="https://img.shields.io/badge/Discord-Join%20Server-5865F2?logo=discord&logoColor=white" alt="Discord"></a>
@@ -107,6 +107,10 @@ uv run exo
 
 This starts the exo dashboard and API at http://localhost:52415/
 
+
+*Please view the section on RDMA to enable this feature on MacOS >=26.2!*
+
+
 ### Run from Source (Linux)
 
 **Prerequisites:**
@@ -230,7 +234,7 @@ This removes:
 
 RDMA is a new capability added to macOS 26.2. It works on any Mac with Thunderbolt 5 (M4 Pro Mac Mini, M4 Max Mac Studio, M4 Max MacBook Pro, M3 Ultra Mac Studio).
 
-Note that on Mac Studio, you cannot use the Thunderbolt 5 port next to the Ethernet port.
+Please refer to the caveats for immediate troubleshooting.
 
 To enable RDMA on macOS, follow these steps:
 
@@ -247,6 +251,14 @@ To enable RDMA on macOS, follow these steps:
 
 After that, RDMA will be enabled in macOS and exo will take care of the rest.
 
+**Important Caveats**
+
+1. Devices that wish to be part of an RDMA cluster must be connected to all other devices in the cluster.
+2. The cables must support TB5.
+3. On a Mac Studio, you cannot use the Thunderbolt 5 port next to the Ethernet port.
+4. If running from source, please use the script found at `tmp/set_rdma_network_config.sh`, which will disable Thunderbolt Bridge and set dhcp on each RDMA port.
+5. RDMA ports may be unable to discover each other on different versions of MacOS. Please ensure that OS versions match exactly (even beta version numbers) on all devices.
+
 ---
 
 ### Using the API

app/EXO/EXO.xcodeproj/project.pbxproj

@@ -342,6 +342,8 @@
 				SDKROOT = macosx;
 				SWIFT_ACTIVE_COMPILATION_CONDITIONS = "DEBUG $(inherited)";
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_TREAT_WARNINGS_AS_ERRORS = YES;
+				GCC_TREAT_WARNINGS_AS_ERRORS = YES;
 			};
 			name = Debug;
 		};
@@ -397,6 +399,8 @@
 				MTL_FAST_MATH = YES;
 				SDKROOT = macosx;
 				SWIFT_COMPILATION_MODE = wholemodule;
+				SWIFT_TREAT_WARNINGS_AS_ERRORS = YES;
+				GCC_TREAT_WARNINGS_AS_ERRORS = YES;
 			};
 			name = Release;
 		};

app/EXO/EXO/EXOApp.swift

@@ -45,8 +45,8 @@ struct EXOApp: App {
         let thunderboltBridge = ThunderboltBridgeService(clusterStateService: service)
         _thunderboltBridgeService = StateObject(wrappedValue: thunderboltBridge)
         enableLaunchAtLoginIfNeeded()
-        // Remove old LaunchDaemon components if they exist (from previous versions)
-        cleanupLegacyNetworkSetup()
+        // Install LaunchDaemon to disable Thunderbolt Bridge on startup (prevents network loops)
+        NetworkSetupHelper.promptAndInstallIfNeeded()
         // Check local network access periodically (warning disappears when user grants permission)
         localNetwork.startPeriodicChecking(interval: 10)
         controller.scheduleLaunch(after: 15)
@@ -136,36 +136,6 @@ struct EXOApp: App {
         }
     }
 
-    private func cleanupLegacyNetworkSetup() {
-        guard NetworkSetupHelper.hasInstalledComponents() else { return }
-        // Dispatch async to ensure app is ready before showing alert
-        DispatchQueue.main.async {
-            let alert = NSAlert()
-            alert.messageText = "EXO Network Configuration"
-            alert.informativeText =
-                "EXO needs to configure local network discovery on your device. This requires granting permission once."
-            alert.alertStyle = .informational
-            alert.addButton(withTitle: "Continue")
-            alert.addButton(withTitle: "Later")
-
-            let response = alert.runModal()
-            guard response == .alertFirstButtonReturn else {
-                Logger().info("User deferred legacy network setup cleanup")
-                return
-            }
-
-            do {
-                try NetworkSetupHelper.uninstall()
-                Logger().info("Cleaned up legacy network setup components")
-            } catch {
-                // Non-fatal: user may have cancelled admin prompt or cleanup may have
-                // partially succeeded. The app will continue normally.
-                Logger().warning(
-                    "Could not clean up legacy network setup (non-fatal): \(error.localizedDescription)"
-                )
-            }
-        }
-    }
 }
 
 /// Helper for managing EXO's launch-at-login registration
@@ -255,7 +225,7 @@ private final class ExoUpdaterDelegate: NSObject, SPUUpdaterDelegate {
         }
     }
 
-    private func showNotification(title: String, body: String) {
+    nonisolated private func showNotification(title: String, body: String) {
         let center = UNUserNotificationCenter.current()
         let content = UNMutableNotificationContent()
         content.title = title

app/EXO/EXO/Services/NetworkSetupHelper.swift

@@ -11,6 +11,100 @@ enum NetworkSetupHelper {
     private static let legacyScriptDestination =
         "/Library/Application Support/EXO/disable_bridge_enable_dhcp.sh"
     private static let plistDestination = "/Library/LaunchDaemons/io.exo.networksetup.plist"
+    private static let requiredStartInterval: Int = 1786
+
+    private static let setupScript = """
+        #!/usr/bin/env bash
+
+        set -euo pipefail
+
+        # Wait for macOS to finish network setup after boot
+        sleep 20
+
+        PREFS="/Library/Preferences/SystemConfiguration/preferences.plist"
+
+        # Remove bridge0 interface
+        ifconfig bridge0 &>/dev/null && {
+          ifconfig bridge0 | grep -q 'member' && {
+            ifconfig bridge0 | awk '/member/ {print $2}' | xargs -n1 ifconfig bridge0 deletem 2>/dev/null || true
+          }
+          ifconfig bridge0 destroy 2>/dev/null || true
+        }
+
+        # Remove Thunderbolt Bridge from VirtualNetworkInterfaces in preferences.plist
+        /usr/libexec/PlistBuddy -c "Delete :VirtualNetworkInterfaces:Bridge:bridge0" "$PREFS" 2>/dev/null || true
+
+        networksetup -listlocations | grep -q exo || {
+          networksetup -createlocation exo
+        }
+
+        networksetup -switchtolocation exo
+        networksetup -listallhardwareports \\
+          | awk -F': ' '/Hardware Port: / {print $2}' \\
+          | while IFS=":" read -r name; do
+              case "$name" in
+                "Ethernet Adapter"*)
+                        ;;
+                "Thunderbolt Bridge")
+                        ;;
+                "Thunderbolt "*)
+                  networksetup -listallnetworkservices \\
+                    | grep -q "EXO $name" \\
+                      || networksetup -createnetworkservice "EXO $name" "$name" 2>/dev/null \\
+                      || continue
+                  networksetup -setdhcp "EXO $name"
+                        ;;
+                *)
+                  networksetup -listallnetworkservices \\
+                    | grep -q "$name" \\
+                      || networksetup -createnetworkservice "$name" "$name" 2>/dev/null \\
+                      || continue
+                        ;;
+              esac
+            done
+
+        networksetup -listnetworkservices | grep -q "Thunderbolt Bridge" && {
+          networksetup -setnetworkserviceenabled "Thunderbolt Bridge" off
+        } || true
+        """
+
+    /// Prompts user and installs the LaunchDaemon if not already installed.
+    /// Shows an alert explaining what will be installed before requesting admin privileges.
+    static func promptAndInstallIfNeeded() {
+        // Use .utility priority to match NSAppleScript's internal QoS and avoid priority inversion
+        Task.detached(priority: .utility) {
+            // If already correctly installed, skip
+            if daemonAlreadyInstalled() {
+                return
+            }
+
+            // Show alert on main thread
+            let shouldInstall = await MainActor.run {
+                let alert = NSAlert()
+                alert.messageText = "EXO Network Configuration"
+                alert.informativeText =
+                    "EXO needs to install a system service to configure local networking. This will disable Thunderbolt Bridge (preventing packet storms) and install a Network Location.\n\nYou will be prompted for your password."
+                alert.alertStyle = .informational
+                alert.addButton(withTitle: "Install")
+                alert.addButton(withTitle: "Not Now")
+                return alert.runModal() == .alertFirstButtonReturn
+            }
+
+            guard shouldInstall else {
+                logger.info("User deferred network setup daemon installation")
+                return
+            }
+
+            do {
+                try installLaunchDaemon()
+                logger.info("Network setup launch daemon installed and started")
+            } catch {
+                logger.error(
+                    "Network setup launch daemon failed: \(error.localizedDescription, privacy: .public)"
+                )
+            }
+        }
+    }
 
     /// Removes all EXO network setup components from the system.
     /// This includes the LaunchDaemon, scripts, logs, and network location.
@@ -30,6 +124,100 @@ enum NetworkSetupHelper {
         return scriptExists || legacyScriptExists || plistExists
     }
 
+    private static func daemonAlreadyInstalled() -> Bool {
+        let manager = FileManager.default
+        let scriptExists = manager.fileExists(atPath: scriptDestination)
+        let plistExists = manager.fileExists(atPath: plistDestination)
+        guard scriptExists, plistExists else { return false }
+        guard
+            let installedScript = try? String(contentsOfFile: scriptDestination, encoding: .utf8),
+            installedScript.trimmingCharacters(in: .whitespacesAndNewlines)
+                == setupScript.trimmingCharacters(in: .whitespacesAndNewlines)
+        else {
+            return false
+        }
+        guard
+            let data = try? Data(contentsOf: URL(fileURLWithPath: plistDestination)),
+            let plist = try? PropertyListSerialization.propertyList(
+                from: data, options: [], format: nil) as? [String: Any]
+        else {
+            return false
+        }
+        guard
+            let interval = plist["StartInterval"] as? Int,
+            interval == requiredStartInterval
+        else {
+            return false
+        }
+        if let programArgs = plist["ProgramArguments"] as? [String],
+            programArgs.contains(scriptDestination) == false
+        {
+            return false
+        }
+        return true
+    }
+
+    private static func installLaunchDaemon() throws {
+        let installerScript = makeInstallerScript()
+        try runShellAsAdmin(installerScript)
+    }
+
+    private static func makeInstallerScript() -> String {
+        """
+        set -euo pipefail
+
+        LABEL="\(daemonLabel)"
+        SCRIPT_DEST="\(scriptDestination)"
+        LEGACY_SCRIPT_DEST="\(legacyScriptDestination)"
+        PLIST_DEST="\(plistDestination)"
+        LOG_OUT="/var/log/\(daemonLabel).log"
+        LOG_ERR="/var/log/\(daemonLabel).err.log"
+
+        # First, completely remove any existing installation
+        launchctl bootout system/"$LABEL" 2>/dev/null || true
+        rm -f "$PLIST_DEST"
+        rm -f "$SCRIPT_DEST"
+        rm -f "$LEGACY_SCRIPT_DEST"
+        rm -f "$LOG_OUT" "$LOG_ERR"
+
+        # Install fresh
+        mkdir -p "$(dirname "$SCRIPT_DEST")"
+
+        cat > "$SCRIPT_DEST" <<'EOF_SCRIPT'
+        \(setupScript)
+        EOF_SCRIPT
+        chmod 755 "$SCRIPT_DEST"
+
+        cat > "$PLIST_DEST" <<'EOF_PLIST'
+        <?xml version="1.0" encoding="UTF-8"?>
+        <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+        <plist version="1.0">
+        <dict>
+          <key>Label</key>
+          <string>\(daemonLabel)</string>
+          <key>ProgramArguments</key>
+          <array>
+            <string>/bin/bash</string>
+            <string>\(scriptDestination)</string>
+          </array>
+          <key>StartInterval</key>
+          <integer>\(requiredStartInterval)</integer>
+          <key>RunAtLoad</key>
+          <true/>
+          <key>StandardOutPath</key>
+          <string>/var/log/\(daemonLabel).log</string>
+          <key>StandardErrorPath</key>
+          <string>/var/log/\(daemonLabel).err.log</string>
+        </dict>
+        </plist>
+        EOF_PLIST
+
+        launchctl bootstrap system "$PLIST_DEST"
+        launchctl enable system/"$LABEL"
+        launchctl kickstart -k system/"$LABEL"
+        """
+    }
+
     private static func makeUninstallScript() -> String {
         """
         set -euo pipefail
@@ -56,11 +244,11 @@ enum NetworkSetupHelper {
         rm -f "$LOG_OUT" "$LOG_ERR"
 
         # Switch back to Automatic network location
-        networksetup -switchtolocation Automatic 2>/dev/null || true
+        networksetup -switchtolocation Automatic >/dev/null 2>&1 || true
 
         # Delete the exo network location if it exists
-        networksetup -listlocations | grep -q '^exo$' && {
-          networksetup -deletelocation exo 2>/dev/null || true
+        networksetup -listlocations 2>/dev/null | grep -q '^exo$' && {
+          networksetup -deletelocation exo >/dev/null 2>&1 || true
         } || true
 
         # Re-enable any Thunderbolt Bridge service if it exists
@@ -70,12 +258,12 @@ enum NetworkSetupHelper {
           tb_devices=$(networksetup -listallhardwareports 2>/dev/null | awk '
             /^Hardware Port:/ { port = tolower(substr($0, 16)) }
             /^Device:/ { if (port ~ /thunderbolt/) print substr($0, 9) }
-          ')
+          ') || true
           [ -z "$tb_devices" ] && return 0
 
           # For each bridge device, check if it contains Thunderbolt interfaces
           for bridge in bridge0 bridge1 bridge2; do
-            members=$(ifconfig "$bridge" 2>/dev/null | awk '/member:/ {print $2}')
+            members=$(ifconfig "$bridge" 2>/dev/null | awk '/member:/ {print $2}') || true
             [ -z "$members" ] && continue
 
             for tb_dev in $tb_devices; do
@@ -84,7 +272,7 @@ enum NetworkSetupHelper {
                 service_name=$(networksetup -listnetworkserviceorder 2>/dev/null | awk -v dev="$bridge" '
                   /^\\([0-9*]/ { gsub(/^\\([0-9*]+\\) /, ""); svc = $0 }
                   /Device:/ && $0 ~ dev { print svc; exit }
-                ')
+                ') || true
                 if [ -n "$service_name" ]; then
                   networksetup -setnetworkserviceenabled "$service_name" on 2>/dev/null || true
                   return 0
@@ -92,8 +280,9 @@ enum NetworkSetupHelper {
               fi
             done
           done
+          return 0
         }
-        find_and_enable_thunderbolt_bridge
+        find_and_enable_thunderbolt_bridge || true
 
         echo "EXO network components removed successfully"
         """

app/EXO/EXO/Services/ThunderboltBridgeService.swift

@@ -127,21 +127,24 @@ final class ThunderboltBridgeService: ObservableObject {
 
         // 2. Request specific network configuration rights
         let rightName = "system.services.systemconfiguration.network"
-        var item = AuthorizationItem(
-            name: rightName,
-            valueLength: 0,
-            value: nil,
-            flags: 0
-        )
-        var rights = AuthorizationRights(count: 1, items: &item)
-
-        status = AuthorizationCopyRights(
-            authRef,
-            &rights,
-            nil,
-            [.extendRights, .interactionAllowed],
-            nil
-        )
+        status = rightName.withCString { nameCString in
+            var item = AuthorizationItem(
+                name: nameCString,
+                valueLength: 0,
+                value: nil,
+                flags: 0
+            )
+            return withUnsafeMutablePointer(to: &item) { itemPointer in
+                var rights = AuthorizationRights(count: 1, items: itemPointer)
+                return AuthorizationCopyRights(
+                    authRef,
+                    &rights,
+                    nil,
+                    [.extendRights, .interactionAllowed],
+                    nil
+                )
+            }
+        }
         guard status == errAuthorizationSuccess else {
             if status == errAuthorizationCanceled {
                 throw ThunderboltBridgeError.authorizationCanceled

app/EXO/uninstall-exo.sh

@@ -29,21 +29,21 @@ YELLOW='\033[1;33m'
 NC='\033[0m' # No Color
 
 echo_info() {
-    echo -e "${GREEN}[INFO]${NC} $1"
+  echo -e "${GREEN}[INFO]${NC} $1"
 }
 
 echo_warn() {
-    echo -e "${YELLOW}[WARN]${NC} $1"
+  echo -e "${YELLOW}[WARN]${NC} $1"
 }
 
 echo_error() {
-    echo -e "${RED}[ERROR]${NC} $1"
+  echo -e "${RED}[ERROR]${NC} $1"
 }
 
 # Check if running as root
 if [[ $EUID -ne 0 ]]; then
-    echo_error "This script must be run as root (use sudo)"
-    exit 1
+  echo_error "This script must be run as root (use sudo)"
+  exit 1
 fi
 
 echo ""
@@ -55,64 +55,64 @@ echo ""
 # Unload the LaunchDaemon if running
 echo_info "Stopping network setup daemon..."
 if launchctl list | grep -q "$LABEL"; then
-    launchctl bootout system/"$LABEL" 2>/dev/null || true
-    echo_info "Daemon stopped"
+  launchctl bootout system/"$LABEL" 2>/dev/null || true
+  echo_info "Daemon stopped"
 else
-    echo_warn "Daemon was not running"
+  echo_warn "Daemon was not running"
 fi
 
 # Remove LaunchDaemon plist
-if [[ -f "$PLIST_DEST" ]]; then
-    rm -f "$PLIST_DEST"
-    echo_info "Removed LaunchDaemon plist"
+if [[ -f $PLIST_DEST ]]; then
+  rm -f "$PLIST_DEST"
+  echo_info "Removed LaunchDaemon plist"
 else
-    echo_warn "LaunchDaemon plist not found (already removed?)"
+  echo_warn "LaunchDaemon plist not found (already removed?)"
 fi
 
 # Remove the script and parent directory
-if [[ -f "$SCRIPT_DEST" ]]; then
-    rm -f "$SCRIPT_DEST"
-    echo_info "Removed network setup script"
+if [[ -f $SCRIPT_DEST ]]; then
+  rm -f "$SCRIPT_DEST"
+  echo_info "Removed network setup script"
 else
-    echo_warn "Network setup script not found (already removed?)"
+  echo_warn "Network setup script not found (already removed?)"
 fi
 
 # Remove EXO directory if empty
 if [[ -d "/Library/Application Support/EXO" ]]; then
-    rmdir "/Library/Application Support/EXO" 2>/dev/null && \
-        echo_info "Removed EXO support directory" || \
-        echo_warn "EXO support directory not empty, leaving in place"
+  rmdir "/Library/Application Support/EXO" 2>/dev/null &&
+    echo_info "Removed EXO support directory" ||
+    echo_warn "EXO support directory not empty, leaving in place"
 fi
 
 # Remove log files
-if [[ -f "$LOG_OUT" ]] || [[ -f "$LOG_ERR" ]]; then
-    rm -f "$LOG_OUT" "$LOG_ERR"
-    echo_info "Removed log files"
+if [[ -f $LOG_OUT ]] || [[ -f $LOG_ERR ]]; then
+  rm -f "$LOG_OUT" "$LOG_ERR"
+  echo_info "Removed log files"
 else
-    echo_warn "Log files not found (already removed?)"
+  echo_warn "Log files not found (already removed?)"
 fi
 
 # Switch back to Automatic network location
 echo_info "Restoring network configuration..."
 if networksetup -listlocations | grep -q "^Automatic$"; then
-    networksetup -switchtolocation Automatic 2>/dev/null || true
-    echo_info "Switched to Automatic network location"
+  networksetup -switchtolocation Automatic 2>/dev/null || true
+  echo_info "Switched to Automatic network location"
 else
-    echo_warn "Automatic network location not found"
+  echo_warn "Automatic network location not found"
 fi
 
 # Delete the exo network location if it exists
 if networksetup -listlocations | grep -q "^exo$"; then
-    networksetup -deletelocation exo 2>/dev/null || true
-    echo_info "Deleted 'exo' network location"
+  networksetup -deletelocation exo 2>/dev/null || true
+  echo_info "Deleted 'exo' network location"
 else
-    echo_warn "'exo' network location not found (already removed?)"
+  echo_warn "'exo' network location not found (already removed?)"
 fi
 
 # Re-enable Thunderbolt Bridge if it exists
 if networksetup -listnetworkservices 2>/dev/null | grep -q "Thunderbolt Bridge"; then
-    networksetup -setnetworkserviceenabled "Thunderbolt Bridge" on 2>/dev/null || true
-    echo_info "Re-enabled Thunderbolt Bridge"
+  networksetup -setnetworkserviceenabled "Thunderbolt Bridge" on 2>/dev/null || true
+  echo_info "Re-enabled Thunderbolt Bridge"
 fi
 
 # Note about launch at login registration
@@ -124,14 +124,14 @@ echo_warn "  System Settings → General → Login Items → Remove EXO"
 # Check if EXO.app exists in common locations
 APP_FOUND=false
 for app_path in "/Applications/EXO.app" "$HOME/Applications/EXO.app"; do
-    if [[ -d "$app_path" ]]; then
-        if [[ "$APP_FOUND" == false ]]; then
-            echo ""
-            APP_FOUND=true
-        fi
-        echo_warn "EXO.app found at: $app_path"
-        echo_warn "You may want to move it to Trash manually."
+  if [[ -d $app_path ]]; then
+    if [[ $APP_FOUND == false ]]; then
+      echo ""
+      APP_FOUND=true
     fi
+    echo_warn "EXO.app found at: $app_path"
+    echo_warn "You may want to move it to Trash manually."
+  fi
 done
 
 echo ""
@@ -151,4 +151,3 @@ echo ""
 echo "Manual step required:"
 echo "  Remove EXO from Login Items in System Settings → General → Login Items"
 echo ""
-

dashboard/package-lock.json

@@ -865,7 +865,6 @@
 			"integrity": "sha512-oH8tXw7EZnie8FdOWYrF7Yn4IKrqTFHhXvl8YxXxbKwTMcD/5NNCryUSEXRk2ZR4ojnub0P8rNrsVGHXWqIDtA==",
 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@standard-schema/spec": "^1.0.0",
 				"@sveltejs/acorn-typescript": "^1.0.5",
@@ -905,7 +904,6 @@
 			"integrity": "sha512-Y1Cs7hhTc+a5E9Va/xwKlAJoariQyHY+5zBgCZg4PFWNYQ1nMN9sjK1zhw1gK69DuqVP++sht/1GZg1aRwmAXQ==",
 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@sveltejs/vite-plugin-svelte-inspector": "^4.0.1",
 				"debug": "^4.4.1",
@@ -1522,7 +1520,6 @@
 			"integrity": "sha512-LCCV0HdSZZZb34qifBsyWlUmok6W7ouER+oQIGBScS8EsZsQbrtFTUrDX4hOl+CS6p7cnNC4td+qrSVGSCTUfQ==",
 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"undici-types": "~6.21.0"
 			}
@@ -1532,7 +1529,6 @@
 			"resolved": "https://registry.npmjs.org/acorn/-/acorn-8.15.0.tgz",
 			"integrity": "sha512-NZyJarBfL7nWwIq+FDL6Zp/yHEhePMNnnJ0y3qfieCrmNvYct8uvtiV41UvlSe6apAfk0fY1FbWx+NwfmpvtTg==",
 			"license": "MIT",
-			"peer": true,
 			"bin": {
 				"acorn": "bin/acorn"
 			},
@@ -1945,7 +1941,6 @@
 			"integrity": "sha512-fmTRWbNMmsmWq6xJV8D19U/gw/bwrHfNXxrIN+HfZgnzqTHp9jOmKMhsTUjXOJnZOdZY9Q28y4yebKzqDKlxlQ==",
 			"dev": true,
 			"license": "ISC",
-			"peer": true,
 			"engines": {
 				"node": ">=12"
 			}
@@ -2653,7 +2648,6 @@
 			"integrity": "sha512-5gTmgEY/sqK6gFXLIsQNH19lWb4ebPDLA4SdLP7dsWkIXHWlG66oPuVvXSGFPppYZz8ZDZq0dYYrbHfBCVUb1Q==",
 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"engines": {
 				"node": ">=12"
 			},
@@ -2696,7 +2690,6 @@
 			"integrity": "sha512-UOnG6LftzbdaHZcKoPFtOcCKztrQ57WkHDeRD9t/PTQtmT0NHSeWWepj6pS0z/N7+08BHFDQVUrfmfMRcZwbMg==",
 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"bin": {
 				"prettier": "bin/prettier.cjs"
 			},
@@ -2869,7 +2862,6 @@
 			"resolved": "https://registry.npmjs.org/svelte/-/svelte-5.45.3.tgz",
 			"integrity": "sha512-ngKXNhNvwPzF43QqEhDOue7TQTrG09em1sd4HBxVF0Wr2gopAmdEWan+rgbdgK4fhBtSOTJO8bYU4chUG7VXZQ==",
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@jridgewell/remapping": "^2.3.4",
 				"@jridgewell/sourcemap-codec": "^1.5.0",
@@ -3014,7 +3006,6 @@
 			"integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
 			"dev": true,
 			"license": "Apache-2.0",
-			"peer": true,
 			"bin": {
 				"tsc": "bin/tsc",
 				"tsserver": "bin/tsserver"
@@ -3036,7 +3027,6 @@
 			"integrity": "sha512-+Oxm7q9hDoLMyJOYfUYBuHQo+dkAloi33apOPP56pzj+vsdJDzr+j1NISE5pyaAuKL4A3UD34qd0lx5+kfKp2g==",
 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"esbuild": "^0.25.0",
 				"fdir": "^6.4.4",

dashboard/parts.nix

@@ -3,6 +3,61 @@
   perSystem =
     { pkgs, lib, ... }:
     let
+      # Filter source to ONLY include package.json and package-lock.json
+      # This ensures prettier-svelte only rebuilds when lockfiles change
+      dashboardLockfileSrc = lib.cleanSourceWith {
+        src = inputs.self;
+        filter =
+          path: type:
+          let
+            baseName = builtins.baseNameOf path;
+            isDashboardDir = baseName == "dashboard" && type == "directory";
+            isPackageFile =
+              (lib.hasInfix "/dashboard/" path || lib.hasSuffix "/dashboard" (builtins.dirOf path))
+              && (baseName == "package.json" || baseName == "package-lock.json");
+          in
+          isDashboardDir || isPackageFile;
+      };
+
+      # Stub source with lockfiles and minimal files for build to succeed
+      # This allows prettier-svelte to avoid rebuilding when dashboard source changes
+      dashboardStubSrc = pkgs.runCommand "dashboard-stub-src" { } ''
+        mkdir -p $out
+        cp ${dashboardLockfileSrc}/dashboard/package.json $out/
+        cp ${dashboardLockfileSrc}/dashboard/package-lock.json $out/
+        # Minimal files so vite build succeeds (produces empty output)
+        echo '<!DOCTYPE html><html><head></head><body></body></html>' > $out/index.html
+        mkdir -p $out/src
+        touch $out/src/app.html
+      '';
+
+      # Deps-only build using stub source (for prettier-svelte)
+      # Only rebuilds when package.json or package-lock.json change
+      dashboardDeps = inputs.dream2nix.lib.evalModules {
+        packageSets.nixpkgs = pkgs;
+        modules = [
+          ./dashboard.nix
+          {
+            paths.projectRoot = inputs.self;
+            paths.projectRootFile = "flake.nix";
+            paths.package = inputs.self + "/dashboard";
+          }
+          {
+            deps.dashboardSrc = lib.mkForce dashboardStubSrc;
+          }
+          # Override build phases to skip the actual build - just need node_modules
+          {
+            mkDerivation = {
+              buildPhase = lib.mkForce "true";
+              installPhase = lib.mkForce ''
+                runHook preInstall
+                runHook postInstall
+              '';
+            };
+          }
+        ];
+      };
+
       # Filter source to only include dashboard directory
       dashboardSrc = lib.cleanSourceWith {
         src = inputs.self;
@@ -42,11 +97,12 @@
       '';
 
       # Prettier with svelte plugin for treefmt
+      # Uses dashboardDeps instead of dashboardFull to avoid rebuilding on source changes
       packages.prettier-svelte = pkgs.writeShellScriptBin "prettier-svelte" ''
-        export NODE_PATH="${dashboardFull}/lib/node_modules/exo-dashboard/node_modules"
+        export NODE_PATH="${dashboardDeps}/lib/node_modules/exo-dashboard/node_modules"
         exec ${pkgs.nodejs}/bin/node \
-          ${dashboardFull}/lib/node_modules/exo-dashboard/node_modules/prettier/bin/prettier.cjs \
-          --plugin "${dashboardFull}/lib/node_modules/exo-dashboard/node_modules/prettier-plugin-svelte/plugin.js" \
+          ${dashboardDeps}/lib/node_modules/exo-dashboard/node_modules/prettier/bin/prettier.cjs \
+          --plugin "${dashboardDeps}/lib/node_modules/exo-dashboard/node_modules/prettier-plugin-svelte/plugin.js" \
           "$@"
       '';
     };

dashboard/src/lib/components/ChatForm.svelte

@@ -89,7 +89,10 @@
 
   const isImageModel = $derived(() => {
     if (!currentModel) return false;
-    return modelSupportsTextToImage(currentModel);
+    return (
+      modelSupportsTextToImage(currentModel) ||
+      modelSupportsImageEditing(currentModel)
+    );
   });
 
   const isEditOnlyWithoutImage = $derived(
@@ -646,6 +649,23 @@
             </svg>
             <span>EDIT</span>
           </span>
+        {:else if isEditOnlyWithoutImage}
+          <span class="inline-flex items-center gap-1.5">
+            <svg
+              class="w-3.5 h-3.5"
+              fill="none"
+              viewBox="0 0 24 24"
+              stroke="currentColor"
+              stroke-width="2"
+            >
+              <path
+                stroke-linecap="round"
+                stroke-linejoin="round"
+                d="M11 5H6a2 2 0 00-2 2v11a2 2 0 002 2h11a2 2 0 002-2v-5m-1.414-9.414a2 2 0 112.828 2.828L11.828 15H9v-2.828l8.586-8.586z"
+              />
+            </svg>
+            <span>EDIT</span>
+          </span>
         {:else if isImageModel()}
           <span class="inline-flex items-center gap-1.5">
             <svg

dashboard/src/lib/components/ImageParamsPanel.svelte

@@ -110,6 +110,36 @@
     setImageGenerationParams({ negativePrompt: value || null });
   }
 
+  function handleNumImagesChange(event: Event) {
+    const input = event.target as HTMLInputElement;
+    const value = input.value.trim();
+    if (value === "") {
+      setImageGenerationParams({ numImages: 1 });
+    } else {
+      const num = parseInt(value, 10);
+      if (!isNaN(num) && num >= 1) {
+        setImageGenerationParams({ numImages: num });
+      }
+    }
+  }
+
+  function handleStreamChange(enabled: boolean) {
+    setImageGenerationParams({ stream: enabled });
+  }
+
+  function handlePartialImagesChange(event: Event) {
+    const input = event.target as HTMLInputElement;
+    const value = input.value.trim();
+    if (value === "") {
+      setImageGenerationParams({ partialImages: 0 });
+    } else {
+      const num = parseInt(value, 10);
+      if (!isNaN(num) && num >= 0) {
+        setImageGenerationParams({ partialImages: num });
+      }
+    }
+  }
+
   function clearSteps() {
     setImageGenerationParams({ numInferenceSteps: null });
   }
@@ -134,90 +164,92 @@
 <div class="border-b border-exo-medium-gray/30 px-3 py-2">
   <!-- Basic params row -->
   <div class="flex items-center gap-3 flex-wrap">
-    <!-- Size -->
-    <div class="flex items-center gap-1.5">
-      <span class="text-xs text-exo-light-gray uppercase tracking-wider"
-        >SIZE:</span
-      >
-      <div class="relative">
-        <button
-          bind:this={sizeButtonRef}
-          type="button"
-          onclick={() => (isSizeDropdownOpen = !isSizeDropdownOpen)}
-          class="bg-exo-medium-gray/50 border border-exo-yellow/30 rounded pl-2 pr-6 py-1 text-xs font-mono text-exo-yellow cursor-pointer transition-all duration-200 hover:border-exo-yellow/50 focus:outline-none focus:border-exo-yellow/70 {isSizeDropdownOpen
-            ? 'border-exo-yellow/70'
-            : ''}"
+    <!-- Size (hidden in edit mode - output size comes from input image) -->
+    {#if !isEditMode}
+      <div class="flex items-center gap-1.5">
+        <span class="text-xs text-exo-light-gray uppercase tracking-wider"
+          >SIZE:</span
         >
-          {params.size}
-        </button>
-        <div
-          class="absolute right-1.5 top-1/2 -translate-y-1/2 pointer-events-none transition-transform duration-200 {isSizeDropdownOpen
-            ? 'rotate-180'
-            : ''}"
-        >
-          <svg
-            class="w-3 h-3 text-exo-yellow/60"
-            fill="none"
-            viewBox="0 0 24 24"
-            stroke="currentColor"
+        <div class="relative">
+          <button
+            bind:this={sizeButtonRef}
+            type="button"
+            onclick={() => (isSizeDropdownOpen = !isSizeDropdownOpen)}
+            class="bg-exo-medium-gray/50 border border-exo-yellow/30 rounded pl-2 pr-6 py-1 text-xs font-mono text-exo-yellow cursor-pointer transition-all duration-200 hover:border-exo-yellow/50 focus:outline-none focus:border-exo-yellow/70 {isSizeDropdownOpen
+              ? 'border-exo-yellow/70'
+              : ''}"
           >
-            <path
-              stroke-linecap="round"
-              stroke-linejoin="round"
-              stroke-width="2"
-              d="M19 9l-7 7-7-7"
-            />
-          </svg>
-        </div>
-      </div>
-
-      {#if isSizeDropdownOpen}
-        <!-- Backdrop to close dropdown -->
-        <button
-          type="button"
-          class="fixed inset-0 z-[9998] cursor-default"
-          onclick={() => (isSizeDropdownOpen = false)}
-          aria-label="Close dropdown"
-        ></button>
-
-        <!-- Dropdown Panel - fixed positioning to escape overflow:hidden -->
-        <div
-          class="fixed bg-exo-dark-gray border border-exo-yellow/30 rounded shadow-lg shadow-black/50 z-[9999] max-h-48 overflow-y-auto min-w-max"
-          style="bottom: calc(100vh - {sizeDropdownPosition()
-            .top}px + 4px); left: {sizeDropdownPosition().left}px;"
-        >
-          <div class="py-1">
-            {#each sizeOptions as size}
-              <button
-                type="button"
-                onclick={() => selectSize(size)}
-                class="w-full px-3 py-1.5 text-left text-xs font-mono tracking-wide transition-colors duration-100 flex items-center gap-2 {params.size ===
-                size
-                  ? 'bg-transparent text-exo-yellow'
-                  : 'text-exo-light-gray hover:text-exo-yellow'}"
-              >
-                {#if params.size === size}
-                  <svg
-                    class="w-3 h-3 flex-shrink-0"
-                    fill="currentColor"
-                    viewBox="0 0 20 20"
-                  >
-                    <path
-                      fill-rule="evenodd"
-                      d="M16.707 5.293a1 1 0 010 1.414l-8 8a1 1 0 01-1.414 0l-4-4a1 1 0 011.414-1.414L8 12.586l7.293-7.293a1 1 0 011.414 0z"
-                      clip-rule="evenodd"
-                    />
-                  </svg>
-                {:else}
-                  <span class="w-3"></span>
-                {/if}
-                <span>{size}</span>
-              </button>
-            {/each}
+            {params.size}
+          </button>
+          <div
+            class="absolute right-1.5 top-1/2 -translate-y-1/2 pointer-events-none transition-transform duration-200 {isSizeDropdownOpen
+              ? 'rotate-180'
+              : ''}"
+          >
+            <svg
+              class="w-3 h-3 text-exo-yellow/60"
+              fill="none"
+              viewBox="0 0 24 24"
+              stroke="currentColor"
+            >
+              <path
+                stroke-linecap="round"
+                stroke-linejoin="round"
+                stroke-width="2"
+                d="M19 9l-7 7-7-7"
+              />
+            </svg>
           </div>
         </div>
-      {/if}
-    </div>
+
+        {#if isSizeDropdownOpen}
+          <!-- Backdrop to close dropdown -->
+          <button
+            type="button"
+            class="fixed inset-0 z-[9998] cursor-default"
+            onclick={() => (isSizeDropdownOpen = false)}
+            aria-label="Close dropdown"
+          ></button>
+
+          <!-- Dropdown Panel - fixed positioning to escape overflow:hidden -->
+          <div
+            class="fixed bg-exo-dark-gray border border-exo-yellow/30 rounded shadow-lg shadow-black/50 z-[9999] max-h-48 overflow-y-auto min-w-max"
+            style="bottom: calc(100vh - {sizeDropdownPosition()
+              .top}px + 4px); left: {sizeDropdownPosition().left}px;"
+          >
+            <div class="py-1">
+              {#each sizeOptions as size}
+                <button
+                  type="button"
+                  onclick={() => selectSize(size)}
+                  class="w-full px-3 py-1.5 text-left text-xs font-mono tracking-wide transition-colors duration-100 flex items-center gap-2 {params.size ===
+                  size
+                    ? 'bg-transparent text-exo-yellow'
+                    : 'text-exo-light-gray hover:text-exo-yellow'}"
+                >
+                  {#if params.size === size}
+                    <svg
+                      class="w-3 h-3 flex-shrink-0"
+                      fill="currentColor"
+                      viewBox="0 0 20 20"
+                    >
+                      <path
+                        fill-rule="evenodd"
+                        d="M16.707 5.293a1 1 0 010 1.414l-8 8a1 1 0 01-1.414 0l-4-4a1 1 0 011.414-1.414L8 12.586l7.293-7.293a1 1 0 011.414 0z"
+                        clip-rule="evenodd"
+                      />
+                    </svg>
+                  {:else}
+                    <span class="w-3"></span>
+                  {/if}
+                  <span>{size}</span>
+                </button>
+              {/each}
+            </div>
+          </div>
+        {/if}
+      </div>
+    {/if}
 
     <!-- Quality -->
     <div class="flex items-center gap-1.5">
@@ -325,6 +357,59 @@
       </div>
     </div>
 
+    <!-- Number of Images (not in edit mode) -->
+    {#if !isEditMode}
+      <div class="flex items-center gap-1.5">
+        <span class="text-xs text-exo-light-gray uppercase tracking-wider"
+          >IMAGES:</span
+        >
+        <input
+          type="number"
+          min="1"
+          value={params.numImages}
+          oninput={handleNumImagesChange}
+          class="w-12 bg-exo-medium-gray/50 border border-exo-yellow/30 rounded px-2 py-1 text-xs font-mono text-exo-yellow text-center transition-all duration-200 hover:border-exo-yellow/50 focus:outline-none focus:border-exo-yellow/70"
+        />
+      </div>
+    {/if}
+
+    <!-- Stream toggle -->
+    <div class="flex items-center gap-1.5">
+      <span class="text-xs text-exo-light-gray uppercase tracking-wider"
+        >STREAM:</span
+      >
+      <button
+        type="button"
+        onclick={() => handleStreamChange(!params.stream)}
+        class="w-8 h-4 rounded-full transition-all duration-200 cursor-pointer relative {params.stream
+          ? 'bg-exo-yellow'
+          : 'bg-exo-medium-gray/50 border border-exo-yellow/30'}"
+        title={params.stream ? "Streaming enabled" : "Streaming disabled"}
+      >
+        <div
+          class="absolute top-0.5 w-3 h-3 rounded-full transition-all duration-200 {params.stream
+            ? 'right-0.5 bg-exo-black'
+            : 'left-0.5 bg-exo-light-gray'}"
+        ></div>
+      </button>
+    </div>
+
+    <!-- Partial Images (only when streaming) -->
+    {#if params.stream}
+      <div class="flex items-center gap-1.5">
+        <span class="text-xs text-exo-light-gray uppercase tracking-wider"
+          >PARTIALS:</span
+        >
+        <input
+          type="number"
+          min="0"
+          value={params.partialImages}
+          oninput={handlePartialImagesChange}
+          class="w-12 bg-exo-medium-gray/50 border border-exo-yellow/30 rounded px-2 py-1 text-xs font-mono text-exo-yellow text-center transition-all duration-200 hover:border-exo-yellow/50 focus:outline-none focus:border-exo-yellow/70"
+        />
+      </div>
+    {/if}
+
     <!-- Input Fidelity (edit mode only) -->
     {#if isEditMode}
       <div class="flex items-center gap-1.5">

dashboard/src/routes/downloads/+page.svelte

@@ -6,6 +6,8 @@
     type DownloadProgress,
     refreshState,
     lastUpdate as lastUpdateStore,
+    startDownload,
+    deleteDownload,
   } from "$lib/stores/app.svelte";
   import HeaderNav from "$lib/components/HeaderNav.svelte";
 
@@ -28,6 +30,7 @@
     etaMs: number;
     status: "completed" | "downloading";
     files: FileProgress[];
+    shardMetadata?: Record<string, unknown>;
   };
 
   type NodeEntry = {
@@ -269,6 +272,12 @@
             }
           }
 
+          // Extract shard_metadata for use with download actions
+          const shardMetadata = (downloadPayload.shard_metadata ??
+            downloadPayload.shardMetadata) as
+            | Record<string, unknown>
+            | undefined;
+
           const entry: ModelEntry = {
             modelId,
             prettyName,
@@ -285,6 +294,7 @@
                 ? "completed"
                 : "downloading",
             files,
+            shardMetadata,
           };
 
           const existing = modelMap.get(modelId);
@@ -469,6 +479,52 @@
                     >
                       {pct.toFixed(1)}%
                     </span>
+                    {#if model.status !== "completed" && model.shardMetadata}
+                      <button
+                        type="button"
+                        class="text-exo-light-gray hover:text-exo-yellow transition-colors"
+                        onclick={() =>
+                          startDownload(node.nodeId, model.shardMetadata!)}
+                        title="Start download"
+                      >
+                        <svg
+                          class="w-4 h-4"
+                          viewBox="0 0 20 20"
+                          fill="none"
+                          stroke="currentColor"
+                          stroke-width="2"
+                        >
+                          <path
+                            d="M10 3v10m0 0l-3-3m3 3l3-3M3 17h14"
+                            stroke-linecap="round"
+                            stroke-linejoin="round"
+                          ></path>
+                        </svg>
+                      </button>
+                    {/if}
+                    {#if model.status === "completed"}
+                      <button
+                        type="button"
+                        class="text-exo-light-gray hover:text-red-400 transition-colors"
+                        onclick={() =>
+                          deleteDownload(node.nodeId, model.modelId)}
+                        title="Delete download"
+                      >
+                        <svg
+                          class="w-4 h-4"
+                          viewBox="0 0 20 20"
+                          fill="none"
+                          stroke="currentColor"
+                          stroke-width="2"
+                        >
+                          <path
+                            d="M4 6h12M8 6V4h4v2m1 0v10a1 1 0 01-1 1H8a1 1 0 01-1-1V6h6"
+                            stroke-linecap="round"
+                            stroke-linejoin="round"
+                          ></path>
+                        </svg>
+                      </button>
+                    {/if}
                     <button
                       type="button"
                       class="text-exo-light-gray hover:text-exo-yellow transition-colors"

dashboard/src/routes/traces/+page.svelte

@@ -0,0 +1,172 @@
+<script lang="ts">
+  import { onMount } from "svelte";
+  import {
+    listTraces,
+    getTraceRawUrl,
+    type TraceListItem,
+  } from "$lib/stores/app.svelte";
+  import HeaderNav from "$lib/components/HeaderNav.svelte";
+
+  let traces = $state<TraceListItem[]>([]);
+  let loading = $state(true);
+  let error = $state<string | null>(null);
+
+  function formatBytes(bytes: number): string {
+    if (!bytes || bytes <= 0) return "0B";
+    const units = ["B", "KB", "MB", "GB"];
+    const i = Math.min(
+      Math.floor(Math.log(bytes) / Math.log(1024)),
+      units.length - 1,
+    );
+    const val = bytes / Math.pow(1024, i);
+    return `${val.toFixed(val >= 10 ? 0 : 1)}${units[i]}`;
+  }
+
+  function formatDate(isoString: string): string {
+    const date = new Date(isoString);
+    return date.toLocaleString();
+  }
+
+  async function openInPerfetto(taskId: string) {
+    // Fetch trace data from our local API
+    const response = await fetch(getTraceRawUrl(taskId));
+    const traceData = await response.arrayBuffer();
+
+    // Open Perfetto UI
+    const perfettoWindow = window.open("https://ui.perfetto.dev");
+    if (!perfettoWindow) {
+      alert("Failed to open Perfetto. Please allow popups.");
+      return;
+    }
+
+    // Wait for Perfetto to be ready, then send trace via postMessage
+    const onMessage = (e: MessageEvent) => {
+      if (e.data === "PONG") {
+        window.removeEventListener("message", onMessage);
+        perfettoWindow.postMessage(
+          {
+            perfetto: {
+              buffer: traceData,
+              title: `Trace ${taskId}`,
+            },
+          },
+          "https://ui.perfetto.dev",
+        );
+      }
+    };
+    window.addEventListener("message", onMessage);
+
+    // Ping Perfetto until it responds
+    const pingInterval = setInterval(() => {
+      perfettoWindow.postMessage("PING", "https://ui.perfetto.dev");
+    }, 50);
+
+    // Clean up after 10 seconds
+    setTimeout(() => {
+      clearInterval(pingInterval);
+      window.removeEventListener("message", onMessage);
+    }, 10000);
+  }
+
+  async function refresh() {
+    loading = true;
+    error = null;
+    try {
+      const response = await listTraces();
+      traces = response.traces;
+    } catch (e) {
+      error = e instanceof Error ? e.message : "Failed to load traces";
+    } finally {
+      loading = false;
+    }
+  }
+
+  onMount(() => {
+    refresh();
+  });
+</script>
+
+<div class="min-h-screen bg-exo-dark-gray text-white">
+  <HeaderNav showHome={true} />
+  <div class="max-w-7xl mx-auto px-4 lg:px-8 py-6 space-y-6">
+    <div class="flex items-center justify-between gap-4 flex-wrap">
+      <div>
+        <h1
+          class="text-2xl font-mono tracking-[0.2em] uppercase text-exo-yellow"
+        >
+          Traces
+        </h1>
+      </div>
+      <div class="flex items-center gap-3">
+        <button
+          type="button"
+          class="text-xs font-mono text-exo-light-gray hover:text-exo-yellow transition-colors uppercase border border-exo-medium-gray/40 px-2 py-1 rounded"
+          onclick={refresh}
+          disabled={loading}
+        >
+          Refresh
+        </button>
+      </div>
+    </div>
+
+    {#if loading}
+      <div
+        class="rounded border border-exo-medium-gray/30 bg-exo-black/30 p-6 text-center text-exo-light-gray"
+      >
+        <div class="text-sm">Loading traces...</div>
+      </div>
+    {:else if error}
+      <div
+        class="rounded border border-red-500/30 bg-red-500/10 p-6 text-center text-red-400"
+      >
+        <div class="text-sm">{error}</div>
+      </div>
+    {:else if traces.length === 0}
+      <div
+        class="rounded border border-exo-medium-gray/30 bg-exo-black/30 p-6 text-center text-exo-light-gray space-y-2"
+      >
+        <div class="text-sm">No traces found.</div>
+        <div class="text-xs text-exo-light-gray/70">
+          Run exo with EXO_TRACING_ENABLED=1 to collect traces.
+        </div>
+      </div>
+    {:else}
+      <div class="space-y-3">
+        {#each traces as trace}
+          <div
+            class="rounded border border-exo-medium-gray/30 bg-exo-black/30 p-4 flex items-center justify-between gap-4"
+          >
+            <div class="min-w-0 flex-1">
+              <a
+                href="#/traces/{trace.taskId}"
+                class="text-sm font-mono text-white hover:text-exo-yellow transition-colors truncate block"
+              >
+                {trace.taskId}
+              </a>
+              <div class="text-xs text-exo-light-gray font-mono mt-1">
+                {formatDate(trace.createdAt)} &bull; {formatBytes(
+                  trace.fileSize,
+                )}
+              </div>
+            </div>
+            <div class="flex items-center gap-2 shrink-0">
+              <a
+                href="#/traces/{trace.taskId}"
+                class="text-xs font-mono text-exo-light-gray hover:text-exo-yellow transition-colors uppercase border border-exo-medium-gray/40 px-2 py-1 rounded"
+              >
+                View Stats
+              </a>
+              <button
+                type="button"
+                class="text-xs font-mono text-exo-dark-gray bg-exo-yellow hover:bg-exo-yellow/90 transition-colors uppercase px-2 py-1 rounded font-semibold"
+                onclick={() => openInPerfetto(trace.taskId)}
+              >
+                View Trace
+              </button>
+            </div>
+          </div>
+        {/each}
+      </div>
+    {/if}
+  </div>
+</div>

dashboard/src/routes/traces/[taskId]/+page.svelte

@@ -0,0 +1,347 @@
+<script lang="ts">
+  import { page } from "$app/stores";
+  import { onMount } from "svelte";
+  import {
+    fetchTraceStats,
+    getTraceRawUrl,
+    type TraceStatsResponse,
+    type TraceCategoryStats,
+  } from "$lib/stores/app.svelte";
+  import HeaderNav from "$lib/components/HeaderNav.svelte";
+
+  const taskId = $derived($page.params.taskId);
+
+  let stats = $state<TraceStatsResponse | null>(null);
+  let loading = $state(true);
+  let error = $state<string | null>(null);
+
+  function formatDuration(us: number): string {
+    if (us < 1000) return `${us.toFixed(0)}us`;
+    if (us < 1_000_000) return `${(us / 1000).toFixed(2)}ms`;
+    return `${(us / 1_000_000).toFixed(2)}s`;
+  }
+
+  function formatPercentage(part: number, total: number): string {
+    if (total === 0) return "0.0%";
+    return `${((part / total) * 100).toFixed(1)}%`;
+  }
+
+  // Parse hierarchical categories like "sync/compute" into phases
+  type PhaseData = {
+    name: string;
+    subcategories: { name: string; stats: TraceCategoryStats }[];
+    totalUs: number; // From outer span (e.g., "sync" category)
+    stepCount: number; // Count of outer span events
+  };
+
+  function parsePhases(
+    byCategory: Record<string, TraceCategoryStats>,
+  ): PhaseData[] {
+    const phases = new Map<
+      string,
+      {
+        subcats: Map<string, TraceCategoryStats>;
+        outerStats: TraceCategoryStats | null;
+      }
+    >();
+
+    for (const [category, catStats] of Object.entries(byCategory)) {
+      if (category.includes("/")) {
+        const [phase, subcat] = category.split("/", 2);
+        if (!phases.has(phase)) {
+          phases.set(phase, { subcats: new Map(), outerStats: null });
+        }
+        phases.get(phase)!.subcats.set(subcat, catStats);
+      } else {
+        // Outer span - this IS the phase total
+        if (!phases.has(category)) {
+          phases.set(category, { subcats: new Map(), outerStats: null });
+        }
+        phases.get(category)!.outerStats = catStats;
+      }
+    }
+
+    return Array.from(phases.entries())
+      .filter(([_, data]) => data.outerStats !== null) // Only phases with outer spans
+      .map(([name, data]) => ({
+        name,
+        subcategories: Array.from(data.subcats.entries())
+          .map(([subName, subStats]) => ({ name: subName, stats: subStats }))
+          .sort((a, b) => b.stats.totalUs - a.stats.totalUs),
+        totalUs: data.outerStats!.totalUs, // Outer span total
+        stepCount: data.outerStats!.count, // Number of steps
+      }))
+      .sort((a, b) => b.totalUs - a.totalUs);
+  }
+
+  async function openInPerfetto() {
+    if (!taskId) return;
+
+    // Fetch trace data from our local API
+    const response = await fetch(getTraceRawUrl(taskId));
+    const traceData = await response.arrayBuffer();
+
+    // Open Perfetto UI
+    const perfettoWindow = window.open("https://ui.perfetto.dev");
+    if (!perfettoWindow) {
+      alert("Failed to open Perfetto. Please allow popups.");
+      return;
+    }
+
+    // Wait for Perfetto to be ready, then send trace via postMessage
+    const onMessage = (e: MessageEvent) => {
+      if (e.data === "PONG") {
+        window.removeEventListener("message", onMessage);
+        perfettoWindow.postMessage(
+          {
+            perfetto: {
+              buffer: traceData,
+              title: `Trace ${taskId}`,
+            },
+          },
+          "https://ui.perfetto.dev",
+        );
+      }
+    };
+    window.addEventListener("message", onMessage);
+
+    // Ping Perfetto until it responds
+    const pingInterval = setInterval(() => {
+      perfettoWindow.postMessage("PING", "https://ui.perfetto.dev");
+    }, 50);
+
+    // Clean up after 10 seconds
+    setTimeout(() => {
+      clearInterval(pingInterval);
+      window.removeEventListener("message", onMessage);
+    }, 10000);
+  }
+
+  onMount(async () => {
+    if (!taskId) {
+      error = "No task ID provided";
+      loading = false;
+      return;
+    }
+
+    try {
+      stats = await fetchTraceStats(taskId);
+    } catch (e) {
+      error = e instanceof Error ? e.message : "Failed to load trace";
+    } finally {
+      loading = false;
+    }
+  });
+
+  const phases = $derived(stats ? parsePhases(stats.byCategory) : []);
+  const sortedRanks = $derived(
+    stats
+      ? Object.keys(stats.byRank)
+          .map(Number)
+          .sort((a, b) => a - b)
+      : [],
+  );
+  const nodeCount = $derived(sortedRanks.length || 1);
+</script>
+
+<div class="min-h-screen bg-exo-dark-gray text-white">
+  <HeaderNav showHome={true} />
+  <div class="max-w-7xl mx-auto px-4 lg:px-8 py-6 space-y-6">
+    <div class="flex items-center justify-between gap-4 flex-wrap">
+      <div>
+        <h1
+          class="text-2xl font-mono tracking-[0.2em] uppercase text-exo-yellow"
+        >
+          Trace
+        </h1>
+        <p class="text-sm text-exo-light-gray font-mono truncate max-w-lg">
+          {taskId}
+        </p>
+      </div>
+      <div class="flex items-center gap-3">
+        <a
+          href="#/traces"
+          class="text-xs font-mono text-exo-light-gray hover:text-exo-yellow transition-colors uppercase border border-exo-medium-gray/40 px-3 py-1.5 rounded"
+        >
+          All Traces
+        </a>
+        <button
+          type="button"
+          class="text-xs font-mono text-exo-dark-gray bg-exo-yellow hover:bg-exo-yellow/90 transition-colors uppercase px-3 py-1.5 rounded font-semibold"
+          onclick={openInPerfetto}
+          disabled={loading || !!error}
+        >
+          View Trace
+        </button>
+      </div>
+    </div>
+
+    {#if loading}
+      <div
+        class="rounded border border-exo-medium-gray/30 bg-exo-black/30 p-6 text-center text-exo-light-gray"
+      >
+        <div class="text-sm">Loading trace data...</div>
+      </div>
+    {:else if error}
+      <div
+        class="rounded border border-red-500/30 bg-red-500/10 p-6 text-center text-red-400"
+      >
+        <div class="text-sm">{error}</div>
+      </div>
+    {:else if stats}
+      <!-- Wall Time Summary -->
+      <div
+        class="rounded border border-exo-medium-gray/30 bg-exo-black/30 p-4 space-y-2"
+      >
+        <h2
+          class="text-sm font-mono uppercase tracking-wider text-exo-light-gray"
+        >
+          Summary
+        </h2>
+        <div class="text-3xl font-mono text-exo-yellow">
+          {formatDuration(stats.totalWallTimeUs)}
+        </div>
+        <div class="text-xs text-exo-light-gray">Total wall time</div>
+      </div>
+
+      <!-- By Phase -->
+      {#if phases.length > 0}
+        <div
+          class="rounded border border-exo-medium-gray/30 bg-exo-black/30 p-4 space-y-4"
+        >
+          <h2
+            class="text-sm font-mono uppercase tracking-wider text-exo-light-gray"
+          >
+            By Phase <span class="text-exo-light-gray/50">(avg per node)</span>
+          </h2>
+          <div class="space-y-4">
+            {#each phases as phase}
+              {@const normalizedTotal = phase.totalUs / nodeCount}
+              {@const normalizedStepCount = phase.stepCount / nodeCount}
+              <div class="space-y-2">
+                <div class="flex items-center justify-between">
+                  <span class="text-sm font-mono text-white">{phase.name}</span>
+                  <span class="text-sm font-mono">
+                    <span class="text-exo-yellow"
+                      >{formatDuration(normalizedTotal)}</span
+                    >
+                    <span class="text-exo-light-gray ml-2">
+                      ({normalizedStepCount} steps, {formatDuration(
+                        normalizedTotal / normalizedStepCount,
+                      )}/step)
+                    </span>
+                  </span>
+                </div>
+                {#if phase.subcategories.length > 0}
+                  <div class="pl-4 space-y-1.5">
+                    {#each phase.subcategories as subcat}
+                      {@const normalizedSubcat =
+                        subcat.stats.totalUs / nodeCount}
+                      {@const pct = formatPercentage(
+                        normalizedSubcat,
+                        normalizedTotal,
+                      )}
+                      {@const perStep = normalizedSubcat / normalizedStepCount}
+                      <div
+                        class="flex items-center justify-between text-xs font-mono"
+                      >
+                        <span class="text-exo-light-gray">{subcat.name}</span>
+                        <span class="text-white">
+                          {formatDuration(normalizedSubcat)}
+                          <span class="text-exo-light-gray ml-2">({pct})</span>
+                          <span class="text-exo-light-gray/60 ml-2"
+                            >{formatDuration(perStep)}/step</span
+                          >
+                        </span>
+                      </div>
+                      <!-- Progress bar -->
+                      <div
+                        class="relative h-1.5 bg-exo-black/60 rounded-sm overflow-hidden"
+                      >
+                        <div
+                          class="absolute inset-y-0 left-0 bg-gradient-to-r from-exo-yellow to-exo-yellow/70 transition-all duration-300"
+                          style="width: {pct}"
+                        ></div>
+                      </div>
+                    {/each}
+                  </div>
+                {/if}
+              </div>
+            {/each}
+          </div>
+        </div>
+      {/if}
+
+      <!-- By Rank -->
+      {#if sortedRanks.length > 0}
+        <div
+          class="rounded border border-exo-medium-gray/30 bg-exo-black/30 p-4 space-y-4"
+        >
+          <h2
+            class="text-sm font-mono uppercase tracking-wider text-exo-light-gray"
+          >
+            By Rank
+          </h2>
+          <div class="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-3 gap-4">
+            {#each sortedRanks as rank}
+              {@const rankStats = stats.byRank[rank]}
+              {@const rankPhases = parsePhases(rankStats.byCategory)}
+              <div
+                class="rounded border border-exo-medium-gray/20 bg-exo-dark-gray/60 p-3 space-y-3"
+              >
+                <div class="text-sm font-mono text-exo-yellow">
+                  Rank {rank}
+                </div>
+                <div class="space-y-2">
+                  {#each rankPhases as phase}
+                    <div class="space-y-1">
+                      <div class="flex items-center justify-between text-xs">
+                        <span class="font-mono text-exo-light-gray"
+                          >{phase.name}</span
+                        >
+                        <span class="font-mono text-white">
+                          {formatDuration(phase.totalUs)}
+                          <span class="text-exo-light-gray/50 ml-1">
+                            ({phase.stepCount}x)
+                          </span>
+                        </span>
+                      </div>
+                      {#if phase.subcategories.length > 0}
+                        <div class="pl-2 space-y-0.5">
+                          {#each phase.subcategories as subcat}
+                            {@const pct = formatPercentage(
+                              subcat.stats.totalUs,
+                              phase.totalUs,
+                            )}
+                            {@const perStep =
+                              subcat.stats.totalUs / phase.stepCount}
+                            <div
+                              class="flex items-center justify-between text-[10px] font-mono"
+                            >
+                              <span class="text-exo-light-gray/70"
+                                >{subcat.name}</span
+                              >
+                              <span class="text-exo-light-gray">
+                                {formatDuration(subcat.stats.totalUs)}
+                                <span class="text-exo-light-gray/50"
+                                  >({pct})</span
+                                >
+                                <span class="text-exo-light-gray/30 ml-1"
+                                  >{formatDuration(perStep)}/step</span
+                                >
+                              </span>
+                            </div>
+                          {/each}
+                        </div>
+                      {/if}
+                    </div>
+                  {/each}
+                </div>
+              </div>
+            {/each}
+          </div>
+        </div>
+      {/if}
+    {/if}
+  </div>
+</div>

flake.lock

@@ -21,7 +21,9 @@
           "nixpkgs"
         ],
         "purescript-overlay": "purescript-overlay",
-        "pyproject-nix": "pyproject-nix"
+        "pyproject-nix": [
+          "pyproject-nix"
+        ]
       },
       "locked": {
         "lastModified": 1765953015,
@@ -149,19 +151,44 @@
         "type": "github"
       }
     },
+    "pyproject-build-systems": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "pyproject-nix": [
+          "pyproject-nix"
+        ],
+        "uv2nix": [
+          "uv2nix"
+        ]
+      },
+      "locked": {
+        "lastModified": 1763662255,
+        "narHash": "sha256-4bocaOyLa3AfiS8KrWjZQYu+IAta05u3gYZzZ6zXbT0=",
+        "owner": "pyproject-nix",
+        "repo": "build-system-pkgs",
+        "rev": "042904167604c681a090c07eb6967b4dd4dae88c",
+        "type": "github"
+      },
+      "original": {
+        "owner": "pyproject-nix",
+        "repo": "build-system-pkgs",
+        "type": "github"
+      }
+    },
     "pyproject-nix": {
       "inputs": {
         "nixpkgs": [
-          "dream2nix",
           "nixpkgs"
         ]
       },
       "locked": {
-        "lastModified": 1763017646,
-        "narHash": "sha256-Z+R2lveIp6Skn1VPH3taQIuMhABg1IizJd8oVdmdHsQ=",
+        "lastModified": 1764134915,
+        "narHash": "sha256-xaKvtPx6YAnA3HQVp5LwyYG1MaN4LLehpQI8xEdBvBY=",
         "owner": "pyproject-nix",
         "repo": "pyproject.nix",
-        "rev": "47bd6f296502842643078d66128f7b5e5370790c",
+        "rev": "2c8df1383b32e5443c921f61224b198a2282a657",
         "type": "github"
       },
       "original": {
@@ -178,7 +205,10 @@
         "flake-parts": "flake-parts",
         "nixpkgs": "nixpkgs",
         "nixpkgs-swift": "nixpkgs-swift",
-        "treefmt-nix": "treefmt-nix"
+        "pyproject-build-systems": "pyproject-build-systems",
+        "pyproject-nix": "pyproject-nix",
+        "treefmt-nix": "treefmt-nix",
+        "uv2nix": "uv2nix"
       }
     },
     "rust-analyzer-src": {
@@ -239,6 +269,29 @@
         "repo": "treefmt-nix",
         "type": "github"
       }
+    },
+    "uv2nix": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "pyproject-nix": [
+          "pyproject-nix"
+        ]
+      },
+      "locked": {
+        "lastModified": 1767701098,
+        "narHash": "sha256-CJhKZnWb3gumR9oTRjFvCg/6lYTGbZRU7xtvcyWIRwU=",
+        "owner": "pyproject-nix",
+        "repo": "uv2nix",
+        "rev": "9d357f0d2ce6f5f35ec7959d7e704452352eb4da",
+        "type": "github"
+      },
+      "original": {
+        "owner": "pyproject-nix",
+        "repo": "uv2nix",
+        "type": "github"
+      }
     }
   },
   "root": "root",

flake.nix

@@ -24,6 +24,26 @@
     dream2nix = {
       url = "github:nix-community/dream2nix";
       inputs.nixpkgs.follows = "nixpkgs";
+      inputs.pyproject-nix.follows = "pyproject-nix";
+    };
+
+    # Python packaging with uv2nix
+    pyproject-nix = {
+      url = "github:pyproject-nix/pyproject.nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+
+    uv2nix = {
+      url = "github:pyproject-nix/uv2nix";
+      inputs.pyproject-nix.follows = "pyproject-nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+
+    pyproject-build-systems = {
+      url = "github:pyproject-nix/build-system-pkgs";
+      inputs.pyproject-nix.follows = "pyproject-nix";
+      inputs.uv2nix.follows = "uv2nix";
+      inputs.nixpkgs.follows = "nixpkgs";
     };
 
     # Pinned nixpkgs for swift-format (swift is broken on x86_64-linux in newer nixpkgs)
@@ -48,6 +68,7 @@
         inputs.treefmt-nix.flakeModule
         ./dashboard/parts.nix
         ./rust/parts.nix
+        ./python/parts.nix
       ];
 
       perSystem =
@@ -58,6 +79,11 @@
           pkgsSwift = import inputs.nixpkgs-swift { inherit system; };
         in
         {
+          # Allow unfree for metal-toolchain (needed for Darwin Metal packages)
+          _module.args.pkgs = import inputs.nixpkgs {
+            inherit system;
+            config.allowUnfreePredicate = pkg: (pkg.pname or "") == "metal-toolchain";
+          };
           treefmt = {
             projectRootFile = "flake.nix";
             programs = {
@@ -79,14 +105,24 @@
                 enable = true;
                 package = pkgsSwift.swiftPackages.swift-format;
               };
+              shfmt.enable = true;
             };
           };
 
-          checks.lint = pkgs.runCommand "lint-check" { } ''
-            export RUFF_CACHE_DIR="$TMPDIR/ruff-cache"
-            ${pkgs.ruff}/bin/ruff check ${inputs.self}/
-            touch $out
-          '';
+          packages = lib.optionalAttrs pkgs.stdenv.hostPlatform.isDarwin (
+            let
+              uvLock = builtins.fromTOML (builtins.readFile ./uv.lock);
+              mlxPackage = builtins.head (builtins.filter (p: p.name == "mlx") uvLock.package);
+              uvLockMlxVersion = mlxPackage.version;
+            in
+            {
+              metal-toolchain = pkgs.callPackage ./nix/metal-toolchain.nix { };
+              mlx = pkgs.callPackage ./nix/mlx.nix {
+                metal-toolchain = self'.packages.metal-toolchain;
+                inherit uvLockMlxVersion;
+              };
+            }
+          );
 
           devShells.default = with pkgs; pkgs.mkShell {
             inputsFrom = [ self'.checks.cargo-build ];

justfile

@@ -1,7 +1,7 @@
 export NIX_CONFIG := "extra-experimental-features = nix-command flakes"
 
 fmt:
-    nix fmt
+    treefmt || nix fmt
 
 lint:
     uv run ruff check --fix

nix/darwin-build-fixes.patch

@@ -0,0 +1,79 @@
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index 0ed30932..d8528132 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -177,11 +177,7 @@ if(MLX_BUILD_METAL)
+     add_compile_definitions(MLX_METAL_DEBUG)
+   endif()
+
+-  # Throw an error if xcrun not found
+-  execute_process(
+-    COMMAND zsh "-c" "/usr/bin/xcrun -sdk macosx --show-sdk-version"
+-    OUTPUT_VARIABLE MACOS_SDK_VERSION
+-    OUTPUT_STRIP_TRAILING_WHITESPACE COMMAND_ERROR_IS_FATAL ANY)
++  set(MACOS_SDK_VERSION @sdkVersion@)
+
+   if(${MACOS_SDK_VERSION} LESS 14.0)
+     message(
+@@ -199,11 +195,8 @@ if(MLX_BUILD_METAL)
+     endif()
+     set(XCRUN_FLAGS "-mmacosx-version-min=${CMAKE_OSX_DEPLOYMENT_TARGET}")
+   endif()
+-  execute_process(
+-    COMMAND
+-      zsh "-c"
+-      "echo \"__METAL_VERSION__\" | xcrun -sdk macosx metal ${XCRUN_FLAGS} -E -x metal -P - | tail -1 | tr -d '\n'"
+-    OUTPUT_VARIABLE MLX_METAL_VERSION COMMAND_ERROR_IS_FATAL ANY)
++  set(
++    MLX_METAL_VERSION @metalVersion@)
+   FetchContent_Declare(metal_cpp URL ${METAL_CPP_URL})
+   FetchContent_MakeAvailable(metal_cpp)
+   target_include_directories(
+diff --git a/cmake/extension.cmake b/cmake/extension.cmake
+index 13db804a..5b385132 100644
+--- a/cmake/extension.cmake
++++ b/cmake/extension.cmake
+@@ -36,7 +36,7 @@ macro(mlx_build_metallib)
+   add_custom_command(
+     OUTPUT ${MTLLIB_BUILD_TARGET}
+     COMMAND
+-      xcrun -sdk macosx metal
++      metal -fmodules-cache-path=${CMAKE_BINARY_DIR}/metal-cache
+       "$<LIST:TRANSFORM,${MTLLIB_INCLUDE_DIRS},PREPEND,-I>"
+       ${MTLLIB_COMPILE_OPTIONS} ${MTLLIB_SOURCES} -o ${MTLLIB_BUILD_TARGET}
+     DEPENDS ${MTLLIB_DEPS} ${MTLLIB_SOURCES}
+diff --git a/mlx/backend/metal/kernels/CMakeLists.txt b/mlx/backend/metal/kernels/CMakeLists.txt
+index 262b0495..5c7446ad 100644
+--- a/mlx/backend/metal/kernels/CMakeLists.txt
++++ b/mlx/backend/metal/kernels/CMakeLists.txt
+@@ -29,7 +29,7 @@ function(build_kernel_base TARGET SRCFILE DEPS)
+                     "-mmacosx-version-min=${CMAKE_OSX_DEPLOYMENT_TARGET}")
+   endif()
+   add_custom_command(
+-    COMMAND xcrun -sdk macosx metal ${METAL_FLAGS} -c ${SRCFILE}
++    COMMAND metal -fmodules-cache-path=${CMAKE_BINARY_DIR}/metal-cache ${METAL_FLAGS} -c ${SRCFILE}
+             -I${PROJECT_SOURCE_DIR} -o ${TARGET}.air
+     DEPENDS ${SRCFILE} ${DEPS} ${BASE_HEADERS}
+     OUTPUT ${TARGET}.air
+@@ -170,7 +170,7 @@ endif()
+
+ add_custom_command(
+   OUTPUT ${MLX_METAL_PATH}/mlx.metallib
+-  COMMAND xcrun -sdk macosx metallib ${KERNEL_AIR} -o
++  COMMAND metallib ${KERNEL_AIR} -o
+           ${MLX_METAL_PATH}/mlx.metallib
+   DEPENDS ${KERNEL_AIR}
+   COMMENT "Building mlx.metallib"
+diff --git a/mlx/backend/metal/make_compiled_preamble.sh b/mlx/backend/metal/make_compiled_preamble.sh
+index bb55ed3a..94ea7dd7 100644
+--- a/mlx/backend/metal/make_compiled_preamble.sh
++++ b/mlx/backend/metal/make_compiled_preamble.sh
+@@ -31,7 +31,7 @@ OUTPUT_FILE=${OUTPUT_DIR}/${SRC_NAME}.cpp
+ mkdir -p "$OUTPUT_DIR"
+
+ # Use the metal compiler to get a list of headers (with depth)
+-CCC="xcrun -sdk macosx metal -x metal"
++CCC="metal -x metal -fmodules-cache-path=${OUTPUT_DIR}/metal-cache"
+ HDRS=$( $CCC -I"$SRC_DIR" -I"$JIT_INCLUDES" -DMLX_METAL_JIT -E -P -CC -C -H "$INPUT_FILE" $CFLAGS -w 2>&1 1>/dev/null )
+
+ # Remove any included system frameworks (for MetalPerformancePrimitive headers)

nix/metal-toolchain.nix

@@ -0,0 +1,56 @@
+{ lib, stdenvNoCC, requireFile, nix }:
+
+let
+  narFile = requireFile {
+    name = "metal-toolchain-17C48.nar";
+    message = ''
+      The Metal Toolchain NAR must be available.
+
+      If you have cachix configured for exo.cachix.org, this should be automatic.
+
+      Otherwise:
+        1. Install Xcode 26+ from the App Store
+        2. Run: xcodebuild -downloadComponent MetalToolchain
+        3. Export the toolchain:
+           hdiutil attach "$(find /System/Library/AssetsV2/com_apple_MobileAsset_MetalToolchain -name '*.dmg' | head -1)" -mountpoint /tmp/metal-dmg
+           cp -R /tmp/metal-dmg/Metal.xctoolchain /tmp/metal-export
+           hdiutil detach /tmp/metal-dmg
+        4. Create NAR and add to store:
+           nix nar pack /tmp/metal-export > /tmp/metal-toolchain-17C48.nar
+           nix store add --mode flat /tmp/metal-toolchain-17C48.nar
+    '';
+    hash = "sha256-ayR5mXN4sZAddwKEG2OszGRF93k9ZFc7H0yi2xbylQw=";
+  };
+in
+stdenvNoCC.mkDerivation {
+  pname = "metal-toolchain";
+  version = "17C48";
+
+  dontUnpack = true;
+  dontBuild = true;
+  dontFixup = true;
+
+  nativeBuildInputs = [ nix ];
+
+  installPhase = ''
+    runHook preInstall
+
+    nix-store --restore $out < ${narFile}
+
+    # Create bin directory with symlinks for PATH
+    mkdir -p $out/bin
+    ln -s $out/usr/bin/metal $out/bin/metal
+    ln -s $out/usr/bin/metallib $out/bin/metallib
+
+    runHook postInstall
+  '';
+
+  # Metal language version for CMake (from: echo __METAL_VERSION__ | metal -E -x metal -P -)
+  passthru.metalVersion = "400";
+
+  meta = {
+    description = "Apple Metal compiler toolchain";
+    platforms = [ "aarch64-darwin" ];
+    license = lib.licenses.unfree;
+  };
+}

nix/mlx.nix

@@ -0,0 +1,158 @@
+{ stdenv
+, lib
+, fetchFromGitHub
+, replaceVars
+, fetchzip
+, cmake
+, nlohmann_json
+, apple-sdk_26
+, metal-toolchain
+, runCommand
+, fmt
+, python313Packages
+, uvLockMlxVersion
+}:
+
+assert stdenv.isDarwin;
+
+let
+  python = python313Packages.python;
+
+  # Static dependencies included directly during compilation
+  gguf-tools = fetchFromGitHub {
+    owner = "antirez";
+    repo = "gguf-tools";
+    rev = "8fa6eb65236618e28fd7710a0fba565f7faa1848";
+    hash = "sha256-15FvyPOFqTOr5vdWQoPnZz+mYH919++EtghjozDlnSA=";
+  };
+
+  metal_cpp = fetchzip {
+    url = "https://developer.apple.com/metal/cpp/files/metal-cpp_26.zip";
+    hash = "sha256-7n2eI2lw/S+Us6l7YPAATKwcIbRRpaQ8VmES7S8ZjY8=";
+  };
+
+  nanobind = fetchFromGitHub {
+    owner = "wjakob";
+    repo = "nanobind";
+    rev = "v2.10.2";
+    hash = "sha256-io44YhN+VpfHFWyvvLWSanRgbzA0whK8WlDNRi3hahU=";
+    fetchSubmodules = true;
+  };
+
+  mlx = stdenv.mkDerivation rec {
+    pname = "mlx";
+    version = let v = "0.30.4"; in
+      assert v == uvLockMlxVersion || throw "MLX version mismatch: nix/mlx.nix has ${v} but uv.lock has ${uvLockMlxVersion}. Update both the version and hash in nix/mlx.nix.";
+      v;
+    pyproject = true;
+
+    src = fetchFromGitHub {
+      owner = "ml-explore";
+      repo = "mlx";
+      tag = "v${version}";
+      hash = "sha256-OJk6jPlbaSlsUdk3ADz3tWcRzTWXRof3/q8Soe1AO6w=";
+    };
+
+    patches = [
+      (replaceVars ./darwin-build-fixes.patch {
+        sdkVersion = apple-sdk_26.version;
+        metalVersion = metal-toolchain.metalVersion;
+      })
+    ];
+
+    postPatch = ''
+      substituteInPlace mlx/backend/cpu/jit_compiler.cpp \
+        --replace-fail "g++" "$CXX"
+    '';
+
+    dontUseCmakeConfigure = true;
+
+    enableParallelBuilding = true;
+
+    # Allows multiple cores to be used in Python builds.
+    postUnpack = ''
+      export MAKEFLAGS+="''${enableParallelBuilding:+-j$NIX_BUILD_CORES}"
+    '';
+
+    # Updates the wrong fetcher rev attribute
+    passthru.skipBulkUpdate = true;
+
+    env = {
+      DEV_RELEASE = 1;
+      CMAKE_ARGS = toString [
+        (lib.cmakeBool "USE_SYSTEM_FMT" true)
+        (lib.cmakeOptionType "filepath" "FETCHCONTENT_SOURCE_DIR_GGUFLIB" "${gguf-tools}")
+        (lib.cmakeOptionType "filepath" "FETCHCONTENT_SOURCE_DIR_JSON" "${nlohmann_json.src}")
+        (lib.cmakeOptionType "filepath" "FETCHCONTENT_SOURCE_DIR_NANOBIND" "${nanobind}")
+        (lib.cmakeBool "FETCHCONTENT_FULLY_DISCONNECTED" true)
+        (lib.cmakeBool "MLX_BUILD_METAL" true)
+        (lib.cmakeOptionType "filepath" "FETCHCONTENT_SOURCE_DIR_METAL_CPP" "${metal_cpp}")
+        (lib.cmakeOptionType "string" "CMAKE_OSX_DEPLOYMENT_TARGET" "${apple-sdk_26.version}")
+        (lib.cmakeOptionType "filepath" "CMAKE_OSX_SYSROOT" "${apple-sdk_26.passthru.sdkroot}")
+      ];
+      SDKROOT = apple-sdk_26.passthru.sdkroot;
+      MACOSX_DEPLOYMENT_TARGET = apple-sdk_26.version;
+    };
+
+    build-system = [
+      python313Packages.setuptools
+    ];
+
+    nativeBuildInputs = [
+      cmake
+      metal-toolchain
+      python313Packages.pypaBuildHook
+      python313Packages.pypaInstallHook
+      python313Packages.setuptools
+      python313Packages.typing-extensions
+      python313Packages.wheel
+      python313Packages.cmake
+      python313Packages.ninja
+    ];
+
+    buildInputs = [
+      fmt
+      gguf-tools
+      python313Packages.nanobind
+      python313Packages.pybind11
+      apple-sdk_26
+    ];
+
+    # Tests require Metal GPU access which isn't available in the Nix sandbox.
+    # To run tests, build with: nix build --option sandbox false .#mlx.passthru.tests.mlxTest
+    doCheck = false;
+
+    pythonImportsCheck = [ "mlx" ];
+
+    passthru.tests = {
+      # Runs example scripts to verify MLX works. Requires --option sandbox false
+      # since Metal GPU access is needed.
+      mlxTest =
+        runCommand "run-mlx-examples"
+          {
+            buildInputs = [ mlx ];
+            nativeBuildInputs = [ python ];
+          }
+          ''
+            cp ${src}/examples/python/logistic_regression.py .
+            ${python.interpreter} logistic_regression.py
+            rm logistic_regression.py
+
+            cp ${src}/examples/python/linear_regression.py .
+            ${python.interpreter} linear_regression.py
+            rm linear_regression.py
+
+            touch $out
+          '';
+    };
+
+    meta = {
+      homepage = "https://github.com/ml-explore/mlx";
+      description = "Array framework for Apple silicon";
+      changelog = "https://github.com/ml-explore/mlx/releases/tag/${src.tag}";
+      license = lib.licenses.mit;
+      platforms = [ "aarch64-darwin" ];
+    };
+  };
+in
+mlx

pyproject.toml

@@ -17,16 +17,16 @@ dependencies = [
     "loguru>=0.7.3",
     "exo_pyo3_bindings", # rust bindings
     "anyio==4.11.0",
-    "mlx==0.30.3; sys_platform == 'darwin'",
-    "mlx[cpu]==0.30.3; sys_platform == 'linux'",
-    "mlx-lm @ git+https://github.com/AlexCheema/mlx-lm.git@fix-transformers-5.0.0rc2",
+    "mlx==0.30.4; sys_platform == 'darwin'",
+    "mlx[cpu]==0.30.4; sys_platform == 'linux'",
+    "mlx-lm",
     "tiktoken>=0.12.0", # required for kimi k2 tokenizer
     "hypercorn>=0.18.0",
     "openai-harmony>=0.0.8",
     "httpx>=0.28.1",
     "tomlkit>=0.14.0",
     "pillow>=11.0,<12.0", # compatibility with mflux
-    "mflux>=0.14.2",
+    "mflux==0.15.4",
     "python-multipart>=0.0.21",
 ]
 
@@ -63,6 +63,7 @@ members = [
 
 [tool.uv.sources]
 exo_pyo3_bindings = { workspace = true }
+mlx-lm = { git = "https://github.com/ml-explore/mlx-lm", branch = "main" }
 # Uncomment to use local mlx/mlx-lm development versions:
 # mlx = { path = "/Users/Shared/mlx", editable=true }
 # mlx-lm = { path = "/Users/Shared/mlx-lm", editable=true }

python/parts.nix

@@ -0,0 +1,93 @@
+{ inputs, ... }:
+{
+  perSystem =
+    { config, self', pkgs, lib, system, ... }:
+    let
+      # Load workspace from uv.lock
+      workspace = inputs.uv2nix.lib.workspace.loadWorkspace {
+        workspaceRoot = inputs.self;
+      };
+
+      # Create overlay from workspace
+      # Use wheels from PyPI for most packages; we override mlx with our pure Nix Metal build
+      overlay = workspace.mkPyprojectOverlay { sourcePreference = "wheel"; };
+
+      # Override overlay to inject Nix-built components
+      exoOverlay = final: prev: {
+        # Replace workspace exo_pyo3_bindings with Nix-built wheel
+        exo-pyo3-bindings = pkgs.stdenv.mkDerivation {
+          pname = "exo-pyo3-bindings";
+          version = "0.1.0";
+          src = self'.packages.exo_pyo3_bindings;
+          # Install from pre-built wheel
+          nativeBuildInputs = [ final.pyprojectWheelHook ];
+          dontStrip = true;
+        };
+      };
+
+      python = pkgs.python313;
+
+      # Overlay to provide build systems and custom packages
+      buildSystemsOverlay = final: prev: {
+        # Use our pure Nix-built MLX with Metal support
+        mlx = self'.packages.mlx;
+
+        # mlx-lm is a git dependency that needs setuptools
+        mlx-lm = prev.mlx-lm.overrideAttrs (old: {
+          nativeBuildInputs = (old.nativeBuildInputs or [ ]) ++ [
+            final.setuptools
+          ];
+        });
+      };
+
+      pythonSet = (pkgs.callPackage inputs.pyproject-nix.build.packages {
+        inherit python;
+      }).overrideScope (
+        lib.composeManyExtensions [
+          inputs.pyproject-build-systems.overlays.default
+          overlay
+          exoOverlay
+          buildSystemsOverlay
+        ]
+      );
+      exoVenv = pythonSet.mkVirtualEnv "exo-env" workspace.deps.default;
+
+      # Virtual environment with dev dependencies for testing
+      testVenv = pythonSet.mkVirtualEnv "exo-test-env" (
+        workspace.deps.default // {
+          exo = [ "dev" ]; # Include pytest, pytest-asyncio, pytest-env
+        }
+      );
+
+      exoPackage = pkgs.runCommand "exo"
+        {
+          nativeBuildInputs = [ pkgs.makeWrapper ];
+        }
+        ''
+          mkdir -p $out/bin
+
+          # Create wrapper scripts
+          for script in exo exo-master exo-worker; do
+            makeWrapper ${exoVenv}/bin/$script $out/bin/$script \
+              --set DASHBOARD_DIR ${self'.packages.dashboard}
+          done
+        '';
+    in
+    {
+      # Python package only available on macOS (requires MLX/Metal)
+      packages = lib.optionalAttrs pkgs.stdenv.hostPlatform.isDarwin {
+        exo = exoPackage;
+        # Test environment for running pytest outside of Nix sandbox (needs GPU access)
+        exo-test-env = testVenv;
+      };
+
+      checks = {
+        # Ruff linting (works on all platforms)
+        lint = pkgs.runCommand "ruff-lint" { } ''
+          export RUFF_CACHE_DIR="$TMPDIR/ruff-cache"
+          ${pkgs.ruff}/bin/ruff check ${inputs.self}/
+          touch $out
+        '';
+      };
+    };
+}

src/exo/download/coordinator.py

@@ -0,0 +1,284 @@
+import asyncio
+from dataclasses import dataclass, field
+from typing import Iterator
+
+import anyio
+from anyio import current_time
+from anyio.abc import TaskGroup
+from loguru import logger
+
+from exo.download.download_utils import (
+    RepoDownloadProgress,
+    delete_model,
+    map_repo_download_progress_to_download_progress_data,
+)
+from exo.download.shard_downloader import ShardDownloader
+from exo.shared.models.model_cards import ModelId
+from exo.shared.types.commands import (
+    DeleteDownload,
+    ForwarderDownloadCommand,
+    StartDownload,
+)
+from exo.shared.types.common import NodeId, SessionId
+from exo.shared.types.events import (
+    Event,
+    ForwarderEvent,
+    NodeDownloadProgress,
+)
+from exo.shared.types.worker.downloads import (
+    DownloadCompleted,
+    DownloadFailed,
+    DownloadOngoing,
+    DownloadPending,
+    DownloadProgress,
+)
+from exo.shared.types.worker.shards import ShardMetadata
+from exo.utils.channels import Receiver, Sender, channel
+
+
+@dataclass
+class DownloadCoordinator:
+    node_id: NodeId
+    session_id: SessionId
+    shard_downloader: ShardDownloader
+    download_command_receiver: Receiver[ForwarderDownloadCommand]
+    local_event_sender: Sender[ForwarderEvent]
+    event_index_counter: Iterator[int]
+
+    # Local state
+    download_status: dict[ModelId, DownloadProgress] = field(default_factory=dict)
+    active_downloads: dict[ModelId, asyncio.Task[None]] = field(default_factory=dict)
+
+    # Internal event channel for forwarding (initialized in __post_init__)
+    event_sender: Sender[Event] = field(init=False)
+    event_receiver: Receiver[Event] = field(init=False)
+    _tg: TaskGroup = field(init=False)
+
+    def __post_init__(self) -> None:
+        self.event_sender, self.event_receiver = channel[Event]()
+        self._tg = anyio.create_task_group()
+
+    async def run(self) -> None:
+        logger.info("Starting DownloadCoordinator")
+        async with self._tg as tg:
+            tg.start_soon(self._command_processor)
+            tg.start_soon(self._forward_events)
+            tg.start_soon(self._emit_existing_download_progress)
+
+    def shutdown(self) -> None:
+        self._tg.cancel_scope.cancel()
+
+    async def _command_processor(self) -> None:
+        with self.download_command_receiver as commands:
+            async for cmd in commands:
+                # Only process commands targeting this node
+                if cmd.command.target_node_id != self.node_id:
+                    continue
+
+                match cmd.command:
+                    case StartDownload(shard_metadata=shard):
+                        await self._start_download(shard)
+                    case DeleteDownload(model_id=model_id):
+                        await self._delete_download(model_id)
+
+    async def _start_download(self, shard: ShardMetadata) -> None:
+        model_id = shard.model_card.model_id
+
+        # Check if already downloading or complete
+        if model_id in self.download_status:
+            status = self.download_status[model_id]
+            if isinstance(status, (DownloadOngoing, DownloadCompleted)):
+                logger.debug(
+                    f"Download for {model_id} already in progress or complete, skipping"
+                )
+                return
+
+        # Emit pending status
+        progress = DownloadPending(shard_metadata=shard, node_id=self.node_id)
+        self.download_status[model_id] = progress
+        await self.event_sender.send(NodeDownloadProgress(download_progress=progress))
+
+        # Check initial status from downloader
+        initial_progress = (
+            await self.shard_downloader.get_shard_download_status_for_shard(shard)
+        )
+
+        if initial_progress.status == "complete":
+            completed = DownloadCompleted(
+                shard_metadata=shard,
+                node_id=self.node_id,
+                total_bytes=initial_progress.total_bytes,
+            )
+            self.download_status[model_id] = completed
+            await self.event_sender.send(
+                NodeDownloadProgress(download_progress=completed)
+            )
+            return
+
+        # Start actual download
+        self._start_download_task(shard, initial_progress)
+
+    def _start_download_task(
+        self, shard: ShardMetadata, initial_progress: RepoDownloadProgress
+    ) -> None:
+        model_id = shard.model_card.model_id
+
+        # Emit ongoing status
+        status = DownloadOngoing(
+            node_id=self.node_id,
+            shard_metadata=shard,
+            download_progress=map_repo_download_progress_to_download_progress_data(
+                initial_progress
+            ),
+        )
+        self.download_status[model_id] = status
+        self.event_sender.send_nowait(NodeDownloadProgress(download_progress=status))
+
+        last_progress_time = 0.0
+        throttle_interval_secs = 1.0
+
+        async def download_progress_callback(
+            callback_shard: ShardMetadata, progress: RepoDownloadProgress
+        ) -> None:
+            nonlocal last_progress_time
+
+            if progress.status == "complete":
+                completed = DownloadCompleted(
+                    shard_metadata=callback_shard,
+                    node_id=self.node_id,
+                    total_bytes=progress.total_bytes,
+                )
+                self.download_status[callback_shard.model_card.model_id] = completed
+                await self.event_sender.send(
+                    NodeDownloadProgress(download_progress=completed)
+                )
+                # Clean up active download tracking
+                if callback_shard.model_card.model_id in self.active_downloads:
+                    del self.active_downloads[callback_shard.model_card.model_id]
+            elif (
+                progress.status == "in_progress"
+                and current_time() - last_progress_time > throttle_interval_secs
+            ):
+                ongoing = DownloadOngoing(
+                    node_id=self.node_id,
+                    shard_metadata=callback_shard,
+                    download_progress=map_repo_download_progress_to_download_progress_data(
+                        progress
+                    ),
+                )
+                self.download_status[callback_shard.model_card.model_id] = ongoing
+                await self.event_sender.send(
+                    NodeDownloadProgress(download_progress=ongoing)
+                )
+                last_progress_time = current_time()
+
+        self.shard_downloader.on_progress(download_progress_callback)
+
+        async def download_wrapper() -> None:
+            try:
+                await self.shard_downloader.ensure_shard(shard)
+            except Exception as e:
+                logger.error(f"Download failed for {model_id}: {e}")
+                failed = DownloadFailed(
+                    shard_metadata=shard,
+                    node_id=self.node_id,
+                    error_message=str(e),
+                )
+                self.download_status[model_id] = failed
+                await self.event_sender.send(
+                    NodeDownloadProgress(download_progress=failed)
+                )
+            finally:
+                if model_id in self.active_downloads:
+                    del self.active_downloads[model_id]
+
+        task = asyncio.create_task(download_wrapper())
+        self.active_downloads[model_id] = task
+
+    async def _delete_download(self, model_id: ModelId) -> None:
+        # Cancel if active
+        if model_id in self.active_downloads:
+            logger.info(f"Cancelling active download for {model_id} before deletion")
+            self.active_downloads[model_id].cancel()
+            del self.active_downloads[model_id]
+
+        # Delete from disk
+        logger.info(f"Deleting model files for {model_id}")
+        deleted = await delete_model(model_id)
+
+        if deleted:
+            logger.info(f"Successfully deleted model {model_id}")
+        else:
+            logger.warning(f"Model {model_id} was not found on disk")
+
+        # Emit pending status to reset UI state, then remove from local tracking
+        if model_id in self.download_status:
+            current_status = self.download_status[model_id]
+            pending = DownloadPending(
+                shard_metadata=current_status.shard_metadata,
+                node_id=self.node_id,
+            )
+            await self.event_sender.send(
+                NodeDownloadProgress(download_progress=pending)
+            )
+            del self.download_status[model_id]
+
+    async def _forward_events(self) -> None:
+        with self.event_receiver as events:
+            async for event in events:
+                idx = next(self.event_index_counter)
+                fe = ForwarderEvent(
+                    origin_idx=idx,
+                    origin=self.node_id,
+                    session=self.session_id,
+                    event=event,
+                )
+                logger.debug(
+                    f"DownloadCoordinator published event {idx}: {str(event)[:100]}"
+                )
+                await self.local_event_sender.send(fe)
+
+    async def _emit_existing_download_progress(self) -> None:
+        try:
+            while True:
+                logger.info(
+                    "DownloadCoordinator: Fetching and emitting existing download progress..."
+                )
+                async for (
+                    _,
+                    progress,
+                ) in self.shard_downloader.get_shard_download_status():
+                    if progress.status == "complete":
+                        status: DownloadProgress = DownloadCompleted(
+                            node_id=self.node_id,
+                            shard_metadata=progress.shard,
+                            total_bytes=progress.total_bytes,
+                        )
+                    elif progress.status in ["in_progress", "not_started"]:
+                        if progress.downloaded_bytes_this_session.in_bytes == 0:
+                            status = DownloadPending(
+                                node_id=self.node_id, shard_metadata=progress.shard
+                            )
+                        else:
+                            status = DownloadOngoing(
+                                node_id=self.node_id,
+                                shard_metadata=progress.shard,
+                                download_progress=map_repo_download_progress_to_download_progress_data(
+                                    progress
+                                ),
+                            )
+                    else:
+                        continue
+
+                    self.download_status[progress.shard.model_card.model_id] = status
+                    await self.event_sender.send(
+                        NodeDownloadProgress(download_progress=status)
+                    )
+                logger.info(
+                    "DownloadCoordinator: Done emitting existing download progress."
+                )
+                await anyio.sleep(5 * 60)  # 5 minutes
+        except Exception as e:
+            logger.error(
+                f"DownloadCoordinator: Error emitting existing download progress: {e}"
+            )

src/exo/download/download_utils.py

@@ -24,7 +24,15 @@ from pydantic import (
     TypeAdapter,
 )
 
+from exo.download.huggingface_utils import (
+    filter_repo_objects,
+    get_allow_patterns,
+    get_auth_headers,
+    get_hf_endpoint,
+    get_hf_token,
+)
 from exo.shared.constants import EXO_MODELS_DIR
+from exo.shared.models.model_cards import ModelTask
 from exo.shared.types.common import ModelId
 from exo.shared.types.memory import Memory
 from exo.shared.types.worker.downloads import (
@@ -35,13 +43,6 @@ from exo.shared.types.worker.downloads import (
     RepoFileDownloadProgress,
 )
 from exo.shared.types.worker.shards import ShardMetadata
-from exo.worker.download.huggingface_utils import (
-    filter_repo_objects,
-    get_allow_patterns,
-    get_auth_headers,
-    get_hf_endpoint,
-    get_hf_token,
-)
 
 
 class HuggingFaceAuthenticationError(Exception):
@@ -120,11 +121,20 @@ async def ensure_models_dir() -> Path:
 
 
 async def delete_model(model_id: ModelId) -> bool:
-    model_dir = await ensure_models_dir() / model_id.normalize()
-    if not await aios.path.exists(model_dir):
-        return False
-    await asyncio.to_thread(shutil.rmtree, model_dir, ignore_errors=False)
-    return True
+    models_dir = await ensure_models_dir()
+    model_dir = models_dir / model_id.normalize()
+    cache_dir = models_dir / "caches" / model_id.normalize()
+
+    deleted = False
+    if await aios.path.exists(model_dir):
+        await asyncio.to_thread(shutil.rmtree, model_dir, ignore_errors=False)
+        deleted = True
+
+    # Also clear cache
+    if await aios.path.exists(cache_dir):
+        await asyncio.to_thread(shutil.rmtree, cache_dir, ignore_errors=False)
+
+    return deleted
 
 
 async def seed_models(seed_dir: str | Path):
@@ -150,16 +160,28 @@ async def fetch_file_list_with_cache(
     target_dir = (await ensure_models_dir()) / "caches" / model_id.normalize()
     await aios.makedirs(target_dir, exist_ok=True)
     cache_file = target_dir / f"{model_id.normalize()}--{revision}--file_list.json"
-    if await aios.path.exists(cache_file):
-        async with aiofiles.open(cache_file, "r") as f:
-            return TypeAdapter(list[FileListEntry]).validate_json(await f.read())
-    file_list = await fetch_file_list_with_retry(
-        model_id, revision, recursive=recursive
-    )
-    await aios.makedirs(cache_file.parent, exist_ok=True)
-    async with aiofiles.open(cache_file, "w") as f:
-        await f.write(TypeAdapter(list[FileListEntry]).dump_json(file_list).decode())
-    return file_list
+
+    # Always try fresh first
+    try:
+        file_list = await fetch_file_list_with_retry(
+            model_id, revision, recursive=recursive
+        )
+        # Update cache with fresh data
+        async with aiofiles.open(cache_file, "w") as f:
+            await f.write(
+                TypeAdapter(list[FileListEntry]).dump_json(file_list).decode()
+            )
+        return file_list
+    except Exception as e:
+        # Fetch failed - try cache fallback
+        if await aios.path.exists(cache_file):
+            logger.warning(
+                f"Failed to fetch file list for {model_id}, using cached data: {e}"
+            )
+            async with aiofiles.open(cache_file, "r") as f:
+                return TypeAdapter(list[FileListEntry]).validate_json(await f.read())
+        # No cache available, propagate the error
+        raise
 
 
 async def fetch_file_list_with_retry(
@@ -331,8 +353,28 @@ async def _download_file(
     target_dir: Path,
     on_progress: Callable[[int, int, bool], None] = lambda _, __, ___: None,
 ) -> Path:
-    if await aios.path.exists(target_dir / path):
-        return target_dir / path
+    target_path = target_dir / path
+
+    if await aios.path.exists(target_path):
+        local_size = (await aios.stat(target_path)).st_size
+
+        # Try to verify against remote, but allow offline operation
+        try:
+            remote_size, _ = await file_meta(model_id, revision, path)
+            if local_size != remote_size:
+                logger.info(
+                    f"File {path} size mismatch (local={local_size}, remote={remote_size}), re-downloading"
+                )
+                await aios.remove(target_path)
+            else:
+                return target_path
+        except Exception as e:
+            # Offline or network error - trust local file
+            logger.debug(
+                f"Could not verify {path} against remote (offline?): {e}, using local file"
+            )
+            return target_path
+
     await aios.makedirs((target_dir / path).parent, exist_ok=True)
     length, etag = await file_meta(model_id, revision, path)
     remote_hash = etag[:-5] if etag.endswith("-gzip") else etag
@@ -481,6 +523,11 @@ async def resolve_allow_patterns(shard: ShardMetadata) -> list[str]:
         return ["*"]
 
 
+def is_image_model(shard: ShardMetadata) -> bool:
+    tasks = shard.model_card.tasks
+    return ModelTask.TextToImage in tasks or ModelTask.ImageToImage in tasks
+
+
 async def get_downloaded_size(path: Path) -> int:
     partial_path = path.with_suffix(path.suffix + ".partial")
     if await aios.path.exists(path):
@@ -522,22 +569,40 @@ async def download_shard(
             file_list, allow_patterns=allow_patterns, key=lambda x: x.path
         )
     )
+
+    # For image models, skip root-level safetensors files since weights
+    # are stored in component subdirectories (e.g., transformer/, vae/)
+    if is_image_model(shard):
+        filtered_file_list = [
+            f
+            for f in filtered_file_list
+            if "/" in f.path or not f.path.endswith(".safetensors")
+        ]
     file_progress: dict[str, RepoFileDownloadProgress] = {}
 
     async def on_progress_wrapper(
         file: FileListEntry, curr_bytes: int, total_bytes: int, is_renamed: bool
     ) -> None:
-        start_time = (
-            file_progress[file.path].start_time
-            if file.path in file_progress
-            else time.time()
-        )
-        downloaded_this_session = (
-            file_progress[file.path].downloaded_this_session.in_bytes
-            + (curr_bytes - file_progress[file.path].downloaded.in_bytes)
-            if file.path in file_progress
-            else curr_bytes
+        previous_progress = file_progress.get(file.path)
+
+        # Detect re-download: curr_bytes < previous downloaded means file was deleted and restarted
+        is_redownload = (
+            previous_progress is not None
+            and curr_bytes < previous_progress.downloaded.in_bytes
         )
+
+        if is_redownload or previous_progress is None:
+            # Fresh download or re-download: reset tracking
+            start_time = time.time()
+            downloaded_this_session = curr_bytes
+        else:
+            # Continuing download: accumulate
+            start_time = previous_progress.start_time
+            downloaded_this_session = (
+                previous_progress.downloaded_this_session.in_bytes
+                + (curr_bytes - previous_progress.downloaded.in_bytes)
+            )
+
         speed = (
             downloaded_this_session / (time.time() - start_time)
             if time.time() - start_time > 0

src/exo/download/impl_shard_downloader.py

@@ -5,13 +5,13 @@ from typing import AsyncIterator, Callable
 
 from loguru import logger
 
+from exo.download.download_utils import RepoDownloadProgress, download_shard
+from exo.download.shard_downloader import ShardDownloader
 from exo.shared.models.model_cards import MODEL_CARDS, ModelCard, ModelId
 from exo.shared.types.worker.shards import (
     PipelineShardMetadata,
     ShardMetadata,
 )
-from exo.worker.download.download_utils import RepoDownloadProgress, download_shard
-from exo.worker.download.shard_downloader import ShardDownloader
 
 
 def exo_shard_downloader(max_parallel_downloads: int = 8) -> ShardDownloader:
@@ -21,7 +21,7 @@ def exo_shard_downloader(max_parallel_downloads: int = 8) -> ShardDownloader:
 
 
 async def build_base_shard(model_id: ModelId) -> ShardMetadata:
-    model_card = await ModelCard.from_hf(model_id)
+    model_card = await ModelCard.load(model_id)
     return PipelineShardMetadata(
         model_card=model_card,
         device_rank=0,
@@ -166,9 +166,8 @@ class ResumableShardDownloader(ShardDownloader):
         for task in asyncio.as_completed(tasks):
             try:
                 yield await task
-            # TODO: except Exception
             except Exception as e:
-                logger.error("Error downloading shard:", e)
+                logger.warning(f"Error downloading shard: {type(e).__name__}")
 
     async def get_shard_download_status_for_shard(
         self, shard: ShardMetadata

src/exo/download/shard_downloader.py

@@ -5,13 +5,13 @@ from datetime import timedelta
 from pathlib import Path
 from typing import AsyncIterator, Callable
 
+from exo.download.download_utils import RepoDownloadProgress
 from exo.shared.models.model_cards import ModelCard, ModelId, ModelTask
 from exo.shared.types.memory import Memory
 from exo.shared.types.worker.shards import (
     PipelineShardMetadata,
     ShardMetadata,
 )
-from exo.worker.download.download_utils import RepoDownloadProgress
 
 
 # TODO: the PipelineShardMetadata getting reinstantiated is a bit messy. Should this be a classmethod?

src/exo/download/tests/test_download_verification.py

@@ -0,0 +1,451 @@
+"""Tests for download verification and cache behavior."""
+
+import time
+from collections.abc import AsyncIterator
+from datetime import timedelta
+from pathlib import Path
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import aiofiles
+import aiofiles.os as aios
+import pytest
+from pydantic import TypeAdapter
+
+from exo.download.download_utils import (
+    delete_model,
+    fetch_file_list_with_cache,
+)
+from exo.shared.types.common import ModelId
+from exo.shared.types.memory import Memory
+from exo.shared.types.worker.downloads import FileListEntry, RepoFileDownloadProgress
+
+
+@pytest.fixture
+def model_id() -> ModelId:
+    return ModelId("test-org/test-model")
+
+
+@pytest.fixture
+async def temp_models_dir(tmp_path: Path) -> AsyncIterator[Path]:
+    """Set up a temporary models directory for testing."""
+    models_dir = tmp_path / "models"
+    await aios.makedirs(models_dir, exist_ok=True)
+    with patch("exo.download.download_utils.EXO_MODELS_DIR", models_dir):
+        yield models_dir
+
+
+class TestFileVerification:
+    """Tests for file size verification in _download_file."""
+
+    async def test_redownload_when_file_size_changes_upstream(
+        self, model_id: ModelId, tmp_path: Path
+    ) -> None:
+        """Test that files with mismatched sizes are re-downloaded."""
+        # Import inside test to allow patching
+        from exo.download.download_utils import (
+            _download_file,  # pyright: ignore[reportPrivateUsage]
+        )
+
+        target_dir = tmp_path / "downloads"
+        await aios.makedirs(target_dir, exist_ok=True)
+
+        # Create a local file with wrong size
+        local_file = target_dir / "test.safetensors"
+        async with aiofiles.open(local_file, "wb") as f:
+            await f.write(b"local content")  # 13 bytes
+
+        remote_size = 1000  # Different from local
+        remote_hash = "abc123"
+
+        with (
+            patch(
+                "exo.download.download_utils.file_meta",
+                new_callable=AsyncMock,
+                return_value=(remote_size, remote_hash),
+            ) as mock_file_meta,
+            patch(
+                "exo.download.download_utils.create_http_session"
+            ) as mock_session_factory,
+        ):
+            # Set up mock HTTP response for re-download
+            mock_response = MagicMock()
+            mock_response.status = 200
+            mock_response.content.read = AsyncMock(  # pyright: ignore[reportAny]
+                side_effect=[b"x" * remote_size, b""]
+            )
+
+            mock_session = MagicMock()
+            mock_session.get.return_value.__aenter__ = AsyncMock(  # pyright: ignore[reportAny]
+                return_value=mock_response
+            )
+            mock_session.get.return_value.__aexit__ = AsyncMock(  # pyright: ignore[reportAny]
+                return_value=None
+            )
+            mock_session_factory.return_value.__aenter__ = AsyncMock(  # pyright: ignore[reportAny]
+                return_value=mock_session
+            )
+            mock_session_factory.return_value.__aexit__ = AsyncMock(  # pyright: ignore[reportAny]
+                return_value=None
+            )
+
+            # Mock calc_hash to return the expected hash
+            with patch(
+                "exo.download.download_utils.calc_hash",
+                new_callable=AsyncMock,
+                return_value=remote_hash,
+            ):
+                await _download_file(model_id, "main", "test.safetensors", target_dir)
+
+            # file_meta should be called twice: once for verification, once for download
+            assert mock_file_meta.call_count == 2
+
+    async def test_skip_download_when_file_size_matches(
+        self, model_id: ModelId, tmp_path: Path
+    ) -> None:
+        """Test that files with matching sizes are not re-downloaded."""
+        from exo.download.download_utils import (
+            _download_file,  # pyright: ignore[reportPrivateUsage]
+        )
+
+        target_dir = tmp_path / "downloads"
+        await aios.makedirs(target_dir, exist_ok=True)
+
+        # Create a local file
+        local_file = target_dir / "test.safetensors"
+        local_content = b"local content"
+        async with aiofiles.open(local_file, "wb") as f:
+            await f.write(local_content)
+
+        remote_size = len(local_content)  # Same as local
+        remote_hash = "abc123"
+
+        with (
+            patch(
+                "exo.download.download_utils.file_meta",
+                new_callable=AsyncMock,
+                return_value=(remote_size, remote_hash),
+            ) as mock_file_meta,
+            patch(
+                "exo.download.download_utils.create_http_session"
+            ) as mock_session_factory,
+        ):
+            result = await _download_file(
+                model_id, "main", "test.safetensors", target_dir
+            )
+
+            # Should return immediately without downloading
+            assert result == local_file
+            mock_file_meta.assert_called_once()
+            mock_session_factory.assert_not_called()
+
+    async def test_offline_fallback_uses_local_file(
+        self, model_id: ModelId, tmp_path: Path
+    ) -> None:
+        """Test that local files are used when network is unavailable."""
+        from exo.download.download_utils import (
+            _download_file,  # pyright: ignore[reportPrivateUsage]
+        )
+
+        target_dir = tmp_path / "downloads"
+        await aios.makedirs(target_dir, exist_ok=True)
+
+        # Create a local file
+        local_file = target_dir / "test.safetensors"
+        async with aiofiles.open(local_file, "wb") as f:
+            await f.write(b"local content")
+
+        with (
+            patch(
+                "exo.download.download_utils.file_meta",
+                new_callable=AsyncMock,
+                side_effect=Exception("Network error"),
+            ),
+            patch(
+                "exo.download.download_utils.create_http_session"
+            ) as mock_session_factory,
+        ):
+            result = await _download_file(
+                model_id, "main", "test.safetensors", target_dir
+            )
+
+            # Should return local file without attempting download
+            assert result == local_file
+            mock_session_factory.assert_not_called()
+
+
+class TestFileListCache:
+    """Tests for file list caching behavior."""
+
+    async def test_fetch_fresh_and_update_cache(
+        self, model_id: ModelId, tmp_path: Path
+    ) -> None:
+        """Test that fresh data is fetched and cache is updated."""
+        models_dir = tmp_path / "models"
+
+        file_list = [
+            FileListEntry(type="file", path="model.safetensors", size=1000),
+            FileListEntry(type="file", path="config.json", size=100),
+        ]
+
+        with (
+            patch("exo.download.download_utils.EXO_MODELS_DIR", models_dir),
+            patch(
+                "exo.download.download_utils.fetch_file_list_with_retry",
+                new_callable=AsyncMock,
+                return_value=file_list,
+            ) as mock_fetch,
+        ):
+            result = await fetch_file_list_with_cache(model_id, "main")
+
+            assert result == file_list
+            mock_fetch.assert_called_once()
+
+            # Verify cache was written
+            cache_file = (
+                models_dir
+                / "caches"
+                / model_id.normalize()
+                / f"{model_id.normalize()}--main--file_list.json"
+            )
+            assert await aios.path.exists(cache_file)
+
+            async with aiofiles.open(cache_file, "r") as f:
+                cached_data = TypeAdapter(list[FileListEntry]).validate_json(
+                    await f.read()
+                )
+            assert cached_data == file_list
+
+    async def test_fallback_to_cache_when_fetch_fails(
+        self, model_id: ModelId, tmp_path: Path
+    ) -> None:
+        """Test that cached data is used when fetch fails."""
+        models_dir = tmp_path / "models"
+        cache_dir = models_dir / "caches" / model_id.normalize()
+        await aios.makedirs(cache_dir, exist_ok=True)
+
+        # Create cache file
+        cached_file_list = [
+            FileListEntry(type="file", path="model.safetensors", size=1000),
+        ]
+        cache_file = cache_dir / f"{model_id.normalize()}--main--file_list.json"
+        async with aiofiles.open(cache_file, "w") as f:
+            await f.write(
+                TypeAdapter(list[FileListEntry]).dump_json(cached_file_list).decode()
+            )
+
+        with (
+            patch("exo.download.download_utils.EXO_MODELS_DIR", models_dir),
+            patch(
+                "exo.download.download_utils.fetch_file_list_with_retry",
+                new_callable=AsyncMock,
+                side_effect=Exception("Network error"),
+            ),
+        ):
+            result = await fetch_file_list_with_cache(model_id, "main")
+
+            assert result == cached_file_list
+
+    async def test_error_propagates_when_no_cache(
+        self, model_id: ModelId, tmp_path: Path
+    ) -> None:
+        """Test that errors propagate when fetch fails and no cache exists."""
+        models_dir = tmp_path / "models"
+
+        with (
+            patch("exo.download.download_utils.EXO_MODELS_DIR", models_dir),
+            patch(
+                "exo.download.download_utils.fetch_file_list_with_retry",
+                new_callable=AsyncMock,
+                side_effect=Exception("Network error"),
+            ),
+            pytest.raises(Exception, match="Network error"),
+        ):
+            await fetch_file_list_with_cache(model_id, "main")
+
+
+class TestModelDeletion:
+    """Tests for model deletion including cache cleanup."""
+
+    async def test_delete_model_clears_cache(
+        self, model_id: ModelId, tmp_path: Path
+    ) -> None:
+        """Test that deleting a model also deletes its cache."""
+        models_dir = tmp_path / "models"
+        model_dir = models_dir / model_id.normalize()
+        cache_dir = models_dir / "caches" / model_id.normalize()
+
+        # Create model and cache directories
+        await aios.makedirs(model_dir, exist_ok=True)
+        await aios.makedirs(cache_dir, exist_ok=True)
+
+        # Add some files
+        async with aiofiles.open(model_dir / "model.safetensors", "w") as f:
+            await f.write("model data")
+        async with aiofiles.open(cache_dir / "file_list.json", "w") as f:
+            await f.write("[]")
+
+        with patch("exo.download.download_utils.EXO_MODELS_DIR", models_dir):
+            result = await delete_model(model_id)
+
+            assert result is True
+            assert not await aios.path.exists(model_dir)
+            assert not await aios.path.exists(cache_dir)
+
+    async def test_delete_model_only_cache_exists(
+        self, model_id: ModelId, tmp_path: Path
+    ) -> None:
+        """Test deleting when only cache exists (model already deleted)."""
+        models_dir = tmp_path / "models"
+        cache_dir = models_dir / "caches" / model_id.normalize()
+
+        # Only create cache directory
+        await aios.makedirs(cache_dir, exist_ok=True)
+        async with aiofiles.open(cache_dir / "file_list.json", "w") as f:
+            await f.write("[]")
+
+        with patch("exo.download.download_utils.EXO_MODELS_DIR", models_dir):
+            result = await delete_model(model_id)
+
+            # Returns False because model dir didn't exist
+            assert result is False
+            # But cache should still be cleaned up
+            assert not await aios.path.exists(cache_dir)
+
+    async def test_delete_nonexistent_model(
+        self, model_id: ModelId, tmp_path: Path
+    ) -> None:
+        """Test deleting a model that doesn't exist."""
+        models_dir = tmp_path / "models"
+        await aios.makedirs(models_dir, exist_ok=True)
+
+        with patch("exo.download.download_utils.EXO_MODELS_DIR", models_dir):
+            result = await delete_model(model_id)
+
+            assert result is False
+
+
+class TestProgressResetOnRedownload:
+    """Tests for progress tracking when files are re-downloaded."""
+
+    async def test_progress_resets_correctly_on_redownload(
+        self, model_id: ModelId
+    ) -> None:
+        """Test that progress tracking resets when a file is re-downloaded.
+
+        When a file is deleted and re-downloaded (due to size mismatch),
+        the progress tracking should reset rather than calculating negative
+        downloaded_this_session values.
+        """
+        # Simulate file_progress dict as it exists in download_shard
+        file_progress: dict[str, RepoFileDownloadProgress] = {}
+
+        # Initialize with old file progress (simulating existing large file)
+        old_file_size = 1_500_000_000  # 1.5 GB
+        file_progress["model.safetensors"] = RepoFileDownloadProgress(
+            repo_id=model_id,
+            repo_revision="main",
+            file_path="model.safetensors",
+            downloaded=Memory.from_bytes(old_file_size),
+            downloaded_this_session=Memory.from_bytes(0),
+            total=Memory.from_bytes(old_file_size),
+            speed=0,
+            eta=timedelta(0),
+            status="not_started",
+            start_time=time.time() - 10,  # Started 10 seconds ago
+        )
+
+        # Simulate the logic from on_progress_wrapper after re-download starts
+        # This is the exact logic from the fixed on_progress_wrapper
+        curr_bytes = 100_000  # 100 KB - new download just started
+        previous_progress = file_progress.get("model.safetensors")
+
+        # Detect re-download: curr_bytes < previous downloaded
+        is_redownload = (
+            previous_progress is not None
+            and curr_bytes < previous_progress.downloaded.in_bytes
+        )
+
+        if is_redownload or previous_progress is None:
+            # Fresh download or re-download: reset tracking
+            start_time = time.time()
+            downloaded_this_session = curr_bytes
+        else:
+            # Continuing download: accumulate
+            start_time = previous_progress.start_time
+            downloaded_this_session = (
+                previous_progress.downloaded_this_session.in_bytes
+                + (curr_bytes - previous_progress.downloaded.in_bytes)
+            )
+
+        # Key assertions
+        assert is_redownload is True, "Should detect re-download scenario"
+        assert downloaded_this_session == curr_bytes, (
+            "downloaded_this_session should equal curr_bytes on re-download"
+        )
+        assert downloaded_this_session > 0, (
+            "downloaded_this_session should be positive, not negative"
+        )
+
+        # Calculate speed (should be positive)
+        elapsed = time.time() - start_time
+        speed = downloaded_this_session / elapsed if elapsed > 0 else 0
+        assert speed >= 0, "Speed should be non-negative"
+
+    async def test_progress_accumulates_on_continuing_download(
+        self, model_id: ModelId
+    ) -> None:
+        """Test that progress accumulates correctly for continuing downloads.
+
+        When a download continues from where it left off (resume),
+        the progress should accumulate correctly.
+        """
+        file_progress: dict[str, RepoFileDownloadProgress] = {}
+
+        # Initialize with partial download progress
+        initial_downloaded = 500_000  # 500 KB already downloaded
+        start_time = time.time() - 5  # Started 5 seconds ago
+        file_progress["model.safetensors"] = RepoFileDownloadProgress(
+            repo_id=model_id,
+            repo_revision="main",
+            file_path="model.safetensors",
+            downloaded=Memory.from_bytes(initial_downloaded),
+            downloaded_this_session=Memory.from_bytes(initial_downloaded),
+            total=Memory.from_bytes(1_000_000),
+            speed=100_000,
+            eta=timedelta(seconds=5),
+            status="in_progress",
+            start_time=start_time,
+        )
+
+        # Progress callback with more bytes downloaded
+        curr_bytes = 600_000  # 600 KB - continuing download
+        previous_progress = file_progress.get("model.safetensors")
+
+        # This is NOT a re-download (curr_bytes > previous downloaded)
+        is_redownload = (
+            previous_progress is not None
+            and curr_bytes < previous_progress.downloaded.in_bytes
+        )
+
+        if is_redownload or previous_progress is None:
+            downloaded_this_session = curr_bytes
+            used_start_time = time.time()
+        else:
+            used_start_time = previous_progress.start_time
+            downloaded_this_session = (
+                previous_progress.downloaded_this_session.in_bytes
+                + (curr_bytes - previous_progress.downloaded.in_bytes)
+            )
+
+        # Key assertions
+        assert is_redownload is False, (
+            "Should NOT detect re-download for continuing download"
+        )
+        assert used_start_time == start_time, "Should preserve original start_time"
+        expected_session = initial_downloaded + (curr_bytes - initial_downloaded)
+        assert downloaded_this_session == expected_session, (
+            f"Should accumulate: {downloaded_this_session} == {expected_session}"
+        )
+        assert downloaded_this_session == 600_000, (
+            "downloaded_this_session should equal total downloaded so far"
+        )

src/exo/main.py

@@ -1,10 +1,11 @@
 import argparse
+import itertools
 import multiprocessing as mp
 import os
 import resource
 import signal
 from dataclasses import dataclass, field
-from typing import Self
+from typing import Iterator, Self
 
 import anyio
 from anyio.abc import TaskGroup
@@ -12,6 +13,8 @@ from loguru import logger
 from pydantic import PositiveInt
 
 import exo.routing.topics as topics
+from exo.download.coordinator import DownloadCoordinator
+from exo.download.impl_shard_downloader import exo_shard_downloader
 from exo.master.api import API  # TODO: should API be in master?
 from exo.master.main import Master
 from exo.routing.router import Router, get_node_id_keypair
@@ -21,7 +24,6 @@ from exo.shared.logging import logger_cleanup, logger_setup
 from exo.shared.types.common import NodeId, SessionId
 from exo.utils.channels import Receiver, channel
 from exo.utils.pydantic_ext import CamelCaseModel
-from exo.worker.download.impl_shard_downloader import exo_shard_downloader
 from exo.worker.main import Worker
 
 
@@ -29,6 +31,7 @@ from exo.worker.main import Worker
 @dataclass
 class Node:
     router: Router
+    download_coordinator: DownloadCoordinator | None
     worker: Worker | None
     election: Election  # Every node participates in election, as we do want a node to become master even if it isn't a master candidate if no master candidates are present.
     election_result_receiver: Receiver[ElectionResult]
@@ -36,6 +39,7 @@ class Node:
     api: API | None
 
     node_id: NodeId
+    event_index_counter: Iterator[int]
     _tg: TaskGroup = field(init=False, default_factory=anyio.create_task_group)
 
     @classmethod
@@ -49,8 +53,26 @@ class Node:
         await router.register_topic(topics.COMMANDS)
         await router.register_topic(topics.ELECTION_MESSAGES)
         await router.register_topic(topics.CONNECTION_MESSAGES)
+        await router.register_topic(topics.DOWNLOAD_COMMANDS)
 
         logger.info(f"Starting node {node_id}")
+
+        # Create shared event index counter for Worker and DownloadCoordinator
+        event_index_counter = itertools.count()
+
+        # Create DownloadCoordinator (unless --no-downloads)
+        if not args.no_downloads:
+            download_coordinator = DownloadCoordinator(
+                node_id,
+                session_id,
+                exo_shard_downloader(),
+                download_command_receiver=router.receiver(topics.DOWNLOAD_COMMANDS),
+                local_event_sender=router.sender(topics.LOCAL_EVENTS),
+                event_index_counter=event_index_counter,
+            )
+        else:
+            download_coordinator = None
+
         if args.spawn_api:
             api = API(
                 node_id,
@@ -58,6 +80,7 @@ class Node:
                 port=args.api_port,
                 global_event_receiver=router.receiver(topics.GLOBAL_EVENTS),
                 command_sender=router.sender(topics.COMMANDS),
+                download_command_sender=router.sender(topics.DOWNLOAD_COMMANDS),
                 election_receiver=router.receiver(topics.ELECTION_MESSAGES),
             )
         else:
@@ -67,11 +90,12 @@ class Node:
             worker = Worker(
                 node_id,
                 session_id,
-                exo_shard_downloader(),
                 connection_message_receiver=router.receiver(topics.CONNECTION_MESSAGES),
                 global_event_receiver=router.receiver(topics.GLOBAL_EVENTS),
                 local_event_sender=router.sender(topics.LOCAL_EVENTS),
                 command_sender=router.sender(topics.COMMANDS),
+                download_command_sender=router.sender(topics.DOWNLOAD_COMMANDS),
+                event_index_counter=event_index_counter,
             )
         else:
             worker = None
@@ -99,13 +123,25 @@ class Node:
             election_result_sender=er_send,
         )
 
-        return cls(router, worker, election, er_recv, master, api, node_id)
+        return cls(
+            router,
+            download_coordinator,
+            worker,
+            election,
+            er_recv,
+            master,
+            api,
+            node_id,
+            event_index_counter,
+        )
 
     async def run(self):
         async with self._tg as tg:
             signal.signal(signal.SIGINT, lambda _, __: self.shutdown())
             tg.start_soon(self.router.run)
             tg.start_soon(self.election.run)
+            if self.download_coordinator:
+                tg.start_soon(self.download_coordinator.run)
             if self.worker:
                 tg.start_soon(self.worker.run)
             if self.master:
@@ -170,13 +206,27 @@ class Node:
                     )
                 if result.is_new_master:
                     await anyio.sleep(0)
+                    # Fresh counter for new session (buffer expects indices from 0)
+                    self.event_index_counter = itertools.count()
+                    if self.download_coordinator:
+                        self.download_coordinator.shutdown()
+                        self.download_coordinator = DownloadCoordinator(
+                            self.node_id,
+                            result.session_id,
+                            exo_shard_downloader(),
+                            download_command_receiver=self.router.receiver(
+                                topics.DOWNLOAD_COMMANDS
+                            ),
+                            local_event_sender=self.router.sender(topics.LOCAL_EVENTS),
+                            event_index_counter=self.event_index_counter,
+                        )
+                        self._tg.start_soon(self.download_coordinator.run)
                     if self.worker:
                         self.worker.shutdown()
                         # TODO: add profiling etc to resource monitor
                         self.worker = Worker(
                             self.node_id,
                             result.session_id,
-                            exo_shard_downloader(),
                             connection_message_receiver=self.router.receiver(
                                 topics.CONNECTION_MESSAGES
                             ),
@@ -185,6 +235,10 @@ class Node:
                             ),
                             local_event_sender=self.router.sender(topics.LOCAL_EVENTS),
                             command_sender=self.router.sender(topics.COMMANDS),
+                            download_command_sender=self.router.sender(
+                                topics.DOWNLOAD_COMMANDS
+                            ),
+                            event_index_counter=self.event_index_counter,
                         )
                         self._tg.start_soon(self.worker.run)
                     if self.api:
@@ -226,6 +280,7 @@ class Args(CamelCaseModel):
     api_port: PositiveInt = 52415
     tb_only: bool = False
     no_worker: bool = False
+    no_downloads: bool = False
     fast_synch: bool | None = None  # None = auto, True = force on, False = force off
 
     @classmethod
@@ -268,6 +323,11 @@ class Args(CamelCaseModel):
             "--no-worker",
             action="store_true",
         )
+        parser.add_argument(
+            "--no-downloads",
+            action="store_true",
+            help="Disable the download coordinator (node won't download models)",
+        )
         fast_synch_group = parser.add_mutually_exclusive_group()
         fast_synch_group.add_argument(
             "--fast-synch",

src/exo/master/api.py

@@ -1,8 +1,11 @@
 import base64
+import contextlib
 import json
 import time
 from collections.abc import AsyncGenerator
+from datetime import datetime, timezone
 from http import HTTPStatus
+from pathlib import Path
 from typing import Annotated, Literal, cast
 from uuid import uuid4
 
@@ -32,7 +35,9 @@ from exo.shared.models.model_cards import (
     ModelCard,
     ModelId,
 )
+from exo.shared.tracing import compute_stats, load_trace_file
 from exo.shared.types.api import (
+    AdvancedImageParams,
     BenchChatCompletionResponse,
     BenchChatCompletionTaskParams,
     BenchImageGenerationResponse,
@@ -42,6 +47,7 @@ from exo.shared.types.api import (
     ChatCompletionResponse,
     CreateInstanceParams,
     CreateInstanceResponse,
+    DeleteDownloadResponse,
     DeleteInstanceResponse,
     ErrorInfo,
     ErrorResponse,
@@ -59,8 +65,19 @@ from exo.shared.types.api import (
     PlaceInstanceParams,
     PlacementPreview,
     PlacementPreviewResponse,
+    StartDownloadParams,
+    StartDownloadResponse,
     StreamingChoiceResponse,
+    StreamOptions,
     ToolCall,
+    TraceCategoryStats,
+    TraceEventResponse,
+    TraceListItem,
+    TraceListResponse,
+    TraceRankStats,
+    TraceResponse,
+    TraceStatsResponse,
+    Usage,
 )
 from exo.shared.types.chunks import (
     ErrorChunk,
@@ -73,12 +90,16 @@ from exo.shared.types.commands import (
     ChatCompletion,
     Command,
     CreateInstance,
+    DeleteDownload,
     DeleteInstance,
+    DownloadCommand,
     ForwarderCommand,
+    ForwarderDownloadCommand,
     ImageEdits,
     ImageGeneration,
     PlaceInstance,
     SendInputChunk,
+    StartDownload,
     TaskFinished,
 )
 from exo.shared.types.common import CommandId, Id, NodeId, SessionId
@@ -104,7 +125,9 @@ def _format_to_content_type(image_format: Literal["png", "jpeg", "webp"] | None)
 
 
 def chunk_to_response(
-    chunk: TokenChunk | ToolCallChunk, command_id: CommandId
+    chunk: TokenChunk | ToolCallChunk,
+    command_id: CommandId,
+    usage: Usage | None,
 ) -> ChatCompletionResponse:
     return ChatCompletionResponse(
         id=command_id,
@@ -129,21 +152,10 @@ def chunk_to_response(
                 finish_reason=chunk.finish_reason,
             )
         ],
+        usage=usage,
     )
 
 
-async def resolve_model_card(model_id: ModelId) -> ModelCard:
-    if model_id in MODEL_CARDS:
-        model_card = MODEL_CARDS[model_id]
-        return model_card
-
-    for card in MODEL_CARDS.values():
-        if card.model_id == ModelId(model_id):
-            return card
-
-    return await ModelCard.from_hf(model_id)
-
-
 class API:
     def __init__(
         self,
@@ -154,12 +166,14 @@ class API:
         # Ideally this would be a MasterForwarderEvent but type system says no :(
         global_event_receiver: Receiver[ForwarderEvent],
         command_sender: Sender[ForwarderCommand],
+        download_command_sender: Sender[ForwarderDownloadCommand],
         # This lets us pause the API if an election is running
         election_receiver: Receiver[ElectionMessage],
     ) -> None:
         self.state = State()
         self._event_log: list[Event] = []
         self.command_sender = command_sender
+        self.download_command_sender = download_command_sender
         self.global_event_receiver = global_event_receiver
         self.election_receiver = election_receiver
         self.event_buffer: OrderedBuffer[Event] = OrderedBuffer[Event]()
@@ -258,10 +272,16 @@ class API:
         self.app.get("/images/{image_id}")(self.get_image)
         self.app.get("/state")(lambda: self.state)
         self.app.get("/events")(lambda: self._event_log)
+        self.app.post("/download/start")(self.start_download)
+        self.app.delete("/download/{node_id}/{model_id:path}")(self.delete_download)
+        self.app.get("/v1/traces")(self.list_traces)
+        self.app.get("/v1/traces/{task_id}")(self.get_trace)
+        self.app.get("/v1/traces/{task_id}/stats")(self.get_trace_stats)
+        self.app.get("/v1/traces/{task_id}/raw")(self.get_trace_raw)
 
     async def place_instance(self, payload: PlaceInstanceParams):
         command = PlaceInstance(
-            model_card=await resolve_model_card(payload.model_id),
+            model_card=await ModelCard.load(payload.model_id),
             sharding=payload.sharding,
             instance_meta=payload.instance_meta,
             min_nodes=payload.min_nodes,
@@ -278,7 +298,7 @@ class API:
         self, payload: CreateInstanceParams
     ) -> CreateInstanceResponse:
         instance = payload.instance
-        model_card = await resolve_model_card(instance.shard_assignments.model_id)
+        model_card = await ModelCard.load(instance.shard_assignments.model_id)
         required_memory = model_card.storage_size
         available_memory = self._calculate_total_available_memory()
 
@@ -306,7 +326,7 @@ class API:
         instance_meta: InstanceMeta = InstanceMeta.MlxRing,
         min_nodes: int = 1,
     ) -> Instance:
-        model_card = await resolve_model_card(model_id)
+        model_card = await ModelCard.load(model_id)
 
         try:
             placements = get_instance_placements(
@@ -343,14 +363,9 @@ class API:
     ) -> PlacementPreviewResponse:
         seen: set[tuple[ModelId, Sharding, InstanceMeta, int]] = set()
         previews: list[PlacementPreview] = []
+        required_nodes = set(node_ids) if node_ids else None
 
-        # Create filtered topology if node_ids specified
-        if node_ids and len(node_ids) > 0:
-            topology = self.state.topology.get_subgraph_from_nodes(node_ids)
-        else:
-            topology = self.state.topology
-
-        if len(list(topology.list_nodes())) == 0:
+        if len(list(self.state.topology.list_nodes())) == 0:
             return PlacementPreviewResponse(previews=[])
 
         cards = [card for card in MODEL_CARDS.values() if card.model_id == model_id]
@@ -363,7 +378,9 @@ class API:
                 instance_combinations.extend(
                     [
                         (sharding, instance_meta, i)
-                        for i in range(1, len(list(topology.list_nodes())) + 1)
+                        for i in range(
+                            1, len(list(self.state.topology.list_nodes())) + 1
+                        )
                     ]
                 )
         # TODO: PDD
@@ -381,8 +398,9 @@ class API:
                         ),
                         node_memory=self.state.node_memory,
                         node_network=self.state.node_network,
-                        topology=topology,
+                        topology=self.state.topology,
                         current_instances=self.state.instances,
+                        required_nodes=required_nodes,
                     )
                 except ValueError as exc:
                     if (model_card.model_id, sharding, instance_meta, 0) not in seen:
@@ -421,14 +439,16 @@ class API:
 
                 instance = new_instances[0]
                 shard_assignments = instance.shard_assignments
-                node_ids = list(shard_assignments.node_to_runner.keys())
+                placement_node_ids = list(shard_assignments.node_to_runner.keys())
 
                 memory_delta_by_node: dict[str, int] = {}
-                if node_ids:
+                if placement_node_ids:
                     total_bytes = model_card.storage_size.in_bytes
-                    per_node = total_bytes // len(node_ids)
-                    remainder = total_bytes % len(node_ids)
-                    for index, node_id in enumerate(sorted(node_ids, key=str)):
+                    per_node = total_bytes // len(placement_node_ids)
+                    remainder = total_bytes % len(placement_node_ids)
+                    for index, node_id in enumerate(
+                        sorted(placement_node_ids, key=str)
+                    ):
                         extra = 1 if index < remainder else 0
                         memory_delta_by_node[str(node_id)] = per_node + extra
 
@@ -436,7 +456,7 @@ class API:
                     model_card.model_id,
                     sharding,
                     instance_meta,
-                    len(node_ids),
+                    len(placement_node_ids),
                 ) not in seen:
                     previews.append(
                         PlacementPreview(
@@ -448,7 +468,14 @@ class API:
                             error=None,
                         )
                     )
-                seen.add((model_card.model_id, sharding, instance_meta, len(node_ids)))
+                seen.add(
+                    (
+                        model_card.model_id,
+                        sharding,
+                        instance_meta,
+                        len(placement_node_ids),
+                    )
+                )
 
         return PlacementPreviewResponse(previews=previews)
 
@@ -502,9 +529,10 @@ class API:
                 del self._chat_completion_queues[command_id]
 
     async def _generate_chat_stream(
-        self, command_id: CommandId
+        self, command_id: CommandId, stream_options: StreamOptions | None = None
     ) -> AsyncGenerator[str, None]:
         """Generate chat completion stream as JSON strings."""
+        include_usage = stream_options.include_usage if stream_options else False
 
         async for chunk in self._chat_chunk_stream(command_id):
             assert not isinstance(chunk, ImageChunk)
@@ -520,8 +548,10 @@ class API:
                 yield "data: [DONE]\n\n"
                 return
 
+            usage = chunk.usage if include_usage else None
+
             chunk_response: ChatCompletionResponse = chunk_to_response(
-                chunk, command_id
+                chunk, command_id, usage=usage
             )
             logger.debug(f"chunk_response: {chunk_response}")
 
@@ -537,8 +567,9 @@ class API:
 
         text_parts: list[str] = []
         tool_calls: list[ToolCall] = []
-        model: str | None = None
+        model: ModelId | None = None
         finish_reason: FinishReason | None = None
+        usage: Usage | None = None
 
         async for chunk in self._chat_chunk_stream(command_id):
             if isinstance(chunk, ErrorChunk):
@@ -563,6 +594,9 @@ class API:
                     for i, tool in enumerate(chunk.tool_calls)
                 )
 
+            if chunk.usage is not None:
+                usage = chunk.usage
+
             if chunk.finish_reason is not None:
                 finish_reason = chunk.finish_reason
 
@@ -584,6 +618,7 @@ class API:
                     finish_reason=finish_reason,
                 )
             ],
+            usage=usage,
         )
 
     async def _collect_chat_completion_with_stats(
@@ -591,7 +626,7 @@ class API:
     ) -> BenchChatCompletionResponse:
         text_parts: list[str] = []
         tool_calls: list[ToolCall] = []
-        model: str | None = None
+        model: ModelId | None = None
         finish_reason: FinishReason | None = None
 
         stats: GenerationStats | None = None
@@ -644,7 +679,7 @@ class API:
         )
         return resp
 
-    async def _trigger_notify_user_to_download_model(self, model_id: str) -> None:
+    async def _trigger_notify_user_to_download_model(self, model_id: ModelId) -> None:
         logger.warning(
             "TODO: we should send a notification to the user to download the model"
         )
@@ -653,7 +688,7 @@ class API:
         self, payload: ChatCompletionTaskParams
     ) -> ChatCompletionResponse | StreamingResponse:
         """Handle chat completions, supporting both streaming and non-streaming responses."""
-        model_card = await resolve_model_card(ModelId(payload.model))
+        model_card = await ModelCard.load(ModelId(payload.model))
         payload.model = model_card.model_id
 
         if not any(
@@ -671,7 +706,7 @@ class API:
         await self._send(command)
         if payload.stream:
             return StreamingResponse(
-                self._generate_chat_stream(command.command_id),
+                self._generate_chat_stream(command.command_id, payload.stream_options),
                 media_type="text/event-stream",
             )
 
@@ -680,7 +715,7 @@ class API:
     async def bench_chat_completions(
         self, payload: BenchChatCompletionTaskParams
     ) -> BenchChatCompletionResponse:
-        model_card = await resolve_model_card(ModelId(payload.model))
+        model_card = await ModelCard.load(ModelId(payload.model))
         payload.model = model_card.model_id
 
         if not any(
@@ -700,12 +735,12 @@ class API:
         response = await self._collect_chat_completion_with_stats(command.command_id)
         return response
 
-    async def _validate_image_model(self, model: str) -> ModelId:
+    async def _validate_image_model(self, model: ModelId) -> ModelId:
         """Validate model exists and return resolved model ID.
 
         Raises HTTPException 404 if no instance is found for the model.
         """
-        model_card = await resolve_model_card(ModelId(model))
+        model_card = await ModelCard.load(model)
         resolved_model = model_card.model_id
         if not any(
             instance.shard_assignments.model_id == resolved_model
@@ -751,7 +786,7 @@ class API:
         When stream=True and partial_images > 0, returns a StreamingResponse
         with SSE-formatted events for partial and final images.
         """
-        payload.model = await self._validate_image_model(payload.model)
+        payload.model = await self._validate_image_model(ModelId(payload.model))
 
         command = ImageGeneration(
             request_params=payload,
@@ -835,6 +870,7 @@ class API:
                             # Yield partial image event (always use b64_json for partials)
                             event_data = {
                                 "type": "partial",
+                                "image_index": chunk.image_index,
                                 "partial_index": partial_idx,
                                 "total_partials": total_partials,
                                 "format": str(chunk.format),
@@ -995,7 +1031,7 @@ class API:
     async def bench_image_generations(
         self, request: Request, payload: BenchImageGenerationTaskParams
     ) -> BenchImageGenerationResponse:
-        payload.model = await self._validate_image_model(payload.model)
+        payload.model = await self._validate_image_model(ModelId(payload.model))
 
         payload.stream = False
         payload.partial_images = 0
@@ -1016,7 +1052,7 @@ class API:
         self,
         image: UploadFile,
         prompt: str,
-        model: str,
+        model: ModelId,
         n: int,
         size: str,
         response_format: Literal["url", "b64_json"],
@@ -1024,6 +1060,9 @@ class API:
         stream: bool,
         partial_images: int,
         bench: bool,
+        quality: Literal["high", "medium", "low"],
+        output_format: Literal["png", "jpeg", "webp"],
+        advanced_params: AdvancedImageParams | None,
     ) -> ImageEdits:
         """Prepare and send an image edits command with chunked image upload."""
         resolved_model = await self._validate_image_model(model)
@@ -1052,6 +1091,9 @@ class API:
                 stream=stream,
                 partial_images=partial_images,
                 bench=bench,
+                quality=quality,
+                output_format=output_format,
+                advanced_params=advanced_params,
             ),
         )
 
@@ -1086,16 +1128,26 @@ class API:
         input_fidelity: Literal["low", "high"] = Form("low"),
         stream: str = Form("false"),
         partial_images: str = Form("0"),
+        quality: Literal["high", "medium", "low"] = Form("medium"),
+        output_format: Literal["png", "jpeg", "webp"] = Form("png"),
+        advanced_params: str | None = Form(None),
     ) -> ImageGenerationResponse | StreamingResponse:
         """Handle image editing requests (img2img)."""
         # Parse string form values to proper types
         stream_bool = stream.lower() in ("true", "1", "yes")
         partial_images_int = int(partial_images) if partial_images.isdigit() else 0
 
+        parsed_advanced_params: AdvancedImageParams | None = None
+        if advanced_params:
+            with contextlib.suppress(Exception):
+                parsed_advanced_params = AdvancedImageParams.model_validate_json(
+                    advanced_params
+                )
+
         command = await self._send_image_edits_command(
             image=image,
             prompt=prompt,
-            model=model,
+            model=ModelId(model),
             n=n,
             size=size,
             response_format=response_format,
@@ -1103,6 +1155,9 @@ class API:
             stream=stream_bool,
             partial_images=partial_images_int,
             bench=False,
+            quality=quality,
+            output_format=output_format,
+            advanced_params=parsed_advanced_params,
         )
 
         if stream_bool and partial_images_int > 0:
@@ -1133,12 +1188,22 @@ class API:
         size: str = Form("1024x1024"),
         response_format: Literal["url", "b64_json"] = Form("b64_json"),
         input_fidelity: Literal["low", "high"] = Form("low"),
+        quality: Literal["high", "medium", "low"] = Form("medium"),
+        output_format: Literal["png", "jpeg", "webp"] = Form("png"),
+        advanced_params: str | None = Form(None),
     ) -> BenchImageGenerationResponse:
         """Handle benchmark image editing requests with generation stats."""
+        parsed_advanced_params: AdvancedImageParams | None = None
+        if advanced_params:
+            with contextlib.suppress(Exception):
+                parsed_advanced_params = AdvancedImageParams.model_validate_json(
+                    advanced_params
+                )
+
         command = await self._send_image_edits_command(
             image=image,
             prompt=prompt,
-            model=model,
+            model=ModelId(model),
             n=n,
             size=size,
             response_format=response_format,
@@ -1146,6 +1211,9 @@ class API:
             stream=False,
             partial_images=0,
             bench=True,
+            quality=quality,
+            output_format=output_format,
+            advanced_params=parsed_advanced_params,
         )
 
         return await self._collect_image_generation_with_stats(
@@ -1257,3 +1325,135 @@ class API:
         await self.command_sender.send(
             ForwarderCommand(origin=self.node_id, command=command)
         )
+
+    async def _send_download(self, command: DownloadCommand):
+        await self.download_command_sender.send(
+            ForwarderDownloadCommand(origin=self.node_id, command=command)
+        )
+
+    async def start_download(
+        self, payload: StartDownloadParams
+    ) -> StartDownloadResponse:
+        command = StartDownload(
+            target_node_id=payload.target_node_id,
+            shard_metadata=payload.shard_metadata,
+        )
+        await self._send_download(command)
+        return StartDownloadResponse(command_id=command.command_id)
+
+    async def delete_download(
+        self, node_id: NodeId, model_id: ModelId
+    ) -> DeleteDownloadResponse:
+        command = DeleteDownload(
+            target_node_id=node_id,
+            model_id=ModelId(model_id),
+        )
+        await self._send_download(command)
+        return DeleteDownloadResponse(command_id=command.command_id)
+
+    def _get_traces_dir(self) -> Path:
+        return Path.home() / ".exo" / "traces"
+
+    def _get_trace_path(self, task_id: str) -> Path:
+        return self._get_traces_dir() / f"trace_{task_id}.json"
+
+    async def list_traces(self) -> TraceListResponse:
+        traces_dir = self._get_traces_dir()
+        traces: list[TraceListItem] = []
+
+        if not traces_dir.exists():
+            return TraceListResponse(traces=[])
+
+        for trace_file in sorted(
+            traces_dir.glob("trace_*.json"),
+            key=lambda p: p.stat().st_mtime,
+            reverse=True,
+        ):
+            # Extract task_id from filename (trace_{task_id}.json)
+            task_id = trace_file.stem.removeprefix("trace_")
+            stat = trace_file.stat()
+            created_at = datetime.fromtimestamp(
+                stat.st_mtime, tz=timezone.utc
+            ).isoformat()
+            traces.append(
+                TraceListItem(
+                    task_id=task_id,
+                    created_at=created_at,
+                    file_size=stat.st_size,
+                )
+            )
+
+        return TraceListResponse(traces=traces)
+
+    async def get_trace(self, task_id: str) -> TraceResponse:
+        trace_path = self._get_trace_path(task_id)
+
+        if not trace_path.exists():
+            raise HTTPException(status_code=404, detail=f"Trace not found: {task_id}")
+
+        trace_events = load_trace_file(trace_path)
+
+        return TraceResponse(
+            task_id=task_id,
+            traces=[
+                TraceEventResponse(
+                    name=event.name,
+                    start_us=event.start_us,
+                    duration_us=event.duration_us,
+                    rank=event.rank,
+                    category=event.category,
+                )
+                for event in trace_events
+            ],
+        )
+
+    async def get_trace_stats(self, task_id: str) -> TraceStatsResponse:
+        trace_path = self._get_trace_path(task_id)
+
+        if not trace_path.exists():
+            raise HTTPException(status_code=404, detail=f"Trace not found: {task_id}")
+
+        trace_events = load_trace_file(trace_path)
+        stats = compute_stats(trace_events)
+
+        return TraceStatsResponse(
+            task_id=task_id,
+            total_wall_time_us=stats.total_wall_time_us,
+            by_category={
+                category: TraceCategoryStats(
+                    total_us=cat_stats.total_us,
+                    count=cat_stats.count,
+                    min_us=cat_stats.min_us,
+                    max_us=cat_stats.max_us,
+                    avg_us=cat_stats.avg_us,
+                )
+                for category, cat_stats in stats.by_category.items()
+            },
+            by_rank={
+                rank: TraceRankStats(
+                    by_category={
+                        category: TraceCategoryStats(
+                            total_us=cat_stats.total_us,
+                            count=cat_stats.count,
+                            min_us=cat_stats.min_us,
+                            max_us=cat_stats.max_us,
+                            avg_us=cat_stats.avg_us,
+                        )
+                        for category, cat_stats in rank_stats.items()
+                    }
+                )
+                for rank, rank_stats in stats.by_rank.items()
+            },
+        )
+
+    async def get_trace_raw(self, task_id: str) -> FileResponse:
+        trace_path = self._get_trace_path(task_id)
+
+        if not trace_path.exists():
+            raise HTTPException(status_code=404, detail=f"Trace not found: {task_id}")
+
+        return FileResponse(
+            path=trace_path,
+            media_type="application/json",
+            filename=f"trace_{task_id}.json",
+        )

src/exo/master/main.py

@@ -1,4 +1,5 @@
 from datetime import datetime, timedelta, timezone
+from pathlib import Path
 
 import anyio
 from anyio.abc import TaskGroup
@@ -11,6 +12,7 @@ from exo.master.placement import (
     place_instance,
 )
 from exo.shared.apply import apply
+from exo.shared.tracing import TraceEvent, export_trace, is_tracing_enabled
 from exo.shared.types.commands import (
     ChatCompletion,
     CreateInstance,
@@ -35,6 +37,8 @@ from exo.shared.types.events import (
     NodeTimedOut,
     TaskCreated,
     TaskDeleted,
+    TraceEventData,
+    TracesCollected,
 )
 from exo.shared.types.state import State
 from exo.shared.types.tasks import (
@@ -86,6 +90,8 @@ class Master:
         self._multi_buffer = MultiSourceBuffer[NodeId, Event]()
         # TODO: not have this
         self._event_log: list[Event] = []
+        self._pending_traces: dict[TaskId, dict[int, list[TraceEventData]]] = {}
+        self._expected_ranks: dict[TaskId, set[int]] = {}
 
     async def run(self):
         logger.info("Starting Master")
@@ -187,13 +193,14 @@ class Master:
                             )
 
                             task_id = TaskId()
+                            selected_instance_id = available_instance_ids[0]
                             generated_events.append(
                                 TaskCreated(
                                     task_id=task_id,
                                     task=ImageGenerationTask(
                                         task_id=task_id,
                                         command_id=command.command_id,
-                                        instance_id=available_instance_ids[0],
+                                        instance_id=selected_instance_id,
                                         task_status=TaskStatus.Pending,
                                         task_params=command.request_params,
                                     ),
@@ -201,6 +208,17 @@ class Master:
                             )
 
                             self.command_task_mapping[command.command_id] = task_id
+
+                            if is_tracing_enabled():
+                                selected_instance = self.state.instances.get(
+                                    selected_instance_id
+                                )
+                                if selected_instance:
+                                    ranks = set(
+                                        shard.device_rank
+                                        for shard in selected_instance.shard_assignments.runner_to_shard.values()
+                                    )
+                                    self._expected_ranks[task_id] = ranks
                         case ImageEdits():
                             for instance in self.state.instances.values():
                                 if (
@@ -229,13 +247,14 @@ class Master:
                             )
 
                             task_id = TaskId()
+                            selected_instance_id = available_instance_ids[0]
                             generated_events.append(
                                 TaskCreated(
                                     task_id=task_id,
                                     task=ImageEditsTask(
                                         task_id=task_id,
                                         command_id=command.command_id,
-                                        instance_id=available_instance_ids[0],
+                                        instance_id=selected_instance_id,
                                         task_status=TaskStatus.Pending,
                                         task_params=command.request_params,
                                     ),
@@ -243,6 +262,17 @@ class Master:
                             )
 
                             self.command_task_mapping[command.command_id] = task_id
+
+                            if is_tracing_enabled():
+                                selected_instance = self.state.instances.get(
+                                    selected_instance_id
+                                )
+                                if selected_instance:
+                                    ranks = set(
+                                        shard.device_rank
+                                        for shard in selected_instance.shard_assignments.runner_to_shard.values()
+                                    )
+                                    self._expected_ranks[task_id] = ranks
                         case DeleteInstance():
                             placement = delete_instance(command, self.state.instances)
                             transition_events = get_transition_events(
@@ -335,6 +365,10 @@ class Master:
                     local_event.origin,
                 )
                 for event in self._multi_buffer.drain():
+                    if isinstance(event, TracesCollected):
+                        self._handle_traces_collected(event)
+                        continue
+
                     logger.debug(f"Master indexing event: {str(event)[:100]}")
                     indexed = IndexedEvent(event=event, idx=len(self._event_log))
                     self.state = apply(self.state, indexed)
@@ -373,3 +407,38 @@ class Master:
                 event=event.event,
             )
         )
+
+    def _handle_traces_collected(self, event: TracesCollected) -> None:
+        task_id = event.task_id
+        if task_id not in self._pending_traces:
+            self._pending_traces[task_id] = {}
+        self._pending_traces[task_id][event.rank] = event.traces
+
+        if (
+            task_id in self._expected_ranks
+            and set(self._pending_traces[task_id].keys())
+            >= self._expected_ranks[task_id]
+        ):
+            self._merge_and_save_traces(task_id)
+
+    def _merge_and_save_traces(self, task_id: TaskId) -> None:
+        all_traces: list[TraceEvent] = []
+        for trace_data in self._pending_traces[task_id].values():
+            for t in trace_data:
+                all_traces.append(
+                    TraceEvent(
+                        name=t.name,
+                        start_us=t.start_us,
+                        duration_us=t.duration_us,
+                        rank=t.rank,
+                        category=t.category,
+                    )
+                )
+
+        output_path = Path.home() / ".exo" / "traces" / f"trace_{task_id}.json"
+        export_trace(all_traces, output_path)
+        logger.info(f"Merged traces saved to {output_path}")
+
+        del self._pending_traces[task_id]
+        if task_id in self._expected_ranks:
+            del self._expected_ranks[task_id]

src/exo/master/placement.py

@@ -35,7 +35,7 @@ from exo.shared.types.worker.shards import Sharding
 
 def random_ephemeral_port() -> int:
     port = random.randint(49153, 65535)
-    return port - 1 if port <= 52415 else 52414
+    return port - 1 if port <= 52415 else port
 
 
 def add_instance_to_placements(
@@ -54,9 +54,18 @@ def place_instance(
     current_instances: Mapping[InstanceId, Instance],
     node_memory: Mapping[NodeId, MemoryUsage],
     node_network: Mapping[NodeId, NodeNetworkInfo],
+    required_nodes: set[NodeId] | None = None,
 ) -> dict[InstanceId, Instance]:
     cycles = topology.get_cycles()
     candidate_cycles = list(filter(lambda it: len(it) >= command.min_nodes, cycles))
+
+    # Filter to cycles containing all required nodes (subset matching)
+    if required_nodes:
+        candidate_cycles = [
+            cycle
+            for cycle in candidate_cycles
+            if required_nodes.issubset(cycle.node_ids)
+        ]
     cycles_with_sufficient_memory = filter_cycles_by_memory(
         candidate_cycles, node_memory, command.model_card.storage_size
     )

src/exo/master/placement_utils.py

@@ -257,7 +257,13 @@ def _find_ip_prioritised(
     ip_to_type = {
         iface.ip_address: iface.interface_type for iface in other_network.interfaces
     }
-    priority = {"ethernet": 0, "wifi": 1, "unknown": 2, "thunderbolt": 3}
+    priority = {
+        "ethernet": 0,
+        "wifi": 1,
+        "unknown": 2,
+        "maybe_ethernet": 3,
+        "thunderbolt": 4,
+    }
     return min(ips, key=lambda ip: priority.get(ip_to_type.get(ip, "unknown"), 2))
 
 

src/exo/routing/router.py

@@ -216,6 +216,8 @@ def get_node_id_keypair(
     Obtains the :class:`Keypair` associated with this node-ID.
     Obtain the :class:`PeerId` by from it.
     """
+    # TODO(evan): bring back node id persistence once we figure out how to deal with duplicates
+    return Keypair.generate_ed25519()
 
     def lock_path(path: str | bytes | PathLike[str] | PathLike[bytes]) -> Path:
         return Path(str(path) + ".lock")

src/exo/routing/topics.py

@@ -3,7 +3,7 @@ from enum import Enum
 
 from exo.routing.connection_message import ConnectionMessage
 from exo.shared.election import ElectionMessage
-from exo.shared.types.commands import ForwarderCommand
+from exo.shared.types.commands import ForwarderCommand, ForwarderDownloadCommand
 from exo.shared.types.events import (
     ForwarderEvent,
 )
@@ -45,3 +45,6 @@ ELECTION_MESSAGES = TypedTopic(
 CONNECTION_MESSAGES = TypedTopic(
     "connection_messages", PublishPolicy.Never, ConnectionMessage
 )
+DOWNLOAD_COMMANDS = TypedTopic(
+    "download_commands", PublishPolicy.Always, ForwarderDownloadCommand
+)

src/exo/shared/apply.py

@@ -25,6 +25,7 @@ from exo.shared.types.events import (
     TestEvent,
     TopologyEdgeCreated,
     TopologyEdgeDeleted,
+    TracesCollected,
 )
 from exo.shared.types.profiling import (
     NodeIdentity,
@@ -55,7 +56,11 @@ def event_apply(event: Event, state: State) -> State:
     """Apply an event to state."""
     match event:
         case (
-            TestEvent() | ChunkGenerated() | TaskAcknowledged() | InputChunkReceived()
+            TestEvent()
+            | ChunkGenerated()
+            | TaskAcknowledged()
+            | InputChunkReceived()
+            | TracesCollected()
         ):  # Pass-through events that don't modify state
             return state
         case InstanceCreated():

src/exo/shared/constants.py

@@ -53,3 +53,9 @@ EXO_IMAGE_CACHE_DIR = EXO_CACHE_HOME / "images"
 EXO_ENABLE_IMAGE_MODELS = (
     os.getenv("EXO_ENABLE_IMAGE_MODELS", "false").lower() == "true"
 )
+
+EXO_TRACING_ENABLED = os.getenv("EXO_TRACING_ENABLED", "").lower() in (
+    "1",
+    "true",
+    "yes",
+)

src/exo/shared/models/model_cards.py

@@ -1,5 +1,5 @@
 from enum import Enum
-from typing import Annotated
+from typing import Annotated, Any
 
 import aiofiles
 import aiofiles.os as aios
@@ -7,7 +7,14 @@ import tomlkit
 from anyio import Path, open_file
 from huggingface_hub import model_info
 from loguru import logger
-from pydantic import BaseModel, Field, PositiveInt, field_validator
+from pydantic import (
+    AliasChoices,
+    BaseModel,
+    Field,
+    PositiveInt,
+    field_validator,
+    model_validator,
+)
 
 from exo.shared.constants import EXO_ENABLE_IMAGE_MODELS
 from exo.shared.types.common import ModelId
@@ -121,6 +128,14 @@ MODEL_CARDS: dict[str, ModelCard] = {
         supports_tensor=True,
         tasks=[ModelTask.TextGeneration],
     ),
+    "kimi-k2.5": ModelCard(
+        model_id=ModelId("mlx-community/Kimi-K2.5"),
+        storage_size=Memory.from_gb(617),
+        n_layers=61,
+        hidden_size=7168,
+        supports_tensor=True,
+        tasks=[ModelTask.TextGeneration],
+    ),
     # llama-3.1
     "llama-3.1-8b": ModelCard(
         model_id=ModelId("mlx-community/Meta-Llama-3.1-8B-Instruct-4bit"),
@@ -413,9 +428,9 @@ MODEL_CARDS: dict[str, ModelCard] = {
     ),
 }
 
-_IMAGE_MODEL_CARDS: dict[str, ModelCard] = {
+_IMAGE_BASE_MODEL_CARDS: dict[str, ModelCard] = {
     "flux1-schnell": ModelCard(
-        model_id=ModelId("black-forest-labs/FLUX.1-schnell"),
+        model_id=ModelId("exolabs/FLUX.1-schnell"),
         storage_size=Memory.from_bytes(23782357120 + 9524621312),
         n_layers=57,
         hidden_size=1,
@@ -428,7 +443,7 @@ _IMAGE_MODEL_CARDS: dict[str, ModelCard] = {
                 storage_size=Memory.from_kb(0),
                 n_layers=12,
                 can_shard=False,
-                safetensors_index_filename=None,  # Single file
+                safetensors_index_filename=None,
             ),
             ComponentInfo(
                 component_name="text_encoder_2",
@@ -442,7 +457,7 @@ _IMAGE_MODEL_CARDS: dict[str, ModelCard] = {
                 component_name="transformer",
                 component_path="transformer/",
                 storage_size=Memory.from_bytes(23782357120),
-                n_layers=57,  # 19 transformer_blocks + 38 single_transformer_blocks
+                n_layers=57,
                 can_shard=True,
                 safetensors_index_filename="diffusion_pytorch_model.safetensors.index.json",
             ),
@@ -457,7 +472,7 @@ _IMAGE_MODEL_CARDS: dict[str, ModelCard] = {
         ],
     ),
     "flux1-dev": ModelCard(
-        model_id=ModelId("black-forest-labs/FLUX.1-dev"),
+        model_id=ModelId("exolabs/FLUX.1-dev"),
         storage_size=Memory.from_bytes(23782357120 + 9524621312),
         n_layers=57,
         hidden_size=1,
@@ -470,7 +485,7 @@ _IMAGE_MODEL_CARDS: dict[str, ModelCard] = {
                 storage_size=Memory.from_kb(0),
                 n_layers=12,
                 can_shard=False,
-                safetensors_index_filename=None,  # Single file
+                safetensors_index_filename=None,
             ),
             ComponentInfo(
                 component_name="text_encoder_2",
@@ -484,7 +499,49 @@ _IMAGE_MODEL_CARDS: dict[str, ModelCard] = {
                 component_name="transformer",
                 component_path="transformer/",
                 storage_size=Memory.from_bytes(23802816640),
-                n_layers=57,  # 19 transformer_blocks + 38 single_transformer_blocks
+                n_layers=57,
+                can_shard=True,
+                safetensors_index_filename="diffusion_pytorch_model.safetensors.index.json",
+            ),
+            ComponentInfo(
+                component_name="vae",
+                component_path="vae/",
+                storage_size=Memory.from_kb(0),
+                n_layers=None,
+                can_shard=False,
+                safetensors_index_filename=None,
+            ),
+        ],
+    ),
+    "flux1-krea-dev": ModelCard(
+        model_id=ModelId("exolabs/FLUX.1-Krea-dev"),
+        storage_size=Memory.from_bytes(23802816640 + 9524621312),  # Same as dev
+        n_layers=57,
+        hidden_size=1,
+        supports_tensor=False,
+        tasks=[ModelTask.TextToImage],
+        components=[
+            ComponentInfo(
+                component_name="text_encoder",
+                component_path="text_encoder/",
+                storage_size=Memory.from_kb(0),
+                n_layers=12,
+                can_shard=False,
+                safetensors_index_filename=None,
+            ),
+            ComponentInfo(
+                component_name="text_encoder_2",
+                component_path="text_encoder_2/",
+                storage_size=Memory.from_bytes(9524621312),
+                n_layers=24,
+                can_shard=False,
+                safetensors_index_filename="model.safetensors.index.json",
+            ),
+            ComponentInfo(
+                component_name="transformer",
+                component_path="transformer/",
+                storage_size=Memory.from_bytes(23802816640),
+                n_layers=57,
                 can_shard=True,
                 safetensors_index_filename="diffusion_pytorch_model.safetensors.index.json",
             ),
@@ -499,9 +556,9 @@ _IMAGE_MODEL_CARDS: dict[str, ModelCard] = {
         ],
     ),
     "qwen-image": ModelCard(
-        model_id=ModelId("Qwen/Qwen-Image"),
+        model_id=ModelId("exolabs/Qwen-Image"),
         storage_size=Memory.from_bytes(16584333312 + 40860802176),
-        n_layers=60,  # Qwen has 60 transformer blocks (all joint-style)
+        n_layers=60,
         hidden_size=1,
         supports_tensor=False,
         tasks=[ModelTask.TextToImage],
@@ -509,10 +566,10 @@ _IMAGE_MODEL_CARDS: dict[str, ModelCard] = {
             ComponentInfo(
                 component_name="text_encoder",
                 component_path="text_encoder/",
-                storage_size=Memory.from_kb(16584333312),
+                storage_size=Memory.from_bytes(16584333312),
                 n_layers=12,
                 can_shard=False,
-                safetensors_index_filename=None,  # Single file
+                safetensors_index_filename=None,
             ),
             ComponentInfo(
                 component_name="transformer",
@@ -533,9 +590,9 @@ _IMAGE_MODEL_CARDS: dict[str, ModelCard] = {
         ],
     ),
     "qwen-image-edit-2509": ModelCard(
-        model_id=ModelId("Qwen/Qwen-Image-Edit-2509"),
+        model_id=ModelId("exolabs/Qwen-Image-Edit-2509"),
         storage_size=Memory.from_bytes(16584333312 + 40860802176),
-        n_layers=60,  # Qwen has 60 transformer blocks (all joint-style)
+        n_layers=60,
         hidden_size=1,
         supports_tensor=False,
         tasks=[ModelTask.ImageToImage],
@@ -543,10 +600,10 @@ _IMAGE_MODEL_CARDS: dict[str, ModelCard] = {
             ComponentInfo(
                 component_name="text_encoder",
                 component_path="text_encoder/",
-                storage_size=Memory.from_kb(16584333312),
+                storage_size=Memory.from_bytes(16584333312),
                 n_layers=12,
                 can_shard=False,
-                safetensors_index_filename=None,  # Single file
+                safetensors_index_filename=None,
             ),
             ComponentInfo(
                 component_name="transformer",
@@ -568,6 +625,92 @@ _IMAGE_MODEL_CARDS: dict[str, ModelCard] = {
     ),
 }
 
+
+def _generate_image_model_quant_variants(
+    base_name: str,
+    base_card: ModelCard,
+) -> dict[str, ModelCard]:
+    """Create quantized variants of an image model card.
+
+    Only the transformer component is quantized; text encoders stay at bf16.
+    Sizes are calculated exactly from the base card's component sizes.
+    """
+    if base_card.components is None:
+        raise ValueError(f"Image model {base_name} must have components defined")
+
+    # quantizations = [8, 6, 5, 4, 3]
+    quantizations = [8, 4]
+
+    num_transformer_bytes = next(
+        c.storage_size.in_bytes
+        for c in base_card.components
+        if c.component_name == "transformer"
+    )
+
+    transformer_bytes = Memory.from_bytes(num_transformer_bytes)
+
+    remaining_bytes = Memory.from_bytes(
+        sum(
+            c.storage_size.in_bytes
+            for c in base_card.components
+            if c.component_name != "transformer"
+        )
+    )
+
+    def with_transformer_size(new_size: Memory) -> list[ComponentInfo]:
+        assert base_card.components is not None
+        return [
+            ComponentInfo(
+                component_name=c.component_name,
+                component_path=c.component_path,
+                storage_size=new_size
+                if c.component_name == "transformer"
+                else c.storage_size,
+                n_layers=c.n_layers,
+                can_shard=c.can_shard,
+                safetensors_index_filename=c.safetensors_index_filename,
+            )
+            for c in base_card.components
+        ]
+
+    variants = {
+        base_name: ModelCard(
+            model_id=base_card.model_id,
+            storage_size=transformer_bytes + remaining_bytes,
+            n_layers=base_card.n_layers,
+            hidden_size=base_card.hidden_size,
+            supports_tensor=base_card.supports_tensor,
+            tasks=base_card.tasks,
+            components=with_transformer_size(transformer_bytes),
+        )
+    }
+
+    for quant in quantizations:
+        quant_transformer_bytes = Memory.from_bytes(
+            (num_transformer_bytes * quant) // 16
+        )
+        total_bytes = remaining_bytes + quant_transformer_bytes
+
+        model_id = ModelId(base_card.model_id + f"-{quant}bit")
+
+        variants[f"{base_name}-{quant}bit"] = ModelCard(
+            model_id=model_id,
+            storage_size=total_bytes,
+            n_layers=base_card.n_layers,
+            hidden_size=base_card.hidden_size,
+            supports_tensor=base_card.supports_tensor,
+            tasks=base_card.tasks,
+            components=with_transformer_size(quant_transformer_bytes),
+        )
+
+    return variants
+
+
+_image_model_cards: dict[str, ModelCard] = {}
+for _base_name, _base_card in _IMAGE_BASE_MODEL_CARDS.items():
+    _image_model_cards |= _generate_image_model_quant_variants(_base_name, _base_card)
+_IMAGE_MODEL_CARDS = _image_model_cards
+
 if EXO_ENABLE_IMAGE_MODELS:
     MODEL_CARDS.update(_IMAGE_MODEL_CARDS)
 
@@ -575,15 +718,18 @@ if EXO_ENABLE_IMAGE_MODELS:
 class ConfigData(BaseModel):
     model_config = {"extra": "ignore"}  # Allow unknown fields
 
-    # Common field names for number of layers across different architectures
-    num_hidden_layers: Annotated[int, Field(ge=0)] | None = None
-    num_layers: Annotated[int, Field(ge=0)] | None = None
-    n_layer: Annotated[int, Field(ge=0)] | None = None
-    n_layers: Annotated[int, Field(ge=0)] | None = None  # Sometimes used
-    num_decoder_layers: Annotated[int, Field(ge=0)] | None = None  # Transformer models
-    decoder_layers: Annotated[int, Field(ge=0)] | None = None  # Some architectures
-    hidden_size: Annotated[int, Field(ge=0)] | None = None
     architectures: list[str] | None = None
+    hidden_size: Annotated[int, Field(ge=0)] | None = None
+    layer_count: int = Field(
+        validation_alias=AliasChoices(
+            "num_hidden_layers",
+            "num_layers",
+            "n_layer",
+            "n_layers",
+            "num_decoder_layers",
+            "decoder_layers",
+        )
+    )
 
     @property
     def supports_tensor(self) -> bool:
@@ -598,30 +744,32 @@ class ConfigData(BaseModel):
             ["GptOssForCausalLM"],
         ]
 
-    @property
-    def layer_count(self) -> int:
-        # Check common field names for layer count
-        layer_fields = [
-            self.num_hidden_layers,
-            self.num_layers,
-            self.n_layer,
-            self.n_layers,
-            self.num_decoder_layers,
-            self.decoder_layers,
-        ]
+    @model_validator(mode="before")
+    @classmethod
+    def defer_to_text_config(cls, data: dict[str, Any]):
+        text_config = data.get("text_config")
+        if text_config is None:
+            return data
 
-        for layer_count in layer_fields:
-            if layer_count is not None:
-                return layer_count
+        for field in [
+            "architectures",
+            "hidden_size",
+            "num_hidden_layers",
+            "num_layers",
+            "n_layer",
+            "n_layers",
+            "num_decoder_layers",
+            "decoder_layers",
+        ]:
+            if (val := text_config.get(field)) is not None:  # pyright: ignore[reportAny]
+                data[field] = val
 
-        raise ValueError(
-            f"No layer count found in config.json: {self.model_dump_json()}"
-        )
+        return data
 
 
 async def get_config_data(model_id: ModelId) -> ConfigData:
     """Downloads and parses config.json for a model."""
-    from exo.worker.download.download_utils import (
+    from exo.download.download_utils import (
         download_file_with_retry,
         ensure_models_dir,
     )
@@ -643,11 +791,11 @@ async def get_config_data(model_id: ModelId) -> ConfigData:
 
 async def get_safetensors_size(model_id: ModelId) -> Memory:
     """Gets model size from safetensors index or falls back to HF API."""
-    from exo.shared.types.worker.downloads import ModelSafetensorsIndex
-    from exo.worker.download.download_utils import (
+    from exo.download.download_utils import (
         download_file_with_retry,
         ensure_models_dir,
     )
+    from exo.shared.types.worker.downloads import ModelSafetensorsIndex
 
     target_dir = (await ensure_models_dir()) / model_id.normalize()
     await aios.makedirs(target_dir, exist_ok=True)

src/exo/shared/tests/test_node_id_persistence.py

@@ -8,7 +8,7 @@ from multiprocessing.synchronize import Event as EventT
 from multiprocessing.synchronize import Semaphore as SemaphoreT
 
 from loguru import logger
-from pytest import LogCaptureFixture
+from pytest import LogCaptureFixture, mark
 
 from exo.routing.router import get_node_id_keypair
 from exo.shared.constants import EXO_NODE_ID_KEYPAIR
@@ -74,6 +74,7 @@ def _delete_if_exists(p: str | bytes | os.PathLike[str] | os.PathLike[bytes]):
         os.remove(p)
 
 
+@mark.skip(reason="this functionality is currently disabled but may return in future")
 def test_node_id_fetching(caplog: LogCaptureFixture):
     reps = 10
 

src/exo/shared/topology.py

@@ -248,8 +248,8 @@ class Topology:
     ) -> list[list[NodeId]]:
         """
         Find cycles in the Thunderbolt topology where all nodes have TB bridge enabled.
-        Only returns cycles with >2 nodes (3+ machines in a loop), as cycles with
-        2 or fewer nodes don't cause the broadcast storm problem.
+        Only returns cycles with >=2 nodes (2+ machines in a loop), as
+        1 node doesn't cause the broadcast storm problem.
         """
         enabled_nodes = {
             node_id
@@ -257,7 +257,7 @@ class Topology:
             if status.enabled
         }
 
-        if len(enabled_nodes) < 3:
+        if len(enabled_nodes) < 2:
             return []
 
         thunderbolt_ips = _get_ips_with_interface_type(
@@ -288,7 +288,7 @@ class Topology:
         return [
             [graph[idx] for idx in cycle]
             for cycle in rx.simple_cycles(graph)
-            if len(cycle) > 2
+            if len(cycle) >= 2
         ]
 
 

src/exo/shared/tracing.py

@@ -0,0 +1,450 @@
+from __future__ import annotations
+
+import json
+import logging
+import time
+from collections import defaultdict
+from collections.abc import Generator
+from contextlib import contextmanager
+from contextvars import ContextVar
+from dataclasses import dataclass, field
+from pathlib import Path
+from typing import cast, final
+
+from exo.shared.constants import EXO_TRACING_ENABLED
+
+logger = logging.getLogger(__name__)
+
+# Context variable to track the current trace category for hierarchical nesting
+_current_category: ContextVar[str | None] = ContextVar("current_category", default=None)
+
+
+@final
+@dataclass(frozen=True)
+class TraceEvent:
+    name: str
+    start_us: int
+    duration_us: int
+    rank: int
+    category: str
+
+
+@final
+@dataclass
+class CategoryStats:
+    total_us: int = 0
+    count: int = 0
+    min_us: int = 0
+    max_us: int = 0
+
+    def add(self, duration_us: int) -> None:
+        if self.count == 0:
+            self.min_us = duration_us
+            self.max_us = duration_us
+        else:
+            self.min_us = min(self.min_us, duration_us)
+            self.max_us = max(self.max_us, duration_us)
+        self.total_us += duration_us
+        self.count += 1
+
+    @property
+    def avg_us(self) -> float:
+        return self.total_us / self.count if self.count > 0 else 0.0
+
+
+@final
+@dataclass
+class TraceStats:
+    total_wall_time_us: int = 0
+    by_category: dict[str, CategoryStats] = field(default_factory=dict)
+    by_rank: dict[int, dict[str, CategoryStats]] = field(default_factory=dict)
+
+
+# Global trace buffer - each rank accumulates traces here
+_trace_buffer: list[TraceEvent] = []
+
+
+def is_tracing_enabled() -> bool:
+    """Check if tracing is enabled via environment variable."""
+    return EXO_TRACING_ENABLED
+
+
+def _record_span(
+    name: str, start_us: int, duration_us: int, rank: int, category: str
+) -> None:
+    _trace_buffer.append(
+        TraceEvent(
+            name=name,
+            start_us=start_us,
+            duration_us=duration_us,
+            rank=rank,
+            category=category,
+        )
+    )
+
+
+@contextmanager
+def trace(
+    name: str,
+    rank: int,
+    category: str = "compute",
+) -> Generator[None, None, None]:
+    """Context manager to trace any operation.
+
+    Nested traces automatically inherit the parent category, creating hierarchical
+    categories like "sync/compute" or "async/comms".
+
+    Args:
+        name: Name of the operation (e.g., "recv 0", "send 1", "joint_blocks")
+        rank: This rank's ID
+        category: Category for grouping in trace viewer ("comm", "compute", "step")
+
+    Example:
+        with trace(f"sync {t}", rank, "sync"):
+            with trace("joint_blocks", rank, "compute"):
+                # Recorded with category "sync/compute"
+                hidden_states = some_computation(...)
+    """
+    if not is_tracing_enabled():
+        yield
+        return
+
+    # Combine with parent category if nested
+    parent = _current_category.get()
+    full_category = f"{parent}/{category}" if parent else category
+
+    # Set as current for nested traces
+    token = _current_category.set(full_category)
+
+    try:
+        start_us = int(time.time() * 1_000_000)
+        start_perf = time.perf_counter()
+        yield
+        duration_us = int((time.perf_counter() - start_perf) * 1_000_000)
+        _record_span(name, start_us, duration_us, rank, full_category)
+    finally:
+        _current_category.reset(token)
+
+
+def get_trace_buffer() -> list[TraceEvent]:
+    return list(_trace_buffer)
+
+
+def clear_trace_buffer() -> None:
+    _trace_buffer.clear()
+
+
+def export_trace(traces: list[TraceEvent], output_path: Path) -> None:
+    trace_events: list[dict[str, object]] = []
+
+    for event in traces:
+        # Chrome trace format uses "X" for complete events (with duration)
+        chrome_event: dict[str, object] = {
+            "name": event.name,
+            "cat": event.category,
+            "ph": "X",
+            "ts": event.start_us,
+            "dur": event.duration_us,
+            "pid": 0,
+            "tid": event.rank,
+            "args": {"rank": event.rank},
+        }
+        trace_events.append(chrome_event)
+
+    ranks_seen = set(t.rank for t in traces)
+    for rank in ranks_seen:
+        trace_events.append(
+            {
+                "name": "thread_name",
+                "ph": "M",  # Metadata event
+                "pid": 0,
+                "tid": rank,
+                "args": {"name": f"Rank {rank}"},
+            }
+        )
+
+    chrome_trace = {"traceEvents": trace_events}
+
+    try:
+        output_path.parent.mkdir(parents=True, exist_ok=True)
+        with open(output_path, "w") as f:
+            json.dump(chrome_trace, f, indent=2)
+    except OSError as e:
+        logger.warning("Failed to export trace to %s: %s", output_path, e)
+
+
+def export_local_traces(rank: int) -> None:
+    if not is_tracing_enabled():
+        return
+
+    local_traces = get_trace_buffer()
+    if local_traces:
+        output_path = Path.home() / ".exo" / "traces" / f"trace_{rank}.json"
+        try:
+            export_trace(local_traces, output_path)
+        except Exception as e:
+            logger.warning("Failed to export local traces for rank %d: %s", rank, e)
+
+    clear_trace_buffer()
+
+
+def merge_trace_files(trace_dir: Path | None = None) -> Path | None:
+    if trace_dir is None:
+        trace_dir = Path.home() / ".exo" / "traces"
+
+    if not trace_dir.exists():
+        return None
+
+    trace_files = sorted(trace_dir.glob("trace_*.json"))
+
+    if not trace_files:
+        return None
+
+    merged_events: list[dict[str, object]] = []
+    for trace_file in trace_files:
+        file_rank = int(trace_file.stem.split("_")[1])
+
+        with open(trace_file) as f:
+            raw = f.read()
+            data = cast(dict[str, list[dict[str, object]]], json.loads(raw))
+            events: list[dict[str, object]] = data.get("traceEvents", [])
+            for event in events:
+                event["tid"] = file_rank
+                if "args" in event and isinstance(event["args"], dict):
+                    event["args"]["rank"] = file_rank
+            merged_events.extend(events)
+
+    output_path = Path.home() / ".exo" / "traces" / "merged_trace.json"
+    try:
+        output_path.parent.mkdir(parents=True, exist_ok=True)
+        with open(output_path, "w") as f:
+            json.dump({"traceEvents": merged_events}, f, indent=2)
+    except OSError as e:
+        logger.warning("Failed to write merged trace to %s: %s", output_path, e)
+        return None
+
+    return output_path
+
+
+def _format_duration(us: int | float) -> str:
+    if us < 1000:
+        return f"{us:.0f}µs"
+    elif us < 1_000_000:
+        return f"{us / 1000:.2f}ms"
+    else:
+        return f"{us / 1_000_000:.2f}s"
+
+
+def load_trace_file(path: Path) -> list[TraceEvent]:
+    """Load a Chrome Trace Format JSON file into TraceEvent objects."""
+    with open(path) as f:
+        data = cast(dict[str, list[dict[str, object]]], json.load(f))
+
+    events = data.get("traceEvents", [])
+    traces: list[TraceEvent] = []
+
+    for event in events:
+        # Skip metadata events
+        if event.get("ph") == "M":
+            continue
+
+        name = str(event.get("name", ""))
+        category = str(event.get("cat", ""))
+        ts_value = event.get("ts", 0)
+        dur_value = event.get("dur", 0)
+        tid_value = event.get("tid", 0)
+        start_us = int(ts_value) if isinstance(ts_value, (int, float, str)) else 0
+        duration_us = int(dur_value) if isinstance(dur_value, (int, float, str)) else 0
+
+        # Get rank from tid or args
+        rank = int(tid_value) if isinstance(tid_value, (int, float, str)) else 0
+        args = event.get("args")
+        if isinstance(args, dict):
+            args_dict = cast(dict[str, object], args)
+            rank_from_args = args_dict.get("rank")
+            if isinstance(rank_from_args, (int, float, str)):
+                rank = int(rank_from_args)
+
+        traces.append(
+            TraceEvent(
+                name=name,
+                start_us=start_us,
+                duration_us=duration_us,
+                rank=rank,
+                category=category,
+            )
+        )
+
+    return traces
+
+
+def compute_stats(traces: list[TraceEvent]) -> TraceStats:
+    """Compute comprehensive statistics from trace events."""
+    stats = TraceStats()
+
+    if not traces:
+        return stats
+
+    # Calculate wall time from earliest start to latest end
+    min_start = min(t.start_us for t in traces)
+    max_end = max(t.start_us + t.duration_us for t in traces)
+    stats.total_wall_time_us = max_end - min_start
+
+    # Initialize nested dicts
+    by_category: dict[str, CategoryStats] = defaultdict(CategoryStats)
+    by_rank: dict[int, dict[str, CategoryStats]] = defaultdict(
+        lambda: defaultdict(CategoryStats)
+    )
+
+    for event in traces:
+        # By category
+        by_category[event.category].add(event.duration_us)
+
+        # By rank and category
+        by_rank[event.rank][event.category].add(event.duration_us)
+
+    stats.by_category = dict(by_category)
+    stats.by_rank = {k: dict(v) for k, v in by_rank.items()}
+
+    return stats
+
+
+def print_stats(stats: TraceStats) -> None:
+    """Print formatted trace statistics."""
+    print("=== Trace Statistics ===")
+    print()
+    print(f"Wall Time: {_format_duration(stats.total_wall_time_us)}")
+    print()
+
+    # Parse hierarchical categories (e.g., "sync/compute" -> phase="sync", subcat="compute")
+    if stats.by_category:
+        phases: dict[str, dict[str, CategoryStats]] = defaultdict(dict)
+        has_hierarchical = False
+
+        for cat, cat_stats in stats.by_category.items():
+            if "/" in cat:
+                phase, subcat = cat.split("/", 1)
+                phases[phase][subcat] = cat_stats
+                has_hierarchical = True
+            else:
+                phases[cat]["_total"] = cat_stats
+
+        if has_hierarchical:
+            print("By Phase:")
+            for phase in sorted(phases.keys()):
+                subcats = phases[phase]
+                # Skip phases that only have _total (non-hierarchical top-level categories)
+                non_total_subcats = {k: v for k, v in subcats.items() if k != "_total"}
+                if not non_total_subcats:
+                    continue
+
+                phase_total = sum(s.total_us for s in non_total_subcats.values())
+                print(f"  {phase}:")
+                for subcat, subcat_stats in sorted(
+                    non_total_subcats.items(),
+                    key=lambda x: x[1].total_us,
+                    reverse=True,
+                ):
+                    pct = (
+                        subcat_stats.total_us / phase_total * 100 if phase_total else 0
+                    )
+                    # Use parent phase's step count for per-step average
+                    phase_step_count = subcats.get("_total", CategoryStats()).count
+                    if phase_step_count > 0:
+                        avg_per_step = subcat_stats.total_us / phase_step_count
+                    else:
+                        avg_per_step = subcat_stats.avg_us  # fallback
+                    print(
+                        f"    {subcat:12s} {_format_duration(subcat_stats.total_us):>10s} "
+                        f"({pct:5.1f}%)  avg: {_format_duration(avg_per_step)}"
+                    )
+            print()
+        else:
+            # Fall back to flat category display if no hierarchical categories
+            print("By Category:")
+            total_time = sum(c.total_us for c in stats.by_category.values())
+            for category, cat_stats in sorted(
+                stats.by_category.items(), key=lambda x: x[1].total_us, reverse=True
+            ):
+                pct = (cat_stats.total_us / total_time * 100) if total_time > 0 else 0
+                print(
+                    f"  {category:12s} {_format_duration(cat_stats.total_us):>10s} "
+                    f"({pct:5.1f}%)  avg: {_format_duration(cat_stats.avg_us):>8s}  "
+                    f"count: {cat_stats.count}"
+                )
+            print()
+
+    # By Rank
+    if stats.by_rank:
+        print("By Rank:")
+        for rank in sorted(stats.by_rank.keys()):
+            rank_stats = stats.by_rank[rank]
+            print(f"  Rank {rank}:")
+
+            # Parse hierarchical categories for this rank
+            rank_phases: dict[str, dict[str, CategoryStats]] = defaultdict(dict)
+            has_hierarchical = False
+            for cat, cat_stats in rank_stats.items():
+                if "/" in cat:
+                    phase, subcat = cat.split("/", 1)
+                    rank_phases[phase][subcat] = cat_stats
+                    has_hierarchical = True
+                else:
+                    rank_phases[cat]["_total"] = cat_stats
+
+            if has_hierarchical:
+                for phase in sorted(rank_phases.keys()):
+                    subcats = rank_phases[phase]
+                    non_total_subcats = {
+                        k: v for k, v in subcats.items() if k != "_total"
+                    }
+                    if not non_total_subcats:
+                        continue
+
+                    phase_total = sum(s.total_us for s in non_total_subcats.values())
+                    print(f"    {phase}:")
+                    for subcat, subcat_stats in sorted(
+                        non_total_subcats.items(),
+                        key=lambda x: x[1].total_us,
+                        reverse=True,
+                    ):
+                        pct = (
+                            subcat_stats.total_us / phase_total * 100
+                            if phase_total
+                            else 0
+                        )
+                        # Use parent phase's step count for per-step average
+                        phase_step_count = subcats.get("_total", CategoryStats()).count
+                        if phase_step_count > 0:
+                            avg_per_step = subcat_stats.total_us / phase_step_count
+                        else:
+                            avg_per_step = subcat_stats.avg_us  # fallback
+                        print(
+                            f"      {subcat:12s} {_format_duration(subcat_stats.total_us):>10s} "
+                            f"({pct:5.1f}%)  avg: {_format_duration(avg_per_step)}"
+                        )
+            else:
+                # Flat display fallback
+                for category, cat_stats in sorted(
+                    rank_stats.items(), key=lambda x: x[1].total_us, reverse=True
+                ):
+                    print(f"    {category}: {_format_duration(cat_stats.total_us)}")
+        print()
+
+
+if __name__ == "__main__":
+    import sys
+
+    path = Path(sys.argv[1]) if len(sys.argv) > 1 else Path("trace.json")
+
+    if not path.exists():
+        print(f"Error: File not found: {path}")
+        sys.exit(1)
+
+    traces = load_trace_file(path)
+    if not traces:
+        print("No trace events found in file.")
+        sys.exit(0)
+
+    computed_stats = compute_stats(traces)
+    print_stats(computed_stats)

src/exo/shared/types/api.py

@@ -7,10 +7,11 @@ from pydantic import BaseModel, Field, field_validator
 from pydantic_core import PydanticUseDefault
 
 from exo.shared.models.model_cards import ModelCard, ModelId
-from exo.shared.types.common import CommandId
+from exo.shared.types.common import CommandId, NodeId
 from exo.shared.types.memory import Memory
 from exo.shared.types.worker.instances import Instance, InstanceId, InstanceMeta
-from exo.shared.types.worker.shards import Sharding
+from exo.shared.types.worker.shards import Sharding, ShardMetadata
+from exo.utils.pydantic_ext import CamelCaseModel, ConfigDict, TaggedModel
 
 FinishReason = Literal[
     "stop", "length", "tool_calls", "content_filter", "function_call", "error"
@@ -115,8 +116,8 @@ class Usage(BaseModel):
     prompt_tokens: int
     completion_tokens: int
     total_tokens: int
-    prompt_tokens_details: PromptTokensDetails | None = None
-    completion_tokens_details: CompletionTokensDetails | None = None
+    prompt_tokens_details: PromptTokensDetails
+    completion_tokens_details: CompletionTokensDetails
 
 
 class StreamingChoiceResponse(BaseModel):
@@ -169,7 +170,13 @@ class BenchChatCompletionResponse(ChatCompletionResponse):
     generation_stats: GenerationStats | None = None
 
 
-class ChatCompletionTaskParams(BaseModel):
+class StreamOptions(BaseModel):
+    include_usage: bool = False
+
+
+class ChatCompletionTaskParams(TaggedModel):
+    model_config = ConfigDict(extra="ignore")
+
     model: str
     frequency_penalty: float | None = None
     messages: list[ChatCompletionMessage]
@@ -183,6 +190,7 @@ class ChatCompletionTaskParams(BaseModel):
     seed: int | None = None
     stop: str | list[str] | None = None
     stream: bool = False
+    stream_options: StreamOptions | None = None
     temperature: float | None = None
     top_p: float | None = None
     tools: list[dict[str, Any]] | None = None
@@ -352,3 +360,58 @@ class ImageListItem(BaseModel, frozen=True):
 
 class ImageListResponse(BaseModel, frozen=True):
     data: list[ImageListItem]
+
+
+class StartDownloadParams(CamelCaseModel):
+    target_node_id: NodeId
+    shard_metadata: ShardMetadata
+
+
+class StartDownloadResponse(CamelCaseModel):
+    command_id: CommandId
+
+
+class DeleteDownloadResponse(CamelCaseModel):
+    command_id: CommandId
+
+
+class TraceEventResponse(CamelCaseModel):
+    name: str
+    start_us: int
+    duration_us: int
+    rank: int
+    category: str
+
+
+class TraceResponse(CamelCaseModel):
+    task_id: str
+    traces: list[TraceEventResponse]
+
+
+class TraceCategoryStats(CamelCaseModel):
+    total_us: int
+    count: int
+    min_us: int
+    max_us: int
+    avg_us: float
+
+
+class TraceRankStats(CamelCaseModel):
+    by_category: dict[str, TraceCategoryStats]
+
+
+class TraceStatsResponse(CamelCaseModel):
+    task_id: str
+    total_wall_time_us: int
+    by_category: dict[str, TraceCategoryStats]
+    by_rank: dict[int, TraceRankStats]
+
+
+class TraceListItem(CamelCaseModel):
+    task_id: str
+    created_at: str
+    file_size: int
+
+
+class TraceListResponse(CamelCaseModel):
+    traces: list[TraceListItem]

src/exo/shared/types/chunks.py

@@ -2,7 +2,7 @@ from collections.abc import Generator
 from typing import Any, Literal
 
 from exo.shared.models.model_cards import ModelId
-from exo.shared.types.api import GenerationStats, ImageGenerationStats
+from exo.shared.types.api import GenerationStats, ImageGenerationStats, Usage
 from exo.utils.pydantic_ext import TaggedModel
 
 from .api import FinishReason
@@ -17,6 +17,7 @@ class BaseChunk(TaggedModel):
 class TokenChunk(BaseChunk):
     text: str
     token_id: int
+    usage: Usage | None
     finish_reason: Literal["stop", "length", "content_filter"] | None = None
     stats: GenerationStats | None = None
 
@@ -28,6 +29,7 @@ class ErrorChunk(BaseChunk):
 
 class ToolCallChunk(BaseChunk):
     tool_calls: list[ToolCallItem]
+    usage: Usage | None
     finish_reason: Literal["tool_calls"] = "tool_calls"
     stats: GenerationStats | None = None
 

src/exo/shared/types/commands.py

@@ -1,7 +1,8 @@
 from pydantic import Field
 
-from exo.shared.models.model_cards import ModelCard
+from exo.shared.models.model_cards import ModelCard, ModelId
 from exo.shared.types.api import (
+    BenchChatCompletionTaskParams,
     ChatCompletionTaskParams,
     ImageEditsInternalParams,
     ImageGenerationTaskParams,
@@ -9,7 +10,7 @@ from exo.shared.types.api import (
 from exo.shared.types.chunks import InputImageChunk
 from exo.shared.types.common import CommandId, NodeId
 from exo.shared.types.worker.instances import Instance, InstanceId, InstanceMeta
-from exo.shared.types.worker.shards import Sharding
+from exo.shared.types.worker.shards import Sharding, ShardMetadata
 from exo.utils.pydantic_ext import CamelCaseModel, TaggedModel
 
 
@@ -22,7 +23,7 @@ class TestCommand(BaseCommand):
 
 
 class ChatCompletion(BaseCommand):
-    request_params: ChatCompletionTaskParams
+    request_params: ChatCompletionTaskParams | BenchChatCompletionTaskParams
 
 
 class ImageGeneration(BaseCommand):
@@ -62,6 +63,19 @@ class RequestEventLog(BaseCommand):
     since_idx: int
 
 
+class StartDownload(BaseCommand):
+    target_node_id: NodeId
+    shard_metadata: ShardMetadata
+
+
+class DeleteDownload(BaseCommand):
+    target_node_id: NodeId
+    model_id: ModelId
+
+
+DownloadCommand = StartDownload | DeleteDownload
+
+
 Command = (
     TestCommand
     | RequestEventLog
@@ -79,3 +93,8 @@ Command = (
 class ForwarderCommand(CamelCaseModel):
     origin: NodeId
     command: Command
+
+
+class ForwarderDownloadCommand(CamelCaseModel):
+    origin: NodeId
+    command: DownloadCommand

src/exo/shared/types/events.py

@@ -1,4 +1,5 @@
 from datetime import datetime
+from typing import final
 
 from pydantic import Field
 
@@ -10,7 +11,7 @@ from exo.shared.types.worker.downloads import DownloadProgress
 from exo.shared.types.worker.instances import Instance, InstanceId
 from exo.shared.types.worker.runners import RunnerId, RunnerStatus
 from exo.utils.info_gatherer.info_gatherer import GatheredInfo
-from exo.utils.pydantic_ext import CamelCaseModel, TaggedModel
+from exo.utils.pydantic_ext import CamelCaseModel, FrozenModel, TaggedModel
 
 
 class EventId(Id):
@@ -109,6 +110,22 @@ class TopologyEdgeDeleted(BaseEvent):
     conn: Connection
 
 
+@final
+class TraceEventData(FrozenModel):
+    name: str
+    start_us: int
+    duration_us: int
+    rank: int
+    category: str
+
+
+@final
+class TracesCollected(BaseEvent):
+    task_id: TaskId
+    rank: int
+    traces: list[TraceEventData]
+
+
 Event = (
     TestEvent
     | TaskCreated
@@ -127,6 +144,7 @@ Event = (
     | InputChunkReceived
     | TopologyEdgeCreated
     | TopologyEdgeDeleted
+    | TracesCollected
 )
 
 

src/exo/shared/types/mlx.py

@@ -0,0 +1,12 @@
+"""Shared types for MLX-related functionality."""
+
+from collections.abc import Sequence
+
+from mlx_lm.models.cache import (
+    KVCache,
+    QuantizedKVCache,
+    RotatingKVCache,
+)
+
+# This list contains one cache entry per transformer layer
+KVCacheType = Sequence[KVCache | RotatingKVCache | QuantizedKVCache]

src/exo/shared/types/profiling.py

@@ -48,7 +48,7 @@ class SystemPerformanceProfile(CamelCaseModel):
     ecpu_usage: float = 0.0
 
 
-InterfaceType = Literal["wifi", "ethernet", "thunderbolt", "unknown"]
+InterfaceType = Literal["wifi", "ethernet", "maybe_ethernet", "thunderbolt", "unknown"]
 
 
 class NetworkInterfaceInfo(CamelCaseModel):

src/exo/shared/types/tasks.py

@@ -3,6 +3,7 @@ from enum import Enum
 from pydantic import Field
 
 from exo.shared.types.api import (
+    BenchChatCompletionTaskParams,
     ChatCompletionTaskParams,
     ImageEditsInternalParams,
     ImageGenerationTaskParams,
@@ -54,7 +55,7 @@ class StartWarmup(BaseTask):  # emitted by Worker
 
 class ChatCompletion(BaseTask):  # emitted by Master
     command_id: CommandId
-    task_params: ChatCompletionTaskParams
+    task_params: ChatCompletionTaskParams | BenchChatCompletionTaskParams
 
     error_type: str | None = Field(default=None)
     error_message: str | None = Field(default=None)

src/exo/shared/types/worker/runner_response.py

@@ -6,6 +6,7 @@ from exo.shared.types.api import (
     GenerationStats,
     ImageGenerationStats,
     ToolCallItem,
+    Usage,
 )
 from exo.utils.pydantic_ext import TaggedModel
 
@@ -24,12 +25,14 @@ class GenerationResponse(BaseRunnerResponse):
     # logprobs: list[float] | None = None # too big. we can change to be top-k
     finish_reason: FinishReason | None = None
     stats: GenerationStats | None = None
+    usage: Usage | None
 
 
 class ImageGenerationResponse(BaseRunnerResponse):
     image_data: bytes
     format: Literal["png", "jpeg", "webp"] = "png"
     stats: ImageGenerationStats | None = None
+    image_index: int = 0
 
     def __repr_args__(self) -> Generator[tuple[str, Any], None, None]:
         for name, value in super().__repr_args__():  # pyright: ignore[reportAny]
@@ -44,6 +47,7 @@ class PartialImageResponse(BaseRunnerResponse):
     format: Literal["png", "jpeg", "webp"] = "png"
     partial_index: int
     total_partials: int
+    image_index: int = 0
 
     def __repr_args__(self) -> Generator[tuple[str, Any], None, None]:
         for name, value in super().__repr_args__():  # pyright: ignore[reportAny]
@@ -55,6 +59,7 @@ class PartialImageResponse(BaseRunnerResponse):
 
 class ToolCallResponse(BaseRunnerResponse):
     tool_calls: list[ToolCallItem]
+    usage: Usage | None
 
 
 class FinishedResponse(BaseRunnerResponse):

src/exo/utils/info_gatherer/info_gatherer.py

@@ -349,13 +349,8 @@ class InfoGatherer:
     async def _monitor_misc(self):
         if self.misc_poll_interval is None:
             return
-        prev = await MiscData.gather()
-        await self.info_sender.send(prev)
         while True:
-            curr = await MiscData.gather()
-            if prev != curr:
-                prev = curr
-                await self.info_sender.send(curr)
+            await self.info_sender.send(await MiscData.gather())
             await anyio.sleep(self.misc_poll_interval)
 
     async def _monitor_system_profiler_thunderbolt_data(self):
@@ -365,15 +360,12 @@ class InfoGatherer:
         if iface_map is None:
             return
 
-        old_idents = []
         while True:
             data = await ThunderboltConnectivity.gather()
             assert data is not None
 
             idents = [it for i in data if (it := i.ident(iface_map)) is not None]
-            if idents != old_idents:
-                await self.info_sender.send(MacThunderboltIdentifiers(idents=idents))
-            old_idents = idents
+            await self.info_sender.send(MacThunderboltIdentifiers(idents=idents))
 
             conns = [it for i in data if (it := i.conn()) is not None]
             await self.info_sender.send(MacThunderboltConnections(conns=conns))
@@ -398,22 +390,17 @@ class InfoGatherer:
     async def _watch_system_info(self):
         if self.interface_watcher_interval is None:
             return
-        old_nics = []
         while True:
-            nics = get_network_interfaces()
-            if nics != old_nics:
-                old_nics = nics
-                await self.info_sender.send(NodeNetworkInterfaces(ifaces=nics))
+            nics = await get_network_interfaces()
+            await self.info_sender.send(NodeNetworkInterfaces(ifaces=nics))
             await anyio.sleep(self.interface_watcher_interval)
 
     async def _monitor_thunderbolt_bridge_status(self):
         if self.thunderbolt_bridge_poll_interval is None:
             return
-        prev: ThunderboltBridgeInfo | None = None
         while True:
             curr = await ThunderboltBridgeInfo.gather()
-            if curr is not None and prev != curr:
-                prev = curr
+            if curr is not None:
                 await self.info_sender.send(curr)
             await anyio.sleep(self.thunderbolt_bridge_poll_interval)
 

src/exo/utils/info_gatherer/system_info.py

@@ -1,6 +1,6 @@
 import socket
 import sys
-from subprocess import CalledProcessError, run
+from subprocess import CalledProcessError
 
 import psutil
 from anyio import run_process
@@ -16,8 +16,7 @@ async def get_friendly_name() -> str:
     """
     hostname = socket.gethostname()
 
-    # TODO: better non mac support
-    if sys.platform != "darwin":  # 'darwin' is the platform name for macOS
+    if sys.platform != "darwin":
         return hostname
 
     try:
@@ -28,21 +27,20 @@ async def get_friendly_name() -> str:
     return process.stdout.decode("utf-8", errors="replace").strip() or hostname
 
 
-def _get_interface_types_from_networksetup() -> dict[str, InterfaceType]:
+async def _get_interface_types_from_networksetup() -> dict[str, InterfaceType]:
     """Parse networksetup -listallhardwareports to get interface types."""
     if sys.platform != "darwin":
         return {}
+
     try:
-        result = run(
-            ["networksetup", "-listallhardwareports"], capture_output=True, text=True
-        )
-    except Exception:
+        result = await run_process(["networksetup", "-listallhardwareports"])
+    except CalledProcessError:
         return {}
 
     types: dict[str, InterfaceType] = {}
     current_type: InterfaceType = "unknown"
 
-    for line in result.stdout.splitlines():
+    for line in result.stdout.decode().splitlines():
         if line.startswith("Hardware Port:"):
             port_name = line.split(":", 1)[1].strip()
             if "Wi-Fi" in port_name:
@@ -55,12 +53,15 @@ def _get_interface_types_from_networksetup() -> dict[str, InterfaceType]:
                 current_type = "unknown"
         elif line.startswith("Device:"):
             device = line.split(":", 1)[1].strip()
+            # enX is ethernet adapters or thunderbolt - these must be deprioritised
+            if device.startswith("en") and device not in ["en0", "en1"]:
+                current_type = "maybe_ethernet"
             types[device] = current_type
 
     return types
 
 
-def get_network_interfaces() -> list[NetworkInterfaceInfo]:
+async def get_network_interfaces() -> list[NetworkInterfaceInfo]:
     """
     Retrieves detailed network interface information on macOS.
     Parses output from 'networksetup -listallhardwareports' and 'ifconfig'
@@ -68,7 +69,7 @@ def get_network_interfaces() -> list[NetworkInterfaceInfo]:
     Returns a list of NetworkInterfaceInfo objects.
     """
     interfaces_info: list[NetworkInterfaceInfo] = []
-    interface_types = _get_interface_types_from_networksetup()
+    interface_types = await _get_interface_types_from_networksetup()
 
     for iface, services in psutil.net_if_addrs().items():
         for service in services:

src/exo/utils/keyed_backoff.py

@@ -0,0 +1,32 @@
+import time
+from typing import Generic, TypeVar
+
+K = TypeVar("K")
+
+
+class KeyedBackoff(Generic[K]):
+    """Tracks exponential backoff state per key."""
+
+    def __init__(self, base: float = 0.5, cap: float = 10.0):
+        self._base = base
+        self._cap = cap
+        self._attempts: dict[K, int] = {}
+        self._last_time: dict[K, float] = {}
+
+    def should_proceed(self, key: K) -> bool:
+        """Returns True if enough time has elapsed since last attempt."""
+        now = time.monotonic()
+        last = self._last_time.get(key, 0.0)
+        attempts = self._attempts.get(key, 0)
+        delay = min(self._cap, self._base * (2.0**attempts))
+        return now - last >= delay
+
+    def record_attempt(self, key: K) -> None:
+        """Record that an attempt was made for this key."""
+        self._last_time[key] = time.monotonic()
+        self._attempts[key] = self._attempts.get(key, 0) + 1
+
+    def reset(self, key: K) -> None:
+        """Reset backoff state for a key (e.g., on success)."""
+        self._attempts.pop(key, None)
+        self._last_time.pop(key, None)

src/exo/worker/engines/image/distributed_model.py

@@ -6,10 +6,10 @@ import mlx.core as mx
 from mflux.models.common.config.config import Config
 from PIL import Image
 
+from exo.download.download_utils import build_model_path
 from exo.shared.types.api import AdvancedImageParams
 from exo.shared.types.worker.instances import BoundInstance
 from exo.shared.types.worker.shards import PipelineShardMetadata
-from exo.worker.download.download_utils import build_model_path
 from exo.worker.engines.image.config import ImageModelConfig
 from exo.worker.engines.image.models import (
     create_adapter_for_model,
@@ -140,6 +140,7 @@ class DistributedImageModel:
             width=width,
             image_path=image_path,
             model_config=self._adapter.model.model_config,  # pyright: ignore[reportAny]
+            guidance=guidance_override if guidance_override is not None else 4.0,
         )
 
         num_sync_steps = self._config.get_num_sync_steps(steps)

src/exo/worker/engines/image/generate.py

@@ -75,19 +75,20 @@ def generate_image(
     intermediate images, then ImageGenerationResponse for the final image.
 
     Yields:
-        PartialImageResponse for intermediate images (if partial_images > 0)
-        ImageGenerationResponse for the final complete image
+        PartialImageResponse for intermediate images (if partial_images > 0, first image only)
+        ImageGenerationResponse for final complete images
     """
     width, height = parse_size(task.size)
     quality: Literal["low", "medium", "high"] = task.quality or "medium"
 
     advanced_params = task.advanced_params
     if advanced_params is not None and advanced_params.seed is not None:
-        seed = advanced_params.seed
+        base_seed = advanced_params.seed
     else:
-        seed = random.randint(0, 2**32 - 1)
+        base_seed = random.randint(0, 2**32 - 1)
 
     is_bench = getattr(task, "bench", False)
+    num_images = task.n or 1
 
     generation_start_time: float = 0.0
 
@@ -95,7 +96,11 @@ def generate_image(
         mx.reset_peak_memory()
         generation_start_time = time.perf_counter()
 
-    partial_images = task.partial_images or (3 if task.stream else 0)
+    partial_images = (
+        task.partial_images
+        if task.partial_images is not None and task.stream is not None and task.stream
+        else 0
+    )
 
     image_path: Path | None = None
 
@@ -105,72 +110,81 @@ def generate_image(
             image_path = Path(tmpdir) / "input.png"
             image_path.write_bytes(base64.b64decode(task.image_data))
 
-        # Iterate over generator results
-        for result in model.generate(
-            prompt=task.prompt,
-            height=height,
-            width=width,
-            quality=quality,
-            seed=seed,
-            image_path=image_path,
-            partial_images=partial_images,
-            advanced_params=advanced_params,
-        ):
-            if isinstance(result, tuple):
-                # Partial image: (Image, partial_index, total_partials)
-                image, partial_idx, total_partials = result
-                buffer = io.BytesIO()
-                image_format = task.output_format.upper()
-                if image_format == "JPG":
-                    image_format = "JPEG"
-                if image_format == "JPEG" and image.mode == "RGBA":
-                    image = image.convert("RGB")
-                image.save(buffer, format=image_format)
+        for image_num in range(num_images):
+            # Increment seed for each image to ensure unique results
+            current_seed = base_seed + image_num
 
-                yield PartialImageResponse(
-                    image_data=buffer.getvalue(),
-                    format=task.output_format,
-                    partial_index=partial_idx,
-                    total_partials=total_partials,
-                )
-            else:
-                image = result
+            for result in model.generate(
+                prompt=task.prompt,
+                height=height,
+                width=width,
+                quality=quality,
+                seed=current_seed,
+                image_path=image_path,
+                partial_images=partial_images,
+                advanced_params=advanced_params,
+            ):
+                if isinstance(result, tuple):
+                    # Partial image: (Image, partial_index, total_partials)
+                    image, partial_idx, total_partials = result
+                    buffer = io.BytesIO()
+                    image_format = task.output_format.upper()
+                    if image_format == "JPG":
+                        image_format = "JPEG"
+                    if image_format == "JPEG" and image.mode == "RGBA":
+                        image = image.convert("RGB")
+                    image.save(buffer, format=image_format)
 
-                stats: ImageGenerationStats | None = None
-                if is_bench:
-                    generation_end_time = time.perf_counter()
-                    total_generation_time = generation_end_time - generation_start_time
-
-                    num_inference_steps = model.get_steps_for_quality(quality)
-
-                    seconds_per_step = (
-                        total_generation_time / num_inference_steps
-                        if num_inference_steps > 0
-                        else 0.0
+                    yield PartialImageResponse(
+                        image_data=buffer.getvalue(),
+                        format=task.output_format,
+                        partial_index=partial_idx,
+                        total_partials=total_partials,
+                        image_index=image_num,
                     )
+                else:
+                    image = result
 
-                    peak_memory_gb = mx.get_peak_memory() / (1024**3)
+                    # Only include stats on the final image
+                    stats: ImageGenerationStats | None = None
+                    if is_bench and image_num == num_images - 1:
+                        generation_end_time = time.perf_counter()
+                        total_generation_time = (
+                            generation_end_time - generation_start_time
+                        )
 
-                    stats = ImageGenerationStats(
-                        seconds_per_step=seconds_per_step,
-                        total_generation_time=total_generation_time,
-                        num_inference_steps=num_inference_steps,
-                        num_images=task.n or 1,
-                        image_width=width,
-                        image_height=height,
-                        peak_memory_usage=Memory.from_gb(peak_memory_gb),
+                        num_inference_steps = model.get_steps_for_quality(quality)
+                        total_steps = num_inference_steps * num_images
+
+                        seconds_per_step = (
+                            total_generation_time / total_steps
+                            if total_steps > 0
+                            else 0.0
+                        )
+
+                        peak_memory_gb = mx.get_peak_memory() / (1024**3)
+
+                        stats = ImageGenerationStats(
+                            seconds_per_step=seconds_per_step,
+                            total_generation_time=total_generation_time,
+                            num_inference_steps=num_inference_steps,
+                            num_images=num_images,
+                            image_width=width,
+                            image_height=height,
+                            peak_memory_usage=Memory.from_gb(peak_memory_gb),
+                        )
+
+                    buffer = io.BytesIO()
+                    image_format = task.output_format.upper()
+                    if image_format == "JPG":
+                        image_format = "JPEG"
+                    if image_format == "JPEG" and image.mode == "RGBA":
+                        image = image.convert("RGB")
+                    image.save(buffer, format=image_format)
+
+                    yield ImageGenerationResponse(
+                        image_data=buffer.getvalue(),
+                        format=task.output_format,
+                        stats=stats,
+                        image_index=image_num,
                     )
-
-                buffer = io.BytesIO()
-                image_format = task.output_format.upper()
-                if image_format == "JPG":
-                    image_format = "JPEG"
-                if image_format == "JPEG" and image.mode == "RGBA":
-                    image = image.convert("RGB")
-                image.save(buffer, format=image_format)
-
-                yield ImageGenerationResponse(
-                    image_data=buffer.getvalue(),
-                    format=task.output_format,
-                    stats=stats,
-                )

src/exo/worker/engines/image/models/__init__.py

@@ -33,6 +33,7 @@ _ADAPTER_REGISTRY: dict[str, AdapterFactory] = {
 # Config registry: maps model ID patterns to configs
 _CONFIG_REGISTRY: dict[str, ImageModelConfig] = {
     "flux.1-schnell": FLUX_SCHNELL_CONFIG,
+    "flux.1-krea-dev": FLUX_DEV_CONFIG,  # Must come before "flux.1-dev" for pattern matching
     "flux.1-dev": FLUX_DEV_CONFIG,
     "qwen-image-edit": QWEN_IMAGE_EDIT_CONFIG,  # Must come before "qwen-image" for pattern matching
     "qwen-image": QWEN_IMAGE_CONFIG,

src/exo/worker/engines/image/pipeline/runner.py

@@ -6,6 +6,11 @@ from mflux.models.common.config.config import Config
 from mflux.utils.exceptions import StopImageGenerationException
 from tqdm import tqdm
 
+from exo.shared.tracing import (
+    clear_trace_buffer,
+    is_tracing_enabled,
+    trace,
+)
 from exo.shared.types.worker.shards import PipelineShardMetadata
 from exo.worker.engines.image.config import ImageModelConfig
 from exo.worker.engines.image.models.base import (
@@ -324,6 +329,7 @@ class DiffusionRunner:
             capture_steps = set()
 
         self._reset_all_caches()
+        clear_trace_buffer()
 
         time_steps = tqdm(range(runtime_config.num_inference_steps))
 
@@ -348,6 +354,7 @@ class DiffusionRunner:
                 ctx.in_loop(  # pyright: ignore[reportAny]
                     t=t,
                     latents=latents,
+                    time_steps=time_steps,
                 )
 
                 mx.eval(latents)
@@ -464,20 +471,22 @@ class DiffusionRunner:
         if self.group is None:
             return self._single_node_step(t, config, latents, prompt_data)
         elif t < config.init_time_step + num_sync_steps:
-            return self._sync_pipeline_step(
-                t,
-                config,
-                latents,
-                prompt_data,
-            )
+            with trace(name=f"sync {t}", rank=self.rank, category="sync"):
+                return self._sync_pipeline_step(
+                    t,
+                    config,
+                    latents,
+                    prompt_data,
+                )
         else:
-            return self._async_pipeline_step(
-                t,
-                config,
-                latents,
-                prompt_data,
-                is_first_async_step=t == config.init_time_step + num_sync_steps,
-            )
+            with trace(name=f"async {t}", rank=self.rank, category="async"):
+                return self._async_pipeline_step(
+                    t,
+                    config,
+                    latents,
+                    prompt_data,
+                    is_first_async_step=t == config.init_time_step + num_sync_steps,
+                )
 
     def _single_node_step(
         self,
@@ -585,30 +594,41 @@ class DiffusionRunner:
 
         if self.has_joint_blocks:
             if not self.is_first_stage:
-                hidden_states = mx.distributed.recv(
-                    (batch_size, num_img_tokens, hidden_dim),
-                    dtype,
-                    self.prev_rank,
-                    group=self.group,
-                )
-                encoder_hidden_states = mx.distributed.recv(
-                    (batch_size, text_seq_len, hidden_dim),
-                    dtype,
-                    self.prev_rank,
-                    group=self.group,
-                )
-                mx.eval(hidden_states, encoder_hidden_states)
+                with trace(
+                    name=f"recv {self.prev_rank}", rank=self.rank, category="comms"
+                ):
+                    hidden_states = mx.distributed.recv(
+                        (batch_size, num_img_tokens, hidden_dim),
+                        dtype,
+                        self.prev_rank,
+                        group=self.group,
+                    )
+                    encoder_hidden_states = mx.distributed.recv(
+                        (batch_size, text_seq_len, hidden_dim),
+                        dtype,
+                        self.prev_rank,
+                        group=self.group,
+                    )
+                    mx.eval(hidden_states, encoder_hidden_states)
 
             assert self.joint_block_wrappers is not None
             assert encoder_hidden_states is not None
-            for wrapper in self.joint_block_wrappers:
-                wrapper.set_patch(BlockWrapperMode.CACHING)
-                encoder_hidden_states, hidden_states = wrapper(
-                    hidden_states=hidden_states,
-                    encoder_hidden_states=encoder_hidden_states,
-                    text_embeddings=text_embeddings,
-                    rotary_embeddings=image_rotary_embeddings,
-                )
+            with trace(
+                name="joint_blocks",
+                rank=self.rank,
+                category="compute",
+            ):
+                for wrapper in self.joint_block_wrappers:
+                    wrapper.set_patch(BlockWrapperMode.CACHING)
+                    encoder_hidden_states, hidden_states = wrapper(
+                        hidden_states=hidden_states,
+                        encoder_hidden_states=encoder_hidden_states,
+                        text_embeddings=text_embeddings,
+                        rotary_embeddings=image_rotary_embeddings,
+                    )
+
+                if is_tracing_enabled():
+                    mx.eval(encoder_hidden_states, hidden_states)
 
         if self.owns_concat_stage:
             assert encoder_hidden_states is not None
@@ -619,45 +639,63 @@ class DiffusionRunner:
             if self.has_single_blocks or self.is_last_stage:
                 hidden_states = concatenated
             else:
-                concatenated = mx.distributed.send(
-                    concatenated, self.next_rank, group=self.group
-                )
-                mx.async_eval(concatenated)
+                with trace(
+                    name=f"send {self.next_rank}", rank=self.rank, category="comms"
+                ):
+                    concatenated = mx.distributed.send(
+                        concatenated, self.next_rank, group=self.group
+                    )
+                    mx.async_eval(concatenated)
 
         elif self.has_joint_blocks and not self.is_last_stage:
             assert encoder_hidden_states is not None
-            hidden_states = mx.distributed.send(
-                hidden_states, self.next_rank, group=self.group
-            )
-            encoder_hidden_states = mx.distributed.send(
-                encoder_hidden_states, self.next_rank, group=self.group
-            )
-            mx.async_eval(hidden_states, encoder_hidden_states)
-
-        if self.has_single_blocks:
-            if not self.owns_concat_stage and not self.is_first_stage:
-                hidden_states = mx.distributed.recv(
-                    (batch_size, text_seq_len + num_img_tokens, hidden_dim),
-                    dtype,
-                    self.prev_rank,
-                    group=self.group,
-                )
-                mx.eval(hidden_states)
-
-            assert self.single_block_wrappers is not None
-            for wrapper in self.single_block_wrappers:
-                wrapper.set_patch(BlockWrapperMode.CACHING)
-                hidden_states = wrapper(
-                    hidden_states=hidden_states,
-                    text_embeddings=text_embeddings,
-                    rotary_embeddings=image_rotary_embeddings,
-                )
-
-            if not self.is_last_stage:
+            with trace(name=f"send {self.next_rank}", rank=self.rank, category="comms"):
                 hidden_states = mx.distributed.send(
                     hidden_states, self.next_rank, group=self.group
                 )
-                mx.async_eval(hidden_states)
+                encoder_hidden_states = mx.distributed.send(
+                    encoder_hidden_states, self.next_rank, group=self.group
+                )
+                mx.async_eval(hidden_states, encoder_hidden_states)
+
+        if self.has_single_blocks:
+            if not self.owns_concat_stage and not self.is_first_stage:
+                with trace(
+                    name=f"recv {self.prev_rank}", rank=self.rank, category="comms"
+                ):
+                    hidden_states = mx.distributed.recv(
+                        (batch_size, text_seq_len + num_img_tokens, hidden_dim),
+                        dtype,
+                        self.prev_rank,
+                        group=self.group,
+                    )
+                    mx.eval(hidden_states)
+
+            assert self.single_block_wrappers is not None
+            with trace(
+                name="single blocks",
+                rank=self.rank,
+                category="compute",
+            ):
+                for wrapper in self.single_block_wrappers:
+                    wrapper.set_patch(BlockWrapperMode.CACHING)
+                    hidden_states = wrapper(
+                        hidden_states=hidden_states,
+                        text_embeddings=text_embeddings,
+                        rotary_embeddings=image_rotary_embeddings,
+                    )
+
+                if is_tracing_enabled():
+                    mx.eval(hidden_states)
+
+            if not self.is_last_stage:
+                with trace(
+                    name=f"send {self.next_rank}", rank=self.rank, category="comms"
+                ):
+                    hidden_states = mx.distributed.send(
+                        hidden_states, self.next_rank, group=self.group
+                    )
+                    mx.async_eval(hidden_states)
 
         hidden_states = hidden_states[:, text_seq_len:, ...]
 
@@ -741,14 +779,20 @@ class DiffusionRunner:
             )
 
             if not self.is_first_stage:
-                hidden_states = mx.distributed.send(hidden_states, 0, group=self.group)
-                mx.async_eval(hidden_states)
+                with trace(name="send 0", rank=self.rank, category="comms"):
+                    hidden_states = mx.distributed.send(
+                        hidden_states, 0, group=self.group
+                    )
+                    mx.async_eval(hidden_states)
 
         elif self.is_first_stage:
-            hidden_states = mx.distributed.recv_like(
-                prev_latents, src=self.world_size - 1, group=self.group
-            )
-            mx.eval(hidden_states)
+            with trace(
+                name=f"recv {self.world_size - 1}", rank=self.rank, category="comms"
+            ):
+                hidden_states = mx.distributed.recv_like(
+                    prev_latents, src=self.world_size - 1, group=self.group
+                )
+                mx.eval(hidden_states)
 
         else:
             hidden_states = prev_latents
@@ -808,10 +852,13 @@ class DiffusionRunner:
                 and not self.is_last_stage
                 and not is_first_async_step
             ):
-                patch = mx.distributed.recv_like(
-                    patch, src=self.prev_rank, group=self.group
-                )
-                mx.eval(patch)
+                with trace(
+                    name=f"recv {self.prev_rank}", rank=self.rank, category="comms"
+                ):
+                    patch = mx.distributed.recv_like(
+                        patch, src=self.prev_rank, group=self.group
+                    )
+                    mx.eval(patch)
 
             step_patch = mx.concatenate([patch, patch], axis=0) if needs_cfg else patch
 
@@ -842,10 +889,13 @@ class DiffusionRunner:
                 )
 
                 if not self.is_first_stage and t != config.num_inference_steps - 1:
-                    patch_latents[patch_idx] = mx.distributed.send(
-                        patch_latents[patch_idx], self.next_rank, group=self.group
-                    )
-                    mx.async_eval(patch_latents[patch_idx])
+                    with trace(
+                        name=f"send {self.next_rank}", rank=self.rank, category="comms"
+                    ):
+                        patch_latents[patch_idx] = mx.distributed.send(
+                            patch_latents[patch_idx], self.next_rank, group=self.group
+                        )
+                        mx.async_eval(patch_latents[patch_idx])
 
         return mx.concatenate(patch_latents, axis=1)
 
@@ -884,22 +934,28 @@ class DiffusionRunner:
         if self.has_joint_blocks:
             if not self.is_first_stage:
                 patch_len = patch.shape[1]
-                patch = mx.distributed.recv(
-                    (batch_size, patch_len, hidden_dim),
-                    patch.dtype,
-                    self.prev_rank,
-                    group=self.group,
-                )
-                mx.eval(patch)
-
-                if patch_idx == 0:
-                    encoder_hidden_states = mx.distributed.recv(
-                        (batch_size, text_seq_len, hidden_dim),
+                with trace(
+                    name=f"recv {self.prev_rank}", rank=self.rank, category="comms"
+                ):
+                    patch = mx.distributed.recv(
+                        (batch_size, patch_len, hidden_dim),
                         patch.dtype,
                         self.prev_rank,
                         group=self.group,
                     )
-                    mx.eval(encoder_hidden_states)
+                    mx.eval(patch)
+
+                if patch_idx == 0:
+                    with trace(
+                        name=f"recv {self.prev_rank}", rank=self.rank, category="comms"
+                    ):
+                        encoder_hidden_states = mx.distributed.recv(
+                            (batch_size, text_seq_len, hidden_dim),
+                            patch.dtype,
+                            self.prev_rank,
+                            group=self.group,
+                        )
+                        mx.eval(encoder_hidden_states)
 
             if self.is_first_stage:
                 patch, encoder_hidden_states = self.adapter.compute_embeddings(
@@ -908,14 +964,22 @@ class DiffusionRunner:
 
             assert self.joint_block_wrappers is not None
             assert encoder_hidden_states is not None
-            for wrapper in self.joint_block_wrappers:
-                wrapper.set_patch(BlockWrapperMode.PATCHED, start_token, end_token)
-                encoder_hidden_states, patch = wrapper(
-                    hidden_states=patch,
-                    encoder_hidden_states=encoder_hidden_states,
-                    text_embeddings=text_embeddings,
-                    rotary_embeddings=image_rotary_embeddings,
-                )
+            with trace(
+                name=f"joint patch {patch_idx}",
+                rank=self.rank,
+                category="compute",
+            ):
+                for wrapper in self.joint_block_wrappers:
+                    wrapper.set_patch(BlockWrapperMode.PATCHED, start_token, end_token)
+                    encoder_hidden_states, patch = wrapper(
+                        hidden_states=patch,
+                        encoder_hidden_states=encoder_hidden_states,
+                        text_embeddings=text_embeddings,
+                        rotary_embeddings=image_rotary_embeddings,
+                    )
+
+                if is_tracing_enabled():
+                    mx.eval(encoder_hidden_states, patch)
 
         if self.owns_concat_stage:
             assert encoder_hidden_states is not None
@@ -924,49 +988,70 @@ class DiffusionRunner:
             if self.has_single_blocks or self.is_last_stage:
                 patch = patch_concat
             else:
-                patch_concat = mx.distributed.send(
-                    patch_concat, self.next_rank, group=self.group
-                )
-                mx.async_eval(patch_concat)
+                with trace(
+                    name=f"send {self.next_rank}", rank=self.rank, category="comms"
+                ):
+                    patch_concat = mx.distributed.send(
+                        patch_concat, self.next_rank, group=self.group
+                    )
+                    mx.async_eval(patch_concat)
 
         elif self.has_joint_blocks and not self.is_last_stage:
-            patch = mx.distributed.send(patch, self.next_rank, group=self.group)
-            mx.async_eval(patch)
+            with trace(name=f"send {self.next_rank}", rank=self.rank, category="comms"):
+                patch = mx.distributed.send(patch, self.next_rank, group=self.group)
+                mx.async_eval(patch)
 
             if patch_idx == 0:
                 assert encoder_hidden_states is not None
-                encoder_hidden_states = mx.distributed.send(
-                    encoder_hidden_states, self.next_rank, group=self.group
-                )
-                mx.async_eval(encoder_hidden_states)
+                with trace(
+                    name=f"send {self.next_rank}", rank=self.rank, category="comms"
+                ):
+                    encoder_hidden_states = mx.distributed.send(
+                        encoder_hidden_states, self.next_rank, group=self.group
+                    )
+                    mx.async_eval(encoder_hidden_states)
 
         if self.has_single_blocks:
             if not self.owns_concat_stage and not self.is_first_stage:
                 patch_len = patch.shape[1]
-                patch = mx.distributed.recv(
-                    (batch_size, text_seq_len + patch_len, hidden_dim),
-                    patch.dtype,
-                    self.prev_rank,
-                    group=self.group,
-                )
-                mx.eval(patch)
+                with trace(
+                    name=f"recv {self.prev_rank}", rank=self.rank, category="comms"
+                ):
+                    patch = mx.distributed.recv(
+                        (batch_size, text_seq_len + patch_len, hidden_dim),
+                        patch.dtype,
+                        self.prev_rank,
+                        group=self.group,
+                    )
+                    mx.eval(patch)
 
             assert self.single_block_wrappers is not None
-            for wrapper in self.single_block_wrappers:
-                wrapper.set_patch(BlockWrapperMode.PATCHED, start_token, end_token)
-                patch = wrapper(
-                    hidden_states=patch,
-                    text_embeddings=text_embeddings,
-                    rotary_embeddings=image_rotary_embeddings,
-                )
+            with trace(
+                name=f"single patch {patch_idx}",
+                rank=self.rank,
+                category="compute",
+            ):
+                for wrapper in self.single_block_wrappers:
+                    wrapper.set_patch(BlockWrapperMode.PATCHED, start_token, end_token)
+                    patch = wrapper(
+                        hidden_states=patch,
+                        text_embeddings=text_embeddings,
+                        rotary_embeddings=image_rotary_embeddings,
+                    )
+
+                if is_tracing_enabled():
+                    mx.eval(patch)
 
             if not self.is_last_stage:
-                patch = mx.distributed.send(patch, self.next_rank, group=self.group)
-                mx.async_eval(patch)
+                with trace(
+                    name=f"send {self.next_rank}", rank=self.rank, category="comms"
+                ):
+                    patch = mx.distributed.send(patch, self.next_rank, group=self.group)
+                    mx.async_eval(patch)
 
         noise: mx.array | None = None
         if self.is_last_stage:
-            patch_img_only = patch[:, text_seq_len:, :]
-            noise = self.adapter.final_projection(patch_img_only, text_embeddings)
+            patch = patch[:, text_seq_len:, :]
+            noise = self.adapter.final_projection(patch, text_embeddings)
 
         return noise, encoder_hidden_states

src/exo/worker/engines/mlx/auto_parallel.py

@@ -19,8 +19,11 @@ from mlx_lm.models.deepseek_v32 import DeepseekV32MLP
 from mlx_lm.models.deepseek_v32 import Model as DeepseekV32Model
 from mlx_lm.models.glm4_moe import Model as Glm4MoeModel
 from mlx_lm.models.glm4_moe import MoE
+from mlx_lm.models.glm4_moe_lite import Glm4MoeLiteDecoderLayer, Glm4MoeLiteMLP
+from mlx_lm.models.glm4_moe_lite import Model as GLM4MoeLiteModel
 from mlx_lm.models.gpt_oss import GptOssMoeModel
 from mlx_lm.models.gpt_oss import Model as GptOssModel
+from mlx_lm.models.kimi_k25 import Model as KimiK25Model
 from mlx_lm.models.llama import Model as LlamaModel
 from mlx_lm.models.minimax import Model as MiniMaxModel
 from mlx_lm.models.ministral3 import Model as Ministral3Model
@@ -145,6 +148,10 @@ class PipelineLastLayer(CustomMlxLayer):
             if cache is not None:
                 cache.keys = mx.depends(cache.keys, output)  # type: ignore[reportUnknownMemberType]
 
+        output = mx.distributed.all_gather(output, group=self.group)[
+            -output.shape[0] :
+        ]  # type :ignore
+
         return output
 
 
@@ -194,6 +201,9 @@ def pipeline_auto_parallel(
     device_rank, world_size = model_shard_meta.device_rank, model_shard_meta.world_size
 
     layers = layers[start_layer:end_layer]
+    for layer in layers:
+        mx.eval(layer)  # type: ignore
+
     layers[0] = PipelineFirstLayer(layers[0], device_rank, group=group)
     layers[-1] = PipelineLastLayer(
         layers[-1],
@@ -252,10 +262,6 @@ def patch_pipeline_model[T](model: T, group: mx.distributed.Group) -> T:
         if cache is not None:
             cache[-1].state = mx.depends(cache[-1].state, logits)  # type: ignore
 
-        logits = mx.distributed.all_gather(logits, group=group)[
-            -logits.shape[0] :
-        ]  # type :ignore
-
         return logits
 
     cls.__call__ = patched_call
@@ -334,15 +340,7 @@ def tensor_auto_parallel(
         group=group,
     )
 
-    if hasattr(model, "shard") and not isinstance(model, GptOssModel):
-        try:
-            model.shard(group)  # type: ignore
-            return patch_tensor_model(model)
-        except (AttributeError, TypeError, NameError):
-            pass
-
     if isinstance(model, (LlamaModel, Ministral3Model)):
-        logger.warning("shouldn't be hit - upstream sharding exists")
         tensor_parallel_sharding_strategy = LlamaShardingStrategy(
             group,
             all_to_sharded_linear,
@@ -350,8 +348,7 @@ def tensor_auto_parallel(
             all_to_sharded_linear_in_place,
             sharded_to_all_linear_in_place,
         )
-    elif isinstance(model, (DeepseekV3Model, DeepseekV32Model)):
-        logger.warning("shouldn't be hit - upstream sharding exists")
+    elif isinstance(model, (DeepseekV3Model, DeepseekV32Model, KimiK25Model)):
         tensor_parallel_sharding_strategy = DeepSeekShardingStrategy(
             group,
             all_to_sharded_linear,
@@ -367,6 +364,14 @@ def tensor_auto_parallel(
             all_to_sharded_linear_in_place,
             sharded_to_all_linear_in_place,
         )
+    elif isinstance(model, GLM4MoeLiteModel):
+        tensor_parallel_sharding_strategy = GLM4MoeLiteShardingStrategy(
+            group,
+            all_to_sharded_linear,
+            sharded_to_all_linear,
+            all_to_sharded_linear_in_place,
+            sharded_to_all_linear_in_place,
+        )
     elif isinstance(model, (Qwen3MoeModel, Glm4MoeModel, Qwen3NextModel)):
         tensor_parallel_sharding_strategy = QwenShardingStrategy(
             group,
@@ -441,7 +446,7 @@ class LlamaShardingStrategy(TensorParallelShardingStrategy):
             layer.mlp.gate_proj = self.all_to_sharded_linear(layer.mlp.gate_proj)
             layer.mlp.down_proj = self.sharded_to_all_linear(layer.mlp.down_proj)
             layer.mlp.up_proj = self.all_to_sharded_linear(layer.mlp.up_proj)
-
+            mx.eval(layer)
         return model
 
 
@@ -452,7 +457,7 @@ def _set_layers(model: nn.Module, layers: list[_LayerCallable]) -> None:
 
         # Update DeepSeek V3 specific parameters when layers are shrunk
         if isinstance(
-            model, (DeepseekV3Model, DeepseekV32Model, Glm4MoeModel)
+            model, (DeepseekV3Model, DeepseekV32Model, Glm4MoeModel, KimiK25Model)
         ) and hasattr(inner_model_instance, "num_layers"):
             logger.info(
                 f"Setting num_layers to {len(layers)} for model {model.model.__class__.__name__}"
@@ -516,6 +521,8 @@ class DeepSeekShardingStrategy(TensorParallelShardingStrategy):
                 layer.mlp = ShardedDeepseekV3MoE(layer.mlp)  # type: ignore
                 layer.mlp.sharding_group = self.group
 
+            mx.eval(layer)
+
         return model
 
 
@@ -533,6 +540,84 @@ class ShardedDeepseekV3MoE(CustomMlxLayer):
         return y
 
 
+class GLM4MoeLiteShardingStrategy(TensorParallelShardingStrategy):
+    def shard_model(
+        self,
+        model: nn.Module,
+        timeout_seconds: float,
+        on_timeout: TimeoutCallback | None,
+    ) -> nn.Module:
+        model = cast(GLM4MoeLiteModel, model)
+        for layer in model.layers:  # type: ignore
+            layer = cast(Glm4MoeLiteDecoderLayer, layer)
+            eval_with_timeout(
+                layer.parameters(),
+                timeout_seconds / len(model.layers),  # type: ignore
+                on_timeout,
+            )
+            if layer.self_attn.q_lora_rank is None:  # type: ignore
+                layer.self_attn.q_proj = self.all_to_sharded_linear(
+                    layer.self_attn.q_proj
+                )
+            else:
+                layer.self_attn.q_b_proj = self.all_to_sharded_linear(
+                    layer.self_attn.q_b_proj
+                )
+
+            layer.self_attn.o_proj = self.sharded_to_all_linear(layer.self_attn.o_proj)
+            layer.self_attn.num_heads //= self.N
+
+            # Logic from upstream mlx
+            num_heads = layer.self_attn.num_heads
+            sh = self.group.rank() * num_heads
+            eh = sh + num_heads
+
+            def shard_heads(w: mx.array, sh: int = sh, eh: int = eh) -> mx.array:
+                return w[sh:eh]
+
+            layer.self_attn.embed_q.apply(shard_heads)
+            layer.self_attn.unembed_out.apply(shard_heads)
+
+            if isinstance(layer.mlp, Glm4MoeLiteMLP):
+                layer.mlp.gate_proj = self.all_to_sharded_linear(layer.mlp.gate_proj)
+                layer.mlp.down_proj = self.sharded_to_all_linear(layer.mlp.down_proj)
+                layer.mlp.up_proj = self.all_to_sharded_linear(layer.mlp.up_proj)
+
+            else:
+                if getattr(layer.mlp, "shared_experts", None) is not None:
+                    self.all_to_sharded_linear_in_place(
+                        layer.mlp.shared_experts.gate_proj
+                    )
+                    self.sharded_to_all_linear_in_place(
+                        layer.mlp.shared_experts.down_proj
+                    )
+                    self.all_to_sharded_linear_in_place(
+                        layer.mlp.shared_experts.up_proj
+                    )
+                self.all_to_sharded_linear_in_place(layer.mlp.switch_mlp.gate_proj)
+                self.sharded_to_all_linear_in_place(layer.mlp.switch_mlp.down_proj)
+                self.all_to_sharded_linear_in_place(layer.mlp.switch_mlp.up_proj)
+                layer.mlp = ShardedGLM4MoeLiteMoE(layer.mlp)  # type: ignore
+                layer.mlp.sharding_group = self.group  # type: ignore
+            mx.eval(layer)
+
+        return model
+
+
+class ShardedGLM4MoeLiteMoE(CustomMlxLayer):
+    def __init__(self, layer: _LayerCallable):
+        super().__init__(layer)
+        self.sharding_group: mx.distributed.Group | None = None
+
+    def __call__(self, x: mx.array) -> mx.array:
+        if self.sharding_group is not None:
+            x = sum_gradients(self.sharding_group)(x)
+        y = self.original_layer.__call__(x)
+        if self.sharding_group is not None:
+            y = mx.distributed.all_sum(y, group=self.sharding_group)
+        return y
+
+
 class MiniMaxShardingStrategy(TensorParallelShardingStrategy):
     def shard_model(
         self,
@@ -541,6 +626,7 @@ class MiniMaxShardingStrategy(TensorParallelShardingStrategy):
         on_timeout: TimeoutCallback | None,
     ) -> nn.Module:
         model = cast(MiniMaxModel, model)
+        rank = self.group.rank()
         for layer in model.layers:
             eval_with_timeout(
                 layer.parameters(), timeout_seconds / len(model.layers), on_timeout
@@ -550,6 +636,16 @@ class MiniMaxShardingStrategy(TensorParallelShardingStrategy):
             layer.self_attn.k_proj = self.all_to_sharded_linear(layer.self_attn.k_proj)
             layer.self_attn.v_proj = self.all_to_sharded_linear(layer.self_attn.v_proj)
             layer.self_attn.o_proj = self.sharded_to_all_linear(layer.self_attn.o_proj)
+
+            # Shard qk_norm weights if present (must match sharded head count)
+            if getattr(layer.self_attn, "use_qk_norm", False):
+                layer.self_attn.q_norm.weight = layer.self_attn.q_norm.weight.split(  # type: ignore
+                    self.N, axis=-1
+                )[rank]
+                layer.self_attn.k_norm.weight = layer.self_attn.k_norm.weight.split(  # type: ignore
+                    self.N, axis=-1
+                )[rank]
+
             layer.self_attn.num_attention_heads //= self.N
             layer.self_attn.num_key_value_heads //= self.N
 
@@ -566,7 +662,7 @@ class MiniMaxShardingStrategy(TensorParallelShardingStrategy):
             )
             layer.block_sparse_moe = ShardedQwenMoE(layer.block_sparse_moe)  # pyright: ignore[reportAttributeAccessIssue, reportArgumentType]
             layer.block_sparse_moe.sharding_group = self.group  # pyright: ignore[reportAttributeAccessIssue]
-
+            mx.eval(layer)
         return model
 
 
@@ -607,6 +703,7 @@ class QwenShardingStrategy(TensorParallelShardingStrategy):
                 layer.mlp.down_proj = self.sharded_to_all_linear(layer.mlp.down_proj)
                 layer.mlp.up_proj = self.all_to_sharded_linear(layer.mlp.up_proj)
 
+            mx.eval(layer)
         return model
 
 
@@ -661,7 +758,7 @@ class GptOssShardingStrategy(TensorParallelShardingStrategy):
 
             layer.mlp = ShardedGptOssMoE(layer.mlp)  # type: ignore
             layer.mlp.sharding_group = self.group  # pyright: ignore[reportAttributeAccessIssue]
-
+            mx.eval(layer)
         return model
 
 

src/exo/worker/engines/mlx/cache.py

@@ -1,104 +1,234 @@
-# type: ignore
-# TODO: Fix this file, including types!
+import os
 from copy import deepcopy
-from typing import Callable
+from typing import Any, cast
 
 import mlx.core as mx
-from mlx_lm import stream_generate
-from mlx_lm.models.cache import _BaseCache, trim_prompt_cache
+import psutil
+from mlx_lm.models.cache import (
+    KVCache,
+    QuantizedKVCache,
+    RotatingKVCache,
+    trim_prompt_cache,
+)
+from mlx_lm.models.gpt_oss import Model as GptOssModel
 from mlx_lm.tokenizer_utils import TokenizerWrapper
 
+from exo.shared.types.memory import Memory
+from exo.shared.types.mlx import KVCacheType
 from exo.worker.engines.mlx import Model
-from exo.worker.engines.mlx.constants import KEEP_KV_SIZE, KV_BITS, KV_GROUP_SIZE
-from exo.worker.engines.mlx.utils_mlx import make_kv_cache
+from exo.worker.engines.mlx.constants import CACHE_GROUP_SIZE, KV_CACHE_BITS
+from exo.worker.runner.bootstrap import logger
+
+# Fraction of device memory above which LRU eviction kicks in
+_DEFAULT_MEMORY_THRESHOLD = 0.9
+_MEMORY_THRESHOLD = float(
+    os.environ.get("EXO_MEMORY_THRESHOLD", _DEFAULT_MEMORY_THRESHOLD)
+)
 
 
 class KVPrefixCache:
-    def __init__(self):
-        # Only one prefix cache per runner.
-        self.prompts: list[mx.array] = []  # mx array of tokens (ints)
-        self.caches: list[list[_BaseCache]] = []
-
-    def add_kv_cache(
-        self, tokenizer: TokenizerWrapper, prompt: str, cache: list[_BaseCache]
+    def __init__(
+        self, tokenizer: TokenizerWrapper, group: mx.distributed.Group | None = None
     ):
-        tokenized_prompt = self.encode_prompt(tokenizer, prompt)
+        self.prompts: list[mx.array] = []  # mx array of tokens (ints)
+        self.caches: list[KVCacheType] = []
+        self._last_used: list[int] = []  # monotonic counter of last access per entry
+        self._access_counter: int = 0
+        self._tokenizer: TokenizerWrapper = tokenizer
+        self._group = group
+
+    def clear(self):
+        """Clear all cached prompts and caches."""
+        self.prompts.clear()
+        self.caches.clear()
+        self._last_used.clear()
+
+    def add_kv_cache(self, prompt: str, cache: KVCacheType):
+        """Add a new cache entry. Evicts LRU entries if memory is high."""
+        self._evict_if_needed()
+        tokenized_prompt = encode_prompt(self._tokenizer, prompt)
         self.prompts.append(tokenized_prompt)
         self.caches.append(deepcopy(cache))
+        self._access_counter += 1
+        self._last_used.append(self._access_counter)
+        logger.info(f"KV cache added: {len(tokenized_prompt)} tokens")
+
+    def update_kv_cache(
+        self,
+        index: int,
+        prompt: str,
+        cache: KVCacheType,
+    ):
+        """Update an existing cache entry in-place."""
+        tokenized_prompt = encode_prompt(self._tokenizer, prompt)
+        self.prompts[index] = tokenized_prompt
+        self.caches[index] = deepcopy(cache)
+        self._access_counter += 1
+        self._last_used[index] = self._access_counter
+        logger.info(f"KV cache updated (index {index}): {len(tokenized_prompt)} tokens")
 
     def get_kv_cache(
         self,
         model: Model,
-        tokenizer: TokenizerWrapper,
-        sampler: Callable[[mx.array], mx.array],
         prompt: str,
-    ) -> list[_BaseCache]:
-        tokenized_prompt = self.encode_prompt(tokenizer, prompt)
+    ) -> tuple[KVCacheType, mx.array, int | None]:
+        """Get KV cache for prompt, returning remaining tokens to prefill.
+
+        Returns:
+            Tuple of (cache, remaining_tokens, matched_index) where:
+            - cache: KV cache to use for generation
+            - remaining_tokens: tokens that still need prefilling
+            - matched_index: index of the matched entry (None if no match)
+        """
+        tokenized_prompt = encode_prompt(self._tokenizer, prompt)
         max_length = len(tokenized_prompt)
 
         best_snapshot_index, best_snapshot_length = None, 0
 
         for i, cached_prompt in enumerate(self.prompts):
-            length = _get_prefix_length(tokenized_prompt, cached_prompt)
+            length = get_prefix_length(tokenized_prompt, cached_prompt)
 
             if length == max_length:
-                return self.caches[i]
+                # Exact match - cached prompt starts with our entire prompt
+                # Trim cache to prompt length - 1, return last token for stream_generate
+                prompt_cache = deepcopy(self.caches[i])
+                cached_length = cache_length(self.caches[i])
+                tokens_to_trim = cached_length - (max_length - 1)
+                if tokens_to_trim > 0:
+                    trim_prompt_cache(cast(list[Any], prompt_cache), tokens_to_trim)
+                self._access_counter += 1
+                self._last_used[i] = self._access_counter
+                logger.info(f"KV cache exact match: {max_length} tokens (instant)")
+                return prompt_cache, tokenized_prompt[-1:], i
 
             if length > best_snapshot_length:
                 best_snapshot_index, best_snapshot_length = i, length
 
         if best_snapshot_index is not None:
-            prompt_cache = deepcopy(self.caches[best_snapshot_index])
-            trim_prompt_cache(prompt_cache, max_length - best_snapshot_length)
-            tokenized_prompt = tokenized_prompt[best_snapshot_index:]
-
-        else:
-            prompt_cache = make_kv_cache(
-                model,
-                # max_kv_size=MAX_KV_SIZE,
-                # keep=KEEP_KV_SIZE
+            new_tokens = max_length - best_snapshot_length
+            logger.info(
+                f"KV cache prefix match: {best_snapshot_length}/{max_length} tokens "
+                f"(reusing {best_snapshot_length}, need to prefill {new_tokens})"
             )
 
-        prefill(model, tokenizer, sampler, tokenized_prompt, prompt_cache)
+            prompt_cache = deepcopy(self.caches[best_snapshot_index])
 
-        return prompt_cache
+            # Trim removes tokens from the end, so we trim (cached_length - prefix_length) to keep the prefix
+            cached_length = cache_length(self.caches[best_snapshot_index])
+            tokens_to_trim = cached_length - best_snapshot_length
+            if tokens_to_trim > 0:
+                trim_prompt_cache(cast(list[Any], prompt_cache), tokens_to_trim)
 
-    def encode_prompt(self, tokenizer: TokenizerWrapper, prompt: str) -> mx.array:
-        add_special_tokens = tokenizer.bos_token is None or not prompt.startswith(
-            tokenizer.bos_token
+            self._access_counter += 1
+            self._last_used[best_snapshot_index] = self._access_counter
+            remaining_tokens = tokenized_prompt[best_snapshot_length:]
+            return prompt_cache, remaining_tokens, best_snapshot_index
+
+        else:
+            prompt_cache = make_kv_cache(model)
+            if len(self.prompts) == 0:
+                logger.info(f"KV cache empty, need to prefill {max_length} tokens")
+            else:
+                logger.info(
+                    f"KV cache no prefix match, need to prefill {max_length} tokens"
+                )
+
+            return prompt_cache, tokenized_prompt, None
+
+    def _evict_if_needed(self):
+        """Evict least recently used entries while memory usage is high."""
+        if len(self.caches) == 0:
+            return
+
+        # Evict LRU entries until below threshold or only one entry left
+        while (
+            len(self.caches) > 1
+            and self.get_memory_used_percentage() > _MEMORY_THRESHOLD
+        ):
+            lru_index = self._last_used.index(min(self._last_used))
+            evicted_tokens = len(self.prompts[lru_index])
+            self.prompts.pop(lru_index)
+            self.caches.pop(lru_index)
+            self._last_used.pop(lru_index)
+            logger.info(
+                f"KV cache evicted LRU entry ({evicted_tokens} tokens) due to memory usage"
+            )
+
+    def get_memory_used_percentage(self) -> float:
+        local_pressure: float = get_memory_used_percentage()
+
+        if self._group is None:
+            return local_pressure
+
+        all_pressure = mx.distributed.all_gather(
+            mx.array([local_pressure], dtype=mx.float32),
+            group=self._group,
         )
-        tokenized_prompt = tokenizer.encode(
-            prompt, add_special_tokens=add_special_tokens
-        )
-        return mx.array(tokenized_prompt)
+        # .item() evals.
+        max_pressure = float(mx.max(all_pressure).item())
+        return max_pressure
 
 
-def _get_prefix_length(prompt: mx.array, cached_prompt: mx.array) -> int:
-    n = min(int(prompt.shape[0]), int(cached_prompt.shape[0]), KEEP_KV_SIZE)
+def encode_prompt(tokenizer: TokenizerWrapper, prompt: str) -> mx.array:
+    """Encode a prompt string to token array.
+
+    For chat-templated prompts (which have their own structure markers like
+    <|im_user|>, <|im_middle|>, etc.), we should NOT add BOS/EOS tokens as
+    that would corrupt the prompt structure.
+    """
+    # Chat templates define their own structure - don't add BOS/EOS
+    tokenized_prompt = tokenizer.encode(prompt, add_special_tokens=False)
+    return mx.array(tokenized_prompt)
+
+
+def cache_length(cache: KVCacheType) -> int:
+    """Get the number of tokens in a KV cache."""
+    # Use .offset attribute which all cache types have (len() not implemented in older QuantizedKVCache)
+    return max(c.offset for c in cache)  # type: ignore
+
+
+def get_prefix_length(prompt: mx.array, cached_prompt: mx.array) -> int:
+    """Find the length of the common prefix between two token arrays."""
+    n = min(int(prompt.shape[0]), int(cached_prompt.shape[0]))
     if n == 0:
         return 0
 
-    equal = (prompt[:n] == cached_prompt[:n]).astype(mx.int32)
+    equal = mx.equal(prompt[:n], cached_prompt[:n]).astype(mx.int32)
     prefix_mask = mx.cumprod(equal)  # stays 1 until first mismatch, then 0 forever
     return int(mx.sum(prefix_mask).item())
 
 
-def prefill(
-    model: Model,
-    tokenizer: TokenizerWrapper,
-    sampler: Callable[[mx.array], mx.array],
-    prompt: mx.array,
-    cache: list[_BaseCache],
-) -> None:
-    for _ in stream_generate(
-        model=model,
-        tokenizer=tokenizer,
-        prompt=prompt,
-        max_tokens=0,
-        sampler=sampler,
-        prompt_cache=cache,
-        prefill_step_size=2048,
-        kv_group_size=KV_GROUP_SIZE,
-        kv_bits=KV_BITS,
-    ):
-        pass
+def get_available_memory() -> Memory:
+    mem: int = psutil.virtual_memory().available
+    return Memory.from_bytes(mem)
+
+
+def get_memory_used_percentage() -> float:
+    mem = psutil.virtual_memory()
+    # percent is 0-100
+    return float(mem.percent / 100)
+
+
+def make_kv_cache(
+    model: Model, max_kv_size: int | None = None, keep: int = 0
+) -> KVCacheType:
+    assert hasattr(model, "layers")
+
+    # TODO: Do this for all models
+    if hasattr(model, "make_cache") and isinstance(model, GptOssModel):
+        logger.info("Using MLX LM's make cache")
+        return model.make_cache()  # type: ignore
+
+    if max_kv_size is None:
+        if KV_CACHE_BITS is None:
+            logger.info("Using default KV cache")
+            return [KVCache() for _ in model.layers]
+        else:
+            logger.info("Using quantized KV cache")
+            return [
+                QuantizedKVCache(group_size=CACHE_GROUP_SIZE, bits=KV_CACHE_BITS)
+                for _ in model.layers
+            ]
+    else:
+        logger.info(f"Using rotating KV cache with {max_kv_size=} with {keep=}")
+        return [RotatingKVCache(max_size=max_kv_size, keep=keep) for _ in model.layers]

src/exo/worker/engines/mlx/constants.py

@@ -4,7 +4,7 @@
 KV_GROUP_SIZE: int | None = 32
 KV_BITS: int | None = None
 ATTENTION_KV_BITS: int | None = 4
-MAX_TOKENS: int = 8192
+MAX_TOKENS: int = 32168
 MAX_KV_SIZE: int | None = 3200
 KEEP_KV_SIZE: int | None = 1600
 QUANTIZE_MODEL_MODE: str | None = "affine"

src/exo/worker/engines/mlx/generator/generate.py

@@ -1,48 +1,94 @@
+import time
 from typing import Any, Callable, Generator, cast, get_args
 
 import mlx.core as mx
 from mlx_lm.generate import stream_generate
-from mlx_lm.models.cache import KVCache
+from mlx_lm.models.cache import trim_prompt_cache
 from mlx_lm.sample_utils import make_sampler
 from mlx_lm.tokenizer_utils import TokenizerWrapper
 
-# from exo.engines.mlx.cache import KVPrefixCache
 from exo.shared.types.api import (
     BenchChatCompletionTaskParams,
     ChatCompletionMessage,
+    CompletionTokensDetails,
     FinishReason,
     GenerationStats,
+    PromptTokensDetails,
+    Usage,
 )
 from exo.shared.types.memory import Memory
+from exo.shared.types.mlx import KVCacheType
 from exo.shared.types.tasks import ChatCompletionTaskParams
 from exo.shared.types.worker.runner_response import (
     GenerationResponse,
 )
 from exo.worker.engines.mlx import Model
+from exo.worker.engines.mlx.cache import KVPrefixCache, encode_prompt, make_kv_cache
 from exo.worker.engines.mlx.constants import KV_BITS, KV_GROUP_SIZE, MAX_TOKENS
 from exo.worker.engines.mlx.utils_mlx import (
     apply_chat_template,
-    make_kv_cache,
     mx_barrier,
 )
 from exo.worker.runner.bootstrap import logger
 
 generation_stream = mx.new_stream(mx.default_device())
 
+_MIN_PREFIX_HIT_TO_UPDATE = 1000
 
-def maybe_quantize_kv_cache(
-    prompt_cache: list[KVCache | Any],
-    quantized_kv_start: int,
-    kv_group_size: int,
-    kv_bits: int | None,
-) -> None:
-    if kv_bits is None:
-        return
-    for e, c in enumerate(prompt_cache):
-        if (
-            hasattr(c, "to_quantized") and c.offset >= quantized_kv_start  # type: ignore
-        ):
-            prompt_cache[e] = c.to_quantized(group_size=kv_group_size, bits=kv_bits)
+
+def prefill(
+    model: Model,
+    tokenizer: TokenizerWrapper,
+    sampler: Callable[[mx.array], mx.array],
+    prompt_tokens: mx.array,
+    cache: KVCacheType,
+) -> tuple[float, int]:
+    """Prefill the KV cache with prompt tokens.
+
+    This runs the model over the prompt tokens to populate the cache,
+    then trims off the extra generated token.
+
+    Returns:
+        tokens_per_sec
+    """
+    num_tokens = len(prompt_tokens)
+    if num_tokens == 0:
+        return 0.0, 0
+
+    logger.debug(f"Prefilling {num_tokens} tokens...")
+    start_time = time.perf_counter()
+
+    def progress_callback(processed: int, total: int) -> None:
+        elapsed = time.time() - start_time
+        tok_per_sec = processed / elapsed if elapsed > 0 else 0
+        logger.debug(
+            f"Prefill progress: {processed}/{total} tokens ({tok_per_sec:.1f} tok/s)"
+        )
+
+    # Use max_tokens=1 because max_tokens=0 does not work.
+    # We just throw away the generated token - we only care about filling the cache
+    for _ in stream_generate(
+        model=model,
+        tokenizer=tokenizer,
+        prompt=prompt_tokens,
+        max_tokens=1,
+        sampler=sampler,
+        prompt_cache=cache,
+        prefill_step_size=2048,
+        kv_group_size=KV_GROUP_SIZE,
+        kv_bits=KV_BITS,
+        prompt_progress_callback=progress_callback,
+    ):
+        break  # Stop after first iteration - cache is now filled
+    trim_prompt_cache(cast(list[Any], cache), 1)
+
+    elapsed = time.perf_counter() - start_time
+    tokens_per_sec = num_tokens / elapsed if elapsed > 0 else 0.0
+    logger.debug(
+        f"Prefill complete: {num_tokens} tokens in {elapsed:.2f}s "
+        f"({tokens_per_sec:.1f} tok/s)"
+    )
+    return tokens_per_sec, num_tokens
 
 
 def warmup_inference(
@@ -120,18 +166,36 @@ def mlx_generate(
     tokenizer: TokenizerWrapper,
     task: ChatCompletionTaskParams,
     prompt: str,
+    kv_prefix_cache: KVPrefixCache | None = None,
 ) -> Generator[GenerationResponse]:
     # Ensure that generation stats only contains peak memory for this generation
     mx.reset_peak_memory()
     is_bench: bool = isinstance(task, BenchChatCompletionTaskParams)
 
+    logger.info(f"{is_bench=}")
+
     # Currently we support chat-completion tasks only.
     logger.debug(f"task_params: {task}")
 
     if task.seed is not None:
         mx.random.seed(task.seed)
 
-    caches = make_kv_cache(model=model)
+    # Do not use the prefix cache if we are trying to do benchmarks.
+    if is_bench:
+        kv_prefix_cache = None
+
+    # Use prefix cache if available, otherwise create fresh cache
+    prefix_hit_length = 0
+    matched_index: int | None = None
+    if kv_prefix_cache is None:
+        caches = make_kv_cache(model=model)
+        prompt_tokens = encode_prompt(tokenizer, prompt)
+    else:
+        caches, prompt_tokens, matched_index = kv_prefix_cache.get_kv_cache(
+            model, prompt
+        )
+        all_prompt_tokens = encode_prompt(tokenizer, prompt)
+        prefix_hit_length = len(all_prompt_tokens) - len(prompt_tokens)
 
     logits_processors: list[Callable[[mx.array, mx.array], mx.array]] = []
     if is_bench:
@@ -144,28 +208,54 @@ def mlx_generate(
         top_p=task.top_p if task.top_p is not None else 1.0,
     )
 
+    # Prefill cache with all tokens except the last one
+    prefill_tps, prefill_tokens = prefill(
+        model, tokenizer, sampler, prompt_tokens[:-1], caches
+    )
+
+    # stream_generate starts from the last token
+    last_token = prompt_tokens[-1:]
+
     max_tokens = task.max_tokens or MAX_TOKENS
-    for out in stream_generate(
-        model=model,
-        tokenizer=tokenizer,
-        prompt=prompt,
-        max_tokens=max_tokens,
-        sampler=sampler,
-        logits_processors=logits_processors,
-        prompt_cache=caches,
-        # TODO: Dynamically change prefill step size to be the maximum possible without timing out.
-        prefill_step_size=2048,
-        kv_group_size=KV_GROUP_SIZE,
-        kv_bits=KV_BITS,
+    generated_text_parts: list[str] = []
+    generation_start_time = time.perf_counter()
+    usage: Usage | None = None
+    in_thinking = False
+    reasoning_tokens = 0
+    think_start = tokenizer.think_start
+    think_end = tokenizer.think_end
+    for completion_tokens, out in enumerate(
+        stream_generate(
+            model=model,
+            tokenizer=tokenizer,
+            prompt=last_token,
+            max_tokens=max_tokens,
+            sampler=sampler,
+            logits_processors=logits_processors,
+            prompt_cache=caches,
+            # TODO: Dynamically change prefill step size to be the maximum possible without timing out.
+            prefill_step_size=2048,
+            kv_group_size=KV_GROUP_SIZE,
+            kv_bits=KV_BITS,
+        ),
+        start=1,
     ):
+        generated_text_parts.append(out.text)
         logger.info(out.text)
 
+        if think_start is not None and out.text == think_start:
+            in_thinking = True
+        elif think_end is not None and out.text == think_end:
+            in_thinking = False
+        if in_thinking:
+            reasoning_tokens += 1
+
         stats: GenerationStats | None = None
         if out.finish_reason is not None:
             stats = GenerationStats(
-                prompt_tps=float(out.prompt_tps),
+                prompt_tps=float(prefill_tps or out.prompt_tps),
                 generation_tps=float(out.generation_tps),
-                prompt_tokens=int(out.prompt_tokens),
+                prompt_tokens=int(prefill_tokens + out.prompt_tokens),
                 generation_tokens=int(out.generation_tokens),
                 peak_memory_usage=Memory.from_gb(out.peak_memory),
             )
@@ -177,14 +267,47 @@ def mlx_generate(
                     f"Model generated unexpected finish_reason: {out.finish_reason}"
                 )
 
+            usage = Usage(
+                prompt_tokens=int(out.prompt_tokens),
+                completion_tokens=completion_tokens,
+                total_tokens=int(out.prompt_tokens) + completion_tokens,
+                prompt_tokens_details=PromptTokensDetails(
+                    cached_tokens=prefix_hit_length
+                ),
+                completion_tokens_details=CompletionTokensDetails(
+                    reasoning_tokens=reasoning_tokens
+                ),
+            )
+
         yield GenerationResponse(
             text=out.text,
             token=out.token,
             finish_reason=cast(FinishReason | None, out.finish_reason),
             stats=stats,
+            usage=usage,
         )
 
         if out.finish_reason is not None:
+            # Log generation stats
+            generation_elapsed = time.perf_counter() - generation_start_time
+            generated_tokens = len(generated_text_parts)
+            generation_tps = (
+                generated_tokens / generation_elapsed if generation_elapsed > 0 else 0.0
+            )
+            logger.debug(
+                f"Generation complete: prefill {prompt_tokens} tokens @ "
+                f"{prefill_tps:.1f} tok/s, generated {generated_tokens} tokens @ "
+                f"{generation_tps:.1f} tok/s"
+            )
+            if kv_prefix_cache is not None:
+                full_prompt = prompt + "".join(generated_text_parts)
+                if (
+                    matched_index is not None
+                    and prefix_hit_length >= _MIN_PREFIX_HIT_TO_UPDATE
+                ):
+                    kv_prefix_cache.update_kv_cache(matched_index, full_prompt, caches)
+                else:
+                    kv_prefix_cache.add_kv_cache(full_prompt, caches)
             break
 
         # TODO: Do we want an mx_barrier?

src/exo/worker/engines/mlx/utils_mlx.py

@@ -18,15 +18,12 @@ try:
 except ImportError:
     pass  # transformers < 5.0 or bytes_to_unicode not available
 
-from mlx_lm.models.cache import KVCache, QuantizedKVCache, RotatingKVCache
+from mlx_lm.models.cache import KVCache
 from mlx_lm.models.deepseek_v3 import DeepseekV3Model
-from mlx_lm.models.gpt_oss import Model as GptOssModel
 from mlx_lm.tokenizer_utils import TokenizerWrapper
 
 from exo.shared.models.model_cards import ModelId
 from exo.worker.engines.mlx.constants import (
-    CACHE_GROUP_SIZE,
-    KV_CACHE_BITS,
     TRUST_REMOTE_CODE,
 )
 
@@ -41,6 +38,7 @@ import mlx.nn as nn
 from mlx_lm.utils import load_model
 from pydantic import RootModel
 
+from exo.download.download_utils import build_model_path
 from exo.shared.types.api import ChatCompletionMessageText
 from exo.shared.types.common import Host
 from exo.shared.types.memory import Memory
@@ -55,7 +53,6 @@ from exo.shared.types.worker.shards import (
     ShardMetadata,
     TensorShardMetadata,
 )
-from exo.worker.download.download_utils import build_model_path
 from exo.worker.engines.mlx import Model
 from exo.worker.engines.mlx.auto_parallel import (
     TimeoutCallback,
@@ -168,12 +165,11 @@ def mlx_distributed_init(
 
                 jaccl_coordinator = jaccl_coordinators[bound_instance.bound_node_id]
 
-                # TODO: update once upstream fixes
                 logger.info(
-                    f"rank {rank} MLX_JACCL_DEVICES: {coordination_file} with devices: {jaccl_devices_json}"
+                    f"rank {rank} MLX_IBV_DEVICES: {coordination_file} with devices: {jaccl_devices_json}"
                 )
                 logger.info(f"rank {rank} MLX_JACCL_COORDINATOR: {jaccl_coordinator}")
-                os.environ["MLX_JACCL_DEVICES"] = coordination_file
+                os.environ["MLX_IBV_DEVICES"] = coordination_file
                 os.environ["MLX_RANK"] = str(rank)
                 os.environ["MLX_JACCL_COORDINATOR"] = jaccl_coordinator
                 group = mx.distributed.init(backend="jaccl", strict=True)
@@ -262,10 +258,10 @@ def shard_and_load(
 
     logger.info(f"Group size: {group.size()}, group rank: {group.rank()}")
 
-    # Estimate timeout based on model size
-    base_timeout = float(os.environ.get("EXO_MODEL_LOAD_TIMEOUT", "60"))
+    # Estimate timeout based on model size (5x default for large queued workloads)
+    base_timeout = float(os.environ.get("EXO_MODEL_LOAD_TIMEOUT", "300"))
     model_size_gb = get_weights_size(shard_metadata).in_bytes / (1024**3)
-    timeout_seconds = base_timeout + model_size_gb / 5
+    timeout_seconds = base_timeout + model_size_gb
     logger.info(
         f"Evaluating model parameters with timeout of {timeout_seconds:.0f}s "
         f"(model size: {model_size_gb:.1f}GB)"
@@ -342,8 +338,35 @@ def load_tokenizer_for_model_id(
 
     # Kimi uses a custom TikTokenTokenizer that transformers 5.x can't load via AutoTokenizer
     if "kimi-k2" in model_id_lower:
+        import importlib.util
+        import types
+
         sys.path.insert(0, str(model_path))
-        from tokenization_kimi import TikTokenTokenizer  # type: ignore[import-not-found]  # noqa: I001
+
+        # Load tool_declaration_ts first (tokenization_kimi imports it with relative import)
+        tool_decl_path = model_path / "tool_declaration_ts.py"
+        if tool_decl_path.exists():
+            spec = importlib.util.spec_from_file_location(
+                "tool_declaration_ts", tool_decl_path
+            )
+            if spec and spec.loader:
+                tool_decl_module = importlib.util.module_from_spec(spec)
+                sys.modules["tool_declaration_ts"] = tool_decl_module
+                spec.loader.exec_module(tool_decl_module)
+
+        # Load tokenization_kimi with patched source (convert relative to absolute import)
+        tok_path = model_path / "tokenization_kimi.py"
+        source = tok_path.read_text()
+        source = source.replace("from .tool_declaration_ts", "from tool_declaration_ts")
+        spec = importlib.util.spec_from_file_location("tokenization_kimi", tok_path)
+        if spec:
+            tok_module = types.ModuleType("tokenization_kimi")
+            tok_module.__file__ = str(tok_path)
+            sys.modules["tokenization_kimi"] = tok_module
+            exec(compile(source, tok_path, "exec"), tok_module.__dict__)  # noqa: S102
+            TikTokenTokenizer = tok_module.TikTokenTokenizer  # type: ignore[attr-defined]  # noqa: N806
+        else:
+            from tokenization_kimi import TikTokenTokenizer  # type: ignore[import-not-found]  # noqa: I001
 
         hf_tokenizer: Any = TikTokenTokenizer.from_pretrained(model_path)  # pyright: ignore[reportUnknownVariableType,reportUnknownMemberType]
 
@@ -405,7 +428,11 @@ def apply_chat_template(
                 continue
 
             message.content = "\n".join(c.text for c in message.content).strip()
-        if message.content is None and message.thinking is None:
+        if (
+            message.content is None
+            and message.thinking is None
+            and message.tool_calls is None
+        ):
             continue
 
         # Null values are not valid when applying templates in tokenizer
@@ -462,31 +489,6 @@ class NullKVCache(KVCache):
         raise NotImplementedError("We should not be setting a NullKVCache.")
 
 
-def make_kv_cache(
-    model: Model, max_kv_size: int | None = None, keep: int = 0
-) -> list[KVCache | RotatingKVCache | QuantizedKVCache]:
-    assert hasattr(model, "layers")
-
-    # TODO: Do this for all models
-    if hasattr(model, "make_cache") and isinstance(model, GptOssModel):
-        logger.info("Using MLX LM's make cache")
-        return model.make_cache()  # type: ignore
-
-    if max_kv_size is None:
-        if KV_CACHE_BITS is None:
-            logger.info("Using default KV cache")
-            return [KVCache() for _ in model.layers]
-        else:
-            logger.info("Using quantized KV cache")
-            return [
-                QuantizedKVCache(group_size=CACHE_GROUP_SIZE, bits=KV_CACHE_BITS)
-                for _ in model.layers
-            ]
-    else:
-        logger.info(f"Using rotating KV cache with {max_kv_size=} with {keep=}")
-        return [RotatingKVCache(max_size=max_kv_size, keep=keep) for _ in model.layers]
-
-
 def mlx_force_oom(size: int = 40000) -> None:
     """
     Force an Out-Of-Memory (OOM) error in MLX by performing large tensor operations.

src/exo/worker/main.py

@@ -1,8 +1,9 @@
 from datetime import datetime, timezone
 from random import random
+from typing import Iterator
 
 import anyio
-from anyio import CancelScope, create_task_group, current_time, fail_after
+from anyio import CancelScope, create_task_group, fail_after
 from anyio.abc import TaskGroup
 from loguru import logger
 
@@ -10,7 +11,12 @@ from exo.routing.connection_message import ConnectionMessage, ConnectionMessageT
 from exo.shared.apply import apply
 from exo.shared.models.model_cards import ModelId
 from exo.shared.types.api import ImageEditsInternalParams
-from exo.shared.types.commands import ForwarderCommand, RequestEventLog
+from exo.shared.types.commands import (
+    ForwarderCommand,
+    ForwarderDownloadCommand,
+    RequestEventLog,
+    StartDownload,
+)
 from exo.shared.types.common import CommandId, NodeId, SessionId
 from exo.shared.types.events import (
     Event,
@@ -18,7 +24,6 @@ from exo.shared.types.events import (
     ForwarderEvent,
     IndexedEvent,
     InputChunkReceived,
-    NodeDownloadProgress,
     NodeGatheredInfo,
     TaskCreated,
     TaskStatusUpdated,
@@ -36,23 +41,12 @@ from exo.shared.types.tasks import (
     TaskStatus,
 )
 from exo.shared.types.topology import Connection, SocketConnection
-from exo.shared.types.worker.downloads import (
-    DownloadCompleted,
-    DownloadFailed,
-    DownloadOngoing,
-    DownloadPending,
-    DownloadProgress,
-)
 from exo.shared.types.worker.runners import RunnerId
-from exo.shared.types.worker.shards import ShardMetadata
 from exo.utils.channels import Receiver, Sender, channel
 from exo.utils.event_buffer import OrderedBuffer
 from exo.utils.info_gatherer.info_gatherer import GatheredInfo, InfoGatherer
 from exo.utils.info_gatherer.net_profile import check_reachable
-from exo.worker.download.download_utils import (
-    map_repo_download_progress_to_download_progress_data,
-)
-from exo.worker.download.shard_downloader import RepoDownloadProgress, ShardDownloader
+from exo.utils.keyed_backoff import KeyedBackoff
 from exo.worker.plan import plan
 from exo.worker.runner.runner_supervisor import RunnerSupervisor
 
@@ -62,7 +56,6 @@ class Worker:
         self,
         node_id: NodeId,
         session_id: SessionId,
-        shard_downloader: ShardDownloader,
         *,
         connection_message_receiver: Receiver[ConnectionMessage],
         global_event_receiver: Receiver[ForwarderEvent],
@@ -70,23 +63,22 @@ class Worker:
         # This is for requesting updates. It doesn't need to be a general command sender right now,
         # but I think it's the correct way to be thinking about commands
         command_sender: Sender[ForwarderCommand],
+        download_command_sender: Sender[ForwarderDownloadCommand],
+        event_index_counter: Iterator[int],
     ):
         self.node_id: NodeId = node_id
         self.session_id: SessionId = session_id
 
-        self.shard_downloader: ShardDownloader = shard_downloader
-        self._pending_downloads: dict[RunnerId, ShardMetadata] = {}
-
         self.global_event_receiver = global_event_receiver
         self.local_event_sender = local_event_sender
-        self.local_event_index = 0
+        self.event_index_counter = event_index_counter
         self.command_sender = command_sender
+        self.download_command_sender = download_command_sender
         self.connection_message_receiver = connection_message_receiver
         self.event_buffer = OrderedBuffer[Event]()
         self.out_for_delivery: dict[EventId, ForwarderEvent] = {}
 
         self.state: State = State()
-        self.download_status: dict[ModelId, DownloadProgress] = {}
         self.runners: dict[RunnerId, RunnerSupervisor] = {}
         self._tg: TaskGroup = create_task_group()
 
@@ -101,6 +93,8 @@ class Worker:
         self.input_chunk_buffer: dict[CommandId, dict[int, str]] = {}
         self.input_chunk_counts: dict[CommandId, int] = {}
 
+        self._download_backoff: KeyedBackoff[ModelId] = KeyedBackoff(base=0.5, cap=10.0)
+
     async def run(self):
         logger.info("Starting Worker")
 
@@ -111,7 +105,6 @@ class Worker:
             tg.start_soon(info_gatherer.run)
             tg.start_soon(self._forward_info, info_recv)
             tg.start_soon(self.plan_step)
-            tg.start_soon(self._emit_existing_download_progress)
             tg.start_soon(self._connection_message_event_writer)
             tg.start_soon(self._resend_out_for_delivery)
             tg.start_soon(self._event_applier)
@@ -121,6 +114,7 @@ class Worker:
         # Actual shutdown code - waits for all tasks to complete before executing.
         self.local_event_sender.close()
         self.command_sender.close()
+        self.download_command_sender.close()
         for runner in self.runners.values():
             runner.shutdown()
 
@@ -179,11 +173,9 @@ class Worker:
     async def plan_step(self):
         while True:
             await anyio.sleep(0.1)
-            # 3. based on the updated state, we plan & execute an operation.
             task: Task | None = plan(
                 self.node_id,
                 self.runners,
-                self.download_status,
                 self.state.downloads,
                 self.state.instances,
                 self.state.runners,
@@ -207,42 +199,26 @@ class Worker:
                         )
                     )
                 case DownloadModel(shard_metadata=shard):
-                    if shard.model_card.model_id not in self.download_status:
-                        progress = DownloadPending(
-                            shard_metadata=shard, node_id=self.node_id
-                        )
-                        self.download_status[shard.model_card.model_id] = progress
-                        await self.event_sender.send(
-                            NodeDownloadProgress(download_progress=progress)
-                        )
-                    initial_progress = (
-                        await self.shard_downloader.get_shard_download_status_for_shard(
-                            shard
+                    model_id = shard.model_card.model_id
+                    if not self._download_backoff.should_proceed(model_id):
+                        continue
+
+                    self._download_backoff.record_attempt(model_id)
+
+                    await self.download_command_sender.send(
+                        ForwarderDownloadCommand(
+                            origin=self.node_id,
+                            command=StartDownload(
+                                target_node_id=self.node_id,
+                                shard_metadata=shard,
+                            ),
                         )
                     )
-                    if initial_progress.status == "complete":
-                        progress = DownloadCompleted(
-                            shard_metadata=shard,
-                            node_id=self.node_id,
-                            total_bytes=initial_progress.total_bytes,
+                    await self.event_sender.send(
+                        TaskStatusUpdated(
+                            task_id=task.task_id, task_status=TaskStatus.Running
                         )
-                        self.download_status[shard.model_card.model_id] = progress
-                        await self.event_sender.send(
-                            NodeDownloadProgress(download_progress=progress)
-                        )
-                        await self.event_sender.send(
-                            TaskStatusUpdated(
-                                task_id=task.task_id,
-                                task_status=TaskStatus.Complete,
-                            )
-                        )
-                    else:
-                        await self.event_sender.send(
-                            TaskStatusUpdated(
-                                task_id=task.task_id, task_status=TaskStatus.Running
-                            )
-                        )
-                        self._handle_shard_download_process(task, initial_progress)
+                    )
                 case Shutdown(runner_id=runner_id):
                     try:
                         with fail_after(3):
@@ -387,104 +363,17 @@ class Worker:
         self._tg.start_soon(runner.run)
         return runner
 
-    def _handle_shard_download_process(
-        self,
-        task: DownloadModel,
-        initial_progress: RepoDownloadProgress,
-    ):
-        """Manages the shard download process with progress tracking."""
-        status = DownloadOngoing(
-            node_id=self.node_id,
-            shard_metadata=task.shard_metadata,
-            download_progress=map_repo_download_progress_to_download_progress_data(
-                initial_progress
-            ),
-        )
-        self.download_status[task.shard_metadata.model_card.model_id] = status
-        self.event_sender.send_nowait(NodeDownloadProgress(download_progress=status))
-
-        last_progress_time = 0.0
-        throttle_interval_secs = 1.0
-
-        async def download_progress_callback(
-            shard: ShardMetadata, progress: RepoDownloadProgress
-        ) -> None:
-            nonlocal self
-            nonlocal last_progress_time
-            if progress.status == "complete":
-                status = DownloadCompleted(
-                    shard_metadata=shard,
-                    node_id=self.node_id,
-                    total_bytes=progress.total_bytes,
-                )
-                self.download_status[shard.model_card.model_id] = status
-                await self.event_sender.send(
-                    NodeDownloadProgress(download_progress=status)
-                )
-                await self.event_sender.send(
-                    TaskStatusUpdated(
-                        task_id=task.task_id, task_status=TaskStatus.Complete
-                    )
-                )
-            elif (
-                progress.status == "in_progress"
-                and current_time() - last_progress_time > throttle_interval_secs
-            ):
-                status = DownloadOngoing(
-                    node_id=self.node_id,
-                    shard_metadata=shard,
-                    download_progress=map_repo_download_progress_to_download_progress_data(
-                        progress
-                    ),
-                )
-                self.download_status[shard.model_card.model_id] = status
-                await self.event_sender.send(
-                    NodeDownloadProgress(download_progress=status)
-                )
-                last_progress_time = current_time()
-
-        self.shard_downloader.on_progress(download_progress_callback)
-
-        async def download_with_error_handling() -> None:
-            try:
-                await self.shard_downloader.ensure_shard(task.shard_metadata)
-            except Exception as e:
-                error_message = str(e)
-                logger.error(
-                    f"Download failed for {task.shard_metadata.model_card.model_id}: {error_message}"
-                )
-                failed_status = DownloadFailed(
-                    node_id=self.node_id,
-                    shard_metadata=task.shard_metadata,
-                    error_message=error_message,
-                )
-                self.download_status[task.shard_metadata.model_card.model_id] = (
-                    failed_status
-                )
-                await self.event_sender.send(
-                    NodeDownloadProgress(download_progress=failed_status)
-                )
-                await self.event_sender.send(
-                    TaskStatusUpdated(
-                        task_id=task.task_id, task_status=TaskStatus.Failed
-                    )
-                )
-
-        self._tg.start_soon(download_with_error_handling)
-
     async def _forward_events(self) -> None:
         with self.event_receiver as events:
             async for event in events:
+                idx = next(self.event_index_counter)
                 fe = ForwarderEvent(
-                    origin_idx=self.local_event_index,
+                    origin_idx=idx,
                     origin=self.node_id,
                     session=self.session_id,
                     event=event,
                 )
-                logger.debug(
-                    f"Worker published event {self.local_event_index}: {str(event)[:100]}"
-                )
-                self.local_event_index += 1
+                logger.debug(f"Worker published event {idx}: {str(event)[:100]}")
                 await self.local_event_sender.send(fe)
                 self.out_for_delivery[event.event_id] = fe
 
@@ -532,42 +421,3 @@ class Worker:
                     await self.event_sender.send(TopologyEdgeDeleted(conn=conn))
 
             await anyio.sleep(10)
-
-    async def _emit_existing_download_progress(self) -> None:
-        try:
-            while True:
-                logger.debug("Fetching and emitting existing download progress...")
-                async for (
-                    _,
-                    progress,
-                ) in self.shard_downloader.get_shard_download_status():
-                    if progress.status == "complete":
-                        status = DownloadCompleted(
-                            node_id=self.node_id,
-                            shard_metadata=progress.shard,
-                            total_bytes=progress.total_bytes,
-                        )
-                    elif progress.status in ["in_progress", "not_started"]:
-                        if progress.downloaded_bytes_this_session.in_bytes == 0:
-                            status = DownloadPending(
-                                node_id=self.node_id, shard_metadata=progress.shard
-                            )
-                        else:
-                            status = DownloadOngoing(
-                                node_id=self.node_id,
-                                shard_metadata=progress.shard,
-                                download_progress=map_repo_download_progress_to_download_progress_data(
-                                    progress
-                                ),
-                            )
-                    else:
-                        continue
-
-                    self.download_status[progress.shard.model_card.model_id] = status
-                    await self.event_sender.send(
-                        NodeDownloadProgress(download_progress=status)
-                    )
-                logger.debug("Done emitting existing download progress.")
-                await anyio.sleep(5 * 60)  # 5 minutes
-        except Exception as e:
-            logger.error(f"Error emitting existing download progress: {e}")

src/exo/worker/plan.py

@@ -2,7 +2,6 @@
 
 from collections.abc import Mapping, Sequence
 
-from exo.shared.models.model_cards import ModelId
 from exo.shared.types.common import CommandId, NodeId
 from exo.shared.types.tasks import (
     ChatCompletion,
@@ -45,9 +44,6 @@ def plan(
     node_id: NodeId,
     # Runners is expected to be FRESH and so should not come from state
     runners: Mapping[RunnerId, RunnerSupervisor],
-    # DL_status is expected to be FRESH and so should not come from state
-    download_status: Mapping[ModelId, DownloadProgress],
-    # gdls is not expected to be fresh
     global_download_status: Mapping[NodeId, Sequence[DownloadProgress]],
     instances: Mapping[InstanceId, Instance],
     all_runners: Mapping[RunnerId, RunnerStatus],  # all global
@@ -59,7 +55,7 @@ def plan(
     return (
         _kill_runner(runners, all_runners, instances)
         or _create_runner(node_id, runners, instances)
-        or _model_needs_download(runners, download_status)
+        or _model_needs_download(node_id, runners, global_download_status)
         or _init_distributed_backend(runners, all_runners)
         or _load_model(runners, all_runners, global_download_status)
         or _ready_to_warmup(runners, all_runners)
@@ -115,9 +111,15 @@ def _create_runner(
 
 
 def _model_needs_download(
+    node_id: NodeId,
     runners: Mapping[RunnerId, RunnerSupervisor],
-    download_status: Mapping[ModelId, DownloadProgress],
+    global_download_status: Mapping[NodeId, Sequence[DownloadProgress]],
 ) -> DownloadModel | None:
+    local_downloads = global_download_status.get(node_id, [])
+    download_status = {
+        dp.shard_metadata.model_card.model_id: dp for dp in local_downloads
+    }
+
     for runner in runners.values():
         model_id = runner.bound_instance.bound_shard.model_card.model_id
         if isinstance(runner.status, RunnerIdle) and (

src/exo/worker/runner/runner.py

@@ -18,6 +18,7 @@ from pydantic import ValidationError
 
 from exo.shared.constants import EXO_MAX_CHUNK_SIZE
 from exo.shared.models.model_cards import ModelId, ModelTask
+from exo.shared.tracing import clear_trace_buffer, get_trace_buffer, is_tracing_enabled
 from exo.shared.types.api import ChatCompletionMessageText, ImageGenerationStats
 from exo.shared.types.chunks import ErrorChunk, ImageChunk, TokenChunk, ToolCallChunk
 from exo.shared.types.common import CommandId
@@ -27,6 +28,8 @@ from exo.shared.types.events import (
     RunnerStatusUpdated,
     TaskAcknowledged,
     TaskStatusUpdated,
+    TraceEventData,
+    TracesCollected,
 )
 from exo.shared.types.tasks import (
     ChatCompletion,
@@ -37,6 +40,7 @@ from exo.shared.types.tasks import (
     Shutdown,
     StartWarmup,
     Task,
+    TaskId,
     TaskStatus,
 )
 from exo.shared.types.worker.instances import BoundInstance
@@ -70,6 +74,7 @@ from exo.worker.engines.image import (
     warmup_image_generator,
 )
 from exo.worker.engines.mlx import Model
+from exo.worker.engines.mlx.cache import KVPrefixCache
 from exo.worker.engines.mlx.generator.generate import mlx_generate, warmup_inference
 from exo.worker.engines.mlx.utils_mlx import (
     apply_chat_template,
@@ -103,14 +108,19 @@ def main(
     model: Model | DistributedImageModel | None = None
     tokenizer = None
     group = None
+    kv_prefix_cache: KVPrefixCache | None = None
 
     current_status: RunnerStatus = RunnerIdle()
     logger.info("runner created")
     event_sender.send(
         RunnerStatusUpdated(runner_id=runner_id, runner_status=current_status)
     )
+    seen = set[TaskId]()
     with task_receiver as tasks:
         for task in tasks:
+            if task.task_id in seen:
+                logger.warning("repeat task - potential error")
+            seen.add(task.task_id)
             event_sender.send(
                 TaskStatusUpdated(task_id=task.task_id, task_status=TaskStatus.Running)
             )
@@ -161,6 +171,8 @@ def main(
                         logger.info(
                             f"model has_tool_calling={tokenizer.has_tool_calling}"
                         )
+                        kv_prefix_cache = KVPrefixCache(tokenizer, group)
+
                     elif (
                         ModelTask.TextToImage in shard_metadata.model_card.tasks
                         or ModelTask.ImageToImage in shard_metadata.model_card.tasks
@@ -170,7 +182,6 @@ def main(
                         raise ValueError(
                             f"Unknown model task(s): {shard_metadata.model_card.tasks}"
                         )
-
                     current_status = RunnerLoaded()
                     logger.info("runner loaded")
                 case StartWarmup() if isinstance(current_status, RunnerLoaded):
@@ -238,12 +249,9 @@ def main(
                             tokenizer=tokenizer,
                             task=task_params,
                             prompt=prompt,
+                            kv_prefix_cache=kv_prefix_cache,
                         )
 
-                        # GPT-OSS specific parsing to match other model formats.
-                        if isinstance(model, GptOssModel):
-                            mlx_generator = parse_gpt_oss(mlx_generator)
-
                         # For other thinking models (GLM, etc.), check if we need to
                         # prepend the thinking tag that was consumed by the chat template
                         if detect_thinking_prompt_suffix(prompt, tokenizer):
@@ -257,10 +265,16 @@ def main(
                             patch_kimi_tokenizer(tokenizer)
 
                         # GLM models need patched parser (upstream has bug with None regex match)
-                        if "glm" in shard_metadata.model_card.model_id.lower():
+                        elif "glm" in shard_metadata.model_card.model_id.lower():
                             patch_glm_tokenizer(tokenizer)
 
-                        if tokenizer.has_tool_calling:
+                        # GPT-OSS specific parsing to match other model formats.
+                        elif isinstance(model, GptOssModel):
+                            mlx_generator = parse_gpt_oss(mlx_generator)
+
+                        if tokenizer.has_tool_calling and not isinstance(
+                            model, GptOssModel
+                        ):
                             assert tokenizer.tool_call_start
                             assert tokenizer.tool_call_end
                             assert tokenizer.tool_parser  # pyright: ignore[reportAny]
@@ -271,9 +285,11 @@ def main(
                                 tokenizer.tool_parser,  # pyright: ignore[reportAny]
                             )
 
+                        completion_tokens = 0
                         for response in mlx_generator:
                             match response:
                                 case GenerationResponse():
+                                    completion_tokens += 1
                                     if (
                                         device_rank == 0
                                         and response.finish_reason == "error"
@@ -301,6 +317,7 @@ def main(
                                                     model=shard_metadata.model_card.model_id,
                                                     text=response.text,
                                                     token_id=response.token,
+                                                    usage=response.usage,
                                                     finish_reason=response.finish_reason,
                                                     stats=response.stats,
                                                 ),
@@ -314,6 +331,7 @@ def main(
                                                 chunk=ToolCallChunk(
                                                     tool_calls=response.tool_calls,
                                                     model=shard_metadata.model_card.model_id,
+                                                    usage=response.usage,
                                                 ),
                                             )
                                         )
@@ -393,6 +411,10 @@ def main(
                                 )
                             )
                         raise
+                    finally:
+                        _send_traces_if_enabled(
+                            event_sender, task.task_id, shard_metadata.device_rank
+                        )
 
                     current_status = RunnerReady()
                     logger.info("runner ready")
@@ -451,6 +473,10 @@ def main(
                                 )
                             )
                         raise
+                    finally:
+                        _send_traces_if_enabled(
+                            event_sender, task.task_id, shard_metadata.device_rank
+                        )
 
                     current_status = RunnerReady()
                     logger.info("runner ready")
@@ -489,9 +515,10 @@ def get_gpt_oss_encoding():
 
 
 def filter_kimi_tokens(
-    responses: Generator[GenerationResponse],
+    responses: Generator[GenerationResponse | ToolCallResponse],
 ) -> Generator[GenerationResponse]:
     for resp in responses:
+        assert isinstance(resp, GenerationResponse)
         if (
             resp.text == "<|tool_calls_section_begin|>"
             or resp.text == "<|tool_calls_section_end|>"
@@ -501,17 +528,44 @@ def filter_kimi_tokens(
 
 
 def parse_gpt_oss(
-    responses: Generator[GenerationResponse],
-) -> Generator[GenerationResponse]:
+    responses: Generator[GenerationResponse | ToolCallResponse],
+) -> Generator[GenerationResponse | ToolCallResponse]:
     encoding = get_gpt_oss_encoding()
     stream = StreamableParser(encoding, role=Role.ASSISTANT)
     thinking = False
+    current_tool_name: str | None = None
+    tool_arg_parts: list[str] = []
 
     for response in responses:
+        assert isinstance(response, GenerationResponse)
         stream.process(response.token)
 
         delta = stream.last_content_delta
         ch = stream.current_channel
+        recipient = stream.current_recipient
+
+        if recipient != current_tool_name:
+            if current_tool_name is not None:
+                prefix = "functions."
+                if current_tool_name.startswith(prefix):
+                    current_tool_name = current_tool_name[len(prefix) :]
+                yield ToolCallResponse(
+                    tool_calls=[
+                        ToolCallItem(
+                            name=current_tool_name,
+                            arguments="".join(tool_arg_parts).strip(),
+                        )
+                    ],
+                    usage=response.usage,
+                )
+                tool_arg_parts = []
+            current_tool_name = recipient
+
+        # If inside a tool call, accumulate arguments
+        if current_tool_name is not None:
+            if delta:
+                tool_arg_parts.append(delta)
+            continue
 
         if ch == "analysis" and not thinking:
             thinking = True
@@ -528,13 +582,12 @@ def parse_gpt_oss(
             if thinking:
                 yield response.model_copy(update={"text": "</think>"})
             yield response
-            break
 
 
 def parse_thinking_models(
-    responses: Generator[GenerationResponse],
+    responses: Generator[GenerationResponse | ToolCallResponse],
     tokenizer: TokenizerWrapper,
-) -> Generator[GenerationResponse]:
+) -> Generator[GenerationResponse | ToolCallResponse]:
     """
     For models that inject thinking tags in the prompt (like GLM-4.7),
     prepend the thinking tag to the output stream so the frontend
@@ -542,6 +595,9 @@ def parse_thinking_models(
     """
     first = True
     for response in responses:
+        if isinstance(response, ToolCallResponse):
+            yield response
+            continue
         if first:
             first = False
             yield response.model_copy(
@@ -595,6 +651,36 @@ def _send_image_chunk(
         )
 
 
+def _send_traces_if_enabled(
+    event_sender: MpSender[Event],
+    task_id: TaskId,
+    rank: int,
+) -> None:
+    if not is_tracing_enabled():
+        return
+
+    traces = get_trace_buffer()
+    if traces:
+        trace_data = [
+            TraceEventData(
+                name=t.name,
+                start_us=t.start_us,
+                duration_us=t.duration_us,
+                rank=t.rank,
+                category=t.category,
+            )
+            for t in traces
+        ]
+        event_sender.send(
+            TracesCollected(
+                task_id=task_id,
+                rank=rank,
+                traces=trace_data,
+            )
+        )
+    clear_trace_buffer()
+
+
 def _process_image_response(
     response: ImageGenerationResponse | PartialImageResponse,
     command_id: CommandId,
@@ -612,7 +698,7 @@ def _process_image_response(
         command_id=command_id,
         model_id=shard_metadata.model_card.model_id,
         event_sender=event_sender,
-        image_index=response.partial_index if is_partial else image_index,
+        image_index=response.image_index,
         is_partial=is_partial,
         partial_index=response.partial_index if is_partial else None,
         total_partials=response.total_partials if is_partial else None,
@@ -622,7 +708,7 @@ def _process_image_response(
 
 
 def parse_tool_calls(
-    responses: Generator[GenerationResponse],
+    responses: Generator[GenerationResponse | ToolCallResponse],
     tool_call_start: str,
     tool_call_end: str,
     tool_parser: Callable[[str], dict[str, Any] | list[dict[str, Any]]],
@@ -630,6 +716,7 @@ def parse_tool_calls(
     in_tool_call = False
     tool_call_text_parts: list[str] = []
     for response in responses:
+        assert isinstance(response, GenerationResponse)
         # assumption: the tool call start is one token
         if response.text == tool_call_start:
             in_tool_call = True
@@ -647,7 +734,7 @@ def parse_tool_calls(
                     tools = [_validate_single_tool(tool) for tool in parsed]
                 else:
                     tools = [_validate_single_tool(parsed)]
-                yield ToolCallResponse(tool_calls=tools)
+                yield ToolCallResponse(tool_calls=tools, usage=response.usage)
 
             except (
                 json.JSONDecodeError,

src/exo/worker/runner/runner_supervisor.py

@@ -127,20 +127,25 @@ class RunnerSupervisor:
         self._tg.cancel_scope.cancel()
 
     async def start_task(self, task: Task):
+        if task.task_id in self.pending:
+            logger.warning(
+                f"Skipping invalid task {task} as it has already been submitted"
+            )
+            return
         if task.task_id in self.completed:
-            logger.info(
+            logger.warning(
                 f"Skipping invalid task {task} as it has already been completed"
             )
+            return
         logger.info(f"Starting task {task}")
         event = anyio.Event()
         self.pending[task.task_id] = event
         try:
-            self._task_sender.send(task)
+            await self._task_sender.send_async(task)
         except ClosedResourceError:
             logger.warning(f"Task {task} dropped, runner closed communication.")
             return
         await event.wait()
-        logger.info(f"Finished task {task}")
 
     async def _forward_events(self):
         with self._ev_recv as events:

src/exo/worker/tests/unittests/test_mlx/test_kv_prefix_cache.py

@@ -0,0 +1,545 @@
+# type: ignore
+import time
+from typing import cast
+from unittest.mock import patch
+
+import mlx.core as mx
+import pytest
+from mlx_lm.models.cache import KVCache
+from mlx_lm.sample_utils import make_sampler
+
+from exo.shared.types.api import ChatCompletionMessage
+from exo.shared.types.common import ModelId
+from exo.shared.types.tasks import ChatCompletionTaskParams
+from exo.worker.engines.mlx import Model
+from exo.worker.engines.mlx.cache import (
+    KVPrefixCache,
+    cache_length,
+    encode_prompt,
+    get_prefix_length,
+    make_kv_cache,
+)
+from exo.worker.engines.mlx.generator.generate import mlx_generate, prefill
+from exo.worker.engines.mlx.utils_mlx import apply_chat_template
+from exo.worker.tests.unittests.test_mlx.conftest import (
+    DEFAULT_GPT_OSS_CONFIG,
+    DEFAULT_GPT_OSS_MODEL_ID,
+)
+
+
+def _check_model_exists() -> bool:
+    return DEFAULT_GPT_OSS_CONFIG.model_path.exists()
+
+
+class TestGetPrefixLength:
+    def test_identical_arrays(self):
+        a = mx.array([1, 2, 3, 4, 5])
+        b = mx.array([1, 2, 3, 4, 5])
+        assert get_prefix_length(a, b) == 5
+
+    def test_no_common_prefix(self):
+        a = mx.array([1, 2, 3])
+        b = mx.array([4, 5, 6])
+        assert get_prefix_length(a, b) == 0
+
+    def test_partial_prefix(self):
+        a = mx.array([1, 2, 3, 4, 5])
+        b = mx.array([1, 2, 3, 7, 8])
+        assert get_prefix_length(a, b) == 3
+
+    def test_prompt_longer_than_cached(self):
+        a = mx.array([1, 2, 3, 4, 5])
+        b = mx.array([1, 2, 3])
+        assert get_prefix_length(a, b) == 3
+
+    def test_cached_longer_than_prompt(self):
+        a = mx.array([1, 2, 3])
+        b = mx.array([1, 2, 3, 4, 5])
+        assert get_prefix_length(a, b) == 3
+
+    def test_single_token_match(self):
+        a = mx.array([1, 2, 3])
+        b = mx.array([1, 5, 6])
+        assert get_prefix_length(a, b) == 1
+
+    def test_empty_prompt(self):
+        a = mx.array([]).astype(mx.int32)
+        b = mx.array([1, 2, 3])
+        assert get_prefix_length(a, b) == 0
+
+    def test_empty_cached(self):
+        a = mx.array([1, 2, 3])
+        b = mx.array([]).astype(mx.int32)
+        assert get_prefix_length(a, b) == 0
+
+    def test_both_empty(self):
+        a = mx.array([]).astype(mx.int32)
+        b = mx.array([]).astype(mx.int32)
+        assert get_prefix_length(a, b) == 0
+
+
+class TestKVPrefix:
+    @pytest.fixture
+    def mock_tokenizer(self):
+        """Create a minimal mock tokenizer for tests that don't need real tokenization."""
+        from unittest.mock import MagicMock
+
+        tokenizer = MagicMock()
+        tokenizer.encode.return_value = [1, 2, 3]
+        return tokenizer
+
+    def test_starts_empty(self, mock_tokenizer):
+        cache = KVPrefixCache(mock_tokenizer)
+        assert len(cache.prompts) == 0
+        assert len(cache.caches) == 0
+
+    def test_clear_empties_cache(self, mock_tokenizer):
+        cache = KVPrefixCache(mock_tokenizer)
+        cache.prompts.append(mx.array([1, 2, 3]))
+        cache.caches.append([KVCache()])
+        cache.clear()
+        assert len(cache.prompts) == 0
+        assert len(cache.caches) == 0
+
+    def test_clear_on_empty_cache(self, mock_tokenizer):
+        cache = KVPrefixCache(mock_tokenizer)
+        cache.clear()
+        assert len(cache.prompts) == 0
+
+
+def _load_gpt_oss() -> tuple[Model, object]:
+    from mlx_lm.utils import load_model
+
+    from exo.worker.engines.mlx.utils_mlx import load_tokenizer_for_model_id
+
+    model_path = DEFAULT_GPT_OSS_CONFIG.model_path
+    model_id = ModelId(DEFAULT_GPT_OSS_MODEL_ID)
+
+    model, _ = load_model(model_path, lazy=False)
+    tokenizer = load_tokenizer_for_model_id(model_id, model_path)
+    return cast(Model, model), tokenizer
+
+
+@pytest.mark.slow
+@pytest.mark.skipif(
+    not _check_model_exists(),
+    reason=f"GPT-OSS model not found at {DEFAULT_GPT_OSS_CONFIG.model_path}",
+)
+class TestKVPrefixCacheWithModel:
+    @pytest.fixture(scope="class")
+    def model_and_tokenizer(self):
+        model, tokenizer = _load_gpt_oss()
+        return model, tokenizer
+
+    def test_prefill_populates_cache(self, model_and_tokenizer):
+        model, tokenizer = model_and_tokenizer
+
+        task = ChatCompletionTaskParams(
+            model=DEFAULT_GPT_OSS_MODEL_ID,
+            messages=[ChatCompletionMessage(role="user", content="Hello!!")],
+            max_tokens=1,
+        )
+        prompt = apply_chat_template(tokenizer, task)
+        tokens = encode_prompt(tokenizer, prompt)
+        cache = make_kv_cache(model)
+
+        prefill(model, tokenizer, make_sampler(0.0), tokens, cache)
+
+        # Cache should now hold the prompt tokens
+        assert cache_length(cache) == len(tokens)
+
+    def test_add_and_get_exact_match(self, model_and_tokenizer):
+        model, tokenizer = model_and_tokenizer
+
+        task = ChatCompletionTaskParams(
+            model=DEFAULT_GPT_OSS_MODEL_ID,
+            messages=[ChatCompletionMessage(role="user", content="Test exact")],
+            max_tokens=1,
+        )
+        prompt = apply_chat_template(tokenizer, task)
+        tokens = encode_prompt(tokenizer, prompt)
+        cache = make_kv_cache(model)
+
+        prefill(model, tokenizer, make_sampler(0.0), tokens, cache)
+
+        kv_prefix_cache = KVPrefixCache(tokenizer)
+        kv_prefix_cache.add_kv_cache(prompt, cache)
+
+        assert len(kv_prefix_cache.prompts) == 1
+        stored_length = cache_length(kv_prefix_cache.caches[0])
+        assert stored_length > 0
+
+        # Retrieve with same prompt: exact match
+        result_cache, remaining_tokens, matched_index = kv_prefix_cache.get_kv_cache(
+            model, prompt
+        )
+        assert matched_index == 0
+
+        # Exact match returns only last token
+        assert len(remaining_tokens) == 1
+        assert mx.array_equal(remaining_tokens, tokens[-1:])
+
+    def test_add_and_get_prefix_match(self, model_and_tokenizer):
+        """get_kv_cache with a longer prompt sharing prefix should return partial match."""
+        model, tokenizer = model_and_tokenizer
+
+        short_task = ChatCompletionTaskParams(
+            model=DEFAULT_GPT_OSS_MODEL_ID,
+            messages=[ChatCompletionMessage(role="user", content="Hi")],
+            max_tokens=1,
+        )
+        short_prompt = apply_chat_template(tokenizer, short_task)
+        short_tokens = encode_prompt(tokenizer, short_prompt)
+        cache = make_kv_cache(model)
+
+        prefill(model, tokenizer, make_sampler(0.0), short_tokens, cache)
+
+        kv_prefix_cache = KVPrefixCache(tokenizer)
+        kv_prefix_cache.add_kv_cache(short_prompt, cache)
+
+        # Query with longer prompt that shares the chat template prefix
+        long_task = ChatCompletionTaskParams(
+            model=DEFAULT_GPT_OSS_MODEL_ID,
+            messages=[
+                ChatCompletionMessage(role="user", content="Hi there, how are you?")
+            ],
+            max_tokens=1,
+        )
+        long_prompt = apply_chat_template(tokenizer, long_task)
+        long_tokens = encode_prompt(tokenizer, long_prompt)
+
+        # The prompts share a prefix (chat template preamble + "Hi")
+        expected_prefix = get_prefix_length(long_tokens, short_tokens)
+        assert expected_prefix > 0, (
+            "Prompts should share a prefix from the chat template"
+        )
+
+        result_cache, remaining_tokens, matched_index = kv_prefix_cache.get_kv_cache(
+            model, long_prompt
+        )
+        assert matched_index == 0
+
+        # remaining_tokens should be the suffix after the shared prefix
+        assert len(remaining_tokens) == len(long_tokens) - expected_prefix
+        assert mx.array_equal(remaining_tokens, long_tokens[expected_prefix:])
+
+    def test_stored_cache_not_mutated_after_get_and_generation(
+        self, model_and_tokenizer
+    ):
+        """Getting a cache and then mutating it (as generation does) must not corrupt stored cache."""
+        model, tokenizer = model_and_tokenizer
+
+        task = ChatCompletionTaskParams(
+            model=DEFAULT_GPT_OSS_MODEL_ID,
+            messages=[ChatCompletionMessage(role="user", content="Mutation test")],
+            max_tokens=1,
+        )
+        prompt = apply_chat_template(tokenizer, task)
+        tokens = encode_prompt(tokenizer, prompt)
+        cache = make_kv_cache(model)
+
+        prefill(model, tokenizer, make_sampler(0.0), tokens, cache)
+
+        kv_prefix_cache = KVPrefixCache(tokenizer)
+        kv_prefix_cache.add_kv_cache(prompt, cache)
+
+        stored_length = cache_length(kv_prefix_cache.caches[0])
+
+        # Get cache and mutate it (simulating what generation does)
+        result_cache, _, matched_index = kv_prefix_cache.get_kv_cache(model, prompt)
+        assert matched_index == 0
+
+        # Simulate generation: feed many additional tokens through the cache
+        head_dim = result_cache[0].keys.shape[-1]
+        num_heads = result_cache[0].keys.shape[1]
+        extra_keys = mx.random.normal((1, num_heads, 50, head_dim))
+        extra_values = mx.random.normal((1, num_heads, 50, head_dim))
+        for layer_cache in result_cache:
+            layer_cache.update_and_fetch(extra_keys, extra_values)
+        mx.eval([c.keys for c in result_cache])
+
+        # Stored cache must be unchanged
+        assert cache_length(kv_prefix_cache.caches[0]) == stored_length
+
+    def test_stored_cache_survives_repeated_get_mutate_cycles(
+        self, model_and_tokenizer
+    ):
+        """Multiple get+mutate cycles (like repeated user requests) must not corrupt cache."""
+        model, tokenizer = model_and_tokenizer
+
+        task = ChatCompletionTaskParams(
+            model=DEFAULT_GPT_OSS_MODEL_ID,
+            messages=[ChatCompletionMessage(role="user", content="Repeat test")],
+            max_tokens=1,
+        )
+        prompt = apply_chat_template(tokenizer, task)
+        tokens = encode_prompt(tokenizer, prompt)
+        cache = make_kv_cache(model)
+
+        prefill(model, tokenizer, make_sampler(0.0), tokens, cache)
+
+        kv_prefix_cache = KVPrefixCache(tokenizer)
+        kv_prefix_cache.add_kv_cache(prompt, cache)
+
+        stored_length = cache_length(kv_prefix_cache.caches[0])
+
+        for i in range(3):
+            result_cache, _, _ = kv_prefix_cache.get_kv_cache(model, prompt)
+
+            head_dim = result_cache[0].keys.shape[-1]
+            num_heads = result_cache[0].keys.shape[1]
+            extra = mx.random.normal((1, num_heads, 30, head_dim))
+            for layer_cache in result_cache:
+                layer_cache.update_and_fetch(extra, extra)
+            mx.eval([c.keys for c in result_cache])
+
+            assert cache_length(kv_prefix_cache.caches[0]) == stored_length, (
+                f"Failed on loop {i}"
+            )
+
+    def test_mlx_generate_populates_cache(self, model_and_tokenizer):
+        """mlx_generate should save the cache after generation completes."""
+        model, tokenizer = model_and_tokenizer
+
+        kv_prefix_cache = KVPrefixCache(tokenizer)
+        task = ChatCompletionTaskParams(
+            model=DEFAULT_GPT_OSS_MODEL_ID,
+            messages=[ChatCompletionMessage(role="user", content="Hello")],
+            max_tokens=5,
+        )
+        prompt = apply_chat_template(tokenizer, task)
+        prompt_tokens = encode_prompt(tokenizer, prompt)
+
+        # Consume the entire generator so the cache-saving code after yield runs
+        generated_tokens = 0
+        for _response in mlx_generate(
+            model=model,
+            tokenizer=tokenizer,
+            task=task,
+            prompt=prompt,
+            kv_prefix_cache=kv_prefix_cache,
+        ):
+            generated_tokens += 1
+
+        assert len(kv_prefix_cache.prompts) == 1
+        assert len(kv_prefix_cache.caches) == 1
+        # Cache should contain prompt + generated tokens
+        expected_length = len(prompt_tokens) + generated_tokens
+        assert cache_length(kv_prefix_cache.caches[0]) == expected_length
+
+    def test_mlx_generate_second_call_gets_prefix_hit(self, model_and_tokenizer):
+        """Second mlx_generate call with same prompt should get a prefix hit from stored cache."""
+        model, tokenizer = model_and_tokenizer
+
+        kv_prefix_cache = KVPrefixCache(tokenizer)
+        task = ChatCompletionTaskParams(
+            model=DEFAULT_GPT_OSS_MODEL_ID,
+            messages=[ChatCompletionMessage(role="user", content="Reuse test")],
+            max_tokens=5,
+        )
+        prompt = apply_chat_template(tokenizer, task)
+        prompt_tokens = encode_prompt(tokenizer, prompt)
+
+        # First generation populates cache
+        for _response in mlx_generate(
+            model=model,
+            tokenizer=tokenizer,
+            task=task,
+            prompt=prompt,
+            kv_prefix_cache=kv_prefix_cache,
+        ):
+            pass
+
+        assert len(kv_prefix_cache.prompts) == 1
+
+        # Second call should find a prefix match (the stored cache contains
+        # prompt + generated tokens, which shares the prompt prefix)
+        result_cache, remaining_tokens, matched_index = kv_prefix_cache.get_kv_cache(
+            model, prompt
+        )
+        # The stored cache is longer than the prompt (it includes generated tokens),
+        # so this is a prefix match where our prompt is fully contained
+        assert matched_index == 0
+        # Exact match: remaining_tokens is just the last token
+        assert len(remaining_tokens) == 1
+        assert mx.array_equal(remaining_tokens, prompt_tokens[-1:])
+
+    def test_mlx_generate_long_prompt_updates_cache_in_place(self, model_and_tokenizer):
+        """With a prompt > 1000 tokens, second generation should update the cache entry in-place."""
+        model, tokenizer = model_and_tokenizer
+
+        kv_prefix_cache = KVPrefixCache(tokenizer)
+
+        # Build a long user message (> 1000 tokens) to exceed _MIN_PREFIX_HIT_TO_UPDATE
+        base_text = "The quick brown fox jumps over the lazy dog. "
+        base_tokens = tokenizer.encode(base_text)
+        repeats = (1200 // len(base_tokens)) + 2
+        long_content = base_text * repeats
+
+        task1 = ChatCompletionTaskParams(
+            model=DEFAULT_GPT_OSS_MODEL_ID,
+            messages=[ChatCompletionMessage(role="user", content=long_content)],
+            max_tokens=5,
+        )
+        prompt1 = apply_chat_template(tokenizer, task1)
+        prompt1_tokens = encode_prompt(tokenizer, prompt1)
+        assert len(prompt1_tokens) > 1000, (
+            "Prompt must exceed _MIN_PREFIX_HIT_TO_UPDATE"
+        )
+
+        # First generation populates the cache (must prefill all tokens)
+        t0 = time.perf_counter()
+        for _response in mlx_generate(
+            model=model,
+            tokenizer=tokenizer,
+            task=task1,
+            prompt=prompt1,
+            kv_prefix_cache=kv_prefix_cache,
+        ):
+            pass
+        first_gen_time = time.perf_counter() - t0
+
+        assert len(kv_prefix_cache.prompts) == 1
+        first_cache_length = cache_length(kv_prefix_cache.caches[0])
+
+        # Second generation: same long prompt + extra content (simulating multi-turn)
+        task2 = ChatCompletionTaskParams(
+            model=DEFAULT_GPT_OSS_MODEL_ID,
+            messages=[
+                ChatCompletionMessage(role="user", content=long_content),
+                ChatCompletionMessage(role="assistant", content="Sure, I can help."),
+                ChatCompletionMessage(role="user", content="Tell me more."),
+            ],
+            max_tokens=5,
+        )
+        prompt2 = apply_chat_template(tokenizer, task2)
+        prompt2_tokens = encode_prompt(tokenizer, prompt2)
+
+        # Verify the prompts share a long prefix
+        prefix_len = get_prefix_length(prompt2_tokens, prompt1_tokens)
+        assert prefix_len > 1000, "Prompts must share > 1000 token prefix"
+
+        # Second generation should reuse the cached prefix (only prefill new tokens)
+        t0 = time.perf_counter()
+        for _response in mlx_generate(
+            model=model,
+            tokenizer=tokenizer,
+            task=task2,
+            prompt=prompt2,
+            kv_prefix_cache=kv_prefix_cache,
+        ):
+            pass
+        second_gen_time = time.perf_counter() - t0
+
+        # Second generation should be significantly faster due to prefix cache hit - hopefully not flaky
+        assert second_gen_time < first_gen_time * 0.5, (
+            f"Expected prefix cache speedup: "
+            f"first={first_gen_time:.2f}s, second={second_gen_time:.2f}s"
+        )
+
+        # With prefix_hit > 1000, should update in-place (not add a second entry)
+        assert len(kv_prefix_cache.prompts) == 1
+        # Updated cache should be longer (prompt2 + generated > prompt1 + generated)
+        updated_cache_length = cache_length(kv_prefix_cache.caches[0])
+        assert updated_cache_length > first_cache_length
+
+    def test_mlx_generate_stored_cache_not_mutated(self, model_and_tokenizer):
+        """After mlx_generate saves a cache, a second generation must not corrupt the stored copy."""
+        model, tokenizer = model_and_tokenizer
+
+        kv_prefix_cache = KVPrefixCache(tokenizer)
+        task = ChatCompletionTaskParams(
+            model=DEFAULT_GPT_OSS_MODEL_ID,
+            messages=[ChatCompletionMessage(role="user", content="Immutable test")],
+            max_tokens=5,
+        )
+        prompt = apply_chat_template(tokenizer, task)
+
+        # First generation populates cache
+        for _response in mlx_generate(
+            model=model,
+            tokenizer=tokenizer,
+            task=task,
+            prompt=prompt,
+            kv_prefix_cache=kv_prefix_cache,
+        ):
+            pass
+
+        firstcache_length = cache_length(kv_prefix_cache.caches[0])
+
+        # Second generation gets the cache and mutates it during generation
+        for _response in mlx_generate(
+            model=model,
+            tokenizer=tokenizer,
+            task=task,
+            prompt=prompt,
+            kv_prefix_cache=kv_prefix_cache,
+        ):
+            pass
+
+        # The first stored cache must not have been mutated by the second generation
+        assert cache_length(kv_prefix_cache.caches[0]) == firstcache_length
+
+    def test_evicts_lru_entry_under_memory_pressure(self, model_and_tokenizer):
+        """Under memory pressure, adding a new cache entry evicts the least recently used one."""
+        model, tokenizer = model_and_tokenizer
+
+        kv_prefix_cache = KVPrefixCache(tokenizer)
+
+        # Add three cache entries with different prompts
+        prompts = ["First entry", "Second entry", "Third entry"]
+        for i, content in enumerate(prompts):
+            task = ChatCompletionTaskParams(
+                model=DEFAULT_GPT_OSS_MODEL_ID,
+                messages=[ChatCompletionMessage(role="user", content=content)],
+                max_tokens=1,
+            )
+            prompt = apply_chat_template(tokenizer, task)
+            tokens = encode_prompt(tokenizer, prompt)
+            cache = make_kv_cache(model)
+            prefill(model, tokenizer, make_sampler(0.0), tokens, cache)
+            kv_prefix_cache.add_kv_cache(prompt, cache)
+            # Stagger _last_used so LRU order is deterministic
+            kv_prefix_cache._last_used[i] = float(i)
+
+        assert len(kv_prefix_cache.prompts) == 3
+
+        # Access the third entry to make it most recently used
+        kv_prefix_cache._last_used[2] = 100.0
+        # Entry 0 (_last_used=0.0) is LRU, entry 1 (_last_used=1.0) is next
+
+        # Simulate memory pressure: active memory exceeds threshold
+        fake_limit = 1000
+        fake_active = int(fake_limit * 0.90)  # Above _MEMORY_THRESHOLD (0.85)
+
+        with (
+            patch(
+                "exo.worker.engines.mlx.cache.mx.metal.get_active_memory",
+                return_value=fake_active,
+            ),
+            patch(
+                "exo.worker.engines.mlx.cache.mx.metal.device_info",
+                return_value={"max_recommended_working_set_size": fake_limit},
+            ),
+        ):
+            # Trigger eviction by adding a new entry
+            task = ChatCompletionTaskParams(
+                model=DEFAULT_GPT_OSS_MODEL_ID,
+                messages=[ChatCompletionMessage(role="user", content="New entry")],
+                max_tokens=1,
+            )
+            prompt = apply_chat_template(tokenizer, task)
+            tokens = encode_prompt(tokenizer, prompt)
+            cache = make_kv_cache(model)
+            prefill(model, tokenizer, make_sampler(0.0), tokens, cache)
+            kv_prefix_cache.add_kv_cache(prompt, cache)
+
+        # LRU entries should have been evicted (entries 0, 1, 2 in order of _last_used)
+        # Since fake_active stays above threshold after each eviction (we don't change it),
+        # all old entries get evicted, leaving only the newly added one
+        assert len(kv_prefix_cache.prompts) == 1
+        # The surviving entry should be the newly added one
+        new_tokens = encode_prompt(tokenizer, prompt)
+        assert get_prefix_length(kv_prefix_cache.prompts[0], new_tokens) == len(
+            new_tokens
+        )

src/exo/worker/tests/unittests/test_mlx/test_tokenizers.py

@@ -11,12 +11,12 @@ from pathlib import Path
 
 import pytest
 
-from exo.shared.models.model_cards import MODEL_CARDS, ModelCard, ModelId
-from exo.worker.download.download_utils import (
+from exo.download.download_utils import (
     download_file_with_retry,
     ensure_models_dir,
     fetch_file_list_with_cache,
 )
+from exo.shared.models.model_cards import MODEL_CARDS, ModelCard, ModelId
 from exo.worker.engines.mlx.utils_mlx import (
     get_eos_token_ids_for_model,
     load_tokenizer_for_model_id,

src/exo/worker/tests/unittests/test_plan/test_download_and_loading.py

@@ -1,5 +1,5 @@
 import exo.worker.plan as plan_mod
-from exo.shared.types.common import ModelId, NodeId
+from exo.shared.types.common import NodeId
 from exo.shared.types.memory import Memory
 from exo.shared.types.tasks import LoadModel
 from exo.shared.types.worker.downloads import DownloadCompleted, DownloadProgress
@@ -45,13 +45,9 @@ def test_plan_requests_download_when_waiting_and_shard_not_downloaded():
     instances = {INSTANCE_1_ID: instance}
     all_runners = {RUNNER_1_ID: RunnerIdle()}
 
-    # No entry for this shard -> should trigger DownloadModel
-    download_status: dict[ModelId, DownloadProgress] = {}
-
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status=download_status,
         global_download_status={NODE_A: []},
         instances=instances,
         all_runners=all_runners,
@@ -92,14 +88,6 @@ def test_plan_loads_model_when_all_shards_downloaded_and_waiting():
         RUNNER_2_ID: RunnerConnected(),
     }
 
-    # Local node has already marked its shard as downloaded (not actually used by _load_model)
-    local_download_status = {
-        MODEL_A_ID: DownloadCompleted(
-            shard_metadata=shard1, node_id=NODE_A, total_bytes=Memory()
-        )
-    }
-
-    # Global view has completed downloads for both nodes
     global_download_status = {
         NODE_A: [
             DownloadCompleted(
@@ -116,7 +104,6 @@ def test_plan_loads_model_when_all_shards_downloaded_and_waiting():
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status=local_download_status,
         global_download_status=global_download_status,
         instances=instances,
         all_runners=all_runners,
@@ -148,30 +135,26 @@ def test_plan_does_not_request_download_when_shard_already_downloaded():
     instances = {INSTANCE_1_ID: instance}
     all_runners = {RUNNER_1_ID: RunnerIdle()}
 
-    # Local status claims the shard is downloaded already
-    local_download_status = {
-        MODEL_A_ID: DownloadCompleted(
-            shard_metadata=shard, node_id=NODE_A, total_bytes=Memory()
-        )
-    }
-
-    # Global view hasn't caught up yet (no completed shards recorded for NODE_A)
+    # Global state shows shard is downloaded for NODE_A
     global_download_status: dict[NodeId, list[DownloadProgress]] = {
-        NODE_A: [],
+        NODE_A: [
+            DownloadCompleted(
+                shard_metadata=shard, node_id=NODE_A, total_bytes=Memory()
+            )
+        ],
         NODE_B: [],
     }
 
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status=local_download_status,
         global_download_status=global_download_status,
         instances=instances,
         all_runners=all_runners,
         tasks={},
     )
 
-    assert result is None
+    assert not isinstance(result, plan_mod.DownloadModel)
 
 
 def test_plan_does_not_load_model_until_all_shards_downloaded_globally():
@@ -202,12 +185,6 @@ def test_plan_does_not_load_model_until_all_shards_downloaded_globally():
         RUNNER_2_ID: RunnerConnected(),
     }
 
-    # Only NODE_A's shard is recorded as downloaded globally
-    local_download_status = {
-        MODEL_A_ID: DownloadCompleted(
-            shard_metadata=shard1, node_id=NODE_A, total_bytes=Memory()
-        )
-    }
     global_download_status = {
         NODE_A: [
             DownloadCompleted(
@@ -220,7 +197,6 @@ def test_plan_does_not_load_model_until_all_shards_downloaded_globally():
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status=local_download_status,
         global_download_status=global_download_status,
         instances=instances,
         all_runners=all_runners,
@@ -245,7 +221,6 @@ def test_plan_does_not_load_model_until_all_shards_downloaded_globally():
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status=local_download_status,
         global_download_status=global_download_status,
         instances=instances,
         all_runners=all_runners,

src/exo/worker/tests/unittests/test_plan/test_runner_lifecycle.py

@@ -47,8 +47,7 @@ def test_plan_kills_runner_when_instance_missing():
 
     result = plan_mod.plan(
         node_id=NODE_A,
-        runners=runners,  # type: ignore
-        download_status={},
+        runners=runners,  # type: ignore[arg-type]
         global_download_status={NODE_A: []},
         instances=instances,
         all_runners=all_runners,
@@ -87,8 +86,7 @@ def test_plan_kills_runner_when_sibling_failed():
 
     result = plan_mod.plan(
         node_id=NODE_A,
-        runners=runners,  # type: ignore
-        download_status={},
+        runners=runners,  # type: ignore[arg-type]
         global_download_status={NODE_A: []},
         instances=instances,
         all_runners=all_runners,
@@ -120,7 +118,6 @@ def test_plan_creates_runner_when_missing_for_node():
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,
-        download_status={},
         global_download_status={NODE_A: []},
         instances=instances,
         all_runners=all_runners,
@@ -158,8 +155,7 @@ def test_plan_does_not_create_runner_when_supervisor_already_present():
 
     result = plan_mod.plan(
         node_id=NODE_A,
-        runners=runners,  # type: ignore
-        download_status={},
+        runners=runners,  # type: ignore[arg-type]
         global_download_status={NODE_A: []},
         instances=instances,
         all_runners=all_runners,
@@ -189,7 +185,6 @@ def test_plan_does_not_create_runner_for_unassigned_node():
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status={},
         global_download_status={NODE_A: []},
         instances=instances,
         all_runners=all_runners,

src/exo/worker/tests/unittests/test_plan/test_task_forwarding.py

@@ -65,7 +65,6 @@ def test_plan_forwards_pending_chat_completion_when_runner_ready():
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status={},
         global_download_status={NODE_A: []},
         instances=instances,
         all_runners=all_runners,
@@ -113,7 +112,6 @@ def test_plan_does_not_forward_chat_completion_if_any_runner_not_ready():
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status={},
         global_download_status={NODE_A: [], NODE_B: []},
         instances=instances,
         all_runners=all_runners,
@@ -158,7 +156,6 @@ def test_plan_does_not_forward_tasks_for_other_instances():
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status={},
         global_download_status={NODE_A: []},
         instances=instances,
         all_runners=all_runners,
@@ -221,7 +218,6 @@ def test_plan_ignores_non_pending_or_non_chat_tasks():
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status={},
         global_download_status={NODE_A: [], NODE_B: []},
         instances=instances,
         all_runners=all_runners,
@@ -261,7 +257,6 @@ def test_plan_returns_none_when_nothing_to_do():
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status={},
         global_download_status={NODE_A: [], NODE_B: []},
         instances=instances,
         all_runners=all_runners,

src/exo/worker/tests/unittests/test_plan/test_warmup.py

@@ -57,7 +57,6 @@ def test_plan_starts_warmup_for_accepting_rank_when_all_loaded_or_warming():
     result = plan_mod.plan(
         node_id=NODE_B,
         runners=runners,  # type: ignore
-        download_status={},
         global_download_status={NODE_A: []},
         instances=instances,
         all_runners=all_runners,
@@ -99,7 +98,6 @@ def test_plan_starts_warmup_for_rank_zero_after_others_warming():
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status={},
         global_download_status={NODE_A: []},
         instances=instances,
         all_runners=all_runners,
@@ -140,7 +138,6 @@ def test_plan_does_not_start_warmup_for_non_zero_rank_until_all_loaded_or_warmin
     result = plan_mod.plan(
         node_id=NODE_B,
         runners=runners,  # type: ignore
-        download_status={},
         global_download_status={NODE_A: [], NODE_B: []},
         instances=instances,
         all_runners=all_runners,
@@ -185,7 +182,6 @@ def test_plan_does_not_start_warmup_for_rank_zero_until_others_warming():
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status={},
         global_download_status={NODE_A: []},
         instances=instances,
         all_runners=all_runners,
@@ -202,7 +198,6 @@ def test_plan_does_not_start_warmup_for_rank_zero_until_others_warming():
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status={},
         global_download_status={NODE_A: []},
         instances=instances,
         all_runners=all_runners,
@@ -246,7 +241,6 @@ def test_plan_starts_warmup_for_connecting_rank_after_others_warming():
     result = plan_mod.plan(
         node_id=NODE_B,
         runners=runners,  # type: ignore
-        download_status={},
         global_download_status={NODE_B: []},
         instances=instances,
         all_runners=all_runners,
@@ -289,7 +283,6 @@ def test_plan_does_not_start_warmup_for_accepting_rank_until_all_loaded_or_warmi
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status={},
         global_download_status={NODE_A: [], NODE_B: []},
         instances=instances,
         all_runners=all_runners,
@@ -331,7 +324,6 @@ def test_plan_does_not_start_warmup_for_connecting_rank_until_others_warming():
     result = plan_mod.plan(
         node_id=NODE_A,
         runners=runners,  # type: ignore
-        download_status={},
         global_download_status={NODE_A: [], NODE_B: []},
         instances=instances,
         all_runners=all_runners,

src/exo/worker/tests/unittests/test_runner/test_event_ordering.py

@@ -109,8 +109,8 @@ def assert_events_equal(test_events: Iterable[Event], true_events: Iterable[Even
 
 @pytest.fixture
 def patch_out_mlx(monkeypatch: pytest.MonkeyPatch):
-    # initialize_mlx returns a "group" equal to 1
-    monkeypatch.setattr(mlx_runner, "initialize_mlx", make_nothin(1))
+    # initialize_mlx returns a mock group
+    monkeypatch.setattr(mlx_runner, "initialize_mlx", make_nothin(MockGroup()))
     monkeypatch.setattr(mlx_runner, "load_mlx_items", make_nothin((1, MockTokenizer)))
     monkeypatch.setattr(mlx_runner, "warmup_inference", make_nothin(1))
     monkeypatch.setattr(mlx_runner, "_check_for_debug_prompts", nothin)
@@ -120,7 +120,7 @@ def patch_out_mlx(monkeypatch: pytest.MonkeyPatch):
     monkeypatch.setattr(mlx_runner, "detect_thinking_prompt_suffix", make_nothin(False))
 
     def fake_generate(*_1: object, **_2: object):
-        yield GenerationResponse(token=0, text="hi", finish_reason="stop")
+        yield GenerationResponse(token=0, text="hi", finish_reason="stop", usage=None)
 
     monkeypatch.setattr(mlx_runner, "mlx_generate", fake_generate)
 
@@ -147,6 +147,14 @@ class MockTokenizer:
     has_tool_calling = False
 
 
+class MockGroup:
+    def rank(self) -> int:
+        return 0
+
+    def size(self) -> int:
+        return 1
+
+
 def _run(tasks: Iterable[Task]):
     bound_instance = get_bound_mlx_ring_instance(
         instance_id=INSTANCE_1_ID,
@@ -182,6 +190,8 @@ def test_events_processed_in_correct_order(patch_out_mlx: pytest.MonkeyPatch):
             text="hi",
             token_id=0,
             finish_reason="stop",
+            usage=None,
+            stats=None,
         ),
     )
 

tests/headless_runner.py

@@ -11,6 +11,10 @@ from hypercorn.asyncio import serve  # pyright: ignore[reportUnknownVariableType
 from loguru import logger
 from pydantic import BaseModel
 
+from exo.download.impl_shard_downloader import (
+    build_full_shard,
+    exo_shard_downloader,
+)
 from exo.shared.logging import InterceptLogger, logger_setup
 from exo.shared.models.model_cards import MODEL_CARDS, ModelId
 from exo.shared.types.api import ChatCompletionMessage, ChatCompletionTaskParams
@@ -36,10 +40,6 @@ from exo.shared.types.worker.runners import RunnerId, ShardAssignments
 from exo.shared.types.worker.shards import PipelineShardMetadata, TensorShardMetadata
 from exo.utils.channels import MpReceiver, MpSender, channel, mp_channel
 from exo.utils.info_gatherer.info_gatherer import GatheredInfo, InfoGatherer
-from exo.worker.download.impl_shard_downloader import (
-    build_full_shard,
-    exo_shard_downloader,
-)
 from exo.worker.runner.bootstrap import entrypoint
 
 

tests/start_distributed_test.sh

@@ -11,7 +11,6 @@ if [[ $# -lt 2 ]]; then
   exit 1
 fi
 
-
 kind=$1
 shift
 
@@ -31,14 +30,14 @@ for name in "${hostnames[@]}"; do
   weaved+=("$name" "$ip")
 done
 
-devs_raw=$(printf "[\"%s\", \"%s\"], " "${weaved[@]}")
+devs_raw=$(printf '["%s", "%s"], ' "${weaved[@]}")
 devs="[${devs_raw%, }]"
 
 model_ids=("qwen3-30b" "gpt-oss-120b-MXFP4-Q8" "kimi-k2-thinking")
 
 for model_id in "${model_ids[@]}"; do
-  for i in "${!ips[@]}"; do  
-    { 
+  for i in "${!ips[@]}"; do
+    {
       req="{
         \"model_id\": \"${model_id}\",
         \"devs\": ${devs},
@@ -48,9 +47,8 @@ for model_id in "${model_ids[@]}"; do
       curl -sN \
         -X POST "http://${ips[$i]}:52415/${kind}" \
         -H "Content-Type: application/json" -d "$req" \
-      2>&1 | sed "s/^/\n${hostnames[$i]}@${ips[$i]}: /" || echo "curl to ${hostnames[$i]} failed" && exit 1
+        2>&1 | sed "s/^/\n${hostnames[$i]}@${ips[$i]}: /" || echo "curl to ${hostnames[$i]} failed" && exit 1
     } &
   done
   wait
 done
-

tmp/config_examples/opencode.json

@@ -0,0 +1,18 @@
+{
+  "$schema": "https://opencode.ai/config.json",
+  "model": "exo/mlx-community/gpt-oss-120b-MXFP4-Q8",
+  "provider": {
+    "exo": {
+      "api": "http://localhost:52415/v1",
+      "models": {
+        "mlx-community/gpt-oss-120b-MXFP4-Q8": {
+          "name": "GPT OSS 120B",
+          "limit": {
+            "context": 32768,
+            "output": 8192
+          }
+        }
+      }
+    }
+  }
+}

tmp/set_rdma_network_config.sh

@@ -0,0 +1,47 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+PREFS="/Library/Preferences/SystemConfiguration/preferences.plist"
+
+# Remove bridge0 interface
+ifconfig bridge0 &>/dev/null && {
+  ifconfig bridge0 | grep -q 'member' && {
+    ifconfig bridge0 | awk '/member/ {print $2}' | xargs -n1 ifconfig bridge0 deletem 2>/dev/null || true
+  }
+  ifconfig bridge0 destroy 2>/dev/null || true
+}
+
+# Remove Thunderbolt Bridge from VirtualNetworkInterfaces in preferences.plist
+/usr/libexec/PlistBuddy -c "Delete :VirtualNetworkInterfaces:Bridge:bridge0" "$PREFS" 2>/dev/null || true
+
+networksetup -listlocations | grep -q exo || {
+  networksetup -createlocation exo
+}
+
+networksetup -switchtolocation exo
+networksetup -listallhardwareports |
+  awk -F': ' '/Hardware Port: / {print $2}' |
+  while IFS=":" read -r name; do
+    case "$name" in
+    "Ethernet Adapter"*) ;;
+    "Thunderbolt Bridge") ;;
+    "Thunderbolt "*)
+      networksetup -listallnetworkservices |
+        grep -q "EXO $name" ||
+        networksetup -createnetworkservice "EXO $name" "$name" 2>/dev/null ||
+        continue
+      networksetup -setdhcp "EXO $name"
+      ;;
+    *)
+      networksetup -listallnetworkservices |
+        grep -q "$name" ||
+        networksetup -createnetworkservice "$name" "$name" 2>/dev/null ||
+        continue
+      ;;
+    esac
+  done
+
+networksetup -listnetworkservices | grep -q "Thunderbolt Bridge" && {
+  networksetup -setnetworkserviceenabled "Thunderbolt Bridge" off
+} || true