nix: add PyInstaller package for macOS DMG

Added exo-pyinstaller derivation that builds the PyInstaller bundle using Nix. Updated build-app.yml to use the Nix-built bundle instead of invoking uv/pyinstaller directly. Test plan: - Build on macOS: `nix build .#exo-pyinstaller` - Push to test-app branch to trigger build-app.yml workflow
nix: add Python packaging with uv2nix
2026-01-22 13:00:28 -05:00 · 2026-01-19 16:25:32 +00:00 · 2026-01-19 16:25:32 +00:00 · 2026-01-19 16:19:52 +00:00
12 changed files with 260 additions and 229 deletions
--- a/.github/actions/typecheck/action.yml
+++ b/.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
--- a/.github/workflows/build-app.yml
+++ b/.github/workflows/build-app.yml
@@ -161,17 +161,6 @@ jobs:
      - name: Install Homebrew packages
        run: brew install just awscli macmon

-      - name: Install UV
-        uses: astral-sh/setup-uv@v6
-        with:
-          enable-cache: true
-          cache-dependency-glob: uv.lock
-
-      - name: Setup Python
-        run: |
-          uv python install
-          uv sync --locked
-
      - name: Install Nix
        uses: cachix/install-nix-action@v31
        with:
@@ -183,12 +172,6 @@ jobs:
          name: exo
          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"

-      - name: Build dashboard
-        run: |
-          DASHBOARD_OUT=$(nix build .#dashboard --print-build-logs --no-link --print-out-paths)
-          mkdir -p dashboard/build
-          cp -r "$DASHBOARD_OUT"/* dashboard/build/
-
      - name: Install Sparkle CLI
        run: |
          CLI_URL="${SPARKLE_CLI_URL:-https://github.com/sparkle-project/Sparkle/releases/download/${SPARKLE_VERSION}/Sparkle-${SPARKLE_VERSION}.tar.xz}"
@@ -244,7 +227,10 @@ jobs:
      # ============================================================

      - name: Build PyInstaller bundle
-        run: uv run pyinstaller packaging/pyinstaller/exo.spec
+        run: |
+          PYINSTALLER_OUT=$(nix build .#exo-pyinstaller --print-build-logs --no-link --print-out-paths)
+          mkdir -p dist
+          cp -r "$PYINSTALLER_OUT" dist/exo

      - name: Build Swift app
        env:
--- a/.github/workflows/pipeline.yml
+++ b/.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 }})
--- a/README.md
+++ b/README.md
@@ -42,7 +42,7 @@ exo includes a built-in dashboard for managing your cluster and chatting with mo
  <summary>Qwen3-235B (8-bit) on 4 × M3 Ultra Mac Studio with Tensor Parallel RDMA</summary>
  <img src="docs/benchmarks/jeffgeerling/mac-studio-cluster-ai-full-1-qwen3-235b.jpeg" alt="Benchmark - Qwen3-235B (8-bit) on 4 × M3 Ultra Mac Studio with Tensor Parallel RDMA" width="80%" />
  <p>
-    <strong>Source:</strong> <a href="https://www.jeffgeerling.com/blog/2025/15-tb-vram-on-mac-studio-rdma-over-thunderbolt-5">Jeff Geerling: 15 TB VRAM on Mac Studio – RDMA over Thunderbolt 5</a>
+    <strong>Source:</strong> <a href="https://www.jeffgeerling.com/blog/2025/15-tb-vram-on-mac-studio-rdma-over-thunderbolt-5">Jeff Geerling: 15 TB VRAM on Mac Studio – RDMA over Thunderbolt 5</a>
  </p>
 </details>

@@ -50,7 +50,7 @@ exo includes a built-in dashboard for managing your cluster and chatting with mo
  <summary>DeepSeek v3.1 671B (8-bit) on 4 × M3 Ultra Mac Studio with Tensor Parallel RDMA</summary>
  <img src="docs/benchmarks/jeffgeerling/mac-studio-cluster-ai-full-2-deepseek-3.1-671b.jpeg" alt="Benchmark - DeepSeek v3.1 671B (8-bit) on 4 × M3 Ultra Mac Studio with Tensor Parallel RDMA" width="80%" />
  <p>
-    <strong>Source:</strong> <a href="https://www.jeffgeerling.com/blog/2025/15-tb-vram-on-mac-studio-rdma-over-thunderbolt-5">Jeff Geerling: 15 TB VRAM on Mac Studio – RDMA over Thunderbolt 5</a>
+    <strong>Source:</strong> <a href="https://www.jeffgeerling.com/blog/2025/15-tb-vram-on-mac-studio-rdma-over-thunderbolt-5">Jeff Geerling: 15 TB VRAM on Mac Studio – RDMA over Thunderbolt 5</a>
  </p>
 </details>

@@ -58,7 +58,7 @@ exo includes a built-in dashboard for managing your cluster and chatting with mo
  <summary>Kimi K2 Thinking (native 4-bit) on 4 × M3 Ultra Mac Studio with Tensor Parallel RDMA</summary>
  <img src="docs/benchmarks/jeffgeerling/mac-studio-cluster-ai-full-3-kimi-k2-thinking.jpeg" alt="Benchmark - Kimi K2 Thinking (native 4-bit) on 4 × M3 Ultra Mac Studio with Tensor Parallel RDMA" width="80%" />
  <p>
-    <strong>Source:</strong> <a href="https://www.jeffgeerling.com/blog/2025/15-tb-vram-on-mac-studio-rdma-over-thunderbolt-5">Jeff Geerling: 15 TB VRAM on Mac Studio – RDMA over Thunderbolt 5</a>
+    <strong>Source:</strong> <a href="https://www.jeffgeerling.com/blog/2025/15-tb-vram-on-mac-studio-rdma-over-thunderbolt-5">Jeff Geerling: 15 TB VRAM on Mac Studio – RDMA over Thunderbolt 5</a>
  </p>
 </details>

@@ -163,24 +163,6 @@ This starts the exo dashboard and API at http://localhost:52415/

 **Important note for Linux users:** Currently, exo runs on CPU on Linux. GPU support for Linux platforms is under development. If you'd like to see support for your specific Linux hardware, please [search for existing feature requests](https://github.com/exo-explore/exo/issues) or create a new one.

-**Configuration Options:**
-
- `--no-worker`: Run exo without the worker component. Useful for coordinator-only nodes that handle networking and orchestration but don't execute inference tasks. This is helpful for machines without sufficient GPU resources but with good network connectivity.
-
-  ```bash
-  uv run exo --no-worker
-  ```
-
-**File Locations (Linux):**
-
-exo follows the [XDG Base Directory Specification](https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html) on Linux:
-
- **Configuration files**: `~/.config/exo/` (or `$XDG_CONFIG_HOME/exo/`)
- **Data files**: `~/.local/share/exo/` (or `$XDG_DATA_HOME/exo/`)
- **Cache files**: `~/.cache/exo/` (or `$XDG_CACHE_HOME/exo/`)
-
-You can override these locations by setting the corresponding XDG environment variables.
-
 ### macOS App

 exo ships a macOS app that runs in the background on your Mac.
@@ -193,19 +175,6 @@ Download the latest build here: [EXO-latest.dmg](https://assets.exolabs.net/EXO-

 The app will ask for permission to modify system settings and install a new Network profile. Improvements to this are being worked on.

-**Custom Namespace for Cluster Isolation:**
-
-The macOS app includes a custom namespace feature that allows you to isolate your exo cluster from others on the same network. This is configured through the `EXO_LIBP2P_NAMESPACE` setting:
-
- **Use cases**:
-  - Running multiple separate exo clusters on the same network
-  - Isolating development/testing clusters from production clusters
-  - Preventing accidental cluster joining
-
- **Configuration**: Access this setting in the app's Advanced settings (or set the `EXO_LIBP2P_NAMESPACE` environment variable when running from source)
-
-The namespace is logged on startup for debugging purposes.
-
 #### Uninstalling the macOS App

 The recommended way to uninstall is through the app itself: click the menu bar icon → Advanced → Uninstall. This cleanly removes all system components.
@@ -352,52 +321,6 @@ For further details, see:

 ---

-## Benchmarking
-
-The `exo-bench` tool measures model prefill and token generation speed across different placement configurations. This helps you optimize model performance and validate improvements.
-
-**Prerequisites:**
- Nodes should be running with `uv run exo` before benchmarking
- The tool uses the `/bench/chat/completions` endpoint
-
-**Basic usage:**
-
-```bash
-uv run bench/exo_bench.py \
-  --model llama-3.2-1b \
-  --pp 128,256,512 \
-  --tg 128,256
-```
-
-**Key parameters:**
-
- `--model`: Model to benchmark (short ID or HuggingFace ID)
- `--pp`: Prompt size hints (comma-separated integers)
- `--tg`: Generation lengths (comma-separated integers)
- `--max-nodes`: Limit placements to N nodes (default: 4)
- `--instance-meta`: Filter by `ring`, `jaccl`, or `both` (default: both)
- `--sharding`: Filter by `pipeline`, `tensor`, or `both` (default: both)
- `--repeat`: Number of repetitions per configuration (default: 1)
- `--warmup`: Warmup runs per placement (default: 0)
- `--json-out`: Output file for results (default: bench/results.json)
-
-**Example with filters:**
-
-```bash
-uv run bench/exo_bench.py \
-  --model llama-3.2-1b \
-  --pp 128,512 \
-  --tg 128 \
-  --max-nodes 2 \
-  --sharding tensor \
-  --repeat 3 \
-  --json-out my-results.json
-```
-
-The tool outputs performance metrics including prompt tokens per second (prompt_tps), generation tokens per second (generation_tps), and peak memory usage for each configuration.
-
---
-
 ## Hardware Accelerator Support

 On macOS, exo uses the GPU. On Linux, exo currently runs on CPU. We are working on extending hardware accelerator support. If you'd like support for a new hardware platform, please [search for an existing feature request](https://github.com/exo-explore/exo/issues) and add a thumbs up so we know what hardware is important to the community.
@@ -406,4 +329,4 @@ On macOS, exo uses the GPU. On Linux, exo currently runs on CPU. We are working

 ## Contributing

-See [CONTRIBUTING.md](CONTRIBUTING.md) for guidelines on how to contribute to exo.
+See [CONTRIBUTING.md](CONTRIBUTING.md) for guidelines on how to contribute to exo.
--- a/flake.lock
+++ b/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",
--- a/flake.nix
+++ b/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 =
@@ -81,16 +102,9 @@
            };
          };

-          checks.lint = pkgs.runCommand "lint-check" { } ''
-            export RUFF_CACHE_DIR="$TMPDIR/ruff-cache"
-            ${pkgs.ruff}/bin/ruff check ${inputs.self}/
-            touch $out
-          '';
-
          packages =
            if pkgs.stdenv.isDarwin then {
              metal = pkgs.callPackage ./nix/metalWrapper.nix { metalVersion = "310"; };
-              mlx = pkgs.callPackage ./nix/mlx.nix {};
            } else { };

          devShells.default = with pkgs; pkgs.mkShell {
--- a/nix/mlx.nix
+++ b/nix/mlx.nix
@@ -1,9 +1,7 @@
 { stdenv
 , lib
+, buildPythonPackage
 , fetchFromGitHub
-, fetchPypi
-, pyprojectHook
-, pypaInstallHook
 , replaceVars
 , fetchzip
 , setuptools
@@ -34,7 +32,7 @@ let
    hash = "sha256-7n2eI2lw/S+Us6l7YPAATKwcIbRRpaQ8VmES7S8ZjY8=";
  };

-  mlx = stdenv.mkDerivation rec {
+  mlx = buildPythonPackage rec {
    pname = "mlx";
    version = "0.30.1";
    pyproject = true;
@@ -100,8 +98,6 @@ let
    nativeBuildInputs = [
      cmake
      metal
-      pyprojectHook
-      pypaInstallHook
    ];

    buildInputs = [
--- a/python/parts.nix
+++ b/python/parts.nix
@@ -0,0 +1,143 @@
+{ inputs, ... }:
+{
+  perSystem =
+    { self', pkgs, lib, system, ... }:
+    let
+      # Load workspace from uv.lock
+      workspace = inputs.uv2nix.lib.workspace.loadWorkspace {
+        workspaceRoot = inputs.self;
+      };
+
+      # Create overlay from workspace
+      overlay = workspace.mkPyprojectOverlay { };
+
+      # Override overlay to inject Nix-built components
+      exoOverlay = final: _: {
+        # 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 for source builds
+      buildSystemsOverlay = final: prev: {
+        # mlx-lm is a git dependency that needs setuptools
+        mlx-lm = prev.mlx-lm.overrideAttrs (old: {
+          nativeBuildInputs = (old.nativeBuildInputs or [ ]) ++ [
+            final.setuptools
+          ];
+        });
+
+        # Build MLX from source with proper dependencies
+        mlx = pkgs.callPythonPackage ./nix/mlx.nix;
+      };
+
+      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 ${self'.packages.dashboard}
+          done
+        '';
+
+      pyinstallerPackage =
+        let
+          venv = pythonSet.mkVirtualEnv "exo-pyinstaller-env" (
+            workspace.deps.default
+            // {
+              # Include pyinstaller in the environment
+              exo = [ "dev" ];
+            }
+          );
+        in
+        pkgs.stdenv.mkDerivation {
+          pname = "exo-pyinstaller";
+          version = "0.3.0";
+
+          src = inputs.self;
+
+          nativeBuildInputs = [ venv pkgs.makeWrapper pkgs.macmon pkgs.darwin.system_cmds ];
+
+          buildPhase = ''
+            # macmon must be in PATH for PyInstaller to bundle it
+            export PATH="${pkgs.macmon}/bin:$PATH"
+            # HOME must be writable for PyInstaller's cache
+            export HOME="$TMPDIR"
+
+            # Copy dashboard to expected location
+            mkdir -p dashboard/build
+            cp -r ${self'.packages.dashboard}/* dashboard/build/
+
+            # Run PyInstaller
+            ${venv}/bin/python -m PyInstaller packaging/pyinstaller/exo.spec
+          '';
+
+          installPhase = ''
+            cp -r dist/exo $out
+          '';
+        };
+    in
+    {
+      # Python package only available on macOS for now due to the dependency on
+      # mlx/mlx-cpu being tricky to build on Linux. We can either remove this
+      # dependency in the PyProject or build it with Nix.
+      packages = lib.optionalAttrs pkgs.stdenv.hostPlatform.isDarwin {
+        exo = exoPackage;
+        exo-pyinstaller = pyinstallerPackage;
+      };
+
+      checks = {
+        # Ruff linting (works on all platforms)
+        lint = pkgs.runCommand "ruff-lint" { } ''
+          export RUFF_CACHE_DIR="$TMPDIR/ruff-cache"
+          ${pkgs.ruff}/bin/ruff check ${inputs.self}/
+          touch $out
+        '';
+      }
+      # Pytest only on macOS (requires MLX)
+      // lib.optionalAttrs pkgs.stdenv.hostPlatform.isDarwin {
+        pytest = pkgs.runCommand "pytest"
+          {
+            nativeBuildInputs = [ testVenv ];
+          } ''
+          export HOME="$TMPDIR"
+          export EXO_TESTS=1
+          cd ${inputs.self}
+          ${testVenv}/bin/python -m pytest src -m "not slow" --import-mode=importlib
+          touch $out
+        '';
+      };
+    };
+}
--- a/src/exo/worker/download/download_utils.py
+++ b/src/exo/worker/download/download_utils.py
@@ -5,7 +5,6 @@ import shutil
 import ssl
 import time
 import traceback
-from collections.abc import Awaitable
 from datetime import timedelta
 from pathlib import Path
 from typing import Callable, Literal
@@ -526,7 +525,7 @@ async def download_progress_for_local_path(

 async def download_shard(
    shard: ShardMetadata,
-    on_progress: Callable[[ShardMetadata, RepoDownloadProgress], Awaitable[None]],
+    on_progress: Callable[[ShardMetadata, RepoDownloadProgress], None],
    max_parallel_downloads: int = 8,
    skip_download: bool = False,
    allow_patterns: list[str] | None = None,
@@ -567,9 +566,9 @@ async def download_shard(
    )
    file_progress: dict[str, RepoFileDownloadProgress] = {}

-    async def on_progress_wrapper(
+    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
@@ -605,7 +604,7 @@ async def download_shard(
            else "in_progress",
            start_time=start_time,
        )
-        await on_progress(
+        on_progress(
            shard,
            calculate_repo_progress(
                shard,
@@ -633,21 +632,14 @@ async def download_shard(

    semaphore = asyncio.Semaphore(max_parallel_downloads)

-    def schedule_progress(
-        file: FileListEntry, curr_bytes: int, total_bytes: int, is_renamed: bool
-    ) -> None:
-        asyncio.create_task(
-            on_progress_wrapper(file, curr_bytes, total_bytes, is_renamed)
-        )
-
-    async def download_with_semaphore(file: FileListEntry) -> None:
+    async def download_with_semaphore(file: FileListEntry):
        async with semaphore:
            await download_file_with_retry(
                str(shard.model_meta.model_id),
                revision,
                file.path,
                target_dir,
-                lambda curr_bytes, total_bytes, is_renamed: schedule_progress(
+                lambda curr_bytes, total_bytes, is_renamed: on_progress_wrapper(
                    file, curr_bytes, total_bytes, is_renamed
                ),
            )
@@ -659,7 +651,7 @@ async def download_shard(
    final_repo_progress = calculate_repo_progress(
        shard, str(shard.model_meta.model_id), revision, file_progress, all_start_time
    )
-    await on_progress(shard, final_repo_progress)
+    on_progress(shard, final_repo_progress)
    if gguf := next((f for f in filtered_file_list if f.path.endswith(".gguf")), None):
        return target_dir / gguf.path, final_repo_progress
    else:
--- a/src/exo/worker/download/impl_shard_downloader.py
+++ b/src/exo/worker/download/impl_shard_downloader.py
@@ -1,5 +1,4 @@
 import asyncio
-from collections.abc import Awaitable
 from pathlib import Path
 from typing import AsyncIterator, Callable

@@ -49,8 +48,7 @@ class SingletonShardDownloader(ShardDownloader):
        self.active_downloads: dict[ShardMetadata, asyncio.Task[Path]] = {}

    def on_progress(
-        self,
-        callback: Callable[[ShardMetadata, RepoDownloadProgress], Awaitable[None]],
+        self, callback: Callable[[ShardMetadata, RepoDownloadProgress], None]
    ) -> None:
        self.shard_downloader.on_progress(callback)

@@ -85,8 +83,7 @@ class CachedShardDownloader(ShardDownloader):
        self.cache: dict[tuple[str, ShardMetadata], Path] = {}

    def on_progress(
-        self,
-        callback: Callable[[ShardMetadata, RepoDownloadProgress], Awaitable[None]],
+        self, callback: Callable[[ShardMetadata, RepoDownloadProgress], None]
    ) -> None:
        self.shard_downloader.on_progress(callback)

@@ -116,18 +113,17 @@ class ResumableShardDownloader(ShardDownloader):
    def __init__(self, max_parallel_downloads: int = 8):
        self.max_parallel_downloads = max_parallel_downloads
        self.on_progress_callbacks: list[
-            Callable[[ShardMetadata, RepoDownloadProgress], Awaitable[None]]
+            Callable[[ShardMetadata, RepoDownloadProgress], None]
        ] = []

-    async def on_progress_wrapper(
+    def on_progress_wrapper(
        self, shard: ShardMetadata, progress: RepoDownloadProgress
    ) -> None:
        for callback in self.on_progress_callbacks:
-            await callback(shard, progress)
+            callback(shard, progress)

    def on_progress(
-        self,
-        callback: Callable[[ShardMetadata, RepoDownloadProgress], Awaitable[None]],
+        self, callback: Callable[[ShardMetadata, RepoDownloadProgress], None]
    ) -> None:
        self.on_progress_callbacks.append(callback)

--- a/src/exo/worker/download/shard_downloader.py
+++ b/src/exo/worker/download/shard_downloader.py
@@ -1,5 +1,4 @@
 from abc import ABC, abstractmethod
-from collections.abc import Awaitable
 from copy import copy
 from datetime import timedelta
 from pathlib import Path
@@ -32,8 +31,7 @@ class ShardDownloader(ABC):

    @abstractmethod
    def on_progress(
-        self,
-        callback: Callable[[ShardMetadata, RepoDownloadProgress], Awaitable[None]],
+        self, callback: Callable[[ShardMetadata, RepoDownloadProgress], None]
    ) -> None:
        pass

@@ -61,8 +59,7 @@ class NoopShardDownloader(ShardDownloader):
        return Path("/tmp/noop_shard")

    def on_progress(
-        self,
-        callback: Callable[[ShardMetadata, RepoDownloadProgress], Awaitable[None]],
+        self, callback: Callable[[ShardMetadata, RepoDownloadProgress], None]
    ) -> None:
        pass

--- a/src/exo/worker/main.py
+++ b/src/exo/worker/main.py
@@ -359,7 +359,8 @@ class Worker:
        last_progress_time = 0.0
        throttle_interval_secs = 1.0

-        async def download_progress_callback(
+        # TODO: i hate callbacks
+        def download_progress_callback(
            shard: ShardMetadata, progress: RepoDownloadProgress
        ) -> None:
            nonlocal self
@@ -371,10 +372,11 @@ class Worker:
                    total_bytes=progress.total_bytes,
                )
                self.download_status[shard.model_meta.model_id] = status
-                await self.event_sender.send(
+                # Footgun!
+                self.event_sender.send_nowait(
                    NodeDownloadProgress(download_progress=status)
                )
-                await self.event_sender.send(
+                self.event_sender.send_nowait(
                    TaskStatusUpdated(
                        task_id=task.task_id, task_status=TaskStatus.Complete
                    )
@@ -391,7 +393,7 @@ class Worker:
                    ),
                )
                self.download_status[shard.model_meta.model_id] = status
-                await self.event_sender.send(
+                self.event_sender.send_nowait(
                    NodeDownloadProgress(download_progress=status)
                )
                last_progress_time = current_time()