dont push to cachix

## Why

Workers currently update their custom model-card cache by reacting to
`CustomModelCardAdded` / `CustomModelCardDeleted` events directly. That
is another snapshot footgun: a worker restored from State may never see
the historical add/delete event, so the durable State must include the
desired custom-card set.

## How

- Add `State.custom_model_cards`, keyed by `ModelId`.
- Reduce `CustomModelCardAdded` into State.
- Reduce `CustomModelCardDeleted` into State.
- Add focused reducer tests for add and delete.

This PR only makes custom cards durable in State. A follow-up PR will
make workers reconcile their on-disk custom-card cache from this state
instead of relying on those events directly.

## Tests

- `uv run pytest
src/exo/shared/tests/test_apply/test_apply_custom_model_cards.py
src/exo/shared/tests/test_state_serialization.py`
- `uv run pytest`
- `uv run ruff check src/exo/shared/types/state.py
src/exo/shared/apply.py
src/exo/shared/tests/test_apply/test_apply_custom_model_cards.py`
- `uv run basedpyright`
- `nix fmt`

.github/workflows/pipeline.yml

@@ -36,6 +36,7 @@ jobs:
         with:
           name: exo
           authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+          pushFilter: '-docker-image.tar.gz$'
 
       - name: Build Metal packages (macOS only)
         if: runner.os == 'macOS'

python/parts.nix

@@ -183,7 +183,24 @@ let
       inherit venv;
       editablePythonSet = pythonSet.overrideScope editableOverlay;
       mkPythonScript = path: mkApp ''python ${path} "$@"'';
-      mkExo = mkApp ''exo "$@"'';
+      mkOutputs = name:
+        let package = mkApp ''exo "$@"'' name;
+        in {
+          ${name} = package;
+          "${name}-docker-image" = pkgs.dockerTools.buildLayeredImage {
+            name = "${name}-docker-image";
+            config = {
+              Entrypoint = [ (lib.getExe package) ];
+              Env = [
+                "EXO_HOME=/var/lib/${name}"
+              ];
+            };
+
+            extraCommands = ''
+              mkdir -p  var/lib/${name}
+            '';
+          };
+        };
     };
 in
 {
@@ -191,7 +208,7 @@ in
     { self', pkgs, unfreePkgs, lib, ... }:
     let
       inherit (pkgs.stdenv.hostPlatform) isLinux;
-      inherit (mkPythonSet { inherit self' pkgs lib; members = { exo = [ "cpu" ]; }; }) editablePythonSet mkExo;
+      inherit (mkPythonSet { inherit self' pkgs lib; members.exo = [ "cpu" ]; }) editablePythonSet mkOutputs;
 
       # Virtual environment with dev dependencies for testing
       testVenv = (mkPythonSet {
@@ -213,10 +230,13 @@ in
         text = ''exec python ${path} "$@"'';
       };
 
+      defaultOutputs = mkOutputs "exo";
+      cuda12Outputs = (mkPythonSet { inherit self' lib; inherit (unfreePkgs.pkgsCuda.cudaPackages_12) pkgs; members.exo=["cuda12"]; }).mkOutputs "exo-cuda-12";
+      cuda13Outputs = (mkPythonSet { inherit self' lib; inherit (unfreePkgs.pkgsCuda.cudaPackages_13) pkgs; members.exo=["cuda13"]; }).mkOutputs "exo-cuda-13";
     in
     {
       packages = {
-        exo = mkExo "exo";
+        # for devShell
         editableVenv = editablePythonSet.mkVirtualEnv "exo-dev-env" { exo = [ "dev" ]; };
         # for running tests in ci
         exo-test-env = testVenv;
@@ -225,10 +245,9 @@ in
         exo-eval-tool-calls = mkBenchScript "exo-eval-tool-calls" (inputs.self + /bench/eval_tool_calls.py);
         # used by ./tests/run_exo_on.sh
         exo-get-all-models-on-cluster = mkSimplePythonScript "exo-get-all-models-on-cluster" (inputs.self + /tests/get_all_models_on_cluster.py);
-      } // lib.optionalAttrs isLinux {
-        exo-cuda-12 = (mkPythonSet { inherit self' lib; inherit (unfreePkgs.pkgsCuda.cudaPackages_12) pkgs; members = { exo = [ "cuda12" ]; }; }).mkExo "exo-cuda-12";
-        exo-cuda-13 = (mkPythonSet { inherit self' lib; inherit (unfreePkgs.pkgsCuda.cudaPackages_13) pkgs; members = { exo = [ "cuda13" ]; }; }).mkExo "exo-cuda-13";
-      };
+      } // defaultOutputs
+      // lib.optionalAttrs isLinux cuda12Outputs
+      // lib.optionalAttrs isLinux cuda13Outputs;
 
       checks = {
         lint = pkgs.runCommand "ruff-lint" { } ''

src/exo/api/main.py

@@ -121,8 +121,6 @@ from exo.api.types.openai_responses import (
 )
 from exo.master.image_store import ImageStore
 from exo.master.placement import place_instance as get_instance_placements
-from exo.routing.event_router import EventRouter
-from exo.routing.snapshot_receiver import SnapshotReceiver
 from exo.shared.apply import apply
 from exo.shared.constants import (
     DASHBOARD_DIR,
@@ -135,12 +133,10 @@ from exo.shared.constants import (
 )
 from exo.shared.election import ElectionMessage
 from exo.shared.logging import InterceptLogger
+from exo.shared.models import model_cards
 from exo.shared.models.model_cards import (
     ModelCard,
     ModelId,
-    add_to_card_cache,
-    get_card,
-    get_model_cards,
 )
 from exo.shared.tracing import TraceEvent, compute_stats, export_trace, load_trace_file
 from exo.shared.types.chunks import (
@@ -166,7 +162,6 @@ from exo.shared.types.commands import (
     ImageEdits,
     ImageGeneration,
     PlaceInstance,
-    RequestSnapshot,
     SendInputChunk,
     SetInstanceLink,
     StartDownload,
@@ -174,7 +169,7 @@ from exo.shared.types.commands import (
     TaskFinished,
     TextGeneration,
 )
-from exo.shared.types.common import CommandId, Id, NodeId, SessionId, SystemId
+from exo.shared.types.common import CommandId, Id, NodeId, SystemId
 from exo.shared.types.events import (
     ChunkGenerated,
     Event,
@@ -184,7 +179,6 @@ from exo.shared.types.events import (
 )
 from exo.shared.types.instance_link import InstanceLink, InstanceLinkId
 from exo.shared.types.memory import Memory
-from exo.shared.types.snapshots import SnapshotChunk
 from exo.shared.types.state import State
 from exo.shared.types.tasks import (
     ImageEdits as ImageEditsTask,
@@ -211,8 +205,6 @@ from exo.utils.task_group import TaskGroup
 _API_EVENT_LOG_DIR = EXO_EVENT_LOG_DIR / "api"
 ONBOARDING_COMPLETE_FILE = EXO_CACHE_HOME / "onboarding_complete"
 
-_SNAPSHOT_FETCH_TIMEOUT_SECONDS = 30
-
 
 def _format_to_content_type(image_format: Literal["png", "jpeg", "webp"] | None) -> str:
     return f"image/{image_format or 'png'}"
@@ -242,12 +234,9 @@ class API:
     def __init__(
         self,
         node_id: NodeId,
-        session_id: SessionId,
         *,
         port: int,
-        event_router: EventRouter,
         event_receiver: Receiver[IndexedEvent],
-        snapshot_chunk_receiver: Receiver[SnapshotChunk],
         command_sender: Sender[ForwarderCommand],
         download_command_sender: Sender[ForwarderDownloadCommand],
         # This lets us pause the API if an election is running
@@ -256,16 +245,14 @@ class API:
         self.state = State()
         self._event_log = DiskEventLog(_API_EVENT_LOG_DIR)
         self._system_id = SystemId()
-        self.session_id = session_id
-        self.event_router = event_router
         self.command_sender = command_sender
         self.download_command_sender = download_command_sender
         self.event_receiver = event_receiver
-        self.snapshot_chunk_receiver = snapshot_chunk_receiver
         self.election_receiver = election_receiver
         self.node_id: NodeId = node_id
         self.last_completed_election: int = 0
         self.port = port
+        self._sent_image_hashes: set[str] = set()
 
         self.paused: bool = False
         self.paused_ev: anyio.Event = anyio.Event()
@@ -303,29 +290,19 @@ class API:
         self._image_store = ImageStore(EXO_IMAGE_CACHE_DIR)
         self._tg: TaskGroup = TaskGroup()
 
-    def reset(
-        self,
-        result_clock: int,
-        session_id: SessionId,
-        event_router: EventRouter,
-        event_receiver: Receiver[IndexedEvent],
-        snapshot_chunk_receiver: Receiver[SnapshotChunk],
-    ):
+    def reset(self, result_clock: int, event_receiver: Receiver[IndexedEvent]):
         logger.info("Resetting API State")
         self._event_log.close()
         self._event_log = DiskEventLog(_API_EVENT_LOG_DIR)
         self.state = State()
         self._system_id = SystemId()
-        self.session_id = session_id
-        self.event_router = event_router
         self._text_generation_queues = {}
         self._image_generation_queues = {}
         self.unpause(result_clock)
         self.event_receiver.close()
         self.event_receiver = event_receiver
-        self.snapshot_chunk_receiver.close()
-        self.snapshot_chunk_receiver = snapshot_chunk_receiver
-        self._tg.start_soon(self._bootstrap_then_apply_state)
+        self._tg.start_soon(self._apply_state)
+        self._sent_image_hashes = set()
 
     def unpause(self, result_clock: int):
         logger.info("Unpausing API")
@@ -502,6 +479,7 @@ class API:
                 topology=self.state.topology,
                 current_instances=self.state.instances,
                 download_status=self.state.downloads,
+                node_rdma_ctl=self.state.node_rdma_ctl,
             )
         except ValueError as exc:
             raise HTTPException(status_code=400, detail=str(exc)) from exc
@@ -565,6 +543,7 @@ class API:
                     current_instances=self.state.instances,
                     required_nodes=required_nodes,
                     download_status=self.state.downloads,
+                    node_rdma_ctl=self.state.node_rdma_ctl,
                 )
             except ValueError as exc:
                 if (model_card.model_id, sharding, instance_meta, 0) not in seen:
@@ -847,8 +826,18 @@ class API:
         )
         command = TextGeneration(task_params=task_params)
 
+        new_images: list[tuple[int, str]] = []
+        for idx, (img, h) in enumerate(zip(images, hashes, strict=True)):
+            if h not in self._sent_image_hashes:
+                self._sent_image_hashes.add(h)
+                new_images.append((idx, img))
+
+        if not new_images:
+            await self._send(command)
+            return command
+
         all_chunks: list[tuple[int, str]] = []
-        for img_idx, img_data in enumerate(images):
+        for img_idx, img_data in new_images:
             for i in range(0, len(img_data), EXO_MAX_CHUNK_SIZE):
                 all_chunks.append((img_idx, img_data[i : i + EXO_MAX_CHUNK_SIZE]))
 
@@ -1644,17 +1633,16 @@ class API:
     async def ollama_tags(self) -> OllamaTagsResponse:
         """Returns list of models in Ollama tags format. We return the downloaded ones only."""
 
-        def none_if_empty(value: str) -> str | None:
-            return value or None
-
-        downloaded_model_ids: set[str] = set()
+        downloaded_model_ids: set[ModelId] = set()
         for node_downloads in self.state.downloads.values():
             for dl in node_downloads:
                 if isinstance(dl, DownloadCompleted):
                     downloaded_model_ids.add(dl.shard_metadata.model_card.model_id)
 
         cards = [
-            c for c in await get_model_cards() if c.model_id in downloaded_model_ids
+            c
+            for c in await model_cards.card_cache.list_all()
+            if c.model_id in downloaded_model_ids
         ]
 
         now = time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime())
@@ -1667,8 +1655,8 @@ class API:
                     size=card.storage_size.in_bytes,
                     digest="sha256:000000000000",
                     details=OllamaModelDetails(
-                        family=none_if_empty(card.family),
-                        quantization_level=none_if_empty(card.quantization),
+                        family=card.family or None,
+                        quantization_level=card.quantization or None,
                     ),
                 )
                 for card in cards
@@ -1731,7 +1719,7 @@ class API:
 
     async def get_models(self, status: str | None = Query(default=None)) -> ModelList:
         """Returns list of available models, optionally filtered by being downloaded."""
-        cards = await get_model_cards()
+        cards = await model_cards.card_cache.list_all()
 
         if status == "downloaded":
             downloaded_model_ids: set[str] = set()
@@ -1782,7 +1770,7 @@ class API:
 
         # Immediately update the local cache so the subsequent GET /models
         # returns the new model without waiting for the event round-trip.
-        add_to_card_cache(card)
+        model_cards.card_cache.cc[card.model_id] = card
 
         return ModelListModel(
             id=card.model_id,
@@ -1798,7 +1786,7 @@ class API:
 
     async def delete_custom_model(self, model_id: ModelId) -> JSONResponse:
         """Delete a user-added custom model card and sync deletion across the cluster."""
-        card = get_card(model_id)
+        card = model_cards.card_cache.get(model_id)
         if card is None or not card.is_custom:
             raise HTTPException(status_code=404, detail="Custom model card not found")
 
@@ -1859,7 +1847,7 @@ class API:
         try:
             async with self._tg as tg:
                 logger.info("Starting API")
-                tg.start_soon(self._bootstrap_then_apply_state)
+                tg.start_soon(self._apply_state)
                 tg.start_soon(self._pause_on_new_election)
                 tg.start_soon(self._cleanup_expired_images)
                 print_startup_banner(self.port)
@@ -1873,7 +1861,6 @@ class API:
             self._event_log.close()
             self.command_sender.close()
             self.event_receiver.close()
-            self.snapshot_chunk_receiver.close()
 
     async def run_api(self, ev: anyio.Event):
         cfg = Config()
@@ -1889,43 +1876,9 @@ class API:
                 shutdown_trigger=ev.wait,
             )
 
-    async def _bootstrap_then_apply_state(self):
-        await self._fetch_snapshot()
-        await self._apply_state()
-
-    async def _fetch_snapshot(self) -> None:
-        receiver = SnapshotReceiver(self.node_id, self.session_id)
-        await self.command_sender.send(
-            ForwarderCommand(
-                origin=self._system_id,
-                command=RequestSnapshot(requester_node_id=self.node_id),
-            )
-        )
-
-        with anyio.move_on_after(_SNAPSHOT_FETCH_TIMEOUT_SECONDS):
-            with self.snapshot_chunk_receiver as chunks:
-                async for chunk in chunks:
-                    received = receiver.ingest(chunk)
-                    if received is None:
-                        continue
-                    self.state = received.state
-                    self.event_router.set_buffer_start(
-                        received.last_event_applied_idx + 1
-                    )
-                    logger.info(
-                        f"API bootstrapped from snapshot at idx "
-                        f"{received.last_event_applied_idx}"
-                    )
-                    return
-        logger.info(
-            "API: no snapshot received before timeout; falling back to full event-log replay"
-        )
-
     async def _apply_state(self):
         with self.event_receiver as events:
             async for i_event in events:
-                if i_event.idx <= self.state.last_event_applied_idx:
-                    continue
                 self._event_log.append(i_event.event)
                 self.state = apply(self.state, i_event)
                 event = i_event.event

src/exo/api/tests/test_api_snapshot_bootstrap.py

@@ -1,136 +0,0 @@
-# pyright: reportPrivateUsage=false
-
-import hashlib
-
-import anyio
-import pytest
-import zstandard
-
-from exo.api.main import API
-from exo.routing.event_router import EventRouter
-from exo.shared.types.commands import ForwarderCommand, RequestSnapshot
-from exo.shared.types.common import NodeId, SessionId, SystemId
-from exo.shared.types.events import (
-    Event,
-    GlobalForwarderEvent,
-    IndexedEvent,
-    LocalForwarderEvent,
-    TestEvent,
-)
-from exo.shared.types.snapshots import SnapshotChunk, SnapshotTransferId
-from exo.shared.types.state import State
-from exo.utils.channels import Receiver, Sender, channel
-
-
-class _FakeEventLog:
-    def __init__(self) -> None:
-        self.appended: list[Event] = []
-
-    def append(self, event: Event) -> None:
-        self.appended.append(event)
-
-
-def _snapshot_chunk(
-    state: State, *, requester_node_id: NodeId, session_id: SessionId
-) -> SnapshotChunk:
-    body = zstandard.ZstdCompressor().compress(state.model_dump_json().encode("utf-8"))
-    return SnapshotChunk.from_data(
-        data=body,
-        transfer_id=SnapshotTransferId("transfer-1"),
-        requester_node_id=requester_node_id,
-        session_id=session_id,
-        schema_version=state.schema_version,
-        last_event_applied_idx=state.last_event_applied_idx,
-        chunk_index=0,
-        total_chunks=1,
-        sha256_hex=hashlib.sha256(body).hexdigest(),
-    )
-
-
-def _api(
-    node_id: NodeId, session_id: SessionId
-) -> tuple[
-    API,
-    EventRouter,
-    Receiver[ForwarderCommand],
-    Sender[SnapshotChunk],
-    Sender[IndexedEvent],
-    _FakeEventLog,
-]:
-    router_command_sender, _router_command_receiver = channel[ForwarderCommand]()
-    _global_event_sender, global_event_receiver = channel[GlobalForwarderEvent]()
-    local_event_sender, _local_event_receiver = channel[LocalForwarderEvent]()
-    event_router = EventRouter(
-        session_id=session_id,
-        command_sender=router_command_sender,
-        external_inbound=global_event_receiver,
-        external_outbound=local_event_sender,
-    )
-
-    event_sender, event_receiver = channel[IndexedEvent]()
-    command_sender, command_receiver = channel[ForwarderCommand]()
-    snapshot_sender, snapshot_receiver = channel[SnapshotChunk]()
-
-    api = object.__new__(API)
-    api.node_id = node_id
-    api.session_id = session_id
-    api.event_router = event_router
-    api.event_receiver = event_receiver
-    api.snapshot_chunk_receiver = snapshot_receiver
-    api.command_sender = command_sender
-    api._system_id = SystemId("api-system")
-    api.state = State()
-    event_log = _FakeEventLog()
-    api._event_log = event_log  # pyright: ignore[reportAttributeAccessIssue]
-    api._image_generation_queues = {}
-    api._text_generation_queues = {}
-    return api, event_router, command_receiver, snapshot_sender, event_sender, event_log
-
-
-@pytest.mark.asyncio
-async def test_api_fetch_snapshot_applies_state_and_fast_forwards_router() -> None:
-    node_id = NodeId("api")
-    session_id = SessionId(master_node_id=NodeId("master"), election_clock=1)
-    api, event_router, command_receiver, snapshot_sender, _event_sender, _event_log = (
-        _api(node_id, session_id)
-    )
-    state = State(last_event_applied_idx=7)
-
-    async with anyio.create_task_group() as tg:
-        tg.start_soon(api._fetch_snapshot)
-        command = await command_receiver.receive()
-        assert isinstance(command.command, RequestSnapshot)
-        assert command.command.requester_node_id == node_id
-
-        await snapshot_sender.send(
-            _snapshot_chunk(state, requester_node_id=node_id, session_id=session_id)
-        )
-
-    assert api.state.last_event_applied_idx == 7
-    assert event_router.event_buffer.next_idx_to_release == 8
-
-
-@pytest.mark.asyncio
-async def test_api_apply_state_ignores_events_covered_by_snapshot() -> None:
-    node_id = NodeId("api")
-    session_id = SessionId(master_node_id=NodeId("master"), election_clock=1)
-    (
-        api,
-        _event_router,
-        _command_receiver,
-        _snapshot_sender,
-        event_sender,
-        event_log,
-    ) = _api(node_id, session_id)
-    api.state = State(last_event_applied_idx=7)
-
-    async with anyio.create_task_group() as tg:
-        tg.start_soon(api._apply_state)
-        await event_sender.send(IndexedEvent(idx=7, event=TestEvent()))
-        await event_sender.send(IndexedEvent(idx=8, event=TestEvent()))
-
-        while api.state.last_event_applied_idx != 8:
-            await anyio.sleep(0.001)
-        tg.cancel_scope.cancel()
-
-    assert len(event_log.appended) == 1

src/exo/download/coordinator.py

@@ -16,7 +16,8 @@ from exo.download.download_utils import (
 )
 from exo.download.shard_downloader import ShardDownloader
 from exo.shared.constants import EXO_DEFAULT_MODELS_DIR, EXO_MODELS_READ_ONLY_DIRS
-from exo.shared.models.model_cards import ModelId, get_model_cards
+from exo.shared.models import model_cards
+from exo.shared.models.model_cards import ModelId
 from exo.shared.types.commands import (
     CancelDownload,
     DeleteDownload,
@@ -422,7 +423,7 @@ class DownloadCoordinator:
                     )
                 # Scan read-only directories for pre-downloaded models
                 if EXO_MODELS_READ_ONLY_DIRS:
-                    for card in await get_model_cards():
+                    for card in await model_cards.card_cache.list_all():
                         mid = card.model_id
                         if mid in self.active_downloads:
                             continue

src/exo/download/impl_shard_downloader.py

@@ -11,11 +11,11 @@ from exo.download.download_utils import (
     download_shard,
 )
 from exo.download.shard_downloader import ShardDownloader
+from exo.shared.models import model_cards
 from exo.shared.models.model_cards import (
     ModelCard,
     ModelId,
     ModelTask,
-    get_model_cards,
 )
 from exo.shared.types.memory import Memory
 from exo.shared.types.worker.shards import (
@@ -258,7 +258,7 @@ class ResumableShardDownloader(ShardDownloader):
 
         tasks = [
             create_task(download_with_semaphore(model_card))
-            for model_card in await get_model_cards()
+            for model_card in await model_cards.card_cache.list_all()
         ]
 
         for task in asyncio.as_completed(tasks):

src/exo/main.py

@@ -59,7 +59,6 @@ class Node:
         await router.register_topic(topics.ELECTION_MESSAGES)
         await router.register_topic(topics.CONNECTION_MESSAGES)
         await router.register_topic(topics.DOWNLOAD_COMMANDS)
-        await router.register_topic(topics.SNAPSHOT_RESPONSES)
         event_router = EventRouter(
             session_id,
             command_sender=router.sender(topics.COMMANDS),
@@ -84,11 +83,8 @@ class Node:
         if args.spawn_api:
             api = API(
                 node_id,
-                session_id,
                 port=args.api_port,
-                event_router=event_router,
                 event_receiver=event_router.receiver(),
-                snapshot_chunk_receiver=router.receiver(topics.SNAPSHOT_RESPONSES),
                 command_sender=router.sender(topics.COMMANDS),
                 download_command_sender=router.sender(topics.DOWNLOAD_COMMANDS),
                 election_receiver=router.receiver(topics.ELECTION_MESSAGES),
@@ -99,11 +95,8 @@ class Node:
         if not args.no_worker:
             worker = Worker(
                 node_id,
-                session_id,
-                event_router=event_router,
                 event_receiver=event_router.receiver(),
                 event_sender=event_router.sender(),
-                snapshot_chunk_receiver=router.receiver(topics.SNAPSHOT_RESPONSES),
                 command_sender=router.sender(topics.COMMANDS),
                 download_command_sender=router.sender(topics.DOWNLOAD_COMMANDS),
                 api_port=args.api_port,
@@ -119,7 +112,6 @@ class Node:
             global_event_sender=router.sender(topics.GLOBAL_EVENTS),
             local_event_receiver=router.receiver(topics.LOCAL_EVENTS),
             command_receiver=router.receiver(topics.COMMANDS),
-            snapshot_chunk_sender=router.sender(topics.SNAPSHOT_RESPONSES),
             download_command_sender=router.sender(topics.DOWNLOAD_COMMANDS),
         )
 
@@ -218,9 +210,6 @@ class Node:
                         global_event_sender=self.router.sender(topics.GLOBAL_EVENTS),
                         local_event_receiver=self.router.receiver(topics.LOCAL_EVENTS),
                         command_receiver=self.router.receiver(topics.COMMANDS),
-                        snapshot_chunk_sender=self.router.sender(
-                            topics.SNAPSHOT_RESPONSES
-                        ),
                         download_command_sender=self.router.sender(
                             topics.DOWNLOAD_COMMANDS
                         ),
@@ -257,13 +246,8 @@ class Node:
                         # TODO: add profiling etc to resource monitor
                         self.worker = Worker(
                             self.node_id,
-                            result.session_id,
-                            event_router=self.event_router,
                             event_receiver=self.event_router.receiver(),
                             event_sender=self.event_router.sender(),
-                            snapshot_chunk_receiver=self.router.receiver(
-                                topics.SNAPSHOT_RESPONSES
-                            ),
                             command_sender=self.router.sender(topics.COMMANDS),
                             download_command_sender=self.router.sender(
                                 topics.DOWNLOAD_COMMANDS
@@ -272,13 +256,7 @@ class Node:
                         )
                         self._tg.start_soon(self.worker.run)
                     if self.api:
-                        self.api.reset(
-                            result.won_clock,
-                            result.session_id,
-                            self.event_router,
-                            self.event_router.receiver(),
-                            self.router.receiver(topics.SNAPSHOT_RESPONSES),
-                        )
+                        self.api.reset(result.won_clock, self.event_router.receiver())
                     self._tg.start_soon(self.event_router.run)
                 else:
                     if self.api:

src/exo/master/main.py

@@ -1,8 +1,6 @@
-import hashlib
 from datetime import datetime, timedelta, timezone
 
 import anyio
-from anyio import to_thread
 from loguru import logger
 
 from exo.master.placement import (
@@ -27,7 +25,6 @@ from exo.shared.types.commands import (
     ImageGeneration,
     PlaceInstance,
     RequestEventLog,
-    RequestSnapshot,
     SendInputChunk,
     SetInstanceLink,
     TaskCancelled,
@@ -57,7 +54,6 @@ from exo.shared.types.events import (
     TracesMerged,
 )
 from exo.shared.types.instance_link import InstanceLink
-from exo.shared.types.snapshots import SnapshotChunk, SnapshotTransferId
 from exo.shared.types.state import State
 from exo.shared.types.tasks import (
     ImageEdits as ImageEditsTask,
@@ -78,15 +74,6 @@ from exo.utils.disk_event_log import DiskEventLog
 from exo.utils.event_buffer import MultiSourceBuffer
 from exo.utils.task_group import TaskGroup
 
-_SNAPSHOT_CHUNK_BYTES = 512 * 1024
-_MAX_EVENT_LOG_REPLAY_BATCH = 1000
-
-
-def _encode_state_for_transfer(state: State) -> bytes:
-    import zstandard
-
-    return zstandard.ZstdCompressor().compress(state.model_dump_json().encode("utf-8"))
-
 
 def _prefill_endpoint_for(state: State, decode_instance_id: InstanceId) -> str | None:
     decode = state.instances.get(decode_instance_id)
@@ -138,7 +125,6 @@ class Master:
         event_sender: Sender[Event],
         local_event_receiver: Receiver[LocalForwarderEvent],
         global_event_sender: Sender[GlobalForwarderEvent],
-        snapshot_chunk_sender: Sender[SnapshotChunk],
         download_command_sender: Sender[ForwarderDownloadCommand],
     ):
         self.node_id = node_id
@@ -149,7 +135,6 @@ class Master:
         self.command_receiver = command_receiver
         self.local_event_receiver = local_event_receiver
         self.global_event_sender = global_event_sender
-        self.snapshot_chunk_sender = snapshot_chunk_sender
         self.download_command_sender = download_command_sender
         self.event_sender = event_sender
         self._system_id = SystemId()
@@ -170,7 +155,6 @@ class Master:
             self._event_log.close()
             self.global_event_sender.close()
             self.local_event_receiver.close()
-            self.snapshot_chunk_sender.close()
             self.command_receiver.close()
 
     async def shutdown(self):
@@ -381,6 +365,7 @@ class Master:
                                 self.state.node_memory,
                                 self.state.node_network,
                                 download_status=self.state.downloads,
+                                node_rdma_ctl=self.state.node_rdma_ctl,
                             )
                             transition_events = get_transition_events(
                                 self.state.instances, placement, self.state.tasks
@@ -457,19 +442,12 @@ class Master:
                         case RequestEventLog():
                             # We should just be able to send everything, since other buffers will ignore old messages
                             # rate limit to 1000 at a time
-                            end = min(
-                                command.since_idx + _MAX_EVENT_LOG_REPLAY_BATCH,
-                                len(self._event_log),
-                            )
+                            end = min(command.since_idx + 1000, len(self._event_log))
                             for i, event in enumerate(
                                 self._event_log.read_range(command.since_idx, end),
                                 start=command.since_idx,
                             ):
                                 await self._send_event(IndexedEvent(idx=i, event=event))
-                        case RequestSnapshot():
-                            self._tg.start_soon(
-                                self._serve_snapshot, command.requester_node_id
-                            )
                     for event in generated_events:
                         await self.event_sender.send(event)
                 except ValueError as e:
@@ -529,42 +507,6 @@ class Master:
                     self._event_log.append(event)
                     await self._send_event(indexed)
 
-    async def _serve_snapshot(self, requester_node_id: NodeId) -> None:
-        state = self.state
-        if state.last_event_applied_idx < 0:
-            logger.info(
-                f"RequestSnapshot from {requester_node_id} but master has no events yet"
-            )
-            return
-
-        body = await to_thread.run_sync(_encode_state_for_transfer, state)
-        sha256 = hashlib.sha256(body).hexdigest()
-        chunks = [
-            body[i : i + _SNAPSHOT_CHUNK_BYTES]
-            for i in range(0, len(body), _SNAPSHOT_CHUNK_BYTES)
-        ] or [b""]
-        transfer_id = SnapshotTransferId()
-
-        logger.info(
-            f"Serving snapshot to {requester_node_id}: "
-            f"idx={state.last_event_applied_idx}, "
-            f"{len(chunks)} chunk(s), {len(body)} bytes total"
-        )
-        for index, chunk in enumerate(chunks):
-            await self.snapshot_chunk_sender.send(
-                SnapshotChunk.from_data(
-                    data=chunk,
-                    transfer_id=transfer_id,
-                    requester_node_id=requester_node_id,
-                    session_id=self.session_id,
-                    schema_version=state.schema_version,
-                    last_event_applied_idx=state.last_event_applied_idx,
-                    chunk_index=index,
-                    total_chunks=len(chunks),
-                    sha256_hex=sha256,
-                )
-            )
-
     # This function is re-entrant, take care!
     async def _send_event(self, event: IndexedEvent):
         # Convenience method since this line is ugly

src/exo/master/placement.py

@@ -28,7 +28,7 @@ from exo.shared.types.events import (
     TaskStatusUpdated,
 )
 from exo.shared.types.memory import Memory
-from exo.shared.types.profiling import MemoryUsage, NodeNetworkInfo
+from exo.shared.types.profiling import MemoryUsage, NodeNetworkInfo, NodeRdmaCtlStatus
 from exo.shared.types.tasks import Task, TaskId, TaskStatus
 from exo.shared.types.worker.downloads import (
     DownloadCompleted,
@@ -105,6 +105,7 @@ def place_instance(
     node_network: Mapping[NodeId, NodeNetworkInfo],
     required_nodes: set[NodeId] | None = None,
     download_status: Mapping[NodeId, Sequence[DownloadProgress]] | None = None,
+    node_rdma_ctl: Mapping[NodeId, NodeRdmaCtlStatus] | None = None,
 ) -> dict[InstanceId, Instance]:
     cycles = topology.get_cycles()
     candidate_cycles = list(filter(lambda it: len(it) >= command.min_nodes, cycles))
@@ -166,8 +167,18 @@ def place_instance(
 
     smallest_cycles = get_smallest_cycles(cycles_with_sufficient_memory)
 
+    rdma_ctl_status = node_rdma_ctl or {}
+
+    def _all_rdma_ctl_enabled(cycle: Cycle) -> bool:
+        return all(
+            ((status := rdma_ctl_status.get(node_id)) is not None and status.enabled)
+            for node_id in cycle
+        )
+
     smallest_rdma_cycles = [
-        cycle for cycle in smallest_cycles if topology.is_rdma_cycle(cycle)
+        cycle
+        for cycle in smallest_cycles
+        if topology.is_rdma_cycle(cycle) and _all_rdma_ctl_enabled(cycle)
     ]
 
     if command.instance_meta == InstanceMeta.MlxJaccl:

src/exo/master/tests/test_master.py

@@ -7,14 +7,12 @@ from loguru import logger
 
 from exo.master.main import Master
 from exo.routing.router import get_node_id_keypair
-from exo.routing.snapshot_receiver import SnapshotReceiver
 from exo.shared.models.model_cards import ModelCard, ModelTask
 from exo.shared.types.commands import (
     CommandId,
     ForwarderCommand,
     ForwarderDownloadCommand,
     PlaceInstance,
-    RequestSnapshot,
     TextGeneration,
 )
 from exo.shared.types.common import ModelId, NodeId, SessionId, SystemId
@@ -31,7 +29,6 @@ from exo.shared.types.memory import Memory
 from exo.shared.types.profiling import (
     MemoryUsage,
 )
-from exo.shared.types.snapshots import SnapshotChunk
 from exo.shared.types.tasks import TaskStatus
 from exo.shared.types.tasks import TextGeneration as TextGenerationTask
 from exo.shared.types.text_generation import (
@@ -59,7 +56,6 @@ async def test_master():
     local_event_sender, le_receiver = channel[LocalForwarderEvent]()
     fcds, _fcdr = channel[ForwarderDownloadCommand]()
     ev_send, ev_recv = channel[Event]()
-    snapshot_chunk_send, _snapshot_chunk_recv = channel[SnapshotChunk]()
 
     async def mock_event_router():
         idx = 0
@@ -96,7 +92,6 @@ async def test_master():
         global_event_sender=ge_sender,
         local_event_receiver=le_receiver,
         command_receiver=co_receiver,
-        snapshot_chunk_sender=snapshot_chunk_send,
         download_command_sender=fcds,
     )
     logger.info("run the master")
@@ -234,52 +229,3 @@ async def test_master():
 
         ev_send.close()
         await master.shutdown()
-
-
-@pytest.mark.asyncio
-async def test_master_serves_snapshot_for_current_state():
-    node_id = NodeId("master")
-    requester_node_id = NodeId("worker")
-    session_id = SessionId(master_node_id=node_id, election_clock=0)
-
-    ge_sender, _global_event_receiver = channel[GlobalForwarderEvent]()
-    command_sender, command_receiver = channel[ForwarderCommand]()
-    _local_event_sender, local_event_receiver = channel[LocalForwarderEvent]()
-    download_command_sender, _download_command_receiver = channel[
-        ForwarderDownloadCommand
-    ]()
-    event_sender, _event_receiver = channel[Event]()
-    snapshot_chunk_sender, snapshot_chunk_receiver = channel[SnapshotChunk]()
-
-    master = Master(
-        node_id,
-        session_id,
-        event_sender=event_sender,
-        global_event_sender=ge_sender,
-        local_event_receiver=local_event_receiver,
-        command_receiver=command_receiver,
-        snapshot_chunk_sender=snapshot_chunk_sender,
-        download_command_sender=download_command_sender,
-    )
-    master.state = master.state.model_copy(update={"last_event_applied_idx": 12})
-
-    receiver = SnapshotReceiver(requester_node_id, session_id)
-    async with anyio.create_task_group() as tg:
-        tg.start_soon(master.run)
-        await command_sender.send(
-            ForwarderCommand(
-                origin=SystemId("api"),
-                command=RequestSnapshot(requester_node_id=requester_node_id),
-            )
-        )
-
-        received = None
-        while received is None:
-            chunk = await snapshot_chunk_receiver.receive()
-            received = receiver.ingest(chunk)
-
-        assert received.last_event_applied_idx == 12
-        assert received.state.last_event_applied_idx == 12
-
-        await master.shutdown()
-        tg.cancel_scope.cancel()

src/exo/master/tests/test_placement.py

@@ -21,7 +21,11 @@ from exo.shared.types.events import (
 )
 from exo.shared.types.memory import Memory
 from exo.shared.types.multiaddr import Multiaddr
-from exo.shared.types.profiling import NetworkInterfaceInfo, NodeNetworkInfo
+from exo.shared.types.profiling import (
+    NetworkInterfaceInfo,
+    NodeNetworkInfo,
+    NodeRdmaCtlStatus,
+)
 from exo.shared.types.tasks import TaskId, TaskStatus, TextGeneration
 from exo.shared.types.text_generation import (
     InputMessage,
@@ -439,8 +443,21 @@ def test_tensor_rdma_backend_connectivity_matrix(
         min_nodes=1,
     )
 
+    node_rdma_ctl = {
+        node_a: NodeRdmaCtlStatus(enabled=True),
+        node_b: NodeRdmaCtlStatus(enabled=True),
+        node_c: NodeRdmaCtlStatus(enabled=True),
+    }
+
     # act
-    placements = place_instance(cic, topology, {}, node_memory, node_network)
+    placements = place_instance(
+        cic,
+        topology,
+        {},
+        node_memory,
+        node_network,
+        node_rdma_ctl=node_rdma_ctl,
+    )
 
     # assert
     assert len(placements) == 1
@@ -482,6 +499,131 @@ def test_tensor_rdma_backend_connectivity_matrix(
             assert len(ip_part.split(".")) == 4
 
 
+def _build_three_node_rdma_topology() -> tuple[
+    Topology, NodeId, NodeId, NodeId, dict[NodeId, NodeNetworkInfo]
+]:
+    topology = Topology()
+    node_a = NodeId()
+    node_b = NodeId()
+    node_c = NodeId()
+
+    ethernet_interface = NetworkInterfaceInfo(name="en0", ip_address="10.0.0.1")
+    ethernet_conn = SocketConnection(
+        sink_multiaddr=Multiaddr(address="/ip4/10.0.0.1/tcp/8000")
+    )
+    node_network = {
+        node_a: NodeNetworkInfo(interfaces=[ethernet_interface]),
+        node_b: NodeNetworkInfo(interfaces=[ethernet_interface]),
+        node_c: NodeNetworkInfo(interfaces=[ethernet_interface]),
+    }
+
+    for n in (node_a, node_b, node_c):
+        topology.add_node(n)
+
+    rdma_pairs = [
+        (node_a, node_b, 3),
+        (node_b, node_a, 3),
+        (node_b, node_c, 4),
+        (node_c, node_b, 4),
+        (node_a, node_c, 5),
+        (node_c, node_a, 5),
+    ]
+    for src, sink, iface in rdma_pairs:
+        topology.add_connection(
+            Connection(source=src, sink=sink, edge=create_rdma_connection(iface))
+        )
+
+    socket_pairs = [
+        (node_a, node_b),
+        (node_b, node_c),
+        (node_c, node_a),
+        (node_a, node_c),
+        (node_b, node_a),
+        (node_c, node_b),
+    ]
+    for src, sink in socket_pairs:
+        topology.add_connection(Connection(source=src, sink=sink, edge=ethernet_conn))
+
+    return topology, node_a, node_b, node_c, node_network
+
+
+def test_place_mlx_jaccl_rejects_when_a_node_has_rdma_ctl_disabled(
+    model_card: ModelCard,
+):
+    # arrange
+    model_card = model_card.model_copy(
+        update={"n_layers": 12, "storage_size": Memory.from_bytes(1500)}
+    )
+    topology, node_a, node_b, node_c, node_network = _build_three_node_rdma_topology()
+    node_memory = {
+        node_a: create_node_memory(500),
+        node_b: create_node_memory(500),
+        node_c: create_node_memory(500),
+    }
+    node_rdma_ctl = {
+        node_a: NodeRdmaCtlStatus(enabled=True),
+        node_b: NodeRdmaCtlStatus(enabled=True),
+        node_c: NodeRdmaCtlStatus(enabled=False),
+    }
+    cic = PlaceInstance(
+        sharding=Sharding.Tensor,
+        instance_meta=InstanceMeta.MlxJaccl,
+        command_id=CommandId(),
+        model_card=model_card,
+        min_nodes=3,
+    )
+
+    # act / assert
+    with pytest.raises(
+        ValueError, match="Requested RDMA \\(MlxJaccl\\) but no RDMA-connected cycles"
+    ):
+        place_instance(
+            cic,
+            topology,
+            {},
+            node_memory,
+            node_network,
+            node_rdma_ctl=node_rdma_ctl,
+        )
+
+
+def test_place_mlx_jaccl_rejects_when_node_rdma_ctl_missing(model_card: ModelCard):
+    """A node with no observed rdma_ctl status must not participate in RDMA placement."""
+    # arrange
+    model_card = model_card.model_copy(
+        update={"n_layers": 12, "storage_size": Memory.from_bytes(1500)}
+    )
+    topology, node_a, node_b, node_c, node_network = _build_three_node_rdma_topology()
+    node_memory = {
+        node_a: create_node_memory(500),
+        node_b: create_node_memory(500),
+        node_c: create_node_memory(500),
+    }
+    # node_c has no rdma_ctl entry at all
+    node_rdma_ctl = {
+        node_a: NodeRdmaCtlStatus(enabled=True),
+        node_b: NodeRdmaCtlStatus(enabled=True),
+    }
+    cic = PlaceInstance(
+        sharding=Sharding.Tensor,
+        instance_meta=InstanceMeta.MlxJaccl,
+        command_id=CommandId(),
+        model_card=model_card,
+        min_nodes=3,
+    )
+
+    # act / assert
+    with pytest.raises(ValueError):
+        place_instance(
+            cic,
+            topology,
+            {},
+            node_memory,
+            node_network,
+            node_rdma_ctl=node_rdma_ctl,
+        )
+
+
 def _make_task(
     instance_id: InstanceId,
     status: TaskStatus = TaskStatus.Running,

src/exo/routing/event_router.py

@@ -80,9 +80,6 @@ class EventRouter:
     def shutdown(self) -> None:
         self._tg.cancel_tasks()
 
-    def set_buffer_start(self, idx: int) -> None:
-        self.event_buffer.fast_forward_to(idx)
-
     async def _ingest(self, system_id: SystemId, recv: Receiver[Event]):
         idx = 0
         with recv as events:
@@ -98,6 +95,7 @@ class EventRouter:
                 self.out_for_delivery[event.event_id] = (anyio.current_time(), f_ev)
 
     async def _run_ext_in(self):
+        buf = OrderedBuffer[Event]()
         with self.external_inbound as events:
             async for event in events:
                 if event.session != self.session_id:
@@ -105,12 +103,12 @@ class EventRouter:
                 if event.origin != self.session_id.master_node_id:
                     continue
 
-                self.event_buffer.ingest(event.origin_idx, event.event)
+                buf.ingest(event.origin_idx, event.event)
                 event_id = event.event.event_id
                 if event_id in self.out_for_delivery:
                     self.out_for_delivery.pop(event_id)
 
-                drained = self.event_buffer.drain_indexed()
+                drained = buf.drain_indexed()
                 if drained:
                     self._nack_attempts = 0
                     if self._nack_cancel_scope:
@@ -121,9 +119,7 @@ class EventRouter:
                     or self._nack_cancel_scope.cancel_called
                 ):
                     # Request the next index.
-                    self._tg.start_soon(
-                        self._nack_request, self.event_buffer.next_idx_to_release
-                    )
+                    self._tg.start_soon(self._nack_request, buf.next_idx_to_release)
                     continue
 
                 for idx, event in drained:

src/exo/routing/snapshot_receiver.py

@@ -1,109 +0,0 @@
-"""Reassembles a snapshot from a stream of `SnapshotChunk`s.
-
-A receiver belongs to one node; it ignores chunks addressed to other
-requesters and chunks from prior sessions. Once a transfer's chunks have
-all been collected and the SHA-256 checks out, the snapshot is decoded into
-a `State`. Concurrent transfers (for the same requester) are tolerated:
-each is keyed by `transfer_id`.
-"""
-
-from __future__ import annotations
-
-import hashlib
-from dataclasses import dataclass, field
-from typing import final
-
-import zstandard
-from loguru import logger
-
-from exo.shared.types.common import NodeId, SessionId
-from exo.shared.types.snapshots import SnapshotChunk, SnapshotTransferId
-from exo.shared.types.state import State
-
-
-@final
-@dataclass
-class _Assembly:
-    """Partial state for one in-flight snapshot transfer."""
-
-    total_chunks: int
-    sha256_hex: str
-    schema_version: int
-    last_event_applied_idx: int
-    chunks: dict[int, bytes] = field(default_factory=dict)
-
-    def is_complete(self) -> bool:
-        return len(self.chunks) == self.total_chunks
-
-    def assemble(self) -> bytes:
-        return b"".join(self.chunks[i] for i in range(self.total_chunks))
-
-
-@dataclass
-class ReceivedSnapshot:
-    last_event_applied_idx: int
-    state: State
-
-
-class SnapshotReceiver:
-    """Filters and reassembles inbound chunks into a `ReceivedSnapshot`.
-
-    Stateless w.r.t. delivery: callers feed `SnapshotChunk`s in via `ingest`
-    and check the return value for completion.
-    """
-
-    def __init__(self, my_node_id: NodeId, session_id: SessionId) -> None:
-        self._my_node_id = my_node_id
-        self._session_id = session_id
-        self._assemblies: dict[SnapshotTransferId, _Assembly] = {}
-
-    def ingest(self, chunk: SnapshotChunk) -> ReceivedSnapshot | None:
-        """Absorb a chunk; return the snapshot once a transfer completes.
-
-        Returns None for partial transfers, mismatched recipients, stale
-        sessions, version mismatches, or corrupt payloads.
-        """
-        if chunk.requester_node_id != self._my_node_id:
-            return None
-        if chunk.session_id != self._session_id:
-            return None
-
-        existing = self._assemblies.get(chunk.transfer_id)
-        if existing is None:
-            existing = _Assembly(
-                total_chunks=chunk.total_chunks,
-                sha256_hex=chunk.sha256_hex,
-                schema_version=chunk.schema_version,
-                last_event_applied_idx=chunk.last_event_applied_idx,
-            )
-            self._assemblies[chunk.transfer_id] = existing
-        existing.chunks[chunk.chunk_index] = chunk.data
-
-        if not existing.is_complete():
-            return None
-
-        # Transfer complete — finalise and remove from the in-flight map.
-        del self._assemblies[chunk.transfer_id]
-        body = existing.assemble()
-        if hashlib.sha256(body).hexdigest() != existing.sha256_hex:
-            logger.warning(f"Snapshot {chunk.transfer_id} failed checksum; discarding")
-            return None
-        try:
-            decompressed = zstandard.ZstdDecompressor().decompress(body)
-            state = State.model_validate_json(decompressed.decode("utf-8"))
-        except (zstandard.ZstdError, ValueError) as e:
-            logger.opt(exception=e).warning(
-                f"Snapshot {chunk.transfer_id} could not be decoded; discarding"
-            )
-            return None
-        if state.schema_version != existing.schema_version:
-            # Should not happen — the master writes schema_version into both
-            # the chunk meta and the State payload — but treat it as corrupt.
-            logger.warning(
-                f"Snapshot {chunk.transfer_id} schema version mismatch "
-                f"(chunk={existing.schema_version}, state={state.schema_version})"
-            )
-            return None
-        return ReceivedSnapshot(
-            last_event_applied_idx=existing.last_event_applied_idx, state=state
-        )

src/exo/routing/tests/test_event_buffer.py

@@ -141,28 +141,3 @@ async def test_drain_and_ingest_with_new_sequence(buffer: OrderedBuffer[Event]):
     assert [e[0] for e in drained] == [2]
     assert buffer.next_idx_to_release == 3
     assert 4 in buffer.store
-
-
-@pytest.mark.asyncio
-async def test_fast_forward_discards_buffered_stale_events(
-    buffer: OrderedBuffer[Event],
-):
-    buffer.ingest(*make_indexed_event(0))
-    buffer.ingest(*make_indexed_event(2))
-    buffer.ingest(*make_indexed_event(4))
-
-    buffer.fast_forward_to(3)
-
-    assert buffer.next_idx_to_release == 3
-    assert set(buffer.store) == {4}
-
-
-@pytest.mark.asyncio
-async def test_fast_forward_only_moves_forward(buffer: OrderedBuffer[Event]):
-    buffer.ingest(*make_indexed_event(0))
-    buffer.ingest(*make_indexed_event(1))
-    buffer.drain()
-
-    buffer.fast_forward_to(1)
-
-    assert buffer.next_idx_to_release == 2

src/exo/routing/tests/test_snapshot_receiver.py

@@ -1,151 +0,0 @@
-import hashlib
-
-import pytest
-import zstandard
-
-from exo.routing.snapshot_receiver import SnapshotReceiver
-from exo.shared.types.common import NodeId, SessionId
-from exo.shared.types.snapshots import SnapshotChunk, SnapshotTransferId
-from exo.shared.types.state import State
-
-
-@pytest.fixture
-def session_id() -> SessionId:
-    return SessionId(master_node_id=NodeId("master"), election_clock=0)
-
-
-@pytest.fixture
-def my_node() -> NodeId:
-    return NodeId("worker-1")
-
-
-def _encode(state: State) -> bytes:
-    return zstandard.ZstdCompressor().compress(state.model_dump_json().encode("utf-8"))
-
-
-def _make_chunks(
-    body: bytes,
-    *,
-    chunk_size: int,
-    requester_node_id: NodeId,
-    session_id: SessionId,
-    state: State,
-    transfer_id: SnapshotTransferId | None = None,
-) -> list[SnapshotChunk]:
-    sha256 = hashlib.sha256(body).hexdigest()
-    transfer_id = transfer_id or SnapshotTransferId()
-    pieces = [body[i : i + chunk_size] for i in range(0, len(body), chunk_size)] or [
-        b""
-    ]
-    return [
-        SnapshotChunk.from_data(
-            data=piece,
-            transfer_id=transfer_id,
-            requester_node_id=requester_node_id,
-            session_id=session_id,
-            schema_version=state.schema_version,
-            last_event_applied_idx=state.last_event_applied_idx,
-            chunk_index=i,
-            total_chunks=len(pieces),
-            sha256_hex=sha256,
-        )
-        for i, piece in enumerate(pieces)
-    ]
-
-
-def test_completes_on_full_transfer(my_node: NodeId, session_id: SessionId):
-    state = State(last_event_applied_idx=42)
-    chunks = _make_chunks(
-        _encode(state),
-        chunk_size=64,
-        requester_node_id=my_node,
-        session_id=session_id,
-        state=state,
-    )
-    receiver = SnapshotReceiver(my_node, session_id)
-
-    received = None
-    for chunk in chunks:
-        received = receiver.ingest(chunk)
-    assert received is not None
-    assert received.last_event_applied_idx == 42
-    assert received.state.last_event_applied_idx == 42
-
-
-def test_handles_out_of_order_chunks(my_node: NodeId, session_id: SessionId):
-    state = State(last_event_applied_idx=99)
-    chunks = _make_chunks(
-        _encode(state),
-        chunk_size=32,
-        requester_node_id=my_node,
-        session_id=session_id,
-        state=state,
-    )
-    receiver = SnapshotReceiver(my_node, session_id)
-
-    # Reverse them.
-    received = None
-    for chunk in reversed(chunks):
-        received = receiver.ingest(chunk)
-    assert received is not None
-    assert received.last_event_applied_idx == 99
-
-
-def test_ignores_chunks_for_other_recipients(my_node: NodeId, session_id: SessionId):
-    state = State(last_event_applied_idx=1)
-    other = NodeId("worker-2")
-    chunks = _make_chunks(
-        _encode(state),
-        chunk_size=64,
-        requester_node_id=other,
-        session_id=session_id,
-        state=state,
-    )
-    receiver = SnapshotReceiver(my_node, session_id)
-    for chunk in chunks:
-        assert receiver.ingest(chunk) is None
-
-
-def test_ignores_chunks_from_stale_session(my_node: NodeId, session_id: SessionId):
-    state = State(last_event_applied_idx=1)
-    other_session = SessionId(master_node_id=NodeId("other-master"), election_clock=99)
-    chunks = _make_chunks(
-        _encode(state),
-        chunk_size=64,
-        requester_node_id=my_node,
-        session_id=other_session,
-        state=state,
-    )
-    receiver = SnapshotReceiver(my_node, session_id)
-    for chunk in chunks:
-        assert receiver.ingest(chunk) is None
-
-
-def test_discards_on_checksum_mismatch(my_node: NodeId, session_id: SessionId):
-    state = State(last_event_applied_idx=1)
-    chunks = _make_chunks(
-        _encode(state),
-        chunk_size=64,
-        requester_node_id=my_node,
-        session_id=session_id,
-        state=state,
-    )
-    # Corrupt the last byte of the last chunk.
-    original = chunks[-1]
-    chunks[-1] = SnapshotChunk.from_data(
-        data=original.data + b"\x00garbage",
-        transfer_id=original.transfer_id,
-        requester_node_id=original.requester_node_id,
-        session_id=original.session_id,
-        schema_version=original.schema_version,
-        last_event_applied_idx=original.last_event_applied_idx,
-        chunk_index=original.chunk_index,
-        total_chunks=original.total_chunks,
-        sha256_hex=original.sha256_hex,
-    )
-
-    receiver = SnapshotReceiver(my_node, session_id)
-    received = None
-    for chunk in chunks:
-        received = receiver.ingest(chunk)
-    assert received is None

src/exo/routing/tests/test_snapshot_routing_types.py

@@ -1,37 +0,0 @@
-from exo.routing import topics
-from exo.shared.types.commands import ForwarderCommand, RequestSnapshot
-from exo.shared.types.common import NodeId, SessionId, SystemId
-from exo.shared.types.snapshots import SnapshotChunk, SnapshotTransferId
-
-
-def test_request_snapshot_round_trips_through_forwarder_command() -> None:
-    command = ForwarderCommand(
-        origin=SystemId("system-1"),
-        command=RequestSnapshot(requester_node_id=NodeId("worker-1")),
-    )
-
-    restored = ForwarderCommand.model_validate_json(command.model_dump_json())
-
-    assert isinstance(restored.command, RequestSnapshot)
-    assert restored.command.requester_node_id == NodeId("worker-1")
-
-
-def test_snapshot_response_topic_round_trips_chunk() -> None:
-    chunk = SnapshotChunk.from_data(
-        data=b"snapshot-bytes",
-        transfer_id=SnapshotTransferId("transfer-1"),
-        requester_node_id=NodeId("worker-1"),
-        session_id=SessionId(master_node_id=NodeId("master"), election_clock=1),
-        schema_version=1,
-        last_event_applied_idx=42,
-        chunk_index=0,
-        total_chunks=1,
-        sha256_hex="unused",
-    )
-
-    restored = topics.SNAPSHOT_RESPONSES.deserialize(
-        topics.SNAPSHOT_RESPONSES.serialize(chunk)
-    )
-
-    assert restored == chunk
-    assert restored.data == b"snapshot-bytes"

src/exo/routing/topics.py

@@ -8,7 +8,6 @@ from exo.shared.types.events import (
     GlobalForwarderEvent,
     LocalForwarderEvent,
 )
-from exo.shared.types.snapshots import SnapshotChunk
 from exo.utils.pydantic_ext import FrozenModel
 
 
@@ -50,6 +49,3 @@ CONNECTION_MESSAGES = TypedTopic(
 DOWNLOAD_COMMANDS = TypedTopic(
     "download_commands", PublishPolicy.Always, ForwarderDownloadCommand
 )
-SNAPSHOT_RESPONSES = TypedTopic(
-    "snapshot_responses", PublishPolicy.Always, SnapshotChunk
-)

src/exo/shared/apply.py

@@ -4,7 +4,8 @@ from datetime import datetime
 
 from loguru import logger
 
-from exo.shared.types.common import NodeId
+from exo.shared.models.model_cards import ModelCard
+from exo.shared.types.common import ModelId, NodeId
 from exo.shared.types.events import (
     ChunkGenerated,
     CustomModelCardAdded,
@@ -40,14 +41,7 @@ from exo.shared.types.profiling import (
     ThunderboltBridgeStatus,
 )
 from exo.shared.types.state import State
-from exo.shared.types.tasks import (
-    ImageEdits,
-    ImageGeneration,
-    Task,
-    TaskId,
-    TaskStatus,
-    TextGeneration,
-)
+from exo.shared.types.tasks import Task, TaskId, TaskStatus
 from exo.shared.types.topology import Connection, RDMAConnection
 from exo.shared.types.worker.downloads import DownloadProgress
 from exo.shared.types.worker.instances import Instance, InstanceId
@@ -72,6 +66,18 @@ from exo.utils.info_gatherer.info_gatherer import (
 )
 
 
+def _is_rdma_ctl_enabled(
+    node_id: NodeId, node_rdma_ctl: Mapping[NodeId, NodeRdmaCtlStatus]
+) -> bool:
+    """A node is RDMA-capable only if rdma_ctl status has been observed as enabled.
+
+    Missing entries default to ``False`` — if we have not yet observed (or the node
+    cannot run) ``rdma_ctl``, it must not participate in an RDMA-backed instance.
+    """
+    status = node_rdma_ctl.get(node_id)
+    return status is not None and status.enabled
+
+
 def event_apply(event: Event, state: State) -> State:
     """Apply an event to state."""
     match event:
@@ -79,12 +85,15 @@ def event_apply(event: Event, state: State) -> State:
             TestEvent()
             | ChunkGenerated()
             | TaskAcknowledged()
+            | InputChunkReceived()
             | TracesCollected()
             | TracesMerged()
-            | CustomModelCardAdded()
-            | CustomModelCardDeleted()
         ):  # Pass-through events that don't modify state
             return state
+        case CustomModelCardAdded():
+            return apply_custom_model_card_added(event, state)
+        case CustomModelCardDeleted():
+            return apply_custom_model_card_deleted(event, state)
         case InstanceCreated():
             return apply_instance_created(event, state)
         case InstanceDeleted():
@@ -99,8 +108,6 @@ def event_apply(event: Event, state: State) -> State:
             return apply_runner_status_updated(event, state)
         case TaskCreated():
             return apply_task_created(event, state)
-        case InputChunkReceived():
-            return apply_input_chunk_received(event, state)
         case TaskDeleted():
             return apply_task_deleted(event, state)
         case TaskFailed():
@@ -165,32 +172,10 @@ def apply_task_created(event: TaskCreated, state: State) -> State:
     return state.model_copy(update={"tasks": new_tasks})
 
 
-def apply_input_chunk_received(event: InputChunkReceived, state: State) -> State:
-    command_chunks = {
-        **state.input_chunks.get(event.command_id, {}),
-        event.chunk.chunk_index: event.chunk,
-    }
-    return state.model_copy(
-        update={
-            "input_chunks": {**state.input_chunks, event.command_id: command_chunks}
-        }
-    )
-
-
 def apply_task_deleted(event: TaskDeleted, state: State) -> State:
-    task = state.tasks.get(event.task_id)
     new_tasks: Mapping[TaskId, Task] = {
         tid: task for tid, task in state.tasks.items() if tid != event.task_id
     }
-    if isinstance(task, (TextGeneration, ImageGeneration, ImageEdits)):
-        new_input_chunks = {
-            command_id: chunks
-            for command_id, chunks in state.input_chunks.items()
-            if command_id != task.command_id
-        }
-        return state.model_copy(
-            update={"tasks": new_tasks, "input_chunks": new_input_chunks}
-        )
     return state.model_copy(update={"tasks": new_tasks})
 
 
@@ -427,6 +412,9 @@ def apply_node_gathered_info(event: NodeGatheredInfo, state: State) -> State:
                 for nid in state.node_thunderbolt
                 for tb_ident in state.node_thunderbolt[nid].interfaces
             }
+            source_is_rdma_enabled = _is_rdma_ctl_enabled(
+                event.node_id, state.node_rdma_ctl
+            )
             as_rdma_conns = [
                 Connection(
                     source=event.node_id,
@@ -439,6 +427,10 @@ def apply_node_gathered_info(event: NodeGatheredInfo, state: State) -> State:
                 for tb_conn in info.conns
                 if tb_conn.source_uuid in conn_map
                 if tb_conn.sink_uuid in conn_map
+                if source_is_rdma_enabled
+                and _is_rdma_ctl_enabled(
+                    conn_map[tb_conn.sink_uuid][0], state.node_rdma_ctl
+                )
             ]
             topology.replace_all_out_rdma_connections(event.node_id, as_rdma_conns)
         case ThunderboltBridgeInfo():
@@ -462,6 +454,12 @@ def apply_node_gathered_info(event: NodeGatheredInfo, state: State) -> State:
                 **state.node_rdma_ctl,
                 event.node_id: NodeRdmaCtlStatus(enabled=info.enabled),
             }
+            # If RDMA just got disabled on this node, drop any RDMA edges touching it
+            # so placement / topology consumers cannot pick a disabled node for an
+            # RDMA-backed instance. (Edges will repopulate on the next
+            # MacThunderboltConnections poll once both endpoints are enabled again.)
+            if not info.enabled:
+                topology.remove_all_rdma_connections_touching(event.node_id)
 
     return state.model_copy(update=update)
 
@@ -477,3 +475,22 @@ def apply_topology_edge_deleted(event: TopologyEdgeDeleted, state: State) -> Sta
     topology.remove_connection(event.conn)
     # TODO: Clean up removing the reverse connection
     return state.model_copy(update={"topology": topology})
+
+
+def apply_custom_model_card_added(event: CustomModelCardAdded, state: State) -> State:
+    new_cards: Mapping[ModelId, ModelCard] = {
+        **state.custom_model_cards,
+        event.model_card.model_id: event.model_card,
+    }
+    return state.model_copy(update={"custom_model_cards": new_cards})
+
+
+def apply_custom_model_card_deleted(
+    event: CustomModelCardDeleted, state: State
+) -> State:
+    new_cards: Mapping[ModelId, ModelCard] = {
+        model_id: card
+        for model_id, card in state.custom_model_cards.items()
+        if model_id != event.model_id
+    }
+    return state.model_copy(update={"custom_model_cards": new_cards})

src/exo/shared/constants.py

@@ -4,13 +4,13 @@ from pathlib import Path
 
 from exo.utils.dashboard_path import find_dashboard, find_resources
 
-_EXO_HOME_ENV = os.environ.get("EXO_HOME", None)
+_EXO_HOME_ENV = os.environ.get("EXO_HOME", "")
 
 
 def _get_xdg_dir(env_var: str, fallback: str) -> Path:
     """Get XDG directory, prioritising EXO_HOME environment variable if its set. On non-Linux platforms, default to ~/.exo."""
 
-    if _EXO_HOME_ENV is not None:
+    if _EXO_HOME_ENV != "":
         return Path.home() / _EXO_HOME_ENV
 
     if sys.platform != "linux":

src/exo/shared/models/model_cards.py

@@ -39,7 +39,57 @@ _BUILTIN_CARD_DIRS = [
     Path(RESOURCES_DIR) / "image_model_cards",
 ]
 
-_card_cache: dict[ModelId, "ModelCard"] = {}
+
+class _CardCache:
+    def __init__(self):
+        self.cc: dict[ModelId, "ModelCard"] = {}
+
+    def get(self, model_id: ModelId) -> "ModelCard | None":
+        return self.cc.get(model_id)
+
+    async def save(self, card: "ModelCard"):
+        self.cc[card.model_id] = card
+        try:
+            await card.save_to_custom_dir()
+        except OSError as e:
+            logger.warning(f"failed to save custom model card ({e.strerror})")
+
+    async def pop(self, model_id: ModelId) -> "ModelCard | None":
+        """Delete a user-added custom model card. Returns True if deleted."""
+        card_path = _custom_cards_dir / (ModelId(model_id).normalize() + ".toml")
+        try:
+            if await card_path.exists():
+                await card_path.unlink()
+                return self.cc.pop(model_id, None)
+        except OSError as e:
+            logger.warning(f"failed to delete custom model card ({e.strerror})")
+
+    async def list_all(self) -> list["ModelCard"]:
+        if len(self.cc) == 0:
+            await self.refresh()
+        if EXO_ENABLE_IMAGE_MODELS:
+            return list(self.cc.values())
+        return [c for c in self.cc.values() if not _is_image_card(c)]
+
+    async def _load_cards_from_dir(self, directory: Path, *, is_custom: bool) -> None:
+        """Load all TOML model cards from a directory into the cache."""
+        async for toml_file in directory.rglob("*.toml"):
+            try:
+                card = await ModelCard.load_from_path(toml_file)
+                if is_custom:
+                    card = card.model_copy(update={"is_custom": True})
+                if self.get(card.model_id) is None:
+                    self.cc[card.model_id] = card
+            except (ValidationError, TOMLKitError):
+                pass
+
+    async def refresh(self) -> None:
+        for path in _BUILTIN_CARD_DIRS:
+            await self._load_cards_from_dir(path, is_custom=False)
+        await self._load_cards_from_dir(_custom_cards_dir, is_custom=True)
+
+
+card_cache = _CardCache()
 
 
 def detect_vision_from_config(model_id: ModelId) -> "VisionCardConfig | None":
@@ -59,42 +109,10 @@ def detect_vision_from_config(model_id: ModelId) -> "VisionCardConfig | None":
     return None
 
 
-async def _load_cards_from_dir(directory: Path, *, is_custom: bool) -> None:
-    """Load all TOML model cards from a directory into the cache."""
-    async for toml_file in directory.rglob("*.toml"):
-        try:
-            card = await ModelCard.load_from_path(toml_file)
-            if is_custom:
-                card = card.model_copy(update={"is_custom": True})
-            if card.model_id not in _card_cache:
-                _card_cache[card.model_id] = card
-        except (ValidationError, TOMLKitError):
-            pass
-
-
-async def _refresh_card_cache() -> None:
-    for path in _BUILTIN_CARD_DIRS:
-        await _load_cards_from_dir(path, is_custom=False)
-    await _load_cards_from_dir(_custom_cards_dir, is_custom=True)
-
-
 def _is_image_card(card: "ModelCard") -> bool:
     return any(t in (ModelTask.TextToImage, ModelTask.ImageToImage) for t in card.tasks)
 
 
-def get_card(model_id: ModelId) -> "ModelCard | None":
-    """Look up a single model card from the cache by ID."""
-    return _card_cache.get(model_id)
-
-
-async def get_model_cards() -> list["ModelCard"]:
-    if len(_card_cache) == 0:
-        await _refresh_card_cache()
-    if EXO_ENABLE_IMAGE_MODELS:
-        return list(_card_cache.values())
-    return [c for c in _card_cache.values() if not _is_image_card(c)]
-
-
 class ModelTask(str, Enum):
     TextGeneration = "TextGeneration"
     TextToImage = "TextToImage"
@@ -196,14 +214,13 @@ class ModelCard(FrozenModel):
     # Is it okay that model card.load defaults to network access if the card doesn't exist? do we want to be more explicit here?
     @staticmethod
     async def load(model_id: ModelId) -> "ModelCard":
-        if model_id not in _card_cache:
-            await _refresh_card_cache()
-        if (mc := _card_cache.get(model_id)) is not None:
+        if card_cache.get(model_id) is None:
+            await card_cache.refresh()
+        if (mc := card_cache.get(model_id)) is not None:
             return mc
 
         mc = await ModelCard.fetch_from_hf(model_id)
         await mc.save_to_custom_dir()
-        _card_cache[model_id] = mc
         return mc
 
     @staticmethod
@@ -233,21 +250,6 @@ class ModelCard(FrozenModel):
         )
 
 
-def add_to_card_cache(card: "ModelCard") -> None:
-    """Add or update a model card in the in-memory cache."""
-    _card_cache[card.model_id] = card
-
-
-async def delete_custom_card(model_id: ModelId) -> bool:
-    """Delete a user-added custom model card. Returns True if deleted."""
-    card_path = _custom_cards_dir / (ModelId(model_id).normalize() + ".toml")
-    if await card_path.exists():
-        await card_path.unlink()
-        _card_cache.pop(model_id, None)
-        return True
-    return False
-
-
 class ConfigData(BaseModel):
     model_config = {"extra": "ignore"}  # Allow unknown fields
 

src/exo/shared/tests/test_apply/test_apply_custom_model_cards.py

@@ -0,0 +1,44 @@
+from exo.shared.apply import apply
+from exo.shared.models.model_cards import ModelCard, ModelTask
+from exo.shared.types.common import ModelId
+from exo.shared.types.events import (
+    CustomModelCardAdded,
+    CustomModelCardDeleted,
+    IndexedEvent,
+)
+from exo.shared.types.memory import Memory
+from exo.shared.types.state import State
+
+
+def _model_card(model_id: ModelId) -> ModelCard:
+    return ModelCard(
+        model_id=model_id,
+        n_layers=1,
+        storage_size=Memory.from_bytes(1),
+        hidden_size=1,
+        supports_tensor=True,
+        tasks=[ModelTask.TextGeneration],
+    )
+
+
+def test_custom_model_card_added_is_reduced_into_state() -> None:
+    card = _model_card(ModelId("custom/model"))
+
+    state = apply(
+        State(),
+        IndexedEvent(idx=0, event=CustomModelCardAdded(model_card=card)),
+    )
+
+    assert state.custom_model_cards == {card.model_id: card}
+
+
+def test_custom_model_card_deleted_removes_card_from_state() -> None:
+    card = _model_card(ModelId("custom/model"))
+    state = State(custom_model_cards={card.model_id: card}, last_event_applied_idx=0)
+
+    state = apply(
+        state,
+        IndexedEvent(idx=1, event=CustomModelCardDeleted(model_id=card.model_id)),
+    )
+
+    assert state.custom_model_cards == {}

src/exo/shared/tests/test_apply/test_apply_input_chunks.py

@@ -1,85 +0,0 @@
-from exo.shared.apply import apply
-from exo.shared.models.model_cards import ModelId
-from exo.shared.types.chunks import InputImageChunk
-from exo.shared.types.common import CommandId
-from exo.shared.types.events import (
-    IndexedEvent,
-    InputChunkReceived,
-    TaskCreated,
-    TaskDeleted,
-)
-from exo.shared.types.state import State
-from exo.shared.types.tasks import TaskId, TaskStatus, TextGeneration
-from exo.shared.types.text_generation import (
-    InputMessage,
-    InputMessageContent,
-    TextGenerationTaskParams,
-)
-from exo.shared.types.worker.instances import InstanceId
-
-
-def test_apply_input_chunk_received_stores_chunk_in_state() -> None:
-    command_id = CommandId("command-1")
-    chunk = InputImageChunk(
-        model=ModelId("mlx-community/test-model"),
-        command_id=command_id,
-        data="abc",
-        chunk_index=0,
-        total_chunks=1,
-        image_index=0,
-    )
-
-    state = apply(
-        State(),
-        IndexedEvent(
-            idx=0,
-            event=InputChunkReceived(command_id=command_id, chunk=chunk),
-        ),
-    )
-
-    assert state.input_chunks == {command_id: {0: chunk}}
-
-
-def test_apply_task_deleted_removes_chunks_for_generation_command() -> None:
-    command_id = CommandId("command-1")
-    task_id = TaskId("task-1")
-    chunk = InputImageChunk(
-        model=ModelId("mlx-community/test-model"),
-        command_id=command_id,
-        data="abc",
-        chunk_index=0,
-        total_chunks=1,
-        image_index=0,
-    )
-    task = TextGeneration(
-        task_id=task_id,
-        instance_id=InstanceId("instance-1"),
-        task_status=TaskStatus.Pending,
-        command_id=command_id,
-        task_params=TextGenerationTaskParams(
-            model=ModelId("mlx-community/test-model"),
-            input=[
-                InputMessage(role="user", content=InputMessageContent("hello")),
-            ],
-        ),
-    )
-
-    state = State()
-    state = apply(
-        state,
-        IndexedEvent(
-            idx=0,
-            event=InputChunkReceived(command_id=command_id, chunk=chunk),
-        ),
-    )
-    state = apply(
-        state,
-        IndexedEvent(idx=1, event=TaskCreated(task_id=task_id, task=task)),
-    )
-    state = apply(
-        state,
-        IndexedEvent(idx=2, event=TaskDeleted(task_id=task_id)),
-    )
-
-    assert state.tasks == {}
-    assert state.input_chunks == {}

src/exo/shared/tests/test_apply/test_apply_rdma_gating.py

@@ -0,0 +1,231 @@
+from datetime import datetime, timezone
+
+from exo.shared.apply import apply_node_gathered_info
+from exo.shared.topology import Topology
+from exo.shared.types.common import NodeId
+from exo.shared.types.events import NodeGatheredInfo
+from exo.shared.types.profiling import (
+    NodeRdmaCtlStatus,
+    NodeThunderboltInfo,
+)
+from exo.shared.types.state import State
+from exo.shared.types.thunderbolt import ThunderboltConnection, ThunderboltIdentifier
+from exo.shared.types.topology import RDMAConnection
+from exo.utils.info_gatherer.info_gatherer import (
+    MacThunderboltConnections,
+    RdmaCtlStatus,
+)
+
+
+def _now() -> str:
+    return datetime.now(timezone.utc).isoformat()
+
+
+def _make_state_with_thunderbolt_idents(
+    *node_ids_and_uuids: tuple[NodeId, str, str],
+    rdma_ctl: dict[NodeId, NodeRdmaCtlStatus] | None = None,
+) -> State:
+    """Build a State with Thunderbolt identifiers per node so the apply MacThunderboltConnections
+    case can resolve uuid -> (node, iface)."""
+    node_thunderbolt = {
+        nid: NodeThunderboltInfo(
+            interfaces=[ThunderboltIdentifier(rdma_interface=iface, domain_uuid=uuid)]
+        )
+        for nid, uuid, iface in node_ids_and_uuids
+    }
+    return State(
+        node_thunderbolt=node_thunderbolt,
+        node_rdma_ctl=rdma_ctl or {},
+    )
+
+
+def _has_rdma_edge(topology: Topology, source: NodeId, sink: NodeId) -> bool:
+    return any(
+        isinstance(edge, RDMAConnection)
+        for edge in topology.get_all_connections_between(source, sink)
+    )
+
+
+def test_mac_thunderbolt_connections_emits_rdma_when_both_endpoints_enabled():
+    node_a = NodeId()
+    node_b = NodeId()
+    state = _make_state_with_thunderbolt_idents(
+        (node_a, "uuid-a", "rdma_en1"),
+        (node_b, "uuid-b", "rdma_en1"),
+        rdma_ctl={
+            node_a: NodeRdmaCtlStatus(enabled=True),
+            node_b: NodeRdmaCtlStatus(enabled=True),
+        },
+    )
+
+    event = NodeGatheredInfo(
+        node_id=node_a,
+        when=_now(),
+        info=MacThunderboltConnections(
+            conns=[ThunderboltConnection(source_uuid="uuid-a", sink_uuid="uuid-b")]
+        ),
+    )
+
+    new_state = apply_node_gathered_info(event, state)
+
+    assert _has_rdma_edge(new_state.topology, node_a, node_b)
+
+
+def test_mac_thunderbolt_connections_skips_rdma_when_source_rdma_ctl_disabled():
+    node_a = NodeId()
+    node_b = NodeId()
+    state = _make_state_with_thunderbolt_idents(
+        (node_a, "uuid-a", "rdma_en1"),
+        (node_b, "uuid-b", "rdma_en1"),
+        rdma_ctl={
+            node_a: NodeRdmaCtlStatus(enabled=False),
+            node_b: NodeRdmaCtlStatus(enabled=True),
+        },
+    )
+
+    event = NodeGatheredInfo(
+        node_id=node_a,
+        when=_now(),
+        info=MacThunderboltConnections(
+            conns=[ThunderboltConnection(source_uuid="uuid-a", sink_uuid="uuid-b")]
+        ),
+    )
+
+    new_state = apply_node_gathered_info(event, state)
+
+    assert not _has_rdma_edge(new_state.topology, node_a, node_b)
+
+
+def test_mac_thunderbolt_connections_skips_rdma_when_sink_rdma_ctl_disabled():
+    node_a = NodeId()
+    node_b = NodeId()
+    state = _make_state_with_thunderbolt_idents(
+        (node_a, "uuid-a", "rdma_en1"),
+        (node_b, "uuid-b", "rdma_en1"),
+        rdma_ctl={
+            node_a: NodeRdmaCtlStatus(enabled=True),
+            node_b: NodeRdmaCtlStatus(enabled=False),
+        },
+    )
+
+    event = NodeGatheredInfo(
+        node_id=node_a,
+        when=_now(),
+        info=MacThunderboltConnections(
+            conns=[ThunderboltConnection(source_uuid="uuid-a", sink_uuid="uuid-b")]
+        ),
+    )
+
+    new_state = apply_node_gathered_info(event, state)
+
+    assert not _has_rdma_edge(new_state.topology, node_a, node_b)
+
+
+def test_mac_thunderbolt_connections_skips_rdma_when_rdma_ctl_status_missing():
+    """Missing rdma_ctl status defaults to not-enabled — node is RDMA-incapable."""
+    node_a = NodeId()
+    node_b = NodeId()
+    state = _make_state_with_thunderbolt_idents(
+        (node_a, "uuid-a", "rdma_en1"),
+        (node_b, "uuid-b", "rdma_en1"),
+        rdma_ctl={
+            node_a: NodeRdmaCtlStatus(enabled=True),
+            # node_b intentionally absent
+        },
+    )
+
+    event = NodeGatheredInfo(
+        node_id=node_a,
+        when=_now(),
+        info=MacThunderboltConnections(
+            conns=[ThunderboltConnection(source_uuid="uuid-a", sink_uuid="uuid-b")]
+        ),
+    )
+
+    new_state = apply_node_gathered_info(event, state)
+
+    assert not _has_rdma_edge(new_state.topology, node_a, node_b)
+
+
+def test_rdma_ctl_status_disabled_purges_existing_rdma_edges():
+    """When a node reports rdma_ctl disabled, all RDMA edges touching it must be removed."""
+    node_a = NodeId()
+    node_b = NodeId()
+
+    # Start with both nodes RDMA-enabled and existing RDMA edges in the topology.
+    state = _make_state_with_thunderbolt_idents(
+        (node_a, "uuid-a", "rdma_en1"),
+        (node_b, "uuid-b", "rdma_en1"),
+        rdma_ctl={
+            node_a: NodeRdmaCtlStatus(enabled=True),
+            node_b: NodeRdmaCtlStatus(enabled=True),
+        },
+    )
+    state = apply_node_gathered_info(
+        NodeGatheredInfo(
+            node_id=node_a,
+            when=_now(),
+            info=MacThunderboltConnections(
+                conns=[ThunderboltConnection(source_uuid="uuid-a", sink_uuid="uuid-b")]
+            ),
+        ),
+        state,
+    )
+    state = apply_node_gathered_info(
+        NodeGatheredInfo(
+            node_id=node_b,
+            when=_now(),
+            info=MacThunderboltConnections(
+                conns=[ThunderboltConnection(source_uuid="uuid-b", sink_uuid="uuid-a")]
+            ),
+        ),
+        state,
+    )
+    assert _has_rdma_edge(state.topology, node_a, node_b)
+    assert _has_rdma_edge(state.topology, node_b, node_a)
+
+    # Now node_a flips to rdma_ctl disabled — both directions of RDMA edge must drop.
+    state = apply_node_gathered_info(
+        NodeGatheredInfo(
+            node_id=node_a, when=_now(), info=RdmaCtlStatus(enabled=False)
+        ),
+        state,
+    )
+
+    assert not _has_rdma_edge(state.topology, node_a, node_b)
+    assert not _has_rdma_edge(state.topology, node_b, node_a)
+    assert state.node_rdma_ctl[node_a].enabled is False
+
+
+def test_topology_remove_all_rdma_connections_touching_keeps_socket_edges():
+    """Purging RDMA edges for a disabled node must not affect non-RDMA edges."""
+    from exo.shared.types.multiaddr import Multiaddr
+    from exo.shared.types.topology import Connection, SocketConnection
+
+    topology = Topology()
+    node_a = NodeId()
+    node_b = NodeId()
+    topology.add_node(node_a)
+    topology.add_node(node_b)
+    topology.add_connection(
+        Connection(
+            source=node_a,
+            sink=node_b,
+            edge=RDMAConnection(
+                source_rdma_iface="rdma_en1", sink_rdma_iface="rdma_en1"
+            ),
+        )
+    )
+    socket_edge = SocketConnection(
+        sink_multiaddr=Multiaddr(address="/ip4/10.0.0.1/tcp/8000")
+    )
+    topology.add_connection(Connection(source=node_a, sink=node_b, edge=socket_edge))
+
+    topology.remove_all_rdma_connections_touching(node_a)
+
+    assert not _has_rdma_edge(topology, node_a, node_b)
+    # Socket edge survives.
+    assert any(
+        isinstance(edge, SocketConnection)
+        for edge in topology.get_all_connections_between(node_a, node_b)
+    )

src/exo/shared/tests/test_state_serialization.py

@@ -25,7 +25,6 @@ def test_state_serialization_roundtrip() -> None:
     json_repr = state.model_dump_json()
     restored_state = State.model_validate_json(json_repr)
 
-    assert restored_state.schema_version == state.schema_version
     assert (
         state.topology.to_snapshot().nodes
         == restored_state.topology.to_snapshot().nodes

src/exo/shared/topology.py

@@ -169,6 +169,22 @@ class Topology:
         for conn in new_connections:
             self.add_connection(conn)
 
+    def remove_all_rdma_connections_touching(self, node_id: NodeId) -> None:
+        """Remove every RDMA edge incident to ``node_id`` (incoming or outgoing)."""
+        if node_id not in self._vertex_indices:
+            return
+        rx_idx = self._vertex_indices[node_id]
+        rdma_edge_idxs = [
+            edge_idx
+            for edge_idx in (
+                *self._graph.out_edge_indices(rx_idx),
+                *self._graph.in_edge_indices(rx_idx),
+            )
+            if isinstance(self._graph.get_edge_data_by_index(edge_idx), RDMAConnection)
+        ]
+        for edge_idx in rdma_edge_idxs:
+            self._graph.remove_edge_from_index(edge_idx)
+
     def remove_connection(self, conn: Connection) -> None:
         if (
             conn.source not in self._vertex_indices

src/exo/shared/types/commands.py

@@ -67,12 +67,6 @@ class RequestEventLog(BaseCommand):
     since_idx: int
 
 
-class RequestSnapshot(BaseCommand):
-    """Ask the current master to send a State snapshot to this node."""
-
-    requester_node_id: NodeId
-
-
 class StartDownload(BaseCommand):
     target_node_id: NodeId
     shard_metadata: ShardMetadata
@@ -112,7 +106,6 @@ DownloadCommand = StartDownload | DeleteDownload | CancelDownload
 Command = (
     TestCommand
     | RequestEventLog
-    | RequestSnapshot
     | TextGeneration
     | ImageGeneration
     | ImageEdits

src/exo/shared/types/snapshots.py

@@ -1,54 +0,0 @@
-"""Wire types for snapshot transfer between master and a joining node.
-
-Snapshots can be tens of MB; the gossipsub message ceiling is around 1 MB.
-We slice the compressed snapshot body into chunks and publish each chunk on
-the SNAPSHOT_RESPONSES topic. The receiver collects chunks for its own
-`requester_node_id`, validates the SHA-256 of the reassembled body, and
-materialises the State.
-"""
-
-import base64
-
-from exo.shared.types.common import Id, NodeId, SessionId
-from exo.utils.pydantic_ext import FrozenModel
-
-
-class SnapshotTransferId(Id):
-    """Identifies a single snapshot transfer (one master response to one
-    `RequestSnapshot`). Distinct transfers may interleave; the id lets
-    receivers keep them apart."""
-
-
-class SnapshotChunk(FrozenModel):
-    """One slice of a snapshot in flight.
-
-    `data_b64` carries a base64-encoded slice of the zstd-compressed JSON
-    dump of State. Concatenating the *decoded* bytes of all chunks for a
-    `transfer_id` in order of `chunk_index` yields the full compressed
-    body; `sha256_hex` is the SHA-256 of that decoded blob.
-
-    We use base64 explicitly because the topic layer JSON-encodes messages,
-    and JSON can't carry raw binary. Helpers `from_data` / `data` keep the
-    base64 detail at the boundaries.
-    """
-
-    transfer_id: SnapshotTransferId
-    requester_node_id: NodeId
-    session_id: SessionId
-    schema_version: int
-    last_event_applied_idx: int
-    chunk_index: int
-    total_chunks: int
-    sha256_hex: str
-    data_b64: str
-
-    @classmethod
-    def from_data(cls, *, data: bytes, **kwargs: object) -> "SnapshotChunk":
-        return cls(data_b64=base64.b64encode(data).decode("ascii"), **kwargs)  # pyright: ignore[reportArgumentType]
-
-    @property
-    def data(self) -> bytes:
-        return base64.b64decode(self.data_b64)
-
-
-__all__ = ["SnapshotChunk", "SnapshotTransferId"]

src/exo/shared/types/state.py

@@ -5,9 +5,9 @@ from typing import Any, cast
 from pydantic import ConfigDict, Field, field_serializer, field_validator
 from pydantic.alias_generators import to_camel
 
+from exo.shared.models.model_cards import ModelCard
 from exo.shared.topology import Topology, TopologySnapshot
-from exo.shared.types.chunks import InputImageChunk
-from exo.shared.types.common import CommandId, NodeId
+from exo.shared.types.common import ModelId, NodeId
 from exo.shared.types.instance_link import InstanceLink, InstanceLinkId
 from exo.shared.types.profiling import (
     DiskUsage,
@@ -42,16 +42,10 @@ class State(FrozenModel):
         strict=True,
         arbitrary_types_allowed=True,
     )
-    # Bump when a State change makes older snapshots unsafe to restore.
-    schema_version: int = Field(default=1, ge=1)
-
     instances: Mapping[InstanceId, Instance] = {}
     runners: Mapping[RunnerId, RunnerStatus] = {}
     downloads: Mapping[NodeId, Sequence[DownloadProgress]] = {}
     tasks: Mapping[TaskId, Task] = {}
-    # Durable request input chunks for active image requests. Workers rebuild
-    # local image caches from this state instead of reading events directly.
-    input_chunks: Mapping[CommandId, Mapping[int, InputImageChunk]] = {}
     last_seen: Mapping[NodeId, datetime] = {}
     topology: Topology = Field(default_factory=Topology)
     last_event_applied_idx: int = Field(default=-1, ge=-1)
@@ -72,6 +66,9 @@ class State(FrozenModel):
     instance_links: Mapping[InstanceLinkId, InstanceLink] = {}
     prefill_server_ports: Mapping[RunnerId, int] = {}
 
+    # User-added model cards. Workers can reconcile their on-disk custom card cache
+    custom_model_cards: Mapping[ModelId, ModelCard] = {}
+
     @field_serializer("topology", mode="plain")
     def _encode_topology(self, value: Topology) -> TopologySnapshot:
         return value.to_snapshot()

src/exo/shared/types/text_generation.py

@@ -135,9 +135,9 @@ class TextGenerationTaskParams(BaseModel, frozen=True):
     prefill_endpoint: str | None = None
 
     def with_card_sampling_defaults(self) -> "TextGenerationTaskParams":
-        from exo.shared.models.model_cards import get_card
+        from exo.shared.models import model_cards
 
-        card = get_card(self.model)
+        card = model_cards.card_cache.get(self.model)
         if card is None:
             return self
 

src/exo/utils/event_buffer.py

@@ -47,18 +47,6 @@ class OrderedBuffer[T]:
         logger.trace(f"Releasing event {ret}")
         return ret
 
-    def fast_forward_to(self, idx: int) -> None:
-        """Skip every event before idx.
-
-        Snapshot restore uses this after applying state that already includes
-        events before idx. Any buffered or future event below idx is stale.
-        """
-        if idx <= self.next_idx_to_release:
-            return
-        self.next_idx_to_release = idx
-        for stale_idx in [i for i in self.store if i < idx]:
-            del self.store[stale_idx]
-
 
 class MultiSourceBuffer[SourceId, T]:
     """

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

@@ -143,6 +143,7 @@ class ImageEngine(Engine):
         Generator[tuple[TaskId, Chunk | FinishedResponse | CancelledResponse]] | None
     ) = field(init=False, default=None)
     queue: deque[ImageTask] = field(init=False, default_factory=deque)
+    _cancelled_tasks: set[TaskId] = field(init=False, default_factory=set)
 
     def warmup(self) -> None:
         image = warmup_image_generator(model=self.image_model)
@@ -168,7 +169,11 @@ class ImageEngine(Engine):
             task = self.queue.popleft()
             self.current_gen = self._run_image_task(task.task_id, task.task_params)
             resp = next(self.current_gen, None)
-        return (resp,) if resp is not None else ()
+        return (
+            (resp,)
+            if resp is not None and _is_primary_output_node(self.shard_metadata)
+            else ()
+        )
 
     def close(self) -> None:
         with contextlib.suppress(NameError, AttributeError):

src/exo/worker/main.py

@@ -8,25 +8,21 @@ from loguru import logger
 
 from exo.api.types import ImageEditsTaskParams
 from exo.download.download_utils import is_read_only_model_dir, resolve_existing_model
-from exo.routing.event_router import EventRouter
-from exo.routing.snapshot_receiver import SnapshotReceiver
 from exo.shared.apply import apply
 from exo.shared.constants import EXO_MAX_INSTANCE_RETRIES
-from exo.shared.models.model_cards import ModelId, add_to_card_cache, delete_custom_card
+from exo.shared.models.model_cards import ModelId, card_cache
 from exo.shared.types.chunks import InputImageChunk
 from exo.shared.types.commands import (
     DeleteInstance,
     ForwarderCommand,
     ForwarderDownloadCommand,
-    RequestSnapshot,
     StartDownload,
 )
-from exo.shared.types.common import CommandId, NodeId, SessionId, SystemId
+from exo.shared.types.common import CommandId, NodeId, SystemId
 from exo.shared.types.events import (
-    CustomModelCardAdded,
-    CustomModelCardDeleted,
     Event,
     IndexedEvent,
+    InputChunkReceived,
     InstanceDeleted,
     NodeDownloadProgress,
     NodeGatheredInfo,
@@ -36,7 +32,6 @@ from exo.shared.types.events import (
     TopologyEdgeDeleted,
 )
 from exo.shared.types.multiaddr import Multiaddr
-from exo.shared.types.snapshots import SnapshotChunk
 from exo.shared.types.state import State
 from exo.shared.types.tasks import (
     CancelTask,
@@ -62,19 +57,14 @@ from exo.utils.task_group import TaskGroup
 from exo.worker.plan import plan
 from exo.worker.runner.supervisor import RunnerSupervisor
 
-_SNAPSHOT_FETCH_TIMEOUT_SECONDS = 30
-
 
 class Worker:
     def __init__(
         self,
         node_id: NodeId,
-        session_id: SessionId,
         *,
-        event_router: EventRouter,
         event_receiver: Receiver[IndexedEvent],
         event_sender: Sender[Event],
-        snapshot_chunk_receiver: Receiver[SnapshotChunk],
         # 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],
@@ -82,11 +72,8 @@ class Worker:
         api_port: int,
     ):
         self.node_id: NodeId = node_id
-        self.session_id: SessionId = session_id
-        self.event_router = event_router
         self.event_receiver = event_receiver
         self.event_sender = event_sender
-        self.snapshot_chunk_receiver = snapshot_chunk_receiver
         self.command_sender = command_sender
         self.download_command_sender = download_command_sender
         self.api_port = api_port
@@ -116,57 +103,23 @@ class Worker:
 
         try:
             async with self._tg as tg:
-                tg.start_soon(self._bootstrap_then_run, info_gatherer, info_recv)
+                tg.start_soon(info_gatherer.run)
+                tg.start_soon(self._forward_info, info_recv)
+                tg.start_soon(self.plan_step)
+                tg.start_soon(self._event_applier)
+                tg.start_soon(self._poll_connection_updates)
+                tg.start_soon(self._reconcile_custom_cards)
+
         finally:
             # Actual shutdown code - waits for all tasks to complete before executing.
             logger.info("Stopping Worker")
             self.event_sender.close()
-            self.snapshot_chunk_receiver.close()
             self.command_sender.close()
             self.download_command_sender.close()
             for runner in self.runners.values():
                 runner.shutdown()
             self._stopped.set()
 
-    async def _bootstrap_then_run(
-        self, info_gatherer: InfoGatherer, info_recv: Receiver[GatheredInfo]
-    ) -> None:
-        await self._fetch_snapshot()
-        self._sync_input_views_from_state()
-        self._tg.start_soon(info_gatherer.run)
-        self._tg.start_soon(self._forward_info, info_recv)
-        self._tg.start_soon(self.plan_step)
-        self._tg.start_soon(self._event_applier)
-        self._tg.start_soon(self._poll_connection_updates)
-
-    async def _fetch_snapshot(self) -> None:
-        receiver = SnapshotReceiver(self.node_id, self.session_id)
-        await self.command_sender.send(
-            ForwarderCommand(
-                origin=self._system_id,
-                command=RequestSnapshot(requester_node_id=self.node_id),
-            )
-        )
-
-        with anyio.move_on_after(_SNAPSHOT_FETCH_TIMEOUT_SECONDS):
-            with self.snapshot_chunk_receiver as chunks:
-                async for chunk in chunks:
-                    received = receiver.ingest(chunk)
-                    if received is None:
-                        continue
-                    self.state = received.state
-                    self.event_router.set_buffer_start(
-                        received.last_event_applied_idx + 1
-                    )
-                    logger.info(
-                        f"Worker bootstrapped from snapshot at idx "
-                        f"{received.last_event_applied_idx}"
-                    )
-                    return
-        logger.info(
-            "No snapshot received before timeout; falling back to full event-log replay"
-        )
-
     async def _forward_info(self, recv: Receiver[GatheredInfo]):
         with recv as info_stream:
             async for info in info_stream:
@@ -181,8 +134,6 @@ class Worker:
     async def _event_applier(self):
         with self.event_receiver as events:
             async for event in events:
-                if event.idx <= self.state.last_event_applied_idx:
-                    continue
                 # 2. for each event, apply it to the state
                 self.state = apply(self.state, event=event)
                 event = event.event
@@ -190,41 +141,48 @@ class Worker:
                 if isinstance(event, InstanceDeleted):
                     self._instance_backoff.reset(event.instance_id)
 
-                if isinstance(event, CustomModelCardAdded):
-                    await event.model_card.save_to_custom_dir()
-                    add_to_card_cache(event.model_card)
+                # Buffer input image chunks for image editing
+                if isinstance(event, InputChunkReceived):
+                    cmd_id = event.command_id
+                    if cmd_id not in self.input_chunk_buffer:
+                        self.input_chunk_buffer[cmd_id] = {}
+                        self.input_chunk_counts[cmd_id] = event.chunk.total_chunks
 
-                if isinstance(event, CustomModelCardDeleted):
-                    await delete_custom_card(event.model_id)
+                    self.input_chunk_buffer[cmd_id][event.chunk.chunk_index] = (
+                        event.chunk
+                    )
+                    if (
+                        len(self.input_chunk_buffer[cmd_id])
+                        == self.input_chunk_counts[cmd_id]
+                    ):
+                        per_image: defaultdict[int, list[InputImageChunk]] = (
+                            defaultdict(list)
+                        )
+                        for chunk in self.input_chunk_buffer[cmd_id].values():
+                            per_image[chunk.image_index].append(chunk)
+                        for chunks_for_image in per_image.values():
+                            sorted_chunks = sorted(
+                                chunks_for_image, key=lambda c: c.chunk_index
+                            )
+                            img = Base64Image("".join(c.data for c in sorted_chunks))
+                            self.image_cache[
+                                Base64ImageHash(
+                                    hashlib.sha256(img.encode("ascii")).hexdigest()
+                                )
+                            ] = img
 
-                self._sync_input_views_from_state()
+    async def _reconcile_custom_cards(self) -> None:
+        while True:
+            await anyio.sleep(1)
+            target = dict(self.state.custom_model_cards)
+            for model_id, card in target.items():
+                if card_cache.get(model_id) == card:
+                    continue
+                await card_cache.save(card)
 
-    def _sync_input_views_from_state(self) -> None:
-        self.input_chunk_buffer = {
-            command_id: dict(chunks)
-            for command_id, chunks in self.state.input_chunks.items()
-        }
-        self.input_chunk_counts = {
-            command_id: next(iter(chunks.values())).total_chunks
-            for command_id, chunks in self.input_chunk_buffer.items()
-            if chunks
-        }
-
-        self.image_cache = {}
-        for command_id, chunks in self.input_chunk_buffer.items():
-            expected_chunks = self.input_chunk_counts.get(command_id)
-            if expected_chunks is None or len(chunks) != expected_chunks:
-                continue
-
-            per_image: defaultdict[int, list[InputImageChunk]] = defaultdict(list)
-            for chunk in chunks.values():
-                per_image[chunk.image_index].append(chunk)
-            for chunks_for_image in per_image.values():
-                sorted_chunks = sorted(chunks_for_image, key=lambda c: c.chunk_index)
-                image = Base64Image("".join(chunk.data for chunk in sorted_chunks))
-                self.image_cache[
-                    Base64ImageHash(hashlib.sha256(image.encode("ascii")).hexdigest())
-                ] = image
+            for card in await card_cache.list_all():
+                if card.model_id not in target:
+                    await card_cache.pop(card.model_id)
 
     async def plan_step(self):
         while True:
@@ -236,7 +194,7 @@ class Worker:
                 self.state.instances,
                 self.state.runners,
                 self.state.tasks,
-                self.state.input_chunks,
+                self.input_chunk_buffer,
                 self.image_cache,
                 self._instance_backoff,
                 self._download_backoff,
@@ -368,9 +326,15 @@ class Worker:
                             advanced_params=task.task_params.advanced_params,
                         ),
                     )
+                    # Cleanup buffers
+                    if cmd_id in self.input_chunk_buffer:
+                        del self.input_chunk_buffer[cmd_id]
+                    if cmd_id in self.input_chunk_counts:
+                        del self.input_chunk_counts[cmd_id]
                     await self._start_runner_task(modified_task)
 
                 case TextGeneration() if task.task_params.image_hashes:
+                    cmd_id = task.command_id
                     resolved_images = [
                         self.image_cache[h]
                         for _, h in sorted(task.task_params.image_hashes.items())
@@ -382,6 +346,10 @@ class Worker:
                             )
                         }
                     )
+                    if cmd_id in self.input_chunk_buffer:
+                        del self.input_chunk_buffer[cmd_id]
+                    if cmd_id in self.input_chunk_counts:
+                        del self.input_chunk_counts[cmd_id]
                     await self._start_runner_task(modified_task)
                 case LoadModel(instance_id=instance_id):
                     if (instance := self.state.instances.get(instance_id)) is not None:

src/exo/worker/runner/llm_inference/batch_generator.py

@@ -138,8 +138,10 @@ class SequentialGenerator(Engine):
     def agree_on_tasks(self) -> None:
         """Agree between all ranks about the task ordering (some may have received in different order or not at all)."""
         agreed, different = mx_all_gather_tasks(self._maybe_queue, self.group)
-        self._queue.extend(task for task in self._maybe_queue if task in agreed)
-        self._maybe_queue = [task for task in self._maybe_queue if task in different]
+        # Extend from `agreed` (sorted by task_id on all ranks) to guarantee every
+        # rank enqueues tasks in the same order, preventing TP collective deadlocks.
+        self._queue.extend(agreed)
+        self._maybe_queue = list(different)
 
     def agree_on_cancellations(self) -> None:
         """Agree between all ranks about which tasks to cancel."""
@@ -197,9 +199,14 @@ class SequentialGenerator(Engine):
             self._active = None
             raise
 
-        return itertools.chain(
-            output,
-            map(lambda task: (task, CancelledResponse()), self._cancelled_tasks),
+        return filter(
+            lambda chunk: (
+                not isinstance(chunk[1], GenerationChunk) or self.device_rank == 0
+            ),
+            itertools.chain(
+                output,
+                map(lambda task: (task, CancelledResponse()), self._cancelled_tasks),
+            ),
         )
 
     def _start_next(self) -> None:
@@ -368,8 +375,10 @@ class BatchGenerator(Engine):
     def agree_on_tasks(self) -> None:
         """Agree between all ranks about the task ordering (some may have received in different order or not at all)."""
         agreed, different = mx_all_gather_tasks(self._maybe_queue, self.group)
-        self._queue.extend(task for task in self._maybe_queue if task in agreed)
-        self._maybe_queue = [task for task in self._maybe_queue if task in different]
+        # Extend from `agreed` (sorted by task_id on all ranks) to guarantee every
+        # rank enqueues tasks in the same order, preventing TP collective deadlocks.
+        self._queue.extend(agreed)
+        self._maybe_queue = list(different)
 
     def agree_on_cancellations(self) -> None:
         """Agree between all ranks about which tasks to cancel."""
@@ -449,7 +458,12 @@ class BatchGenerator(Engine):
                 output.append((task.task_id, FinishedResponse()))
                 del self._active_tasks[uid]
 
-        return itertools.chain(output, self._apply_cancellations())
+        return filter(
+            lambda chunk: (
+                not isinstance(chunk[1], GenerationChunk) or self.device_rank == 0
+            ),
+            itertools.chain(output, self._apply_cancellations()),
+        )
 
     def _apply_cancellations(
         self,

src/exo/worker/runner/runner.py

@@ -390,5 +390,5 @@ class Runner:
         chunk: Chunk,
         command_id: CommandId,
     ):
-        if self.device_rank == 0:
-            self.event_sender.send(ChunkGenerated(command_id=command_id, chunk=chunk))
+        assert isinstance(self.generator, Engine)
+        self.event_sender.send(ChunkGenerated(command_id=command_id, chunk=chunk))

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

@@ -16,7 +16,7 @@ from exo.download.download_utils import (
     fetch_file_list_with_cache,
     resolve_model_dir,
 )
-from exo.shared.models.model_cards import ModelCard, ModelId, get_model_cards
+from exo.shared.models.model_cards import ModelCard, ModelId, card_cache
 from exo.worker.engines.mlx.utils_mlx import (
     get_eos_token_ids_for_model,
     load_tokenizer_for_model_id,
@@ -76,7 +76,7 @@ def get_test_models() -> list[ModelCard]:
     """Get a representative sample of models to test."""
     # Pick one model from each family to test
     families: dict[str, ModelCard] = {}
-    for card in asyncio.run(get_model_cards()):
+    for card in asyncio.run(card_cache.list_all()):
         # Extract family name (e.g., "llama-3.1" from "llama-3.1-8b")
         parts = card.model_id.short().split("-")
         family = "-".join(parts[:2]) if len(parts) >= 2 else parts[0]
@@ -298,7 +298,7 @@ async def test_tokenizer_special_tokens(model_card: ModelCard) -> None:
 async def test_kimi_tokenizer_specifically():
     """Test Kimi tokenizer with its specific patches and quirks."""
     kimi_models = [
-        card for card in await get_model_cards() if "kimi" in card.model_id.lower()
+        card for card in await card_cache.list_all() if "kimi" in card.model_id.lower()
     ]
 
     if not kimi_models:
@@ -350,7 +350,7 @@ async def test_glm_tokenizer_specifically():
 
     glm_model_cards = [
         card
-        for card in await get_model_cards()
+        for card in await card_cache.list_all()
         if contains(card, "glm")
         and not contains(card, "-5")
         and not contains(card, "4.7")

src/exo/worker/tests/unittests/test_worker_snapshot_bootstrap.py

@@ -1,126 +0,0 @@
-# pyright: reportPrivateUsage=false
-
-import hashlib
-
-import anyio
-import pytest
-import zstandard
-
-from exo.routing.event_router import EventRouter
-from exo.shared.types.commands import (
-    ForwarderCommand,
-    ForwarderDownloadCommand,
-    RequestSnapshot,
-)
-from exo.shared.types.common import NodeId, SessionId
-from exo.shared.types.events import (
-    Event,
-    GlobalForwarderEvent,
-    IndexedEvent,
-    LocalForwarderEvent,
-    TestEvent,
-)
-from exo.shared.types.snapshots import SnapshotChunk, SnapshotTransferId
-from exo.shared.types.state import State
-from exo.utils.channels import Receiver, Sender, channel
-from exo.worker.main import Worker
-
-
-def _snapshot_chunk(
-    state: State, *, requester_node_id: NodeId, session_id: SessionId
-) -> SnapshotChunk:
-    body = zstandard.ZstdCompressor().compress(state.model_dump_json().encode("utf-8"))
-    return SnapshotChunk.from_data(
-        data=body,
-        transfer_id=SnapshotTransferId("transfer-1"),
-        requester_node_id=requester_node_id,
-        session_id=session_id,
-        schema_version=state.schema_version,
-        last_event_applied_idx=state.last_event_applied_idx,
-        chunk_index=0,
-        total_chunks=1,
-        sha256_hex=hashlib.sha256(body).hexdigest(),
-    )
-
-
-def _worker(
-    node_id: NodeId, session_id: SessionId
-) -> tuple[
-    Worker,
-    EventRouter,
-    Receiver[ForwarderCommand],
-    Sender[SnapshotChunk],
-    Sender[IndexedEvent],
-]:
-    router_command_sender, _router_command_receiver = channel[ForwarderCommand]()
-    _global_event_sender, global_event_receiver = channel[GlobalForwarderEvent]()
-    local_event_sender, _local_event_receiver = channel[LocalForwarderEvent]()
-    event_router = EventRouter(
-        session_id=session_id,
-        command_sender=router_command_sender,
-        external_inbound=global_event_receiver,
-        external_outbound=local_event_sender,
-    )
-
-    event_sender, event_receiver = channel[IndexedEvent]()
-    local_event_output_sender, _local_event_output_receiver = channel[Event]()
-    command_sender, command_receiver = channel[ForwarderCommand]()
-    download_command_sender, _download_command_receiver = channel[
-        ForwarderDownloadCommand
-    ]()
-    snapshot_sender, snapshot_receiver = channel[SnapshotChunk]()
-
-    worker = Worker(
-        node_id,
-        session_id,
-        event_router=event_router,
-        event_receiver=event_receiver,
-        event_sender=local_event_output_sender,
-        snapshot_chunk_receiver=snapshot_receiver,
-        command_sender=command_sender,
-        download_command_sender=download_command_sender,
-        api_port=52415,
-    )
-    return worker, event_router, command_receiver, snapshot_sender, event_sender
-
-
-@pytest.mark.asyncio
-async def test_worker_fetch_snapshot_applies_state_and_fast_forwards_router() -> None:
-    node_id = NodeId("worker")
-    session_id = SessionId(master_node_id=NodeId("master"), election_clock=1)
-    worker, event_router, command_receiver, snapshot_sender, _event_sender = _worker(
-        node_id, session_id
-    )
-    state = State(last_event_applied_idx=7)
-
-    async with anyio.create_task_group() as tg:
-        tg.start_soon(worker._fetch_snapshot)
-        command = await command_receiver.receive()
-        assert isinstance(command.command, RequestSnapshot)
-        assert command.command.requester_node_id == node_id
-
-        await snapshot_sender.send(
-            _snapshot_chunk(state, requester_node_id=node_id, session_id=session_id)
-        )
-
-    assert worker.state.last_event_applied_idx == 7
-    assert event_router.event_buffer.next_idx_to_release == 8
-
-
-@pytest.mark.asyncio
-async def test_worker_event_applier_ignores_events_covered_by_snapshot() -> None:
-    node_id = NodeId("worker")
-    session_id = SessionId(master_node_id=NodeId("master"), election_clock=1)
-    worker, _event_router, _command_receiver, _snapshot_sender, event_sender = _worker(
-        node_id, session_id
-    )
-    worker.state = State(last_event_applied_idx=7)
-
-    async with anyio.create_task_group() as tg:
-        tg.start_soon(worker._event_applier)
-        await event_sender.send(IndexedEvent(idx=7, event=TestEvent()))
-        await event_sender.send(IndexedEvent(idx=8, event=TestEvent()))
-
-        while worker.state.last_event_applied_idx != 8:
-            await anyio.sleep(0.001)
-        tg.cancel_scope.cancel()