fix: keep TRUST_REMOTE_CODE=True for built-in models

The constant is the default for built-in models with known model cards,
which are trusted. Custom models added via API already default to
trust_remote_code=False in ModelCard.fetch_from_hf(). The CLI flag
overrides custom models only.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/exo/main.py

@@ -261,6 +261,13 @@ def main():
     if args.offline:
         logger.info("Running in OFFLINE mode — no internet checks, local models only")
 
+    # Set trust_remote_code override env var for runner subprocesses
+    if args.trust_remote_code:
+        os.environ["EXO_TRUST_REMOTE_CODE"] = "1"
+        logger.warning(
+            "--trust-remote-code enabled: models may execute arbitrary code during loading"
+        )
+
     # Set FAST_SYNCH override env var for runner subprocesses
     if args.fast_synch is True:
         os.environ["EXO_FAST_SYNCH"] = "on"
@@ -285,6 +292,7 @@ class Args(CamelCaseModel):
     no_downloads: bool = False
     offline: bool = False
     fast_synch: bool | None = None  # None = auto, True = force on, False = force off
+    trust_remote_code: bool = False
 
     @classmethod
     def parse(cls) -> Self:
@@ -336,6 +344,11 @@ class Args(CamelCaseModel):
             action="store_true",
             help="Run in offline/air-gapped mode: skip internet checks, use only pre-staged local models",
         )
+        parser.add_argument(
+            "--trust-remote-code",
+            action="store_true",
+            help="Allow models to execute custom code during tokenizer loading (security-sensitive, CLI-only)",
+        )
         fast_synch_group = parser.add_mutually_exclusive_group()
         fast_synch_group.add_argument(
             "--fast-synch",

src/exo/master/tests/test_placement.py

@@ -14,10 +14,12 @@ from exo.shared.models.model_cards import ModelCard, ModelId, ModelTask
 from exo.shared.topology import Topology
 from exo.shared.types.commands import PlaceInstance
 from exo.shared.types.common import CommandId, NodeId
-from exo.shared.types.events import InstanceCreated, InstanceDeleted
+from exo.shared.types.events import InstanceCreated, InstanceDeleted, TaskStatusUpdated
 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.tasks import TaskId, TaskStatus, TextGeneration
+from exo.shared.types.text_generation import InputMessage, TextGenerationTaskParams
 from exo.shared.types.topology import Connection, SocketConnection
 from exo.shared.types.worker.instances import (
     Instance,
@@ -456,3 +458,117 @@ def test_tensor_rdma_backend_connectivity_matrix(
         else:
             ip_part = coordinator.split(":")[0]
             assert len(ip_part.split(".")) == 4
+
+
+def _make_task(
+    instance_id: InstanceId,
+    status: TaskStatus = TaskStatus.Running,
+) -> TextGeneration:
+    return TextGeneration(
+        task_id=TaskId(),
+        task_status=status,
+        instance_id=instance_id,
+        command_id=CommandId(),
+        task_params=TextGenerationTaskParams(
+            model=ModelId("test-model"),
+            input=[InputMessage(role="user", content="hello")],
+        ),
+    )
+
+
+def test_get_transition_events_delete_instance_cancels_running_tasks(
+    instance: Instance,
+):
+    # arrange
+    instance_id = InstanceId()
+    current_instances: dict[InstanceId, Instance] = {instance_id: instance}
+    target_instances: dict[InstanceId, Instance] = {}
+    task = _make_task(instance_id, TaskStatus.Running)
+    tasks = {task.task_id: task}
+
+    # act
+    events = get_transition_events(current_instances, target_instances, tasks)
+
+    # assert – cancellation event should come before the deletion event
+    assert len(events) == 2
+    assert isinstance(events[0], TaskStatusUpdated)
+    assert events[0].task_id == task.task_id
+    assert events[0].task_status == TaskStatus.Cancelled
+    assert isinstance(events[1], InstanceDeleted)
+    assert events[1].instance_id == instance_id
+
+
+def test_get_transition_events_delete_instance_cancels_pending_tasks(
+    instance: Instance,
+):
+    # arrange
+    instance_id = InstanceId()
+    current_instances: dict[InstanceId, Instance] = {instance_id: instance}
+    target_instances: dict[InstanceId, Instance] = {}
+    task = _make_task(instance_id, TaskStatus.Pending)
+    tasks = {task.task_id: task}
+
+    # act
+    events = get_transition_events(current_instances, target_instances, tasks)
+
+    # assert
+    assert len(events) == 2
+    assert isinstance(events[0], TaskStatusUpdated)
+    assert events[0].task_id == task.task_id
+    assert events[0].task_status == TaskStatus.Cancelled
+    assert isinstance(events[1], InstanceDeleted)
+
+
+def test_get_transition_events_delete_instance_ignores_completed_tasks(
+    instance: Instance,
+):
+    # arrange
+    instance_id = InstanceId()
+    current_instances: dict[InstanceId, Instance] = {instance_id: instance}
+    target_instances: dict[InstanceId, Instance] = {}
+    tasks = {
+        t.task_id: t
+        for t in [
+            _make_task(instance_id, TaskStatus.Complete),
+            _make_task(instance_id, TaskStatus.Failed),
+            _make_task(instance_id, TaskStatus.TimedOut),
+            _make_task(instance_id, TaskStatus.Cancelled),
+        ]
+    }
+
+    # act
+    events = get_transition_events(current_instances, target_instances, tasks)
+
+    # assert – only the InstanceDeleted event, no cancellations
+    assert len(events) == 1
+    assert isinstance(events[0], InstanceDeleted)
+
+
+def test_get_transition_events_delete_instance_cancels_only_matching_tasks(
+    instance: Instance,
+):
+    # arrange
+    instance_id_a = InstanceId()
+    instance_id_b = InstanceId()
+    current_instances: dict[InstanceId, Instance] = {
+        instance_id_a: instance,
+        instance_id_b: instance,
+    }
+    # only delete instance A, keep instance B
+    target_instances: dict[InstanceId, Instance] = {instance_id_b: instance}
+
+    task_a = _make_task(instance_id_a, TaskStatus.Running)
+    task_b = _make_task(instance_id_b, TaskStatus.Running)
+    tasks = {task_a.task_id: task_a, task_b.task_id: task_b}
+
+    # act
+    events = get_transition_events(current_instances, target_instances, tasks)
+
+    # assert – only task_a should be cancelled
+    cancel_events = [e for e in events if isinstance(e, TaskStatusUpdated)]
+    delete_events = [e for e in events if isinstance(e, InstanceDeleted)]
+    assert len(cancel_events) == 1
+    assert cancel_events[0].task_id == task_a.task_id
+    assert cancel_events[0].task_status == TaskStatus.Cancelled
+    assert len(delete_events) == 1
+    assert delete_events[0].instance_id == instance_id_a

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

@@ -13,5 +13,6 @@ KV_CACHE_BITS: int | None = None
 
 DEFAULT_TOP_LOGPROBS: int = 5
 
-# TODO: We should really make this opt-in, but Kimi requires trust_remote_code=True
+# True for built-in models with known model cards; custom models added via API default to False
+# and can be overridden with the --trust-remote-code CLI flag.
 TRUST_REMOTE_CODE: bool = True

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

@@ -291,10 +291,14 @@ def shard_and_load(
 
 def get_tokenizer(model_path: Path, shard_metadata: ShardMetadata) -> TokenizerWrapper:
     """Load tokenizer for a model shard. Delegates to load_tokenizer_for_model_id."""
+    trust_remote_code = (
+        shard_metadata.model_card.trust_remote_code
+        or os.environ.get("EXO_TRUST_REMOTE_CODE") == "1"
+    )
     return load_tokenizer_for_model_id(
         shard_metadata.model_card.model_id,
         model_path,
-        trust_remote_code=shard_metadata.model_card.trust_remote_code,
+        trust_remote_code=trust_remote_code,
     )
 
 

tests/get_all_models_on_cluster.py

@@ -8,7 +8,7 @@ from urllib.request import urlopen
 
 h = sys.argv[1] if len(sys.argv) > 1 else sys.exit(f"USAGE: {sys.argv[0]} host")
 ts = subprocess.run(
-    ["/Applications/Tailscale.app/Contents/MacOS/Tailscale", "status"], check=True, text=True, capture_output=True
+    ["tailscale", "status"], check=True, text=True, capture_output=True
 ).stdout.splitlines()
 ip = next(
     (sl[0] for line in ts if len(sl := line.split()) >= 2 if sl[1] == h), None

tests/start_distributed_test.py

@@ -15,7 +15,7 @@ if not (args := sys.argv[1:]):
 kind = args[0] if args[0] in ("jaccl", "ring") else "both"
 hosts = args[1:] if kind != "both" else args
 ts = subprocess.run(
-    ["/Applications/Tailscale.app/Contents/MacOS/Tailscale", "status"], check=True, text=True, capture_output=True
+    ["tailscale", "status"], check=True, text=True, capture_output=True
 ).stdout.splitlines()
 ip = {sl[1]: sl[0] for line in ts if len(sl := line.split()) >= 2}
 ips = [ip[h] for h in hosts]