feat(cloud): surface cancellation over the internal Host<->Cloud protocol

- LeaseRenewalResponse gains cancel_requested (populated from the
  repository's renew_lease result)
- TerminalResultRequest.status widened to accept "cancelled"
- Add internal API tests for a renewal surfacing cancel_requested=True
  and a cancelled terminal report being accepted/idempotent

openspec/changes/task-cancellation/tasks.md

@@ -21,11 +21,11 @@
 
 ## 3. Internal Host↔Cloud protocol
 
-- [ ] 3.1 Add `cancel_requested: bool = False` field to `LeaseRenewalResponse` (`internal_api/models.py`).
+- [x] 3.1 Add `cancel_requested: bool = False` field to `LeaseRenewalResponse` (`internal_api/models.py`).
-- [ ] 3.2 Widen `TerminalResultRequest.status` (`internal_api/models.py`) to `Literal["done", "failed", "cancelled"]`.
+- [x] 3.2 Widen `TerminalResultRequest.status` (`internal_api/models.py`) to `Literal["done", "failed", "cancelled"]`.
-- [ ] 3.3 Update `renew_assignment` route (`internal_api/api.py`) to populate `LeaseRenewalResponse.cancel_requested` from the repository's `renew_lease` result.
+- [x] 3.3 Update `renew_assignment` route (`internal_api/api.py`) to populate `LeaseRenewalResponse.cancel_requested` from the repository's `renew_lease` result.
-- [ ] 3.4 Update `report_result` route (`internal_api/api.py`) to accept and forward the `"cancelled"` status to `record_task_result`.
+- [x] 3.4 Update `report_result` route (`internal_api/api.py`) to accept and forward the `"cancelled"` status to `record_task_result`.
-- [ ] 3.5 Add/extend internal API tests covering a renewal response surfacing `cancel_requested=True` and a `"cancelled"` terminal report being accepted and idempotent on repeat.
+- [x] 3.5 Add/extend internal API tests covering a renewal response surfacing `cancel_requested=True` and a `"cancelled"` terminal report being accepted and idempotent on repeat.
 
 ## 4. Host Agent collaborative stop
 

packages/cloud-platform/cloud/internal_api/api.py

@@ -316,7 +316,7 @@ def create_internal_router(
                 summary=payload.progress.summary[:500],
                 updated_at=now,
             )
-        renewal_status = pool.store.renew_lease(
+        renewal = pool.store.renew_lease(
             task_id=task_id,
             attempt=payload.attempt,
             lease_id=payload.lease_id,
@@ -325,16 +325,17 @@ def create_internal_router(
             now=now,
             progress=progress_snapshot,
         )
-        if renewal_status == "not_found":
+        if renewal.status == "not_found":
             raise HTTPException(
                 status_code=status.HTTP_404_NOT_FOUND,
                 detail="assignment not found",
             )
-        if renewal_status != "renewed":
+        if renewal.status != "renewed":
             return _stale_lease_conflict("assignment lease is stale or expired")
         return LeaseRenewalResponse(
             status="renewed",
             lease_expires_at=lease_expires_at,
+            cancel_requested=renewal.cancel_requested,
         )
 
     @router.post(

packages/cloud-platform/cloud/internal_api/models.py

@@ -95,6 +95,7 @@ class LeaseRenewalRequest(BaseModel):
 class LeaseRenewalResponse(BaseModel):
     status: Literal["renewed"]
     lease_expires_at: datetime
+    cancel_requested: bool = False
 
 
 class TerminalResultRequest(BaseModel):
@@ -102,7 +103,7 @@ class TerminalResultRequest(BaseModel):
     task_id: str = Field(min_length=1)
     attempt: int = Field(ge=1)
     lease_id: str = Field(min_length=1)
-    status: Literal["done", "failed"]
+    status: Literal["done", "failed", "cancelled"]
     failure_reason: str | None = None
     result: dict[str, Any] | None = None
 

tests/test_host_agent_internal_api.py

@@ -473,10 +473,32 @@ def test_lease_renewal_extends_active_assignment(tmp_path) -> None:
 
     assert response.status_code == 200
     assert response.json()["status"] == "renewed"
+    assert response.json()["cancel_requested"] is False
     renewed_expiry = datetime.fromisoformat(response.json()["lease_expires_at"])
     assert renewed_expiry > original_time + timedelta(seconds=30)
 
 
+def test_lease_renewal_surfaces_pending_cancellation(tmp_path) -> None:
+    client, pool = _build_client(tmp_path)
+    _seed_active_assignment(pool)
+    pool.store.request_task_cancellation("active-task", requested_at=datetime.now(UTC))
+
+    response = client.post(
+        "/internal/v1/hosts/host-a/assignments/active-task/renew",
+        headers={"Authorization": "Bearer token-a"},
+        json={
+            "host_id": "host-a",
+            "task_id": "active-task",
+            "attempt": 1,
+            "lease_id": "active-lease",
+        },
+    )
+
+    assert response.status_code == 200
+    assert response.json()["status"] == "renewed"
+    assert response.json()["cancel_requested"] is True
+
+
 def test_stale_renewal_returns_typed_conflict(tmp_path) -> None:
     client, pool = _build_client(tmp_path)
     _seed_active_assignment(pool)
@@ -526,6 +548,37 @@ def test_terminal_result_is_idempotent_through_internal_api(tmp_path) -> None:
     assert pool.store.get_task("active-task").status == "done"  # type: ignore[union-attr]
 
 
+def test_cancelled_terminal_result_is_accepted_and_idempotent(tmp_path) -> None:
+    client, pool = _build_client(tmp_path)
+    _seed_active_assignment(pool)
+    pool.store.request_task_cancellation("active-task", requested_at=datetime.now(UTC))
+    payload = {
+        "host_id": "host-a",
+        "task_id": "active-task",
+        "attempt": 1,
+        "lease_id": "active-lease",
+        "status": "cancelled",
+        "failure_reason": "cancellation requested by control plane",
+    }
+
+    first = client.post(
+        "/internal/v1/hosts/host-a/assignments/active-task/result",
+        headers={"Authorization": "Bearer token-a"},
+        json=payload,
+    )
+    repeated = client.post(
+        "/internal/v1/hosts/host-a/assignments/active-task/result",
+        headers={"Authorization": "Bearer token-a"},
+        json=payload,
+    )
+
+    assert first.status_code == 200
+    assert first.json()["status"] == "recorded"
+    assert repeated.status_code == 200
+    assert repeated.json()["status"] == "already_recorded"
+    assert pool.store.get_task("active-task").status == "cancelled"  # type: ignore[union-attr]
+
+
 def test_conflicting_repeated_result_returns_stale_lease_conflict(tmp_path) -> None:
     client, pool = _build_client(tmp_path)
     _seed_active_assignment(pool)