fix(trigger): recover interrupted deliveries

tests/triggers/test_external_triggers.py

@@ -49,6 +49,33 @@ def test_enqueue_rejects_disabled_trigger(tmp_path: Path) -> None:
         store.enqueue(trigger.id, "Review PR #4502")
 
 
+def test_recover_processing_deliveries_requeues_claimed_delivery(tmp_path: Path) -> None:
+    store = ExternalTriggerStore(tmp_path)
+    trigger = store.create(
+        name="PR review",
+        channel="websocket",
+        chat_id="chat-1",
+        session_key="websocket:chat-1",
+    )
+    store.enqueue(trigger.id, "Review PR #4591")
+
+    claimed = store.claim_deliveries()
+    assert len(claimed) == 1
+    assert claimed[0].path is not None
+    assert claimed[0].path.parent.name == "processing"
+    assert ExternalTriggerStore(tmp_path).claim_deliveries() == []
+
+    restarted = ExternalTriggerStore(tmp_path)
+    assert restarted.recover_processing_deliveries() == 1
+
+    reclaimed = restarted.claim_deliveries()
+    assert len(reclaimed) == 1
+    assert reclaimed[0].trigger_id == trigger.id
+    assert reclaimed[0].content == "Review PR #4591"
+    assert reclaimed[0].attempts == 1
+    assert reclaimed[0].last_error == "delivery was recovered from interrupted processing"
+
+
 @pytest.mark.asyncio
 async def test_external_trigger_queue_publishes_bound_inbound_message(tmp_path: Path) -> None:
     store = ExternalTriggerStore(tmp_path)
@@ -99,3 +126,42 @@ async def test_external_trigger_queue_publishes_bound_inbound_message(tmp_path:
     assert stored.last_status == "ok"
     assert stored.last_run_at_ms is not None
     assert store.claim_deliveries() == []
+
+
+@pytest.mark.asyncio
+async def test_external_trigger_queue_recovers_processing_delivery_on_start(
+    tmp_path: Path,
+) -> None:
+    store = ExternalTriggerStore(tmp_path)
+    trigger = store.create(
+        name="PR review",
+        channel="websocket",
+        chat_id="chat-1",
+        session_key="websocket:chat-1",
+    )
+    store.enqueue(trigger.id, "Review PR #4591")
+    assert len(store.claim_deliveries()) == 1
+    published: list[InboundMessage] = []
+
+    class _Bus:
+        async def publish_inbound(self, msg: InboundMessage) -> None:
+            published.append(msg)
+
+    restarted = ExternalTriggerStore(tmp_path)
+    task = asyncio.create_task(
+        run_external_trigger_queue(store=restarted, bus=_Bus(), poll_interval_s=0.01)
+    )
+    try:
+        for _ in range(100):
+            if published:
+                break
+            await asyncio.sleep(0.01)
+    finally:
+        task.cancel()
+        with suppress(asyncio.CancelledError):
+            await task
+
+    assert len(published) == 1
+    assert published[0].content == "Review PR #4591"
+    assert published[0].metadata["_external_trigger"]["trigger_id"] == trigger.id
+    assert restarted.claim_deliveries() == []