Fix duplicate WhatsApp outbound delivery.

Claim pending rows atomically and serialize the sidecar poller so overlapping polls cannot send the same reply twice; also stop inbound queue delivery from falling through to a second enqueue.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_channel_outbound_retry.py

@@ -54,3 +54,26 @@ def test_channel_outbound_retry_success_clears_schedule(tmp_path) -> None:
     assert row["status"] == "sent"
     assert int(row["send_attempts"] or 0) == 2
     assert not str(row["next_attempt_at"] or "").strip()
+
+
+def test_claim_pending_channel_outbound_messages_is_exclusive(tmp_path) -> None:
+    store = SqliteStore(str(tmp_path / "ops.sqlite"))
+    msg_id = store.enqueue_channel_outbound_message(
+        channel="whatsapp",
+        account_id="wa-default",
+        chat_id="120363012345678@g.us",
+        text="once only",
+    )
+    first = store.claim_pending_channel_outbound_messages(
+        channel="whatsapp", account_id="wa-default", limit=5
+    )
+    second = store.claim_pending_channel_outbound_messages(
+        channel="whatsapp", account_id="wa-default", limit=5
+    )
+    assert len(first) == 1
+    assert first[0]["id"] == msg_id
+    assert second == []
+    row = _row(store, msg_id)
+    assert row["status"] == "sending"
+    assert store.ack_channel_outbound_message(message_id=msg_id, ok=True, stanza_id="S1") is True
+    assert _row(store, msg_id)["status"] == "sent"

tests/test_whatsapp_inbound_queue_cancel.py

@@ -101,6 +101,26 @@ class WhatsappInboundSerialQueueTests(unittest.TestCase):
         self.assertEqual(source.get("kind"), "inbound_reply")
         self.assertEqual(source.get("quote_stanza_id"), "stanza1")
 
+    def test_whatsapp_queue_delivery_does_not_double_enqueue(self) -> None:
+        """Regression: agent-path enqueue must not fall through to bottom enqueue."""
+        with self._patch_common(), mock.patch("runtime.gateway.OclawGateway") as gw_cls, mock.patch(
+            "runtime.orchestration.group_ingest.should_process_group_inbound", return_value=True
+        ), mock.patch(
+            "runtime.application.gateway.whatsapp_inbound_access.handle_whatsapp_access",
+            return_value=None,
+        ):
+            gw = gw_cls.return_value
+            gw.handle_turn.return_value = _FakeTurn("only once")
+            out = inbound_mod.process_inbound_payload(self._payload("ping"))
+
+        self.assertEqual(out.get("delivery"), "queued")
+        self.assertEqual(out.get("replies"), [])
+        pending = self.store.list_pending_channel_outbound_messages(
+            channel="whatsapp", account_id="wa-default", limit=10
+        )
+        self.assertEqual(len(pending), 1)
+        self.assertEqual(pending[0].get("text"), "only once")
+
     def test_busy_inbound_is_accepted_queued_then_merged(self) -> None:
         release = threading.Event()
         seen_texts: list[str] = []