fix(agent): propagate effective session key through subagent pipeline

The previous fix hardcoded session_key_override as channel:chat_id which
broke unified session mode where pending queues use "unified:default".
Propagate the effective key from _set_tool_context through SpawnTool
into the origin dict so _announce_result routes to the correct pending
queue in both normal and unified session modes.

nanobot/agent/loop.py

@@ -318,10 +318,16 @@ class AgentLoop:
 
     def _set_tool_context(self, channel: str, chat_id: str, message_id: str | None = None) -> None:
         """Update context for all tools that need routing info."""
+        # Compute the effective session key (accounts for unified sessions)
+        # so that subagent results route to the correct pending queue.
+        effective_key = UNIFIED_SESSION_KEY if self._unified_session else f"{channel}:{chat_id}"
         for name in ("message", "spawn", "cron", "my"):
             if tool := self.tools.get(name):
                 if hasattr(tool, "set_context"):
-                    tool.set_context(channel, chat_id, *([message_id] if name == "message" else []))
+                    if name == "spawn":
+                        tool.set_context(channel, chat_id, effective_key=effective_key)
+                    else:
+                        tool.set_context(channel, chat_id, *([message_id] if name == "message" else []))
 
     @staticmethod
     def _strip_think(text: str | None) -> str | None:

nanobot/agent/subagent.py

@@ -107,7 +107,7 @@ class SubagentManager:
         """Spawn a subagent to execute a task in the background."""
         task_id = str(uuid.uuid4())[:8]
         display_label = label or task[:30] + ("..." if len(task) > 30 else "")
-        origin = {"channel": origin_channel, "chat_id": origin_chat_id}
+        origin = {"channel": origin_channel, "chat_id": origin_chat_id, "session_key": session_key}
 
         status = SubagentStatus(
             task_id=task_id,
@@ -241,15 +241,17 @@ class SubagentManager:
         )
 
         # Inject as system message to trigger main agent.
-        # Use session_key_override to align with the main agent's session key
-        # so the result is routed to the pending queue (mid-turn injection)
-        # instead of being dispatched as a competing independent task.
+        # Use session_key_override to align with the main agent's effective
+        # session key (which accounts for unified sessions) so the result is
+        # routed to the correct pending queue (mid-turn injection) instead of
+        # being dispatched as a competing independent task.
+        override = origin.get("session_key") or f"{origin['channel']}:{origin['chat_id']}"
         msg = InboundMessage(
             channel="system",
             sender_id="subagent",
             chat_id=f"{origin['channel']}:{origin['chat_id']}",
             content=announce_content,
-            session_key_override=f"{origin['channel']}:{origin['chat_id']}",
+            session_key_override=override,
             metadata={
                 "injected_event": "subagent_result",
                 "subagent_task_id": task_id,

nanobot/agent/tools/spawn.py

@@ -25,11 +25,11 @@ class SpawnTool(Tool):
         self._origin_chat_id = "direct"
         self._session_key = "cli:direct"
 
-    def set_context(self, channel: str, chat_id: str) -> None:
+    def set_context(self, channel: str, chat_id: str, effective_key: str | None = None) -> None:
         """Set the origin context for subagent announcements."""
         self._origin_channel = channel
         self._origin_chat_id = chat_id
-        self._session_key = f"{channel}:{chat_id}"
+        self._session_key = effective_key or f"{channel}:{chat_id}"
 
     @property
     def name(self) -> str:

tests/agent/test_task_cancel.py

@@ -412,3 +412,91 @@ class TestSubagentCancellation:
         assert cancelled.is_set()
         assert task.cancelled()
         mgr._announce_result.assert_not_awaited()
+
+
+class TestSubagentAnnounceSessionKey:
+    """Verify _announce_result uses the effective session key for mid-turn routing."""
+
+    def _make_mgr(self):
+        """Create a SubagentManager with mocked deps and its bus."""
+        from nanobot.agent.subagent import SubagentManager
+        from nanobot.bus.queue import MessageBus
+
+        bus = MessageBus()
+        provider = MagicMock()
+        provider.get_default_model.return_value = "test-model"
+        mgr = SubagentManager(
+            provider=provider,
+            workspace=MagicMock(),
+            bus=bus,
+            max_tool_result_chars=_MAX_TOOL_RESULT_CHARS,
+        )
+        return mgr, bus
+
+    @pytest.mark.asyncio
+    async def test_announce_uses_effective_key_in_unified_mode(self):
+        """In unified session mode, session_key_override must be 'unified:default'
+        so the result matches the pending queue key."""
+        mgr, bus = self._make_mgr()
+
+        origin = {"channel": "telegram", "chat_id": "111", "session_key": "unified:default"}
+        await mgr._announce_result("sub-1", "label", "task", "result", origin, "ok")
+
+        msg = await bus.consume_inbound()
+        assert msg.session_key_override == "unified:default"
+        assert msg.session_key == "unified:default"
+
+    @pytest.mark.asyncio
+    async def test_announce_uses_raw_key_in_normal_mode(self):
+        """Without unified sessions, session_key_override is the raw channel:chat_id."""
+        mgr, bus = self._make_mgr()
+
+        origin = {"channel": "telegram", "chat_id": "222", "session_key": "telegram:222"}
+        await mgr._announce_result("sub-2", "label", "task", "result", origin, "ok")
+
+        msg = await bus.consume_inbound()
+        assert msg.session_key_override == "telegram:222"
+        assert msg.session_key == "telegram:222"
+
+    @pytest.mark.asyncio
+    async def test_announce_falls_back_to_origin_when_no_session_key(self):
+        """When session_key is None, fallback to f'{channel}:{chat_id}'."""
+        mgr, bus = self._make_mgr()
+
+        origin = {"channel": "discord", "chat_id": "333", "session_key": None}
+        await mgr._announce_result("sub-3", "label", "task", "result", origin, "ok")
+
+        msg = await bus.consume_inbound()
+        assert msg.session_key_override == "discord:333"
+        assert msg.channel == "system"
+        assert msg.chat_id == "discord:333"
+
+    @pytest.mark.asyncio
+    async def test_session_key_flows_through_run_subagent(self):
+        """Verify session_key in origin propagates from _run_subagent to _announce_result."""
+        from nanobot.agent.subagent import SubagentStatus
+
+        mgr, bus = self._make_mgr()
+
+        async def fake_run(spec):
+            return SimpleNamespace(
+                stop_reason="done",
+                final_content="done",
+                error=None,
+                tool_events=[],
+            )
+
+        mgr.runner.run = AsyncMock(side_effect=fake_run)
+
+        status = SubagentStatus(
+            task_id="sub-4", label="label", task_description="task",
+            started_at=time.monotonic(),
+        )
+        await mgr._run_subagent(
+            "sub-4", "task", "label",
+            {"channel": "telegram", "chat_id": "444", "session_key": "unified:default"},
+            status,
+        )
+
+        msg = await bus.consume_inbound()
+        assert msg.session_key_override == "unified:default"