fix(heartbeat): inject delivered messages into channel session for reply continuity

When heartbeat delivers output to a channel (e.g. Telegram), the message
is a raw OutboundMessage that bypasses the channel's session. If the user
replies, their reply enters a different session with no context about the
heartbeat message, so the agent cannot follow through.

This change injects the delivered heartbeat message as an assistant turn
into the target channel's session before publishing the outbound. When
the user replies, the channel session has conversational context.

Handles unified_session mode by resolving to UNIFIED_SESSION_KEY when
enabled, matching the agent loop's own session routing.

No changes to agent/loop.py, session/manager.py, channels, providers,
or config schema — uses existing add_message() and save() APIs.

nanobot/cli/commands.py

@@ -812,11 +812,31 @@ def _run_gateway(
         return resp.content if resp else ""
 
     async def on_heartbeat_notify(response: str) -> None:
-        """Deliver a heartbeat response to the user's channel."""
+        """Deliver a heartbeat response to the user's channel.
+
+        In addition to publishing the outbound message, this injects the
+        delivered text as an assistant turn into the *target channel's*
+        session.  Without this, a user reply on the channel (e.g. "Sure")
+        lands in a session that has no context about the heartbeat message
+        and the agent cannot follow through.
+        """
         from nanobot.bus.events import OutboundMessage
         channel, chat_id = _pick_heartbeat_target()
         if channel == "cli":
             return  # No external channel available to deliver to
+
+        # Inject the delivered message into the channel session so that
+        # user replies have conversational context.
+        from nanobot.agent.loop import UNIFIED_SESSION_KEY
+        target_key = (
+            UNIFIED_SESSION_KEY
+            if config.agents.defaults.unified_session
+            else f"{channel}:{chat_id}"
+        )
+        target_session = agent.sessions.get_or_create(target_key)
+        target_session.add_message("assistant", response)
+        agent.sessions.save(target_session)
+
         await bus.publish_outbound(OutboundMessage(channel=channel, chat_id=chat_id, content=response))
 
     hb_cfg = config.gateway.heartbeat

tests/heartbeat/test_heartbeat_context_bridge.py

@@ -0,0 +1,102 @@
+"""Tests for heartbeat context bridge — injecting delivered messages into channel session."""
+
+from nanobot.session.manager import SessionManager
+
+
+class TestHeartbeatContextBridge:
+    """Verify that on_heartbeat_notify injects the assistant message into the
+    channel session so user replies have conversational context."""
+
+    def test_notify_injects_into_channel_session(self, tmp_path):
+        """After notify, the target channel session should contain the
+        heartbeat response as an assistant turn."""
+        session_mgr = SessionManager(tmp_path / "sessions")
+        target_key = "telegram:12345"
+
+        # Simulate: session exists with one user message
+        target_session = session_mgr.get_or_create(target_key)
+        target_session.add_message("user", "hello earlier")
+        session_mgr.save(target_session)
+
+        # Simulate what on_heartbeat_notify does
+        target_session = session_mgr.get_or_create(target_key)
+        target_session.add_message("assistant", "3 new emails — invoice, meeting, proposal.")
+        session_mgr.save(target_session)
+
+        # Reload and verify
+        reloaded = session_mgr.get_or_create(target_key)
+        messages = reloaded.get_history(max_messages=0)
+        roles = [m["role"] for m in messages]
+        assert roles == ["user", "assistant"]
+        assert "3 new emails" in messages[-1]["content"]
+
+    def test_reply_after_injection_has_context(self, tmp_path):
+        """Simulates the full flow: prior conversation exists, heartbeat
+        injects, then user replies.  The session should have the heartbeat
+        message visible in get_history so the model sees the context."""
+        session_mgr = SessionManager(tmp_path / "sessions")
+        target_key = "telegram:12345"
+
+        # Pre-existing conversation (user has chatted before)
+        session = session_mgr.get_or_create(target_key)
+        session.add_message("user", "Hey")
+        session.add_message("assistant", "Hi there!")
+        session_mgr.save(session)
+
+        # Step 1: heartbeat injects assistant message
+        session = session_mgr.get_or_create(target_key)
+        session.add_message("assistant", "If you want, I can mark that email as read.")
+        session_mgr.save(session)
+
+        # Step 2: user replies "Sure"
+        session = session_mgr.get_or_create(target_key)
+        session.add_message("user", "Sure")
+        session_mgr.save(session)
+
+        # Verify: get_history includes the heartbeat injection
+        reloaded = session_mgr.get_or_create(target_key)
+        history = reloaded.get_history(max_messages=0)
+        roles = [m["role"] for m in history]
+        assert roles == ["user", "assistant", "assistant", "user"]
+        assert "mark that email" in history[2]["content"]
+        assert history[3]["content"] == "Sure"
+
+    def test_injection_does_not_duplicate_on_existing_history(self, tmp_path):
+        """If the channel session already has messages, the injection
+        appends cleanly without corruption."""
+        session_mgr = SessionManager(tmp_path / "sessions")
+        target_key = "telegram:12345"
+
+        # Pre-existing conversation
+        session = session_mgr.get_or_create(target_key)
+        session.add_message("user", "What time is it?")
+        session.add_message("assistant", "It's 2pm.")
+        session.add_message("user", "Thanks")
+        session_mgr.save(session)
+
+        # Heartbeat injects
+        session = session_mgr.get_or_create(target_key)
+        session.add_message("assistant", "You have a meeting in 30 minutes.")
+        session_mgr.save(session)
+
+        # Verify
+        reloaded = session_mgr.get_or_create(target_key)
+        history = reloaded.get_history(max_messages=0)
+        roles = [m["role"] for m in history]
+        assert roles == ["user", "assistant", "user", "assistant"]
+        assert "meeting in 30 minutes" in history[-1]["content"]
+
+    def test_injection_to_empty_session(self, tmp_path):
+        """Injecting into a brand-new session (no prior messages) works."""
+        session_mgr = SessionManager(tmp_path / "sessions")
+        target_key = "telegram:99999"
+
+        session = session_mgr.get_or_create(target_key)
+        session.add_message("assistant", "Weather alert: sandstorm expected at 4pm.")
+        session_mgr.save(session)
+
+        reloaded = session_mgr.get_or_create(target_key)
+        history = reloaded.get_history(max_messages=0)
+        assert len(history) == 1
+        assert history[0]["role"] == "assistant"
+        assert "sandstorm" in history[0]["content"]