diff --git a/gateway/run.py b/gateway/run.py
index 2eb745f92b..670ec4c869 100644
--- a/gateway/run.py
+++ b/gateway/run.py
@@ -3958,7 +3958,7 @@ class GatewayRunner:
                     synth_text = _format_gateway_process_notification(evt)
                     if synth_text:
                         try:
-                            await self._inject_watch_notification(synth_text, event)
+                            await self._inject_watch_notification(synth_text, evt)
                         except Exception as e2:
                             logger.error("Watch notification injection error: %s", e2)
             except Exception as e:
@@ -7452,14 +7452,75 @@ class GatewayRunner:
             return prefix
         return user_text
 
-    async def _inject_watch_notification(self, synth_text: str, original_event) -> None:
+    def _build_process_event_source(self, evt: dict):
+        """Resolve the canonical source for a synthetic background-process event.
+
+        Prefer the persisted session-store origin for the event's session key.
+        Falling back to the currently active foreground event is what causes
+        cross-topic bleed, so don't do that.
+        """
+        from gateway.session import SessionSource
+
+        session_key = str(evt.get("session_key") or "").strip()
+        derived_platform = ""
+        derived_chat_type = ""
+        derived_chat_id = ""
+
+        if session_key:
+            try:
+                self.session_store._ensure_loaded()
+                entry = self.session_store._entries.get(session_key)
+                if entry and getattr(entry, "origin", None):
+                    return entry.origin
+            except Exception as exc:
+                logger.debug(
+                    "Synthetic process-event session-store lookup failed for %s: %s",
+                    session_key,
+                    exc,
+                )
+
+            parts = session_key.split(":")
+            if len(parts) >= 5 and parts[0] == "agent" and parts[1] == "main":
+                derived_platform = parts[2]
+                derived_chat_type = parts[3]
+                derived_chat_id = parts[4]
+
+        platform_name = str(evt.get("platform") or derived_platform or "").strip().lower()
+        chat_type = str(evt.get("chat_type") or derived_chat_type or "").strip().lower()
+        chat_id = str(evt.get("chat_id") or derived_chat_id or "").strip()
+        if not platform_name or not chat_type or not chat_id:
+            return None
+
+        try:
+            platform = Platform(platform_name)
+        except Exception:
+            logger.warning(
+                "Synthetic process event has invalid platform metadata: %r",
+                platform_name,
+            )
+            return None
+
+        return SessionSource(
+            platform=platform,
+            chat_id=chat_id,
+            chat_type=chat_type,
+            thread_id=str(evt.get("thread_id") or "").strip() or None,
+            user_id=str(evt.get("user_id") or "").strip() or None,
+            user_name=str(evt.get("user_name") or "").strip() or None,
+        )
+
+    async def _inject_watch_notification(self, synth_text: str, evt: dict) -> None:
         """Inject a watch-pattern notification as a synthetic message event.
 
-        Uses the source from the original user event to route the notification
-        back to the correct chat/adapter.
+        Routing must come from the queued watch event itself, not from whatever
+        foreground message happened to be active when the queue was drained.
         """
-        source = getattr(original_event, "source", None)
+        source = self._build_process_event_source(evt)
         if not source:
+            logger.warning(
+                "Dropping watch notification with no routing metadata for process %s",
+                evt.get("session_id", "unknown"),
+            )
             return
         platform_name = source.platform.value if hasattr(source.platform, "value") else str(source.platform)
         adapter = None
@@ -7477,7 +7538,12 @@ class GatewayRunner:
                 source=source,
                 internal=True,
             )
-            logger.info("Watch pattern notification — injecting for %s", platform_name)
+            logger.info(
+                "Watch pattern notification — injecting for %s chat=%s thread=%s",
+                platform_name,
+                source.chat_id,
+                source.thread_id,
+            )
             await adapter.handle_message(synth_event)
         except Exception as e:
             logger.error("Watch notification injection error: %s", e)
@@ -7547,33 +7613,42 @@ class GatewayRunner:
                         f"Command: {session.command}\n"
                         f"Output:\n{_out}]"
                     )
+                    source = self._build_process_event_source({
+                        "session_id": session_id,
+                        "session_key": session_key,
+                        "platform": platform_name,
+                        "chat_id": chat_id,
+                        "thread_id": thread_id,
+                        "user_id": user_id,
+                        "user_name": user_name,
+                    })
+                    if not source:
+                        logger.warning(
+                            "Dropping completion notification with no routing metadata for process %s",
+                            session_id,
+                        )
+                        break
+
                     adapter = None
                     for p, a in self.adapters.items():
-                        if p.value == platform_name:
+                        if p == source.platform:
                             adapter = a
                             break
-                    if adapter and chat_id:
+                    if adapter and source.chat_id:
                         try:
                             from gateway.platforms.base import MessageEvent, MessageType
-                            from gateway.session import SessionSource
-                            from gateway.config import Platform
-                            _platform_enum = Platform(platform_name)
-                            _source = SessionSource(
-                                platform=_platform_enum,
-                                chat_id=chat_id,
-                                thread_id=thread_id or None,
-                                user_id=user_id or None,
-                                user_name=user_name or None,
-                            )
                             synth_event = MessageEvent(
                                 text=synth_text,
                                 message_type=MessageType.TEXT,
-                                source=_source,
+                                source=source,
                                 internal=True,
                             )
                             logger.info(
-                                "Process %s finished — injecting agent notification for session %s",
-                                session_id, session_key,
+                                "Process %s finished — injecting agent notification for session %s chat=%s thread=%s",
+                                session_id,
+                                session_key,
+                                source.chat_id,
+                                source.thread_id,
                             )
                             await adapter.handle_message(synth_event)
                         except Exception as e:
diff --git a/tests/gateway/test_background_process_notifications.py b/tests/gateway/test_background_process_notifications.py
index 9c1404f89c..90e9e063a1 100644
--- a/tests/gateway/test_background_process_notifications.py
+++ b/tests/gateway/test_background_process_notifications.py
@@ -45,7 +45,7 @@ def _build_runner(monkeypatch, tmp_path, mode: str) -> GatewayRunner:
     monkeypatch.setattr(gateway_run, "_hermes_home", tmp_path)
 
     runner = GatewayRunner(GatewayConfig())
-    adapter = SimpleNamespace(send=AsyncMock())
+    adapter = SimpleNamespace(send=AsyncMock(), handle_message=AsyncMock())
     runner.adapters[Platform.TELEGRAM] = adapter
     return runner
 
@@ -243,3 +243,62 @@ async def test_no_thread_id_sends_no_metadata(monkeypatch, tmp_path):
     assert adapter.send.await_count == 1
     _, kwargs = adapter.send.call_args
     assert kwargs["metadata"] is None
+
+
+@pytest.mark.asyncio
+async def test_inject_watch_notification_routes_from_session_store_origin(monkeypatch, tmp_path):
+    from gateway.session import SessionSource
+
+    runner = _build_runner(monkeypatch, tmp_path, "all")
+    adapter = runner.adapters[Platform.TELEGRAM]
+    runner.session_store._entries["agent:main:telegram:group:-100:42"] = SimpleNamespace(
+        origin=SessionSource(
+            platform=Platform.TELEGRAM,
+            chat_id="-100",
+            chat_type="group",
+            thread_id="42",
+            user_id="123",
+            user_name="Emiliyan",
+        )
+    )
+
+    evt = {
+        "session_id": "proc_watch",
+        "session_key": "agent:main:telegram:group:-100:42",
+    }
+
+    await runner._inject_watch_notification("[SYSTEM: Background process matched]", evt)
+
+    adapter.handle_message.assert_awaited_once()
+    synth_event = adapter.handle_message.await_args.args[0]
+    assert synth_event.internal is True
+    assert synth_event.source.platform == Platform.TELEGRAM
+    assert synth_event.source.chat_id == "-100"
+    assert synth_event.source.chat_type == "group"
+    assert synth_event.source.thread_id == "42"
+    assert synth_event.source.user_id == "123"
+    assert synth_event.source.user_name == "Emiliyan"
+
+
+def test_build_process_event_source_falls_back_to_session_key_chat_type(monkeypatch, tmp_path):
+    runner = _build_runner(monkeypatch, tmp_path, "all")
+
+    evt = {
+        "session_id": "proc_watch",
+        "session_key": "agent:main:telegram:group:-100:42",
+        "platform": "telegram",
+        "chat_id": "-100",
+        "thread_id": "42",
+        "user_id": "123",
+        "user_name": "Emiliyan",
+    }
+
+    source = runner._build_process_event_source(evt)
+
+    assert source is not None
+    assert source.platform == Platform.TELEGRAM
+    assert source.chat_id == "-100"
+    assert source.chat_type == "group"
+    assert source.thread_id == "42"
+    assert source.user_id == "123"
+    assert source.user_name == "Emiliyan"
diff --git a/tests/gateway/test_internal_event_bypass_pairing.py b/tests/gateway/test_internal_event_bypass_pairing.py
index 1c3f9f0c94..d10195b2d5 100644
--- a/tests/gateway/test_internal_event_bypass_pairing.py
+++ b/tests/gateway/test_internal_event_bypass_pairing.py
@@ -230,6 +230,59 @@ async def test_notify_on_complete_preserves_user_identity(monkeypatch, tmp_path)
     assert event.source.user_name == "alice"
 
 
+@pytest.mark.asyncio
+async def test_notify_on_complete_uses_session_store_origin_for_group_topic(monkeypatch, tmp_path):
+    import tools.process_registry as pr_module
+    from gateway.session import SessionSource
+
+    sessions = [
+        SimpleNamespace(
+            output_buffer="done\n", exited=True, exit_code=0, command="echo test"
+        ),
+    ]
+    monkeypatch.setattr(pr_module, "process_registry", _FakeRegistry(sessions))
+
+    async def _instant_sleep(*_a, **_kw):
+        pass
+    monkeypatch.setattr(asyncio, "sleep", _instant_sleep)
+
+    runner = GatewayRunner(GatewayConfig())
+    adapter = SimpleNamespace(send=AsyncMock(), handle_message=AsyncMock())
+    runner.adapters[Platform.TELEGRAM] = adapter
+    runner.session_store._entries["agent:main:telegram:group:-100:42"] = SimpleNamespace(
+        origin=SessionSource(
+            platform=Platform.TELEGRAM,
+            chat_id="-100",
+            chat_type="group",
+            thread_id="42",
+            user_id="user-42",
+            user_name="alice",
+        )
+    )
+
+    watcher = {
+        "session_id": "proc_test_internal",
+        "check_interval": 0,
+        "session_key": "agent:main:telegram:group:-100:42",
+        "platform": "telegram",
+        "chat_id": "-100",
+        "thread_id": "42",
+        "notify_on_complete": True,
+    }
+
+    await runner._run_process_watcher(watcher)
+
+    assert adapter.handle_message.await_count == 1
+    event = adapter.handle_message.await_args.args[0]
+    assert event.internal is True
+    assert event.source.platform == Platform.TELEGRAM
+    assert event.source.chat_id == "-100"
+    assert event.source.chat_type == "group"
+    assert event.source.thread_id == "42"
+    assert event.source.user_id == "user-42"
+    assert event.source.user_name == "alice"
+
+
 @pytest.mark.asyncio
 async def test_none_user_id_skips_pairing(monkeypatch, tmp_path):
     """A non-internal event with user_id=None should be silently dropped."""
diff --git a/tests/tools/test_watch_patterns.py b/tests/tools/test_watch_patterns.py
index e31844f9f6..0621edc14d 100644
--- a/tests/tools/test_watch_patterns.py
+++ b/tests/tools/test_watch_patterns.py
@@ -92,6 +92,25 @@ class TestCheckWatchPatterns:
         assert "disk full" in evt["output"]
         assert evt["session_id"] == "proc_test_watch"
 
+    def test_match_carries_session_key_and_watcher_routing_metadata(self, registry):
+        session = _make_session(watch_patterns=["ERROR"])
+        session.session_key = "agent:main:telegram:group:-100:42"
+        session.watcher_platform = "telegram"
+        session.watcher_chat_id = "-100"
+        session.watcher_user_id = "u123"
+        session.watcher_user_name = "alice"
+        session.watcher_thread_id = "42"
+
+        registry._check_watch_patterns(session, "ERROR: disk full\n")
+        evt = registry.completion_queue.get_nowait()
+
+        assert evt["session_key"] == "agent:main:telegram:group:-100:42"
+        assert evt["platform"] == "telegram"
+        assert evt["chat_id"] == "-100"
+        assert evt["user_id"] == "u123"
+        assert evt["user_name"] == "alice"
+        assert evt["thread_id"] == "42"
+
     def test_multiple_patterns(self, registry):
         """First matching pattern is reported."""
         session = _make_session(watch_patterns=["WARN", "ERROR"])
diff --git a/tools/process_registry.py b/tools/process_registry.py
index a5dbc3b1bd..3a274eaa3d 100644
--- a/tools/process_registry.py
+++ b/tools/process_registry.py
@@ -191,9 +191,15 @@ class ProcessRegistry:
                     session._watch_disabled = True
                     self.completion_queue.put({
                         "session_id": session.id,
+                        "session_key": session.session_key,
                         "command": session.command,
                         "type": "watch_disabled",
                         "suppressed": session._watch_suppressed,
+                        "platform": session.watcher_platform,
+                        "chat_id": session.watcher_chat_id,
+                        "user_id": session.watcher_user_id,
+                        "user_name": session.watcher_user_name,
+                        "thread_id": session.watcher_thread_id,
                         "message": (
                             f"Watch patterns disabled for process {session.id} — "
                             f"too many matches ({session._watch_suppressed} suppressed). "
@@ -219,11 +225,17 @@ class ProcessRegistry:
 
         self.completion_queue.put({
             "session_id": session.id,
+            "session_key": session.session_key,
             "command": session.command,
             "type": "watch_match",
             "pattern": matched_pattern,
             "output": output,
             "suppressed": suppressed,
+            "platform": session.watcher_platform,
+            "chat_id": session.watcher_chat_id,
+            "user_id": session.watcher_user_id,
+            "user_name": session.watcher_user_name,
+            "thread_id": session.watcher_thread_id,
         })
 
     @staticmethod