fix: suppress duplicate completion notifications when agent already consumed output via wait/poll/log (#8228)

When the agent calls process(action='wait') or process(action='poll')
and gets the exited status, the completion_queue notification is
redundant — the agent already has the output from the tool return.
Previously, the drain loops in CLI and gateway would still inject
the [SYSTEM: Background process completed] message, causing the
agent to receive the same information twice.

Fix: track session IDs in _completion_consumed set when wait/poll/log
returns an exited process. Drain loops in cli.py and gateway watcher
skip completion events for consumed sessions. Watch pattern events
are never suppressed (they have independent semantics).

Adds 4 tests covering wait/poll/log marking and running-process
negative case.

cli.py

@@ -9385,9 +9385,14 @@ class HermesCLI:
                                 from tools.process_registry import process_registry
                                 if not process_registry.completion_queue.empty():
                                     evt = process_registry.completion_queue.get_nowait()
-                                    _synth = _format_process_notification(evt)
-                                    if _synth:
-                                        self._pending_input.put(_synth)
+                                    # Skip if the agent already consumed this via wait/poll/log
+                                    _evt_sid = evt.get("session_id", "")
+                                    if evt.get("type") == "completion" and process_registry.is_completion_consumed(_evt_sid):
+                                        pass  # already delivered via tool result
+                                    else:
+                                        _synth = _format_process_notification(evt)
+                                        if _synth:
+                                            self._pending_input.put(_synth)
                             except Exception:
                                 pass
                         continue
@@ -9513,6 +9518,10 @@ class HermesCLI:
                             from tools.process_registry import process_registry
                             while not process_registry.completion_queue.empty():
                                 evt = process_registry.completion_queue.get_nowait()
+                                # Skip if the agent already consumed this via wait/poll/log
+                                _evt_sid = evt.get("session_id", "")
+                                if evt.get("type") == "completion" and process_registry.is_completion_consumed(_evt_sid):
+                                    continue  # already delivered via tool result
                                 _synth = _format_process_notification(evt)
                                 if _synth:
                                     self._pending_input.put(_synth)

gateway/run.py

@@ -7009,7 +7009,9 @@ class GatewayRunner:
 
             if session.exited:
                 # --- Agent-triggered completion: inject synthetic message ---
-                if agent_notify:
+                # Skip if the agent already consumed the result via wait/poll/log
+                from tools.process_registry import process_registry as _pr_check
+                if agent_notify and not _pr_check.is_completion_consumed(session_id):
                     from tools.ansi_strip import strip_ansi
                     _out = strip_ansi(session.output_buffer[-2000:]) if session.output_buffer else ""
                     synth_text = (

tests/gateway/test_internal_event_bypass_pairing.py

@@ -28,12 +28,16 @@ class _FakeRegistry:
 
     def __init__(self, sessions):
         self._sessions = list(sessions)
+        self._completion_consumed: set = set()
 
     def get(self, session_id):
         if self._sessions:
             return self._sessions.pop(0)
         return None
 
+    def is_completion_consumed(self, session_id):
+        return session_id in self._completion_consumed
+
 
 def _build_runner(monkeypatch, tmp_path) -> GatewayRunner:
     """Create a GatewayRunner with notifications set to 'all'."""

tests/tools/test_notify_on_complete.py

@@ -289,3 +289,62 @@ class TestCodeExecutionBlocked:
     def test_notify_on_complete_blocked_in_sandbox(self):
         from tools.code_execution_tool import _TERMINAL_BLOCKED_PARAMS
         assert "notify_on_complete" in _TERMINAL_BLOCKED_PARAMS
+
+
+# =========================================================================
+# Completion consumed suppression
+# =========================================================================
+
+class TestCompletionConsumed:
+    """Test that wait/poll/log suppress redundant completion notifications."""
+
+    def test_wait_marks_completion_consumed(self, registry):
+        """wait() returning exited status marks session as consumed."""
+        s = _make_session(sid="proc_wait", notify_on_complete=True, output="done")
+        s.exited = True
+        s.exit_code = 0
+        registry._running[s.id] = s
+        with patch.object(registry, "_write_checkpoint"):
+            registry._move_to_finished(s)
+
+        # Notification is in the queue
+        assert not registry.completion_queue.empty()
+        assert not registry.is_completion_consumed("proc_wait")
+
+        # Agent calls wait() — gets the result directly
+        result = registry.wait("proc_wait", timeout=1)
+        assert result["status"] == "exited"
+
+        # Now the completion is marked as consumed
+        assert registry.is_completion_consumed("proc_wait")
+
+    def test_poll_marks_completion_consumed(self, registry):
+        """poll() returning exited status marks session as consumed."""
+        s = _make_session(sid="proc_poll", notify_on_complete=True, output="done")
+        s.exited = True
+        s.exit_code = 0
+        registry._finished[s.id] = s
+
+        result = registry.poll("proc_poll")
+        assert result["status"] == "exited"
+        assert registry.is_completion_consumed("proc_poll")
+
+    def test_log_marks_completion_consumed(self, registry):
+        """read_log() on exited session marks as consumed."""
+        s = _make_session(sid="proc_log", notify_on_complete=True, output="line1\nline2")
+        s.exited = True
+        s.exit_code = 0
+        registry._finished[s.id] = s
+
+        result = registry.read_log("proc_log")
+        assert result["status"] == "exited"
+        assert registry.is_completion_consumed("proc_log")
+
+    def test_running_process_not_consumed(self, registry):
+        """poll() on a still-running process does not mark as consumed."""
+        s = _make_session(sid="proc_running", notify_on_complete=True, output="partial")
+        registry._running[s.id] = s
+
+        result = registry.poll("proc_running")
+        assert result["status"] == "running"
+        assert not registry.is_completion_consumed("proc_running")

tools/process_registry.py

@@ -136,6 +136,10 @@ class ProcessRegistry:
         import queue as _queue_mod
         self.completion_queue: _queue_mod.Queue = _queue_mod.Queue()
 
+        # Track sessions whose completion was already consumed by the agent
+        # via wait/poll/log.  Drain loops skip notifications for these.
+        self._completion_consumed: set = set()
+
     @staticmethod
     def _clean_shell_noise(text: str) -> str:
         """Strip shell startup warnings from the beginning of output."""
@@ -613,6 +617,10 @@ class ProcessRegistry:
 
     # ----- Query Methods -----
 
+    def is_completion_consumed(self, session_id: str) -> bool:
+        """Check if a completion notification was already consumed via wait/poll/log."""
+        return session_id in self._completion_consumed
+
     def get(self, session_id: str) -> Optional[ProcessSession]:
         """Get a session by ID (running or finished)."""
         with self._lock:
@@ -640,6 +648,7 @@ class ProcessRegistry:
         }
         if session.exited:
             result["exit_code"] = session.exit_code
+            self._completion_consumed.add(session_id)
         if session.detached:
             result["detached"] = True
             result["note"] = "Process recovered after restart -- output history unavailable"
@@ -665,13 +674,16 @@ class ProcessRegistry:
         else:
             selected = lines[offset:offset + limit]
 
-        return {
+        result = {
             "session_id": session.id,
             "status": "exited" if session.exited else "running",
             "output": "\n".join(selected),
             "total_lines": total_lines,
             "showing": f"{len(selected)} lines",
         }
+        if session.exited:
+            self._completion_consumed.add(session_id)
+        return result
 
     def wait(self, session_id: str, timeout: int = None) -> dict:
         """
@@ -714,6 +726,7 @@ class ProcessRegistry:
         while time.monotonic() < deadline:
             session = self._refresh_detached_session(session)
             if session.exited:
+                self._completion_consumed.add(session_id)
                 result = {
                     "status": "exited",
                     "exit_code": session.exit_code,