fix(companion): Cancel pending restart when stopping a companion

A stop issued while a restart was in flight (state STOPPING,
restart_pending set) was ignored: handle_exit checked restart_pending
first and respawned the companion the user had just stopped. Clear
restart_pending in stop_process so manual stop wins.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

gunicorn/companion/manager.py

@@ -419,6 +419,9 @@ class CompanionManager:
         if process is None:
             return False, "unknown companion %s" % name
         process.manual_stop = True
+        # A stop must win over an in-flight restart: clearing this keeps
+        # handle_exit from respawning a companion the user asked to stop.
+        process.restart_pending = False
         if process.state in (State.STOPPED, State.STOPPING):
             return True, "%s already %s" % (name, process.state.lower())
         if process.state == State.BACKOFF:

tests/test_companion_manager.py

@@ -420,6 +420,23 @@ def test_stop_process_unknown():
     assert not ok
 
 
+def test_stop_during_restart_cancels_pending_restart():
+    manager = make_manager("rq")
+    proc = manager.processes["rq"]
+    proc.state = State.STOPPING
+    proc.pid = 70
+    proc.restart_pending = True
+    with mock.patch("os.kill") as kill:
+        ok, _ = manager.stop_process("rq")
+    kill.assert_not_called()
+    assert ok and proc.manual_stop is True and proc.restart_pending is False
+    # On exit the companion now settles STOPPED instead of being respawned.
+    with mock.patch.object(manager, "spawn_process") as spawn:
+        manager.handle_exit(proc)
+    spawn.assert_not_called()
+    assert proc.state == State.STOPPED
+
+
 def test_signal_number_resolves_name():
     assert CompanionManager._signal_number("SIGKILL") == signal.SIGKILL
     assert CompanionManager._signal_number(9) == 9