test: the on-demand routes' other callers ack over the socket, not the mailbox

test_api_v3_bool_coercion, test_api_v3_lazy_plugin_discovery and
test_web_api's stop test checked the mailbox write; they now get an ack
from a mocked control socket. The stop route touches no manager any more,
so it leaves the removed-catch-all sample. A request that was sent is
never 'not listening' (pins the sent check the mutation run let through).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/test_api_v3_bool_coercion.py

@@ -54,7 +54,10 @@ class TestOnDemandStart:
     def service(self, api_v3_module):
         api_v3_module.api_v3.plugin_catalog = None
         api_v3_module.api_v3.config_manager = None
-        with patch("web_interface.blueprints.api_v3.display._get_display_service_status",
+        # The display answers the control socket (the only way in).
+        with patch("web_interface.blueprints.api_v3.display.control_client.on_demand_start",
+                   side_effect=lambda request_id, *a: {"accepted": True}), \
+             patch("web_interface.blueprints.api_v3.display._get_display_service_status",
                    return_value={"active": True}), \
              patch("web_interface.blueprints.api_v3.display._stop_display_service") as stop, \
              patch("web_interface.blueprints.api_v3.display._ensure_display_service_running",

test/test_api_v3_lazy_plugin_discovery.py

@@ -77,11 +77,22 @@ def fresh_web_process(api_v3_module, plugins_dir):
 
 @pytest.fixture
 def display_service(api_v3_module):
-    """Keep on-demand start away from systemctl and the real cache."""
+    """Keep on-demand start away from systemctl and the real cache; the
-    cache = api_v3_module.api_v3.cache_manager = MagicMock()
+    display's control socket is a mock that acks. What it was sent is
-    with patch('web_interface.blueprints.api_v3.display._get_display_service_status') as status:
+    recorded as ``.set(cmd, request)`` calls on the yielded mock."""
+    api_v3_module.api_v3.cache_manager = MagicMock()
+    sent = MagicMock()
+
+    def ack(request_id, plugin_id, mode, *a, **kw):
+        sent.set('on_demand.start', {'request_id': request_id,
+                                     'plugin_id': plugin_id, 'mode': mode})
+        return {'accepted': True}
+
+    with patch('web_interface.blueprints.api_v3.display._get_display_service_status') as status, \
+         patch('web_interface.blueprints.api_v3.display.control_client.on_demand_start',
+               side_effect=ack):
         status.return_value = {'active': True}
-        yield cache
+        yield sent
 
 
 def _start(client, **body):

test/test_ipc_stage4.py

@@ -144,6 +144,12 @@ class TestSent:
     def test_a_client_without_the_socket_is_not_waiting_for_a_display(self, reason):
         assert not client.display_not_listening(client.ControlError(reason))
 
+    @pytest.mark.parametrize('reason', sorted(client.NOT_LISTENING_REASONS))
+    def test_a_request_that_was_sent_had_a_display(self, reason):
+        # Only a request that never left can be waited on and sent again: one
+        # that was sent may have been applied.
+        assert not client.display_not_listening(client.ControlError(reason, sent=True))
+
     def test_a_client_bug_is_not_a_missing_display(self):
         assert not client.display_not_listening(RuntimeError('boom'))
 

test/test_web_api.py

@@ -529,13 +529,16 @@ class TestDisplayAPI:
 
         mock_cache_manager = api_v3.cache_manager = MagicMock()
 
+        with patch('web_interface.blueprints.api_v3.display.control_client.on_demand_stop',
+                   side_effect=lambda request_id, **kw: {'accepted': True}) as stop:
             response = client.post('/api/v3/display/on-demand/stop')
 
-        # May return 200 if successful or 500 on error
+        assert response.status_code == 200
-        assert response.status_code in [200, 500]
+        assert response.get_json()['data']['transport'] == 'socket'
-        # Verify stop request was set in cache if successful
+        stop.assert_called_once()
-        if response.status_code == 200:
+        # The request goes over the control socket; nothing is written to
-            assert mock_cache_manager.set.called
+        # the cache (the file mailbox is gone).
+        mock_cache_manager.set.assert_not_called()
 
 
 class TestPluginsAPI:

test/web_interface/test_api_v3_unhandled_errors.py

@@ -81,7 +81,6 @@ REMOVED_CATCH_ALLS = [
     ("GET", "/api/v3/config/main", None),
     ("GET", "/api/v3/config/secrets", None),
     ("GET", "/api/v3/display/modes", None),
-    ("POST", "/api/v3/display/on-demand/stop", {}),
     ("GET", "/api/v3/cache/list", None),
     ("GET", "/api/v3/plugins/installed", None),
     ("GET", "/api/v3/plugins/health", None),