feat: add prompt opening behavior modes

backend/tests/test_pipeline_events.py

@@ -52,6 +52,7 @@ class _Brain:
         self.prepared_greeting = ""
         self.greeting_pending = False
         self.greeting_finished = 0
+        self.interruptions_processed = 0
 
     def prepare_greeting_context(self, greeting, _context):
         self.prepared_greeting = greeting
@@ -62,6 +63,9 @@ class _Brain:
     async def on_greeting_finished(self):
         self.greeting_finished += 1
 
+    async def on_interruption_processed(self):
+        self.interruptions_processed += 1
+
     async def on_client_ready(self):
         for content, timestamp in (
             ("Message 节点播报", "2026-07-14T10:00:00.200+00:00"),
@@ -111,6 +115,7 @@ class PipelineEventTest(unittest.IsolatedAsyncioTestCase):
         )
 
         self.assertEqual(acknowledgements, [True])
+        self.assertEqual(brain.interruptions_processed, 1)
 
     async def test_greeting_keeps_playback_timestamp_until_client_ready(self):
         transport = _EventSource()