fix(steering): skip phantom zero-turn result on --resume; guard empty replies

On --resume, a background task stopped by the previous restart is replayed
as its own zero-turn turn with an empty result, before the real turn.
consume_stream took it as the answer -> empty Discord message (400) ->
"Sorry, something went wrong", while the real turn ran orphaned.

- stream_json: skip result with num_turns=0, empty, non-error
- router: empty Claude response becomes a visible notice, not an adapter crash

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014y1sJNe6mkWwFMwkWmCg8J

src/router.py

@@ -616,6 +616,11 @@ def route_message(
             # Same pattern as the existing __AUDIO__: sentinel — no
             # _set_last_response, the adapter reacts instead of replying.
             return response, False
+        if not (response or "").strip():
+            # Adapters can't send an empty message (Discord 400 → generic
+            # "something went wrong"); say so instead of failing opaquely.
+            log.warning("channel=%s: Claude returned an empty response", channel_id)
+            return "⚠️ Claude a terminat turul fără niciun răspuns text. Mai trimite o dată mesajul.", False
         _set_last_response(channel_id, response)
         return response, False
     except Exception as e:

src/stream_json.py

@@ -102,6 +102,14 @@ def consume_stream(
                     logger.exception("on_init callback error")
 
         elif msg_type == "result":
+            # On --resume, a leftover background-task notification is
+            # replayed as its own zero-turn "turn" with an empty result,
+            # BEFORE the real one. Taking it as the answer returned "" (Discord
+            # 400 "Cannot send an empty message") and orphaned the real turn.
+            if (event.get("num_turns") == 0 and not event.get("is_error")
+                    and not event.get("result") and not text_blocks):
+                logger.info("skipping zero-turn result (task notification replay)")
+                continue
             result_obj = event
             break  # never read past the turn boundary
 
@@ -146,6 +154,16 @@ def demo() -> None:
     # Blank/garbage lines are skipped, not fatal.
     assert consume_stream(["", "not json", json.dumps({"type": "result", "result": "ok"})])["result"] == "ok"
 
+    # --resume replays a stopped background task as a zero-turn empty result
+    # before the real turn — skip it, return the real one.
+    phantom = [
+        json.dumps({"type": "system", "subtype": "task_notification", "status": "stopped"}),
+        json.dumps({"type": "result", "result": "", "num_turns": 0, "is_error": False}),
+        json.dumps({"type": "assistant", "message": {"content": [{"type": "text", "text": "PONG"}]}}),
+        json.dumps({"type": "result", "result": "PONG", "num_turns": 1, "is_error": False}),
+    ]
+    assert consume_stream(phantom)["result"] == "PONG"
+
     print("stream_json self-check OK")
 
 

tests/test_claude_runner.py

@@ -349,3 +349,8 @@ def test_max_live_non_positive_logs_and_always_degrades(caplog):
         registry = claude_runner.RunnerRegistry(max_live=0, idle_minutes=20)
     assert any("max_live" in rec.message for rec in caplog.records)
     assert registry.get("any-channel") is None
+
+
+def test_stream_json_self_check_skips_phantom_resume_result():
+    from src import stream_json
+    stream_json.demo()

tests/test_router.py

@@ -195,6 +195,13 @@ class TestRegularMessage:
         assert is_cmd is False
         mock_send.assert_called_once_with("ch-1", "hello", model="sonnet", on_text=None, voice_mode=False, adapter_name=None)
 
+    @patch("src.router._get_channel_config", return_value=None)
+    @patch("src.router.send_message", return_value="  ")
+    def test_empty_response_becomes_notice(self, mock_send, _chan):
+        response, is_cmd = route_message("ch-1", "user-1", "hello", model="sonnet")
+        assert response.strip()
+        assert is_cmd is False
+
     @patch("src.router.send_message")
     def test_model_override(self, mock_send):
         mock_send.return_value = "Response"