fix(web): close Heid pass-2 findings — stream vocab + disconnect catch (v0.16.1)

Second Heid panel pass (thread 01KSPBMFRRQE) on the v0.16.0 tree:
Gróa returned zero findings; Hulda surfaced two minor tightening
items, both closed here.

1. test-gap — TestStreamFullEventVocab drove only 8 of 11 Event types
   through the stream endpoint (omitted Error, Cancelled, AffectUpdate).
   Serialization for all 11 was already covered by the presentation-
   contract fixture tests; this was a stream-integration coverage gap.
   - Added AffectUpdate to the vocab stream (non-terminal, coexists
     with done).
   - Added dedicated test_error_terminal_event + test_cancelled_terminal_event
     (terminal events are mutually exclusive with done, so they can't
     share one stream).

2. precision — the disconnect-cancel path caught bare `except Exception:
   pass`, silently swallowing real CancelFailed / transport errors. The
   contract intent is to swallow only the cooperative race
   (CancelAlreadyCompleted). Narrowed: swallow CancelAlreadyCompleted /
   CancelTurnNotFound as the no-op race; log unexpected cancel failures
   as a structured stderr line for diagnosability. Never re-raises (we're
   unwinding the cancelled generator and must not mask CancelledError).

Tests: +2 (376 → 378). Patch per SemVer discipline — coverage +
diagnosability tightening, no behavior change observable to callers.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "ratatoskr"
-version = "0.16.0"
+version = "0.16.1"
 description = "Worldtree Conversation API debug TUI — multi-pane observability dashboard"
 readme = "README.md"
 requires-python = ">=3.12"

src/ratatoskr/web/server.py

@@ -265,8 +265,21 @@ async def _stream_turn_endpoint(request: Request) -> StreamingResponse:
                 if handle.status == "streaming" and handle.upstream_turn_id is not None:
                     try:
                         await cancel_turn(client, session_id, handle.upstream_turn_id)
-                    except Exception:
-                        pass
+                    except (CancelAlreadyCompleted, CancelTurnNotFound):
+                        pass  # cooperative race — turn already terminal upstream
+                    except Exception as exc:
+                        # v0.16.1: unexpected cancel failure during disconnect
+                        # cleanup (e.g. CancelFailed, transport error) — log for
+                        # diagnosability instead of silently swallowing. Never
+                        # re-raise: we're already unwinding the cancelled
+                        # generator and must not mask the CancelledError.
+                        import sys as _sys
+                        _sys.stderr.write(
+                            f'{{"kind":"disconnect_cancel","event":"cancel_failed",'
+                            f'"session_id":"{session_id}",'
+                            f'"upstream_turn_id":{handle.upstream_turn_id},'
+                            f'"exc":"{type(exc).__name__}"}}\n'
+                        )
                 raise
         finally:
             registry.pop((session_id, turn_id), None)

tests/test_web_server.py

@@ -647,33 +647,70 @@ class TestCreateAppShape:
 class TestStreamFullEventVocab:
     """stream_turn_endpoint full_event_vocab — one of each Event type proxied."""
 
-    @respx.mock
-    def test_full_event_vocab(self) -> None:
-        """full_event_vocab [scenario]: a stream with one of each Event type
-        → each serialized to its fixture-shaped browser event."""
-        stream = b"".join([
-            _sse_chunk("42:1", {"type": "worker_phase", "phase": "BuildingPrompt", "turn_id": 42}),
-            _sse_chunk("42:2", {"type": "thinking", "content": "hmm"}),
-            _sse_chunk("42:3", {"type": "text", "content": "hi"}),
-            _sse_chunk("42:4", {"type": "text_boundary", "kind": "sentence", "char_offset": 2, "ts": "t"}),
-            _sse_chunk("42:5", {"type": "tool_start", "name": "s", "arguments": {"q": "x"}}),
-            _sse_chunk("42:6", {"type": "tool_result", "name": "s", "result": {"n": 1}, "duration_ms": 3}),
-            _sse_chunk("42:7", {"type": "awaiting_llm_first_token", "turn_id": 42,
-                                "elapsed_ms_since_building_prompt": 5000.0}),
-            _sse_chunk("42:8", _DONE_BODY),
-        ])
-        respx.post("https://w.example/sessions/s-1/messages").mock(return_value=_sse_resp(stream))
-        from ratatoskr.web.server import create_app
-        app = create_app(_mock_client_factory())
+    def _drive_stream(self, app, stream: bytes) -> list[str]:
+        respx.post("https://w.example/sessions/s-1/messages").mock(
+            return_value=_sse_resp(stream)
+        )
         c = TestClient(app)
         tid = c.post("/api/turns/s-1", json={"content": "hi"}).json()["turn_id"]
         with c.stream("GET", f"/api/turns/s-1/stream?turn_id={tid}") as resp:
             raw = b"".join(resp.iter_bytes())
-        types = [e["event"] for e in _parse_browser_sse(raw)]
-        for expected in ("worker_phase", "thinking", "text", "text_boundary",
+        return [e["event"] for e in _parse_browser_sse(raw)]
+
+    @respx.mock
+    def test_full_event_vocab(self) -> None:
+        """full_event_vocab [scenario]: a stream with the non-terminal Event
+        types (incl. AffectUpdate) + Done → each serialized to its fixture-
+        shaped browser event. Error / Cancelled are terminal and exclusive
+        with Done, so they get dedicated tests below.
+        """
+        from ratatoskr.web.server import create_app
+
+        stream = b"".join([
+            _sse_chunk("42:1", {"type": "affect_update", "status": "current", "turn_id": 42,
+                                "snapshot": {"agent_id": "mimir", "pad": {}, "dominant_emotion": "x"}}),
+            _sse_chunk("42:2", {"type": "worker_phase", "phase": "BuildingPrompt", "turn_id": 42}),
+            _sse_chunk("42:3", {"type": "thinking", "content": "hmm"}),
+            _sse_chunk("42:4", {"type": "text", "content": "hi"}),
+            _sse_chunk("42:5", {"type": "text_boundary", "kind": "sentence", "char_offset": 2, "ts": "t"}),
+            _sse_chunk("42:6", {"type": "tool_start", "name": "s", "arguments": {"q": "x"}}),
+            _sse_chunk("42:7", {"type": "tool_result", "name": "s", "result": {"n": 1}, "duration_ms": 3}),
+            _sse_chunk("42:8", {"type": "awaiting_llm_first_token", "turn_id": 42,
+                                "elapsed_ms_since_building_prompt": 5000.0}),
+            _sse_chunk("42:9", _DONE_BODY),
+        ])
+        types = self._drive_stream(create_app(_mock_client_factory()), stream)
+        for expected in ("affect_update", "worker_phase", "thinking", "text", "text_boundary",
                          "tool_start", "tool_result", "awaiting_llm_first_token", "done"):
             assert expected in types, f"missing browser event {expected}"
 
+    @respx.mock
+    def test_error_terminal_event(self) -> None:
+        """error terminal [scenario]: an SSE `error` event (distinct from the
+        synthetic connection-error event) proxies to a browser `error` event.
+        """
+        from ratatoskr.web.server import create_app
+
+        stream = _sse_chunk("42:1", {"type": "text", "content": "x"}) + _sse_chunk(
+            "42:2", {"type": "error", "phase": "failed",
+                     "error_code": "llm_output_invalid", "message": "boom"},
+        )
+        types = self._drive_stream(create_app(_mock_client_factory()), stream)
+        assert "error" in types
+
+    @respx.mock
+    def test_cancelled_terminal_event(self) -> None:
+        """cancelled terminal [scenario]: an SSE `cancelled` event proxies to
+        a browser `cancelled` event."""
+        from ratatoskr.web.server import create_app
+
+        stream = _sse_chunk("42:1", {"type": "text", "content": "x"}) + _sse_chunk(
+            "42:2", {"type": "cancelled", "phase": "cancelled", "turn_id": 42,
+                     "reason": "user_cancel", "partial_message_id": None},
+        )
+        types = self._drive_stream(create_app(_mock_client_factory()), stream)
+        assert "cancelled" in types
+
 
 class TestDisconnectCancel:
     """stream_turn_endpoint INV-005 — browser disconnect mid-stream triggers

uv.lock

@@ -1013,7 +1013,7 @@ wheels = [
 
 [[package]]
 name = "ratatoskr"
-version = "0.16.0"
+version = "0.16.1"
 source = { editable = "." }
 dependencies = [
     { name = "httpx" },