fix(effect-status): harden effect_status decode + fix tests for typed synth

- Turn.effect_status also catches TypeError: a corrupt non-string meta value
  (e.g. a dict that survived into the column) would otherwise crash a consumer
  on access, since EffectStatus(non-str) raises TypeError, not ValueError.
  Degrade to None, mirroring the meta decoders (Copilot review).
- test_lowering: the wire-repair synth now carries the _effect_status side
  channel (stripped before the provider wire) — assert it.
- test_session_mcp_dispatch_error: the _capture stub swallows the new status
  kwarg via **_ so it stays signature-compatible with _report_tool_result.

tests/test_lowering.py

@@ -126,6 +126,9 @@ def test_repair_synthesizes_trailing_orphan() -> None:
         "tool_call_id": "c1",
         "content": CANCELLED_TOOL_RESULT,
         "is_error": True,
+        # The unobserved synth carries the typed disposition (wire-invisible
+        # side channel, stripped by the translator before the provider wire).
+        "_effect_status": "unknown",
     }
 
 

tests/test_session_mcp_dispatch_error.py

@@ -105,7 +105,11 @@ def _record_outputs(session) -> list[tuple[str, str, str, bool]]:
     """Patch ``_report_tool_result`` to capture (call_id, name, output, is_error)."""
     captures: list[tuple[str, str, str, bool]] = []
 
-    def _capture(call_id: str, name: str, output: str, *, is_error: bool = False) -> None:
+    def _capture(
+        call_id: str, name: str, output: str, *, is_error: bool = False, **_: object
+    ) -> None:
+        # ``**_`` swallows the typed ``status`` kwarg (and any future ones) so
+        # the stub stays signature-compatible with ``_report_tool_result``.
         captures.append((call_id, name, output, is_error))
 
     session._report_tool_result = _capture  # type: ignore[method-assign]

turnstone/core/trajectory.py

@@ -161,7 +161,10 @@ class Turn:
             return None
         try:
             return EffectStatus(raw)
-        except ValueError:
+        except (ValueError, TypeError):
+            # ValueError: not a known status string. TypeError: a corrupt
+            # non-string value (e.g. a dict survived into the meta). Mirror the
+            # meta decoders and degrade to None rather than crash a consumer.
             return None
 
     # -- construction helpers (blunt the wrapping cost of uniform block content) --