Implement post-triage operational hardening

src/activity_core/activities.py

@@ -377,6 +377,7 @@ async def emit_tasks(payload: dict) -> list[str]:
     Session = _get_session_factory()
 
     refs: list[str] = []
+    errors: list[str] = []
     async with Session() as session:
         async with session.begin():
             for spec_dict in task_specs_raw:
@@ -411,6 +412,11 @@ async def emit_tasks(payload: dict) -> list[str]:
                     )
                     session.add(log_row)
                 except Exception as exc:
+                    message = f"{spec.source_type}:{spec.source_id}: {exc}"
+                    errors.append(message)
                     activity.logger.warning("emit_tasks: sink.emit failed — %s", exc)
 
+    if errors:
+        raise RuntimeError(f"task emission sink failure: {errors!r}")
+
     return refs