degrade optional workspace writes safely

agent.py

@@ -409,7 +409,11 @@ def _read_uploaded_workspace_file(ctx: RunContext[PlatformUserAuth], path: str)
 
 async def _write_workspace_output(ctx: RunContext[PlatformUserAuth], path: str, payload: dict[str, Any], warnings: list[str]) -> None:
     data = json.dumps(payload, indent=2, sort_keys=True).encode("utf-8")
-    workspace = ctx.workspace
+    try:
+        workspace = ctx.workspace
+    except PermissionError as exc:
+        warnings.append(f"workspace write skipped: {str(exc)[:160]}")
+        return
     writer = getattr(workspace, "write_bytes", None)
     if callable(writer):
         writer(path, data)