Fix/qa defects df002 df011 (#9)

## Summary

What changed and why?

## Change Type

- [ ] Cowork feature
- [ ] Bug fix
- [ ] Core AI contribution
- [ ] Test / hardening
- [ ] Performance
- [ ] Documentation

## Related Work

Cowork Task:

Core Repo: http://34.143.229.138/gitea-admin/fsg-ai-core-assets

Core AI Issue:

Core Task:

Related PR:

## Scope

What is intentionally included?

What is intentionally NOT included?

## Validation

- [ ] Unit tests
- [ ] Integration tests
- [ ] Manual verification
- [ ] Regression check

Commands / evidence:

## Security Impact

Permission / credential / network / customer data impact:

## Compatibility

- [ ] No breaking change
- [ ] Breaking change documented

## Reviewer Notes

Anything Cowork reviewers should pay attention to.

---------

Co-authored-by: thanhnv <thanhnv.ip@gmail.com>
Co-authored-by: Vu Dam Tuan <vudt15@fpt.com>
Reviewed-on: #9

application/conversations/core_runtime_adapter.py

@@ -74,6 +74,14 @@ class CoreToolRuntime:
         đều phải tra tên, tra trên danh sách sẽ chậm dần theo số tool.
         """
         self._output_dir = Path(output_dir)
+        # Every sandboxed tool (run_command included) gets this as its cwd —
+        # it must exist BEFORE the first tool call, same as the older
+        # run_cowork() (core/chat_agent.py) already does at its output_dir.
+        # Without this, a per-turn ".turns/<id>" folder that was never created
+        # makes run_command's subprocess.Popen(cwd=...) fail immediately with
+        # WinError 267 ("directory name is invalid") before the command even
+        # starts — no network, no output, just an opaque OS error.
+        self._output_dir.mkdir(parents=True, exist_ok=True)
         self._title = title
         self._extra_tools = list(extra_tools or ())
         self._extra_names = {getattr(t, "name", "") for t in self._extra_tools}