## Implementation Plan

### Changes Required

1. **`devplacepy/project_files.py` – remove spurious write guard**  
   At line 688, delete the line `_guard_writable(project_uid)`.  
   *Context:* `export_to_dir` is a read‑only operation; the guard incorrectly blocks exports for any project with `read_only=True`.

2. **`devplacepy/cli/jobs.py` – fix stale constant import**  
   *Line 10:* Replace  
   `from devplacepy.services.jobs.zip_service import STAGING_DIR`  
   with  
   `from devplacepy.config import ZIP_STAGING_DIR`  
   *Line 15:* Replace  
   `STAGING_DIR / job["uid"]`  
   with  
   `ZIP_STAGING_DIR / job["uid"]`

3. **`tests/api/forks.py` – correct stale monkeypatch**  
   *Line 19:* Change the target string from  
   `"devplacepy.services.jobs.fork_service.STAGING_DIR"`  
   to  
   `"devplacepy.services.jobs.fork_service.FORK_STAGING_DIR"`

No other files need modification. All three changes are isolated, syntax‑safe, and independently testable.

### Definition of Done

- [ ] All three source changes above are applied and verified (`git diff` shows only those lines changed).
- [ ] Lint command passes without errors:  
  `pip install -q ruff && ruff check .`
- [ ] Test command passes with exit code 0:  
  `pip install -e '.[dev]' -q && make test-unit`  
  (If the environment restricts system‑site‑packages, the executing agent must first create and activate a virtual environment before running the pip command.)
- [ ] No leftover uncommitted changes after verification.