fix(setup): allow repeated Windows setup

[lorenzozanee]

What

Allow bmad setup to replace an existing _bmad directory on Windows.

Why

Windows rejects the replacement when the temporary backup directory already exists, causing repeated setup to fail with WinError 183.

Fixes #2879

How

• Remove the empty temporary backup directory before renaming the existing runtime.
• Add regression coverage for the Windows directory-rename behavior.

Testing

The focused regression, setup test suite, repository quality checks, and git diff --check pass. Native Windows execution was not available locally.

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge, with the Windows replacement behavior directly covered by a focused regression test.

Summary

The PR fixes repeated Windows setup by removing the empty temporary backup directory before renaming the existing _bmad runtime into its place.

• Preserves the existing replacement and rollback flow.
• Adds focused regression coverage that emulates Windows refusing to rename onto an existing directory.

_{Reviews (1) · Last reviewed commit: "fix: allow repeated setup on Windows"}

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Advanced

Run ID: 9c683efd-7a96-45fa-aeac-8c9b8e863323

📥 Commits

Reviewing files that changed from the base of the PR and between f033e70 and d9a555f.

📒 Files selected for processing (2)

• skills/bmad/scripts/setup.py
• tools/tests/test_bmad_setup.py

Included review availability: Your plan provides up to 10 included reviews per hour; 9 remain after this review.

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📝 Walkthrough

Walkthrough

replace_dir removes the empty temporary backup directory before renaming an existing destination. A regression test simulates Windows OSError(183) behavior and verifies that the new directory replaces the old one without leftover backups.

Changes

Windows directory replacement

Layer / File(s)	Summary
Backup directory replacement and regression coverage skills/bmad/scripts/setup.py, tools/tests/test_bmad_setup.py	replace_dir removes the empty mkdtemp directory before renaming the existing destination. The test simulates Windows rename behavior and verifies the new file, removal of the old file, and cleanup of _bmad.old-* directories.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Medium

Suggested reviewers: alexeyv

Merge Risk: ⚪ Minimal · up to d9a55

The Windows replacement fix preserves setup and doctor behavior with no unresolved merge-blocking risk.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The change addresses #2879 in skills/bmad/scripts/setup.py. It removes the empty tempfile.mkdtemp() directory before dest.rename(backup), which removes the Windows WinError 183 target-exists f…
Out of Scope Changes check	✅ Passed	The changes are limited to the replace_dir fix and its regression test. Both changes directly support #2879. No unrelated behavior or files are identified.
Title check	✅ Passed	The title clearly and concisely describes the Windows setup fix.
Description check	✅ Passed	The description directly explains the Windows replacement failure, the fix, regression coverage, and testing status.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create a new PR

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