[sxlijin]

Windows wrapper tests in merge queue fail before running the suite because Git Bash converts ARFLAGS_<target>=/Brepro into C:/Program Files/Git/Brepro. lib.exe then treats the split value as input files and fails with LNK1181: cannot open input file 'C:\Program'.

Exclude only the two MSVC archiver environment variables from MSYS2 environment conversion. This retains the reproducible static-library flag added in #5487 and preserves existing conversion exclusions, including the wildcard. The setting is applied before .envrc starts native subprocesses such as direnv dump.

Validation: bash -n .envrc, applicable prek checks, and sourcing .envrc with unset, existing-prefix, and wildcard exclusions all pass. The queued Windows wrapper jobs provide the native validation once this fix reaches their base.

This fixes the Windows blocker for stack #5464. Failure example: https://github.com/BoundaryML/baml/actions/runs/41557370744/job/125659637503. MSYS2 documents this control at https://www.msys2.org/docs/filesystem-paths/#environment-variables.

Summary by CodeRabbit

• Chores
  • Updated Windows build environment configuration to preserve existing environment exclusions while accounting for additional archiver flags, supporting more consistent build behavior. This is an internal development workflow update and does not change user-facing functionality.

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[coderabbitai]

No actionable comments were generated in the recent review.

Walkthrough

.envrc now adds two MSVC ARFLAGS variable names to MSYS2_ENV_CONV_EXCL unless its value is exactly *. Existing exclusions remain, separated by a semicolon.

Changes: MSVC ARFLAGS exclusions

Layer / File(s)	Summary
Update environment exclusions .envrc	When MSYS2_ENV_CONV_EXCL is not *, the setting gains the two MSVC ARFLAGS variable names. A semicolon separates them from a nonempty existing value.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Bug fix · Severity of issue fixed: Medium

Possibly related PRs

• BoundaryML/baml#5487: Adds the two ARFLAGS_<target> variables that this change excludes from conversion.
• BoundaryML/baml#5488: Reports the Windows failure caused by conversion of /Brepro and lib.exe.
• BoundaryML/baml#5483: Adds Windows wrapper build and test jobs affected by the MSVC ARFLAGS conversion.

Suggested reviewers: hellovai

Merge Risk: Minimal · up to 360d9

No merge-blocking risk was identified in this targeted environment configuration change.

Architecture risk: Low · up to 360d9

The changed surface does not map to a changed system, dependency edge, entrypoint, or external dependency.

Changed systems: None identified.

Architecture concerns
No architecture-level concerns identified.

Review details

Before / after behavior

• observed — Modified behavior in .envrc: When MSYS2_ENV_CONV_EXCL is not exactly *, .envrc appends the two MSVC ARFLAGS variable names to its existing value, using a semicolon when that value is nonempty. When it is *, the setting is left unchanged.

Pre-merge checks: 5

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: preserving MSVC /Brepro flags in Git Bash.
Docstring Coverage		No eligible functions found in the changed files. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentat…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

No eligible functions found in the changed files. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 0 functions across 0 files. (1 skipped: 1 unsupported.)

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Commits

Reviewing files that changed from the base of the PR and between 4ef2454 and 360d923.

Files selected for processing: 1

• .envrc

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