fix: .tool-versions regex

[ronnnnn]

Overview

I had a mistake on #94.
We can't find bun's version correctly when .tool-versions have other versions begin "bun".

Reproduce steps

In .tool-versions:

bundler 1.0.0
bun     1.0.0

Regex check

https://regex101.com/r/2aCusB/4

[coderabbitai]

Walkthrough

Updated regex pattern in src/utils.ts for parsing '.tool-versions' file. Changed bun version pattern to use negative lookahead preventing letter continuation, and requires non-whitespace version tokens instead of optional content.

Changes

Cohort / File(s)	Summary
Version parsing regex update src/utils.ts	Modified bun version pattern in FILE_VERSION_READERS: added negative lookahead (?![a-zA-Z]) to prevent matching "bun" followed by letters, changed version capture from .*? to \S+ to require non-empty, non-space tokens

Pre-merge checks

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'fix: .tool-versions regex' accurately summarizes the main change: fixing a regex pattern for .tool-versions file parsing to handle the bun version detection issue.
Description check	✅ Passed	The description is clearly related to the changeset, explaining the bug introduced in #94 where bun's version detection fails when tool names beginning with 'bun' are present, with reproduction steps and a regex test link.

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• dist/setup/index.js is excluded by !**/dist/**

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• src/utils.ts

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src/utils.ts (1)

78-78: LGTM! The negative lookahead correctly fixes the bundler false-match bug.

The regex successfully prevents matching tool names like "bundler" while correctly extracting the bun version. The implementation correctly handles:

• Prevents false matches: "bundler 1.0.0" fails at (?![a-zA-Z]) ✓
• Standard format: "bun 1.0.0" matches with version "1.0.0" ✓
• Compact format: "bun1.0.0" matches with version "1.0.0" ✓ (as mentioned in your commit message)
• All version specifiers: \S+ supports "latest", "canary", semver, pre-releases, etc. ✓

Note on design choice: Using \s* (zero or more spaces) instead of \s+ (one or more) makes the parser more permissive than the standard .tool-versions format, but this aligns with your stated intent to support compact entries like "bun1.1.0". The negative lookahead elegantly solves the core issue while maintaining this flexibility.

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[coderabbitai]

Actionable comments posted: 1

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[xhyrom]

LGTM

[ronnnnn]

@xhyrom
Thank you for your review. I fixed the CI failure.

[coderabbitai]

Actionable comments posted: 1

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Reviewing files that changed from the base of the PR and between e5ed3e1 and b08cdef.

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• dist/setup/index.js is excluded by !**/dist/**

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• src/utils.ts (1 hunks)

[ronnnnn]

this format is not supported on asdf

[xhyrom]

we should continue supporting this, even though it’s invalid, until the next major version so we don’t break semver

[ronnnnn]

Thanks for the feedback. I've updated the regex to use negative lookahead (?![a-zA-Z]) which:

• Excludes bundler and similar patterns (the original bug)
• Maintains backward compatibility for bun1.1.0 format (no space)
• Keeps support for the standard bun 1.1.0 format

This approach preserves semver compatibility as @xhyrom suggested.

[xhyrom]

we should continue supporting this, even though it’s invalid, until the next major version so we don’t break semver