ci: lint changed files against PR merge base

[PavelPashov]

Description

Describe your pull request here

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Checklist

• Does npm test pass with this change (including linting)?
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?

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Note

Low Risk
Low risk CI scripting change; main impact is which files get linted on PRs and it could fail if PR SHAs or git history aren’t available as expected.

Overview
Updates the PR lint job to use a full git checkout (fetch-depth: 0) so merge-base comparisons can be computed reliably.

Changes scripts/lint-changed.mjs to determine changed files on PRs using the GitHub event’s base and head SHAs and a merge-base diff (base...head), ensuring only PR-introduced files are linted; it also now ensures both commits are present locally before diffing.

^{Reviewed by Cursor Bugbot for commit e6fbc01. Bugbot is set up for automated code reviews on this repo. Configure here.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Reviewed by Cursor Bugbot for commit e6fbc01. Configure here.}

[cursor]

Shallow fetch incompatible with three-dot merge-base diff

Low Severity

The ensureCommitAvailable fallback fetch uses --depth=1, which only retrieves the commit object itself. The new three-dot diff syntax (${base}...${head}) requires git to compute the merge-base by traversing commit history from both refs to a common ancestor. If ensureCommitAvailable actually needs to fetch (i.e., a commit isn't already present), the --depth=1 fetch won't provide enough history for git merge-base to succeed, causing the git diff call to fail. CI is unaffected due to fetch-depth: 0, but the --base flag path for local reproduction is broken in this scenario.

Additional Locations (1)

• scripts/lint-changed.mjs#L96-L97

 

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