fix: use merge-base for accurate PR diff in code review example - #64
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thisismydesign wants to merge 3 commits into
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fix: use merge-base for accurate PR diff in code review example#64thisismydesign wants to merge 3 commits into
thisismydesign wants to merge 3 commits into
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The previous code review example used base.sha...head.sha which incorrectly shows commits added to main after the PR branch was created as 'removed' when the branch is not up to date with main. This change: - Adds fetch-depth: 0 to get full git history - Computes merge-base to find the common ancestor between PR and base branch - Uses git diff with merge-base to show only changes introduced by the PR This ensures the code review focuses on actual PR changes regardless of whether the branch is up to date with main.
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All contributors have signed the CLA ✍️ ✅ |
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I have read the CLA Document and I hereby sign the CLA |
bolinfest
reviewed
Mar 17, 2026
| # Find the common ancestor between the PR branch and base branch. | ||
| # This ensures we only review changes introduced by the PR, not | ||
| # changes added to main after the PR branch was created. | ||
| MERGE_BASE=$(git merge-base origin/${{ github.event.pull_request.base.ref }} HEAD) |
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Can we accomplish this with gh to avoid fetch-depth: 0?
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@bolinfest Managed to solve it without fetch-depth: 0
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The code review example prompts Codex with
git log --oneline base.sha...head.sha. Forgit log,...is the symmetric difference, so when the PR branch is behind its base branch the list also includes every commit added to the base since the branch point. Codex then treats those as part of the PR and reports the base's changes as "removed".This switches the prompt to
git diff base.sha...head.sha. Forgit diff,...means "diff from the merge-base to head", which is exactly the PR's own changes regardless of whether the branch is up to date with its base. The refs are already fetched by the pre-fetch step, so no extra history or steps are needed.