[ajitpratap0]

Description

website/scripts/vercel-ignore.sh (added in #821) runs git diff $VERCEL_GIT_PREVIOUS_SHA HEAD. When a PR branch is force-pushed (a rebase, for example), the previously deployed commit is no longer in Vercel's clone:

• git diff exits 128 with fatal: bad object <sha>.
• Vercel fails the deployment for any exit code other than 0 (skip) or 1 (build).
• The Vercel check therefore goes red for reasons unrelated to the code.

Observed on #825, #827 and #828 after rebasing them onto main. Deployment dpl_8HzjNoKTPk5VJkkKRZW8AgUMyLyx log: fatal: bad object 5b5aa61e….

Changes Made

• If the previous commit cannot be resolved (git cat-file -e), build (exit 1).
• Every non-skip outcome now exits 1, so the script can no longer fail a deployment.
• Logs why a preview was skipped.
• Production and [vercel skip] behaviour are unchanged.

Type of Change

• Bug fix (non-breaking)

Testing

Exercised every path in a scratch git repo:

Case	Exit code	Expected
production	1	1
[vercel skip]	0	0
no site change (via HEAD^)	0	0
missing previous SHA	1	1 (previously 128)
site change	1	1
root commit with no HEAD^	1	1

bash -n passes.

Breaking Changes

None.

🤖 Generated with Claude Code

https://claude.ai/code/session_01KTj1PEbxzVCETkeYrZKcrE

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
gosqlx-website	Ready	Preview	Oct 20, 2026 7:30am UTC

[github-actions]

Claude finished @ajitpratap0's task in 21s —— View job

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Review of PR #832

• Read website/scripts/vercel-ignore.sh
• Analyze the exit-code paths

Verdict: LGTM. The fix is correct, small, and targeted.

What I checked

• Root cause fixed. git cat-file -e "${prev}^{commit}" is the right way to test that the commit object exists. It avoids the exit 128 from git diff on a missing object. The ^{commit} peel also handles the HEAD^ fallback.
• No path can fail the deployment now. The only exit codes are 0 and 1. if git diff --quiet … is true only on exit 0 (no diff). Exit 1 (diff) and 128 (any other git error) both fall through to exit 1, so unexpected errors fail safe toward building.
• Behaviour unchanged for production and [vercel skip]. Both still behave as before. The new log lines make skip and build decisions visible in the Vercel logs.
• Security. All variables are quoted. $VERCEL_GIT_COMMIT_MESSAGE is only matched in a case and never evaluated. A $prev that starts with - can't be interpreted as an option by cat-file in practice, because it is suffixed with ^{commit} and the SHA is Vercel-provided.

Minor, non-blocking suggestions

1. git diff "$prev" HEAD would be slightly safer written as git diff --quiet "$prev" HEAD --, with an explicit -- before the pathspecs. You already have -- . there, so this is fine as is.
2. Consider echoing a "Preview building: changes detected" line before the final exit 1. That would make every outcome visible in the logs.
3. Test coverage: the scratch-repo table in the description is good. If you want regression protection, a small shell test script could live next to this one, but that is optional for a 25-line script.

No bugs found.