[ci] Compare size against merge base - #37355
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Comparing: bd6ea41...fa7e59f Critical size changesIncludes critical production bundles, as well as any change greater than 2%:
Significant size changesIncludes any change greater than 0.2%: (No significant changes) Generated by sizebot against fa7e59f |
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…e merge-base This pull request contains a comment-only change on top of 675a29c, the parent of the size-changing commit dc631ef, because an empty diff is skipped by the workflow's path filters. It exists to demonstrate the problem that #37355 fixes: sizebot compares the head build against the build of `pull_request.base.sha`, the current tip of main, rather than against the merge-base. The sizebot comment on this pull request should therefore contain the entire size footprint of dc631ef even though this branch contains none of its changes. After #37355 lands, the sizebot comment on this pull request should instead be empty. Co-Authored-By: Claude Code (kimi-k3[1m]) <noreply@anthropic.com>
Sizebot compared the pull request head build against the build of `pull_request.base.sha`, which is the tip of the base branch at event time, not the commit the pull request diverged from. The field's semantics are undocumented in GitHub's API schema; the observed behavior and the compare API's `merge_base_commit` confirm the difference. Once main moved ahead, every pull request based on an older commit reported the size changes of unrelated main commits as if they were its own, which is why a branch predating a large size-changing commit produced a report too large to display. The sizebot job now resolves the merge-base through the compare API and downloads the base build for that commit instead. When no base build can be downloaded for the merge-base, for example because its artifacts aged out of the retention window or its run failed, the sizebot job now records a `base-build-not-found` result instead of failing immediately. `render-comment.js` on the default branch renders that as a warning comment naming the base commit and writes the `sizebot-problem.txt` marker, so the comment workflow fails its check after posting the warning, the same pattern already used for build configuration drift. The sizebot job itself stays green because a failed run would make the renderer discard the results and mask the warning with a generic "did not complete" message. Co-Authored-By: Claude Code (kimi-k3[1m]) <noreply@anthropic.com>
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Sizebot compared the pull request head build against the build of
pull_request.base.sha, which is the tip of the base branch at event time, not the commit the pull request diverged from. The field's semantics are undocumented in GitHub's API schema (the OpenAPI description types it as a bare string); the observed behavior and the compare API'smerge_base_commitconfirm the difference.The difference between
pull_request.base.shaand the merge base is confirmed with an example in #37356The sizebot job now resolves the merge-base through the compare API and downloads the base build for that commit instead, so the report only ever contains the pull request's own changes. The job gains
contents: readfor the compare call.When no base build can be downloaded for the merge-base, for example because its artifacts aged out of the retention window or its run failed, the sizebot job records a
base-build-not-foundresult instead of failing immediately.render-comment.json the default branch renders that as a warning comment naming the base commit and writes thesizebot-problem.txtmarker, so the comment workflow fails its check after posting the warning, the same pattern already used for build configuration drift. The sizebot job itself intentionally stays green: a failed run would make the renderer discard the results and mask the warning with a generic "did not complete" message.