docs(pull-request-workflow): parallel-merged config PR turns green checks red on main - #135
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…ecks red on main Second mechanism under 'PR-green is not main-green': lint/analysis runs are pinned to the PR branch's config, so a sibling PR adopting a stricter shared config that merges between the last CI run and the merge makes main fail a check both PRs passed. Rebase does not close the window; post-merge main watch is the only place this class is visible. Real case: t3x-nr-vault Rector config adoption, 2026-08-04. Signed-off-by: Sebastian Mendel <info@sebastianmendel.de>
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Pull request overview
Updates the Git workflow documentation to explain an additional, practical way a “green PR” can still produce failing checks on main after merge, specifically when shared lint/analysis configuration changes land in parallel.
Changes:
- Add a new “PR-green is not main-green” subsection describing config drift between PR CI runs and the eventual merge-to-
mainresult. - Document mitigations (merge queue / require-up-to-date branches) and the operational consequence (monitoring post-merge
mainCI and fix-forward). - Include a concrete real-world example (t3x-nr-vault) to illustrate the failure mode and recovery.
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Adds a second mechanism under "PR-green is not main-green": lint/analysis runs are pinned to the PR branch's config, so a sibling PR adopting a stricter shared config (rector/eslint/phpstan) that merges between your last CI run and your merge makes
mainfail a check both PRs passed. Rebasing does not close the window (the config PR can land after the rebase); only a merge queue or "require branches up to date" does. Consequence spelled out: watching the post-merge run onmainis part of the merge, and the recovery is a mechanical fix-forward against the new config.Real case: t3x-nr-vault 2026-08-04 — #287 merged in parallel with #288 (org rector config with
NewlineAfterStatementRector);ci / Rectorwent red onmainover one blank line, fixed forward in #289.