Resolve PR by head SHA in coverage-comment workflow#847
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Two issues with the previous "Resolve PR number" step:
1. Inline `${{ toJson(github.event) }}` interpolation inside `'...'`
shell quoting could be broken by any single quote in the payload
(e.g. an apostrophe in a commit message), producing the
notorious `syntax error near unexpected token "else"`.
2. `workflow_run.pull_requests[]` is *always empty* for PRs whose
head ref lives in a fork. By GitHub design, the default-branch
`workflow_run` handler (which holds the write token) does not
receive cross-repo PR linkage. The first PR through the new
coverage workflow happened to come from a fork, so the comment
was posted to the tracking issue instead of the PR.
Replace the bash step with a github-script step:
- reads `github.event` via an environment variable, immune to
payload-quoting issues;
- first tries `workflow_run.pull_requests[0]` for the same-repo
branch case;
- falls back to
`GET /repos/{owner}/{repo}/commits/{sha}/pulls` (the
"pull requests associated with commit" API), which is the only
way to recover a PR number from a fork `workflow_run` payload;
- prefers an open PR but tolerates a closed one if there's a
squash-merge race between the build and this comment job;
- falls through to the tracking-issue path only when neither
source produces a PR.
The downstream "Comment on PR" step is unchanged — it consumes the
same `steps.pr.outputs.pr` it always did.
Coverage report (cross-platform merged)Lines covered ( Merged line coverage is the per-line union across all platforms. Region coverage is reported per-platform only; no cross-platform region total is computed. Per-directory breakdown
Per-platform contributions (advisory)
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mjp41
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May 10, 2026
The SHA-based fallback added in #847 (resolve PR by head SHA when `workflow_run.pull_requests[]` is empty) handles fork PRs correctly, but it also fires for `schedule` and `push` runs on `main`. The nightly's head SHA is the merge commit of whichever PR last landed, and `listPullRequestsAssociatedWithCommit` returns that PR — so the nightly coverage report ended up posted as a comment on the just- merged (now closed) PR instead of on the tracking issue. Two changes, both narrowing the fallback: 1. Only run the SHA fallback when `workflow_run.event === 'pull_request'`. `schedule`/`push` runs on the default branch always belong on the tracking issue and have no business looking up a PR by SHA. 2. Require the matched PR to be in the `open` state. The previous "fall back to any PR if only closed ones match (e.g. squash-merge race)" is undesirable: if the PR has already merged, posting a fresh coverage comment on it is noise, not information. If a contributor really wanted the comment on a merged PR they can re-run the workflow. Together these mean the SHA fallback only ever fires for an open fork PR, which is the only case it was ever meant to handle.
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workflow_run.pull_requests[]is always empty for PRs whose head ref lives in a fork. By GitHub design, the default-branchworkflow_runhandler (which holds the write token) does not receive cross-repo PR linkage. The first PR through the new coverage workflow happened to come from a fork, so the comment was posted to the tracking issue instead of the PR.Replace the bash step with a github-script step:
github.eventvia an environment variable, immune to payload-quoting issues;workflow_run.pull_requests[0]for the same-repo branch case;GET /repos/{owner}/{repo}/commits/{sha}/pulls(the "pull requests associated with commit" API), which is the only way to recover a PR number from a forkworkflow_runpayload;The downstream "Comment on PR" step is unchanged — it consumes the same
steps.pr.outputs.prit always did.