On a fork PR, GITHUB_TOKEN is demoted to read-only regardless of the
workflow's permissions: block, so issues.addLabels() returns 403. The
label workflow silently works for PRs that skip the template (no
checkboxes ticked → no API call) and fails for PRs that actually
follow it — a hostile incentive against contributors who do the right
thing.
pull_request_target runs in the context of the base branch with full
declared permissions, which is the documented fix for this case. Safe
here because the workflow is metadata-only: it reads
context.payload.pull_request.body and calls addLabels. No checkout,
no PR-supplied code executes. A SECURITY comment is added above the
trigger to keep it that way.
Refs:
- https://docs.github.com/en/actions/reference/events-that-trigger-workflows#pull_request_target
- https://securitylab.github.com/resources/github-actions-preventing-pwn-requests/
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Two long-line violations introduced in d121cd1 (isGroup plumbing)
exceed the printWidth limit. CI format:check fails on every PR
opened against main until this is fixed; the fix is isolated here
so no behavior change is mixed in.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
