[viceice]

Changes

Make the PR size labeler work for pull requests from forks without pull_request_target (on pull_request a fork run only gets a read-only token, and pull_request_target is blocked by GitHub's new default policy for public repositories from November 2, 2026).

The labeler is split into two workflows:

• pr-size-labeler.yml runs on pull_request with no permissions and only uploads the pull request number as an artifact.
• pr-size-labeler-apply.yml runs on workflow_run from the default branch with actions: read, contents: read and pull-requests: write. It treats the artifact as untrusted: the number must be an integer and the pull request head must match workflow_run.head_sha, otherwise the run is skipped. It then sparse-checks out .github/pull-request-size.yml from the default branch and applies the label. No pull request code is checked out or run.

workflow_run only triggers once the apply workflow is on the default branch, so it can only be verified after merge.

Context

Please select one of the following:

• This closes an existing Issue, Closes: #
• This doesn't close an Issue, but I accept the risk that this PR may be closed if maintainers disagree with its opening or implementation

AI assistance disclosure

Did you use AI tools to create any part of this pull request?

Please select one option and, if yes, briefly describe how AI was used (e.g., code, tests, docs) and which tool(s) you used.

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• Yes — other (please describe):

Workflow changes written with Claude Code (Claude Opus 5.5).

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🤖 Generated with Claude Code

[jamietanna]

Let's review https://docs.github.com/en/actions/reference/security/securely-using-pull_request_target before we merge this - and see about whether we want to change the default policy for us right now to harden things

[viceice]

Good call. The page adds a new default policy that blocks pull_request_target on public repos from November 2, 2026, so the previous version would have stopped running then (as would auto-pr.yml and label-actions.yml). Instead of adding an allow policy, this PR now keeps the hardened default: an unprivileged pull_request workflow uploads the PR number, and a workflow_run workflow on the default branch validates it (integer, PR head matches the run's head SHA) and applies the label. No PR code is checked out or run, and permissions are minimal. Note that workflow_run only triggers once the apply workflow is on main, so it can only be verified after merge.

Posted by Claude (Claude Code) on behalf of @viceice.

[RahulGautamSingh]

lgtm

[Copilot]

Copilot review overview

🔵 Needs a closer look

The privileged workflow_run path is security-sensitive and cannot be exercised end-to-end until merged.

Review effort: Balanced
Findings: None

What changed in this PR

Splits PR size labeling into unprivileged collection and privileged application workflows, enabling fork support without pull_request_target.

Changes:

• Uploads the PR number from the fork-safe workflow.
• Validates the artifact and head SHA before applying labels.

File	Description
.github/​workflows/​pr-size-labeler.yml	Records and uploads the PR number.
.github/​workflows/​pr-size-labeler-apply.yml	Securely validates and labels the PR.

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[github-actions]

🎉 This PR is included in version 44.128.2 🎉

The release is available on:

• GitHub release
• 44.128.2

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