guard_unassigned_prs.yml

name: Guard Unassigned PRs

on:
  pull_request_target:
    types: [opened]

jobs:
  check-assignee:
    runs-on: ubuntu-latest
    permissions:
      pull-requests: write
      issues: read
    steps:
      - uses: actions/github-script@v7
        with:
          script: |
            const { owner, repo, number } = context.issue;
            const pr = context.payload.pull_request;
            const author = pr.user.login;

            // Extract linked issue number (e.g., "Closes #12" or "Fixes #5")
            const match = pr.body?.match(/(?:fixes|closes|resolves)\s+#(\d+)/i);
            
            if (!match) {
              await github.rest.issues.createComment({
                owner, repo, issue_number: number,
                body: `Hi @${author}! Please reference an issue in your PR body (e.g., \`Closes #12\`) and make sure it is assigned to you.`
              });
              await github.rest.pulls.update({ owner, repo, pull_number: number, state: 'closed' });
              return;
            }

            const issueNum = parseInt(match[1]);
            const issue = await github.rest.issues.get({ owner, repo, issue_number: issueNum });
            const isAssigned = issue.data.assignees.some(a => a.login === author);

            if (!isAssigned) {
              await github.rest.issues.createComment({
                owner, repo, issue_number: number,
                body: `Hi @${author}! This PR was automatically closed because Issue #${issueNum} is not assigned to you. Please comment on the issue to claim it first!`
              });
              await github.rest.pulls.update({ owner, repo, pull_number: number, state: 'closed' });
            }