close-linked-issues.yml

name: Close Linked Issues

# Auto-close issues referenced with Closes/Fixes/Resolves #N when a PR merges.
#
# GitHub's built-in auto-close only fires for PRs merged into the default branch
# (main). This repo's feature PRs merge into integration branches such as
# feat/t-replace, so linked issues are otherwise left open. This workflow closes
# them on any base branch.
#
# pull_request_target runs in the base-repo context, so it has an issues:write
# token even for PRs opened from forks (the normal pull_request event would get
# a read-only token). It never checks out or runs PR head code, so it is safe.

on:
  pull_request_target:
    types: [closed]

permissions:
  issues: write
  contents: read

jobs:
  close-linked-issues:
    name: Close linked issues
    runs-on: ubuntu-latest
    if: github.event.pull_request.merged == true
    steps:
      - name: Close issues referenced in the PR body
        uses: actions/github-script@v7
        with:
          script: |
            const pr = context.payload.pull_request;
            const body = pr.body || '';

            // Match "<keyword> #123" / "<keyword>: #123", keyword case-insensitive.
            const keyword = '(?:close[sd]?|fix(?:e[sd])?|resolve[sd]?)';
            const re = new RegExp(`${keyword}\\s*:?\\s+#(\\d+)`, 'gi');

            const numbers = new Set();
            for (const m of body.matchAll(re)) {
              numbers.add(Number(m[1]));
            }

            if (numbers.size === 0) {
              core.info('No "Closes/Fixes/Resolves #N" references found in the PR body.');
              return;
            }

            for (const issue_number of numbers) {
              try {
                const { data: issue } = await github.rest.issues.get({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  issue_number,
                });

                // Skip PRs (the API treats PRs as issues) and already-closed issues.
                if (issue.pull_request) {
                  core.info(`#${issue_number} is a pull request, skipping.`);
                  continue;
                }
                if (issue.state === 'closed') {
                  core.info(`#${issue_number} is already closed, skipping.`);
                  continue;
                }

                await github.rest.issues.createComment({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  issue_number,
                  body: `Closed by #${pr.number} (merged into \`${pr.base.ref}\`).`,
                });
                await github.rest.issues.update({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  issue_number,
                  state: 'closed',
                  state_reason: 'completed',
                });
                core.info(`Closed #${issue_number}.`);
              } catch (err) {
                core.warning(`Could not close #${issue_number}: ${err.message}`);
              }
            }