name: Issue triage

on:
  issues:
    types: [opened, reopened]

permissions:
  issues: write
  contents: read

jobs:
  label:
    runs-on: ubuntu-latest
    steps:
      - name: Auto-label by title and body
        uses: actions/github-script@v9
        with:
          script: |
            const issue = context.payload.issue;
            const title = (issue.title || '').toLowerCase();
            const body = (issue.body || '').toLowerCase();
            const text = `${title}\n${body}`;
            const labels = new Set();

            // Type — matched against the TITLE only.
            //
            // These ran against title+body and mislabelled long, well-specified
            // issues. Any body containing an acceptance criterion like "fails
            // when a pack drifts" matched the bug rule, and a "How to add a
            // locale" heading matched the question rule, so planned work landed
            // tagged `bug, question`. A title states the type; a body just
            // discusses it. `error`/`fail` are dropped entirely — they describe
            // what almost every issue talks about, not what any issue *is*.
            if (/\b(bug|crash|panic|broken|stack ?trace|regression)\b/.test(title)) labels.add('bug');
            if (/\b(feat(?:ure)?|request|enhancement|wishlist|proposal|please add|would be nice|support for)\b/.test(title)) labels.add('enhancement');
            if (/\b(docs?|readme|documentation|typo|grammar|wording|spelling)\b/.test(title)) labels.add('documentation');
            if (/\b(question|how (?:do|to)|why does|what does|is it possible)\b/.test(title)) labels.add('question');

            // Locale — title contains CJK (Chinese, Japanese, Korean) characters
            if (/[぀-ヿ㐀-鿿가-힯]/.test(issue.title || '')) labels.add('lang:zh');

            // Areas (path-driven hints)
            if (/crates\/tui|\btui\b|ratatui|composer|sidebar/.test(text)) labels.add('area:tui');
            if (/crates\/core|engine|turn ?loop|agent ?loop/.test(text)) labels.add('area:core');
            if (/crates\/mcp|\bmcp\b/.test(text)) labels.add('area:mcp');
            if (/crates\/state|sqlite|sessions?|persistence/.test(text)) labels.add('area:state');
            if (/crates\/execpolicy|approval|sandbox|seatbelt|landlock/.test(text)) labels.add('area:execpolicy');
            if (/crates\/tools|tool[ _]call|tool[ _]registry/.test(text)) labels.add('area:tools');
            if (/install|cargo install|npm install|scoop|homebrew|prebuilt|binary/.test(text)) labels.add('area:install');
            if (/windows/.test(text)) labels.add('os:windows');
            if (/macos|darwin|apple silicon/.test(text)) labels.add('os:macos');
            if (/\blinux\b|ubuntu|debian|fedora|arch ?linux/.test(text)) labels.add('os:linux');

            if (labels.size === 0) return;

            // Only add labels that already exist on the repo to avoid creating noise.
            const existing = await github.paginate(github.rest.issues.listLabelsForRepo, {
              owner: context.repo.owner,
              repo: context.repo.repo,
              per_page: 100,
            });
            const existingNames = new Set(existing.map(l => l.name));
            const toAdd = [...labels].filter(name => existingNames.has(name));
            if (toAdd.length === 0) return;

            await github.rest.issues.addLabels({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: issue.number,
              labels: toAdd,
            });