pr-describe.yml

name: Generate PR Description

on:
  issue_comment:
    types: [created]

permissions:
  contents: read

jobs:
  generate-description:
    # Only run if comment contains /describe and is on a PR
    if: ${{ (github.event.issue.pull_request && contains(github.event.comment.body, '/describe')) }}
    runs-on: ubuntu-latest
    env:
      HAS_APP_SECRETS: ${{ secrets.CAGENT_REVIEWER_APP_ID != '' }}
    permissions:
      contents: read
      pull-requests: write
      issues: write
      checks: write
    steps:
      - name: Check out Git repository
        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938 # v4.2.0

      - name: Create check run
        id: create-check
        continue-on-error: true # Don't fail if checks: write permission is missing
        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
        with:
          script: |
            const prNumber = context.issue.number;
            const { data: pr } = await github.rest.pulls.get({
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: prNumber
            });
            const { data: check } = await github.rest.checks.create({
              owner: context.repo.owner,
              repo: context.repo.repo,
              name: 'Generate PR Description',
              head_sha: pr.head.sha,
              status: 'in_progress',
              started_at: new Date().toISOString()
            });
            core.setOutput('check-id', check.id);

      # Generate GitHub App token so actions appear as the custom app (optional - falls back to github.token)
      - name: Get GitHub App token
        id: app-token
        if: env.HAS_APP_SECRETS == 'true'
        continue-on-error: true  # Don't fail workflow if token generation fails
        uses: tibdex/github-app-token@3beb63f4bd073e61482598c45c71c1019b59b73a # v2
        with:
          app_id: ${{ secrets.CAGENT_REVIEWER_APP_ID }}
          private_key: ${{ secrets.CAGENT_REVIEWER_APP_PRIVATE_KEY }}

      - name: Validate PR and add reaction
        id: validate_pr
        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
        with:
          github-token: ${{ steps.app-token.outputs.token || github.token }}
          script: |
            const prNumber = context.issue.number;
            const commentId = context.payload.comment.id;

            // Validate PR number
            if (!Number.isInteger(prNumber) || prNumber < 1 || prNumber > 99999) {
              core.setFailed(`❌ Error: Invalid PR number (got: ${prNumber})`);
              return;
            }

            console.log(`✅ Validated PR number: ${prNumber}`);
            core.setOutput('pr_number', prNumber);

            // Add "eyes" reaction to comment
            try {
              await github.rest.reactions.createForIssueComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: commentId,
                content: 'eyes'
              });
              console.log('👀 Added reaction to comment');
            } catch (error) {
              console.log(`⚠️ Warning: Could not add reaction: ${error.message}`);
            }

      - name: Get PR details
        id: pr_details
        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
        with:
          github-token: ${{ steps.app-token.outputs.token || github.token }}
          script: |
            const fs = require('fs');
            const prNumber = ${{ steps.validate_pr.outputs.pr_number }};

            try {
              // Get PR information
              const { data: pr } = await github.rest.pulls.get({
                owner: context.repo.owner,
                repo: context.repo.repo,
                pull_number: prNumber
              });

              // Set outputs for PR metadata
              core.setOutput('title', pr.title);
              core.setOutput('branch', pr.head.ref);
              core.setOutput('base', pr.base.ref);
              core.setOutput('additions', pr.additions);
              core.setOutput('deletions', pr.deletions);
              core.setOutput('changed_files', pr.changed_files);

              console.log(`✅ Retrieved PR details for #${prNumber}`);
              console.log(`📊 Stats: ${pr.changed_files} files, +${pr.additions}/-${pr.deletions} lines`);

              // Get commit messages
              const { data: commits } = await github.rest.pulls.listCommits({
                owner: context.repo.owner,
                repo: context.repo.repo,
                pull_number: prNumber
              });

              const commitMessages = commits.map(commit => {
                const message = commit.commit.message.split('\n')[0];
                const sha = commit.sha.substring(0, 7);
                return `- ${message} (${sha})`;
              }).join('\n');

              fs.writeFileSync('commits.txt', commitMessages);

              // Get list of changed files with stats
              const { data: files } = await github.rest.pulls.listFiles({
                owner: context.repo.owner,
                repo: context.repo.repo,
                pull_number: prNumber
              });

              const filesList = files.map(file =>
                `- \`${file.filename}\` (+${file.additions}/-${file.deletions}) - ${file.status}`
              ).join('\n');

              fs.writeFileSync('files.txt', filesList);

              // Get the actual diff
              const { data: diff } = await github.request('GET /repos/{owner}/{repo}/pulls/{pull_number}', {
                owner: context.repo.owner,
                repo: context.repo.repo,
                pull_number: prNumber,
                mediaType: {
                  format: 'diff'
                }
              });

              fs.writeFileSync('pr.diff', diff);

              console.log(`📝 Generated commits.txt, files.txt, and pr.diff`);

            } catch (error) {
              core.setFailed(`❌ Failed to fetch PR details: ${error.message}`);
            }

      - name: Generate description with AI
        id: generate
        uses: ./
        with:
          agent: agentcatalog/github-action-pr-description-generator
          prompt: |
            **PR Metadata:**
            - **Title:** ${{ steps.pr_details.outputs.title }}
            - **Branch:** ${{ steps.pr_details.outputs.branch }} → ${{ steps.pr_details.outputs.base }}
            - **PR Number:** #${{ steps.validate_pr.outputs.pr_number }}
            - **Stats:** ${{ steps.pr_details.outputs.changed_files }} files changed, +${{ steps.pr_details.outputs.additions }}/-${{ steps.pr_details.outputs.deletions }} lines

            **Commit Messages:**
            $(cat commits.txt)

            **Changed Files:**
            $(cat files.txt)

            **Diff:**
            $(cat pr.diff)
          anthropic-api-key: ${{ secrets.ANTHROPIC_API_KEY }}
          github-token: ${{ steps.app-token.outputs.token || github.token }}
          timeout: 300 # 5 minutes

      - name: Update PR description
        if: ${{ steps.generate.conclusion == 'success' }}
        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
        with:
          github-token: ${{ steps.app-token.outputs.token || github.token }}
          script: |
            const fs = require('fs');
            const prNumber = ${{ steps.validate_pr.outputs.pr_number }};
            const descriptionFile = '${{ steps.generate.outputs.output-file }}';

            try {
              // Read generated description and extract cagent-output block if present.
              // The composite action should already clean this, but the agent may
              // emit conversational text before the code fence that slips through.
              const raw = fs.readFileSync(descriptionFile, 'utf8');
              const fenceMatch = raw.match(/```cagent-output[\s\S]*?\n([\s\S]*?)```/);
              let description;
              if (fenceMatch) {
                description = fenceMatch[1].trim();
              } else {
                // Fallback: extract from the first markdown heading onward
                // to avoid leaking tool call traces into the PR body
                const headingMatch = raw.match(/(^|\n)(## .+[\s\S]*)$/);
                description = headingMatch ? headingMatch[2].trim() : raw.trim();
              }

              // Preserve issue-closing keywords from the existing PR body
              const { data: pr } = await github.rest.pulls.get({
                owner: context.repo.owner,
                repo: context.repo.repo,
                pull_number: prNumber
              });
              const existingBody = pr.body || '';
              const closingLines = existingBody
                .split('\n')
                .filter(line => /^\s*(closes|fixes|resolves)\s*:?\s+/i.test(line))
                .map(line => line.trim());
              if (closingLines.length > 0) {
                // Only append lines not already present in the generated description
                const missing = closingLines.filter(line => !description.includes(line));
                if (missing.length > 0) {
                  description += '\n\n' + missing.join('\n');
                }
              }

              // Update PR body
              await github.rest.pulls.update({
                owner: context.repo.owner,
                repo: context.repo.repo,
                pull_number: prNumber,
                body: description
              });

              console.log(`✅ Updated PR #${prNumber} with generated description`);
            } catch (error) {
              core.setFailed(`❌ Failed to update PR description: ${error.message}`);
            }

      - name: Post success comment
        if: ${{ steps.generate.conclusion == 'success' }}
        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
        with:
          github-token: ${{ steps.app-token.outputs.token || github.token }}
          script: |
            const prNumber = ${{ steps.validate_pr.outputs.pr_number }};

            await github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: prNumber,
              body: '✅ PR description has been generated and updated!'
            });

      - name: Post failure comment
        if: ${{ failure() && steps.generate.conclusion != 'success' }}
        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
        with:
          github-token: ${{ steps.app-token.outputs.token || github.token }}
          script: |
            const prNumber = ${{ steps.validate_pr.outputs.pr_number }};

            await github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: prNumber,
              body: '❌ Failed to generate PR description. Check workflow logs for details.'
            });

      - name: Post summary
        if: always()
        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
        env:
          PR_TITLE: ${{ steps.pr_details.outputs.title }}
          PR_BRANCH: ${{ steps.pr_details.outputs.branch }}
          PR_BASE: ${{ steps.pr_details.outputs.base }}
          PR_CONCLUSION: ${{ steps.generate.conclusion }}
        with:
          github-token: ${{ steps.app-token.outputs.token || github.token }}
          script: |
            const prNumber = context.issue.number;
            const title = process.env.PR_TITLE || 'Unknown';
            const branch = process.env.PR_BRANCH || 'Unknown';
            const base = process.env.PR_BASE || 'Unknown';
            const conclusion = process.env.PR_CONCLUSION || 'failure';

            const summary = [
              '## 📝 PR Description Generator',
              '',
              `**PR:** #${prNumber}`,
              `**Title:** ${title}`,
              `**Branch:** ${branch} → ${base}`,
              '',
              conclusion === 'success'
                ? '**Result:** ✅ Description generated and PR updated'
                : '**Result:** ❌ Failed to generate description'
            ].join('\n');

            await core.summary
              .addRaw(summary)
              .write();

      - name: Cleanup temporary files
        if: always()
        run: |
          set -euo pipefail
          rm -f commits.txt files.txt pr.diff || true
          echo "🧹 Cleaned up temporary files"

      - name: Update check run
        if: always() && steps.create-check.outputs.check-id != ''
        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
        env:
          CHECK_ID: ${{ steps.create-check.outputs.check-id }}
          JOB_STATUS: ${{ job.status }}
        with:
          script: |
            const conclusion = process.env.JOB_STATUS === 'cancelled' ? 'cancelled' : process.env.JOB_STATUS === 'success' ? 'success' : 'failure';
            try {
              await github.rest.checks.update({
                owner: context.repo.owner,
                repo: context.repo.repo,
                check_run_id: parseInt(process.env.CHECK_ID, 10),
                status: 'completed',
                conclusion: conclusion,
                completed_at: new Date().toISOString()
              });
            } catch (error) {
              core.warning(`Failed to update check run: ${error.message}`);
            }