feat(context-ledger): add helpful API key missing comment

- Check for missing ANTHROPIC_API_KEY before running
- Post helpful setup comment on PRs when API key is missing
- Skip changelog generation gracefully with API_KEY_MISSING status
- Provide clear instructions for getting and setting up the API key

Author: lukemun

.github/workflows/changelog.yml

@@ -50,3 +50,4 @@ jobs:
           version_increment: ${{ inputs.version_increment || 'auto' }}
           auto_commit: ${{ github.event_name != 'pull_request' }}
           create_pr_suggestions: ${{ github.event_name == 'pull_request' }}
+        continue-on-error: true  # Allow PR to succeed even if API key is missing

action.yml

@@ -327,8 +327,57 @@ runs:
             console.log('✅ Changelog already in PR diff');
           }
 
-    - name: Generate changelog with Claude
+    - name: Check for API key
       if: steps.check-suggestions.outputs.should_skip != 'true'
+      id: check-api-key
+      shell: bash
+      run: |
+        if [ -z "${{ inputs.anthropic_api_key }}" ]; then
+          echo "api_key_missing=true" >> $GITHUB_OUTPUT
+          echo "⚠️ ANTHROPIC_API_KEY is missing"
+        else
+          echo "api_key_missing=false" >> $GITHUB_OUTPUT
+          echo "✅ ANTHROPIC_API_KEY is present"
+        fi
+
+    - name: Comment about missing API key
+      if: steps.check-suggestions.outputs.should_skip != 'true' && steps.check-api-key.outputs.api_key_missing == 'true' && github.event_name == 'pull_request'
+      uses: actions/github-script@v7
+      with:
+        github-token: ${{ inputs.github_token }}
+        script: |
+          const message = `## 🔑 Context Ledger Setup Required
+
+          Hi! I'm Context Ledger, an AI-powered changelog generator. I'd love to help maintain your changelog, but I need an API key to get started.
+
+          ### To enable automatic changelog generation:
+
+          1. **Get an Anthropic API key**: Sign up at https://console.anthropic.com/
+          2. **Add it to your repository secrets**:
+             - Go to your repository Settings → Secrets and variables → Actions
+             - Click "New repository secret"
+             - Name: \`ANTHROPIC_API_KEY\`
+             - Value: Your API key from Anthropic
+          3. **Re-run this workflow** or push a new commit
+
+          ### What I'll do once set up:
+          - 📝 Analyze your code changes with AI
+          - 🎯 Generate relevant changelog entries
+          - 💡 Suggest them as PR comments (like this one!)
+          - 🚀 Keep your documentation in sync automatically
+
+          ---
+          *This comment was generated by [Context Ledger](https://github.com/lukemun/context-ledger)*`;
+
+          github.rest.issues.createComment({
+            issue_number: context.issue.number,
+            owner: context.repo.owner,
+            repo: context.repo.repo,
+            body: message
+          });
+
+    - name: Generate changelog with Claude
+      if: steps.check-suggestions.outputs.should_skip != 'true' && steps.check-api-key.outputs.api_key_missing != 'true'
       id: generate-changelog
       shell: bash
       env:
@@ -587,12 +636,20 @@ runs:
       run: |
         # Set outputs based on what happened
         SHOULD_SKIP="${{ steps.check-suggestions.outputs.should_skip }}"
+        API_KEY_MISSING="${{ steps.check-api-key.outputs.api_key_missing }}"
+        
         if [ "$SHOULD_SKIP" == "true" ]; then
           echo "status=SKIPPED" >> $GITHUB_OUTPUT
           echo "changelog_updated=false" >> $GITHUB_OUTPUT
           echo "has_changes=false" >> $GITHUB_OUTPUT
           echo "changelog_content=" >> $GITHUB_OUTPUT
           echo "version_generated=" >> $GITHUB_OUTPUT
+        elif [ "$API_KEY_MISSING" == "true" ]; then
+          echo "status=API_KEY_MISSING" >> $GITHUB_OUTPUT
+          echo "changelog_updated=false" >> $GITHUB_OUTPUT
+          echo "has_changes=false" >> $GITHUB_OUTPUT
+          echo "changelog_content=" >> $GITHUB_OUTPUT
+          echo "version_generated=" >> $GITHUB_OUTPUT
         else
           STATUS="${{ steps.check-status.outputs.status }}"
           if [ -z "$STATUS" ]; then