Add Claude Code GitHub Workflow (#10)

## 🤖 Installing Claude Code GitHub App

This PR adds a GitHub Actions workflow that enables Claude Code
integration in our repository.

### What is Claude Code?

[Claude Code](https://claude.com/claude-code) is an AI coding agent that
can help with:
- Bug fixes and improvements  
- Documentation updates
- Implementing new features
- Code reviews and suggestions
- Writing tests
- And more!

### Context
Our team is currently constrained in capacity, and frequent code reviews
have been a burden. In order to increase the quality of code before it
reaches human reviewers, we should use AI to try and catch things
earlier on.

I have used claude code review previously on Cannon, and I found it
effective. It often identifies major deficienies or easily missed issues
by the author and can work with a variety of changes. Here is I think a
good representative example (keep in mind this is an older version and I
suspect this newer version will work a lot better)
usecannon/cannon#1835 (comment)

The AI will be using my (@kaze-cow )'s CoW account API key for now.

The commits and initial files were generated from `/install-github-app`
command in claude code and following the wizard and selecting all
default options. I then updated the claude code review file using
[anthropic's official
examples](https://github.com/anthropics/claude-code-action/blob/main/examples/pr-review-comprehensive.yml)

### How it works

Once this PR is merged, we'll be able to interact with Claude by
mentioning @claude in a pull request or issue comment.
Once the workflow is triggered, Claude will analyze the comment and
surrounding context, and execute on the request in a GitHub action.

### Important Notes

- **This workflow won't take effect until this PR is merged**
- **@claude mentions won't work until after the merge is complete**
- The workflow runs automatically whenever Claude is mentioned in PR or
issue comments
- Claude gets access to the entire PR or issue context including files,
diffs, and previous comments

### Security

- Our Anthropic API key is securely stored as a GitHub Actions secret
- Only users with write access to the repository can trigger the
workflow
- All Claude runs are stored in the GitHub Actions run history
- Claude's default tools are limited to reading/writing files and
interacting with our repo by creating comments, branches, and commits.
- We can add more allowed tools by adding them to the workflow file
like:

```
allowed_tools: Bash(npm install),Bash(npm run build),Bash(npm run lint),Bash(npm run test)
```

There's more information in the [Claude Code action
repo](https://github.com/anthropics/claude-code-action).

After merging this PR, let's try mentioning @claude in a comment on any
PR to get started!

---------

Co-authored-by: Federico Giacon <[email protected]>

Author: kaze-cow

.github/workflows/claude-code-review.yml

@@ -0,0 +1,76 @@
+# Mostly copied from https://github.com/anthropics/claude-code-action/blob/main/examples/pr-review-comprehensive.yml
+
+name: Claude Code Review
+
+# This example demonstrates how to use the track_progress feature to get
+# visual progress tracking for PR reviews, similar to v0.x agent mode.
+
+on:
+  pull_request:
+    types: [opened, synchronize, ready_for_review, reopened]
+
+jobs:
+  review-with-tracking:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: write
+      id-token: write
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 1
+
+      - name: PR Review with Progress Tracking
+        uses: anthropics/claude-code-action@v1
+        with:
+          claude_code_oauth_token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }}
+
+          # Enable progress tracking
+          track_progress: true
+
+          # Your custom review instructions
+          prompt: |
+            REPO: ${{ github.repository }}
+            PR NUMBER: ${{ github.event.pull_request.number }}
+
+            Perform a comprehensive code review with the following focus areas:
+
+            1. **Code Quality**
+               - Clean code principles and best practices
+               - Proper error handling and edge cases
+               - Code readability and maintainability
+
+            2. **Security**
+               - Check for potential security vulnerabilities
+               - Validate input sanitization
+               - Review authentication/authorization logic
+
+            3. **Performance**
+               - Identify potential performance bottlenecks
+               - Review database queries for efficiency
+               - Check for memory leaks or resource issues
+
+            4. **Testing**
+               - Verify adequate test coverage
+               - Review test quality and edge cases
+               - Check for missing test scenarios
+
+            5. **Documentation**
+               - Ensure code is properly documented
+               - Verify README updates for new features
+               - Check API documentation accuracy
+
+            Provide detailed feedback using inline comments for specific issues.
+            Use top-level comments for general observations or praise.
+
+          # Tools for comprehensive PR review
+          claude_args: |
+            --allowedTools "mcp__github_inline_comment__create_inline_comment,Bash(gh pr comment:*),Bash(gh pr diff:*),Bash(gh pr view:*)"
+
+# When track_progress is enabled:
+# - Creates a tracking comment with progress checkboxes
+# - Includes all PR context (comments, attachments, images)
+# - Updates progress as the review proceeds
+# - Marks as completed when done

.github/workflows/claude.yml

@@ -0,0 +1,52 @@
+# Mostly copied from https://github.com/anthropics/claude-code-action/blob/main/examples/claude.yml
+
+name: Claude Code
+
+on:
+  issue_comment:
+    types: [created]
+  pull_request_review_comment:
+    types: [created]
+  issues:
+    types: [opened, assigned]
+  pull_request_review:
+    types: [submitted]
+
+jobs:
+  claude:
+    if: |
+      (github.event_name == 'issue_comment' && contains(github.event.comment.body, '@claude')) ||
+      (github.event_name == 'pull_request_review_comment' && contains(github.event.comment.body, '@claude')) ||
+      (github.event_name == 'pull_request_review' && contains(github.event.review.body, '@claude')) ||
+      (github.event_name == 'issues' && (contains(github.event.issue.body, '@claude') || contains(github.event.issue.title, '@claude')))
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: read
+      issues: read
+      id-token: write
+      actions: read # Required for Claude to read CI results on PRs
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 1
+
+      - name: Run Claude Code
+        id: claude
+        uses: anthropics/claude-code-action@v1
+        with:
+          claude_code_oauth_token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }}
+
+          # This is an optional setting that allows Claude to read CI results on PRs
+          additional_permissions: |
+            actions: read
+
+          # Optional: Give a custom prompt to Claude. If this is not specified, Claude will perform the instructions specified in the comment that tagged it.
+          # prompt: 'Update the pull request description to include a summary of changes.'
+
+          # Optional: Add claude_args to customize behavior and configuration
+          # See https://github.com/anthropics/claude-code-action/blob/main/docs/usage.md
+          # or https://docs.claude.com/en/docs/claude-code/cli-reference for available options
+          # claude_args: '--allowed-tools Bash(gh pr:*)'
+