Add Claude Code configuration files

.gitignore

@@ -4,3 +4,6 @@
 # Local dev files
 /go.work
 /go.work.sum
+
+# Claude Code local settings
+.claude/settings.local.json

CLAUDE.md

@@ -0,0 +1,119 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+This is **danger-go**, a Go implementation of the popular Danger tool that runs automation rules during PR reviews. It's a wrapper around Danger JS that allows writing Dangerfiles in Go instead of JavaScript.
+
+The project consists of:
+
+- A Go library for writing Danger rules (`api.go`, `types.go`)
+- A command-line tool (`cmd/danger-go/`) that wraps Danger JS
+- Type definitions for various platforms (GitHub, GitLab) in `danger-js/` directory
+- Platform-specific types in separate files (`types_*.go`)
+
+## Architecture
+
+### Core Components
+
+1. **API Layer** (`api.go`): Main public API with the `T` struct providing methods:
+   - `Message()` - Add informational messages
+   - `Warn()` - Add warnings that don't fail the build
+   - `Fail()` - Add failures that fail the build
+   - `Markdown()` - Add raw markdown to comments
+
+2. **Types** (`types.go`): Core data structures like `Results`, `Violation`, `GitHubResults`
+
+3. **Danger JS Bridge** (`danger-js/`): Integration layer that:
+   - Calls the `danger` (JS) binary to get DSL data
+   - Processes commands (`ci`, `local`, `pr`) by wrapping Danger JS
+   - Contains platform-specific type definitions
+
+4. **CLI Tool** (`cmd/danger-go/`): Command-line interface supporting:
+   - `ci` - Run on CI/CD
+   - `local` - Run locally for git hooks
+   - `pr` - Test against existing GitHub PR
+   - `runner` - Internal command for processing DSL via STDIN
+
+## Development Commands
+
+### Building and Testing
+
+```bash
+# Run tests
+go test -v ./...
+
+# Build the CLI tool
+go build -o danger-go cmd/danger-go/main.go
+
+# Install the CLI tool globally
+go install github.com/danger/golang/cmd/danger-go@latest
+```
+
+### Running Danger Locally
+
+```bash
+# Install dependencies first
+npm install -g danger
+go install github.com/danger/golang/cmd/danger-go@latest
+
+# Run danger in CI mode (from build/ci directory)
+cd build/ci && danger-go ci
+
+# Run locally for testing
+danger-go local
+
+# Test against a specific PR
+danger-go pr https://github.com/owner/repo/pull/123
+```
+
+### Development Workflow
+
+The project follows standard Go conventions:
+
+- Use `go fmt` for formatting
+- Run `go vet` for static analysis
+- Follow [Effective Go](https://go.dev/doc/effective_go) guidelines
+- Write table-driven tests where appropriate
+- Use conventional commit messages
+
+## Dangerfile Structure
+
+Dangerfiles are Go programs that must:
+
+1. Be in a separate directory (e.g., `build/ci/`)
+2. Have a `Run(d *danger.T, pr danger.DSL)` function
+3. Import `github.com/danger/golang`
+4. Have their own go.mod file
+
+Example Dangerfile setup:
+
+```bash
+mkdir build/ci
+cd build/ci
+go mod init dangerfile
+go get github.com/danger/golang
+```
+
+## Key Dependencies
+
+- **Go 1.24+** required
+- **Danger JS** must be installed globally (`npm install -g danger`)
+- **github.com/stretchr/testify** for testing
+
+## CI/CD Integration
+
+The project uses GitHub Actions (`.github/workflows/test.yml`) which:
+
+- Installs Go 1.24+
+- Installs Node.js and Danger JS
+- Runs both Go tests and danger-go CI checks
+- Requires `GITHUB_TOKEN` for GitHub API access
+
+## Testing
+
+- Use `go test -v ./...` to run all tests
+- Tests are in `*_test.go` files
+- Internal tests in `api_internal_test.go` test unexported functions
+- Follow table-driven test patterns where applicable