Add CLAUDE.md documentation

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Development Commands
+
+### Build
+- `make build` - Build the OCM agent binary to `build/_output/ocm-agent`
+- `make build-image` - Build container image with tag based on git hash
+- `make clean` - Remove build artifacts
+
+### Testing
+- `make test` - Run all Go tests (alias for `make go-test`)
+- `make go-test` - Run Go unit tests with vet checks
+- `make coverage` - Generate test coverage report using `hack/codecov.sh`
+
+### Linting and Code Quality
+- `make lint` - Run golangci-lint (installs automatically if not present)
+- `make vet` - Run gofmt and go vet checks
+- `make mockgen` - Generate mocks for testing (installs mockgen if needed)
+
+### Running Locally
+- `make serve` - Run OCM agent locally with sample configuration
+  - Requires `$TOKEN`, `$SERVICE` environment variables
+  - Uses sample OCM URL for testing
+
+### Container Operations
+- `make build-push` - Build and push container image
+- `make skopeo-push` - Push image using skopeo (requires QUAY_USER and QUAY_TOKEN)
+
+## Project Architecture
+
+### Core Components
+
+**Main Entry Point**: `cmd/ocm-agent/main.go` - Simple CLI wrapper around the root command
+
+**CLI Framework**: `pkg/cli/`
+- Uses Cobra for command structure
+- Main command is `serve` which starts the HTTP server
+- Configuration handled via Viper with support for config files, env vars, and flags
+
+**HTTP Server**: `pkg/cli/serve/serve.go`
+- Gorilla Mux router for handling webhook endpoints
+- Supports both traditional OSD/ROSA mode and Fleet (HyperShift) mode
+- Prometheus metrics endpoint at `/metrics`
+
+**Request Handlers**: `pkg/handlers/`
+- `webhookreceiver.go` - Main AlertManager webhook receiver
+- `webhookrhobsreceiver.go` - RHOBS (Red Hat Observability Service) webhook receiver
+- `cluster.go` - Cluster management operations
+- `upgrade_policies.go` - Cluster upgrade policy management
+- `readyz.go` / `livez.go` - Health check endpoints
+
+**OCM Integration**: `pkg/ocm/`
+- Wrapper around OCM SDK for API communication
+- Handles authentication (token-based or client credentials)
+- Connection management and retry logic
+
+**Kubernetes Client**: `pkg/k8s/`
+- Kubernetes client-go wrapper for cluster operations
+- Used for reading cluster metadata and applying configurations
+
+### Key Packages
+
+- `pkg/config/` - Configuration management using Viper
+- `pkg/metrics/` - Prometheus metrics collection
+- `pkg/logging/` - Structured logging with logrus
+- `pkg/httpchecker/` - HTTP health checking utilities with retry logic
+- `pkg/consts/` - Application constants
+
+### Operational Modes
+
+**Traditional Mode**: Runs on OSD/ROSA clusters to forward alerts to OCM Service Log
+**Fleet Mode**: Runs in HyperShift management clusters to handle fleet-wide notifications
+
+### Testing Structure
+
+- Unit tests alongside source files (`*_test.go`)
+- Ginkgo/Gomega BDD testing framework
+- Mock generation using `golang/mock`
+- E2E tests in `test/e2e/` directory
+- Test utilities and scripts in `test/` directory
+
+### Container Build
+
+Uses multi-stage Dockerfile in `build/Dockerfile` with FIPS-enabled Go build for security compliance.
+
+## Development Notes
+
+This is a Kubernetes-native Go service that acts as a bridge between cluster monitoring (AlertManager/RHOBS) and OpenShift Cluster Manager services. The agent receives webhook notifications about cluster events and forwards them to appropriate OCM services for SRE visibility and automation.