# ADR-0014: Health Check Implementation

## Status
Accepted

## Context
The platform needs health check endpoints for:
- Kubernetes liveness probes (`/healthz`)
- Kubernetes readiness probes (`/ready`)
- Monitoring and alerting
- Load balancer health checks

Health checks should be:
- Fast and lightweight
- Check critical dependencies (database, cache, etc.)
- Provide clear status indicators

## Decision
Implement **custom health check registry** with composable checkers:

1. **Liveness endpoint** (`/healthz`): Always returns 200 if process is running
2. **Readiness endpoint** (`/ready`): Checks all registered health checkers
3. **Health check interface**: `type HealthChecker interface { Check(ctx context.Context) error }`
4. **Registry pattern**: Modules can register additional health checkers

**Rationale:**
- Custom implementation gives full control
- Composable design allows modules to add checks
- Simple interface is easy to test
- No external dependency for basic functionality
- Can extend with Prometheus metrics later

## Consequences

### Positive
- Lightweight and fast
- Extensible by modules
- Easy to test
- Clear separation of liveness vs readiness

### Negative
- Need to implement ourselves (though simple)
- Must maintain the registry

### Implementation Notes
- Create `pkg/health/health.go` interface
- Implement `internal/health/registry.go` with checker map
- Register core checkers: database, cache (if enabled)
- Add endpoints to HTTP router
- Return JSON response: `{"status": "ok", "checks": {...}}`
- Consider timeout (e.g., 5 seconds) for readiness checks