V3 Go toolchain capability pack. By-value connector composition (service_kind=cli, no separate ingredient): one local go CLI ingredient exposes bounded project operations for readiness, project Go environment context, go.mod JSON inspection, local package discovery, module dependency inventory, tests, and vet diagnostics. All project operations run from an explicit project directory cwd supplied at execution time, use readonly module resolution where package/module loading is involved, avoid caller-supplied Go flags, avoid shell wrappers, and keep diagnostics visible as structured output. Test, vet, and dependency inventory operations are approval-gated because the Go toolchain can compile project code, may invoke cgo/toolchain helpers, may execute test code, may contact module sources if dependencies are missing from cache, and may write build/test/module cache state. Requires go on PATH.