Replaces the skipped stdin placeholder with three real tests covering: - reading a single data chunk from stdin - concatenating multiple chunks - propagating stdin error events process.stdin is non-configurable on the real process object, so the tests mock the entire node:process module using a Proxy that intercepts the stdin property and returns a local EventEmitter fixture while forwarding all other property accesses to the real module. The readFromStdin Promise constructor registers handlers synchronously, so events can be emitted immediately after readBodyInput returns its pending Promise without needing setImmediate. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>