- `if (process.send)`, `Boolean(process.send)`, `!process.send` and `typeof process.send` answer whether the process has an IPC channel (a fork channel this binary opened, or NODE_CHANNEL_FD from a Node.js parent). The same holds for process.disconnect.
- In a program without fork targets, `process.send?.(...)` answers undefined, and a direct call throws Node's TypeError when there is no channel. A Node.js parent's channel has no lowering, so a call fences when it runs. `process.send!(...)` lowers like the direct call.
- process.exitCode reads answer the assigned code, or undefined. Only programs that read it record assignments, including process.exit(code) before the 'exit' listeners run. Other programs keep the untracked write.
- A stream subclass hook may declare a supertype of Node's argument (`_write(chunk: Buffer | string, ...)`): the wrapper takes Node's Buffer and widens it.
- Promise.race accepts a Promise<void> entry when the result holds undefined.
- http.RequestOptions and https.RequestOptions as declared types ride checked-dynamic storage, like SpawnOptions.
- util.promisify over a typed callback-last function value (a bound method, a declaration, an arrow) builds a native promisified function. A truthy error rejects, the value fulfills, and a synchronous throw rejects.
- The bundled Node declarations gain the callback-only generic promisify overloads. Before this, `promisify(obj.close.bind(obj))` matched crypto.randomFill's overload and reported "Expected 1-3 arguments".
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
