I split my daemon in two so a Node subprocess could own the PTY

nickboy@users.noreply.github.com (Nick Liu) — Sun, 10 May 2026 00:00:00 +0000

I built a Claude Code permission gate that holds an HTTP response open until a Stream Deck key is pressed. Then I needed to inject a keystroke into Claude Code's own TTY so a key press could write `1\r` straight into Claude's stdin. Bun can hold HTTP open all day. Bun cannot reliably wrap a child PTY through `node-pty` and capture the parent shell's PID. So I split my daemon: HTTP and WebSocket stay on Bun, and a Node CommonJS subprocess owns the PTY that runs Claude.

🧪 Tested with Claude Code 2.1.x · macOS

(Quick grounding before the story: a PTY (pseudo-terminal) is the kernel object every interactive shell talks to. It’s a pair of file descriptors, master and slave; the program reads/writes the slave end as if it were a real terminal, and anything you write to the master end looks to that program like a human typing. The TTY is the slave end seen from the child’s side. node-pty is Microsoft’s library that gives a JavaScript parent process a writable handle to the master. Bun is a JavaScript runtime, Node’s faster sibling, and Node CommonJS is plain old require()-based Node, no transpile step. The story below is about which runtime owns the PTY.)

Bun on Nick Liu - Software Engineer

I split my daemon in two so a Node subprocess could own the PTY