Bun's terminal option data callback doesn't fire inside Bun.serve context (Bun 1.3.9 bug). Switch to script(1) for PTY allocation with piped stdin/stdout. Fix terminal not taking full width/height by adding min-h-0, min-w-0 and width: 100% for proper flex layout. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>