Review fold: build "\a" + sequence once and dispatch it to exactly one sink (app loop
when the Application runs, write_tty otherwise) instead of two branches with two writes
and two try/excepts. terminal_notify.notify() had a single caller (that fallback), so
write_tty is the public no-app entry and notify() is gone. The loop-side write keeps the
never-raises contract on a dead tty (EIO/closed file) the same way _pet_flush_kitty_frame
does, and _ring_bell skips entirely once _terminal_io_broken is set.
pty A/B re-run on this stack: 400 rings vs 90 frames, 0 aborted, 0 painted, 400/400 delivered.
Symptom (Ghostty, display.pet on, display.bell_on_complete on): at the end of a turn the
input line fills with several rows of base64 and a stale copy of the status bar + pet
stays above the response panel.
Root cause: _ring_bell runs on the agent thread and terminal_notify wrote the OSC 9 /
OSC 777 sequence through its own open("/dev/tty") (or sys.stdout). The prompt_toolkit
loop thread may at that moment be mid-write of a 12 KB kitty APC pet frame, which the tty
drains ~1 KB at a time. The second writer splices into the frame; the foreign ESC aborts
the APC and the terminal paints the remainder of the payload as text at the input cursor.
The wrapped garbage scrolls the screen, so the panel that follows is printed against a
stale cursor position and the old chrome survives above it.
Change: when the CLI's Application is running, _ring_bell hands "\a" + the notification
sequence to the app loop (_run_on_app_loop -> _write_terminal_sequence), serializing it
behind the renderer and the after_render frame writer. terminal_notify.notify() keeps the
/dev/tty path for callers without a running app; the sequence builder is split out as
notification_sequence().
Verification: pty A/B with the real Application + after_render frame writer, 400 rings
vs 91 frames — base: 3 leaks (4,324 base64 chars painted); fixed: 0 leaks, 400/400
notifications delivered, 0 aborted frames.
- tests/hermes_cli/test_terminal_notify.py: OSC 9 body emitted+sanitized
only when bell flag on; Warp payload only under a supported Warp build.
- configuration.md display section: document the notification behavior
of bell_on_prompt / bell_on_complete.
- contributors/emails: glitchbunny0 (#58957), harshmoney123 (#100805).
kshitijk4poor