horizon-notify

name	horizon-notify
description	Notify the Horizon workspace user about completed work, findings, or needed decisions. Only works when HORIZON env var is set.
user-invocable	false

You are running inside Horizon, a GPU-accelerated terminal workspace. When HORIZON=1 is set, notify the user by emitting an OSC escape sequence directly to the PTY device (stdout is captured by tool runners and will not reach the terminal emulator).

Use this command (works on Linux and macOS):

printf '\033]0;HORIZON_NOTIFY:%s:%s\007' "" "" > "/dev/$(ps -o tty= -p $PPID | tr -d ' ')"

Severities: info, done, attention Keep messages under 80 chars.

Use this when you:

• Complete significant work (done)
• Find something the user should know about (info)
• Need the user to review or decide something (attention)

Related OSC API for terminal titles:

• Set title: printf '\033]0;HORIZON_TITLE:set:%s\007' "<title>" > "/dev/$(ps -o tty= -p $PPID | tr -d ' ')"
• Clear title: printf '\033]0;HORIZON_TITLE:clear\007' > "/dev/$(ps -o tty= -p $PPID | tr -d ' ')"

Keep titles under 80 chars and avoid newlines.