The thing that made me grin today: I tell Claude Code to “work in a git worktree,” the agent jumps into a fresh checkout, and my Ghostty terminal follows it — new tabs and splits open right inside the worktree, not where I launched. The agent moves; the terminal moves with it. Feels like magic, and it’s one escape sequence.
A bit about OSC
Escape sequences aren’t just colors. OSC — Operating System Command — is the family that sends side-channel messages to your terminal: window title, clipboard, and the one here, the current directory (OSC 7):
ESC ] 7 ; file://HOST/path ESC \
Your shell fires it on every cd. I wire a Claude Code hook to fire it whenever the agent changes directory too. That’s the whole trick.
The Gotcha (The Actual TIL)
Ghostty silently drops OSC 7 when the HOST doesn’t match the machine’sgethostname() — logging OSC 7 host must be local — and freezes the directory at its last good value. My hook sent the short name; macOS wants the full one:
- file://lemon/... # hostname -s ✗ rejected
+ file://lemon.local/... # hostname ✓ accepted
One word. The hook had silently never worked.
Bonus Trap
You can’t test it at a prompt — your shell re-emits OSC 7 the instant the command returns and clobbers your test. Hold the prompt hostage:
printf '\033]7;file://%s/tmp/\033\\' "$(hostname)"; sleep 15
# open a new tab within 15s → it lands in /tmp
This was built while debugging my dotfiles hooks for Claude Code + Ghostty.