The TMUX environment variable is not inherited when Claude Code runs
bash commands, even though we are inside a tmux session. This caused
the Stop hook's 'gt costs record' to fail with:
Error: --session flag required
Fix: Remove the early return that checked TMUX env var. The
tmux display-message command will naturally fail if we're not
in tmux, so the check was unnecessary and harmful.
Fixes: hq-to0lr
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
9b5c889795