diff --git a/lib/hooks.sh b/lib/hooks.sh
index a39f637..84a6f60 100644
--- a/lib/hooks.sh
+++ b/lib/hooks.sh
@@ -16,7 +16,9 @@ SETTINGS_FILE="${PROJECT_ROOT}/.claude/settings.local.json"
 
 # The hook command checks we're inside the agent-loop tmux session before killing.
 # This prevents the hook from affecting other CC sessions open in the same project.
-HOOK_COMMAND='tmux display-message -p "#{session_name}" 2>/dev/null | grep -q "^agent-loop$" && kill -INT $PPID || true'
+# IMPORTANT: Must check $TMUX first — tmux display-message can succeed even outside
+# tmux by falling back to the most recently created session, which would be agent-loop.
+HOOK_COMMAND='[ -n "$TMUX" ] && tmux display-message -p "#{session_name}" 2>/dev/null | grep -q "^agent-loop$" && kill -INT $PPID || true'
 
 install_hooks() {
     if [ ! -f "$SETTINGS_FILE" ]; then