Override ^p/^n in agent session to switch between root windows

agent.sh

@@ -9,6 +9,16 @@ dir="${PWD:-$HOME}"
 # Use the directory basename as window name
 window_name=$dir
 
+# The client that opened the popup, recorded by the `bind A` binding. Its
+# current window is the root window <prefix>A was pressed in; the popup cannot
+# pass that through itself, so resolve it here before attaching.
+popup_client=$(tmux display-message -p '#{@agent_popup_client}' 2>/dev/null || true)
+origin_window=""
+if [ -n "$popup_client" ]; then
+  origin_window=$(tmux list-clients -F $'#{client_name}\x1f#{window_id}' \
+    | awk -v FS=$'\x1f' -v client="$popup_client" '$1 == client { print $2; exit }')
+fi
+
 # Create the agent session if it doesn't exist
 if ! tmux has-session -t agent; then
   tmux new-session -ds agent -c "$dir" -n "$window_name" "$script_dir/agent-cmd.sh"
@@ -20,6 +30,9 @@ fi
 tmux set-option -t agent status off
 tmux set-option -t agent remain-on-exit on
 tmux set-option -t agent default-command "$script_dir/agent-cmd.sh"
+# Session-scoped (not -g) so the root-session window changes agent-sync.sh makes
+# cannot re-trigger it.
+tmux set-hook -t agent session-window-changed "run -b '$script_dir/agent-sync.sh'"
 
 # Search for an existing window with matching directory
 target_window=""
@@ -32,6 +45,12 @@ for window_id in $(tmux list-windows -t agent -F '#{window_id}'); do
 done
 
 if [ -n "$target_window" ]; then
+  # Remember which root window this agent window came from, refreshed on every
+  # invocation. Recorded *before* selecting, so the sync hook select-window
+  # fires sees this invocation's origin rather than the previous one's.
+  if [ -n "$origin_window" ]; then
+    tmux set-window-option -t "$target_window" @agent_origin_window "$origin_window"
+  fi
   # Select the existing window
   tmux select-window -t "$target_window"
 else
@@ -39,6 +58,9 @@ else
   tmux new-window -t agent -c "$dir" -n "$window_name"
   # Store the directory in a window option for later matching
   tmux set-window-option -t agent @agent_dir "$dir"
+  if [ -n "$origin_window" ]; then
+    tmux set-window-option -t agent @agent_origin_window "$origin_window"
+  fi
 fi
 
 # Prune windows whose recorded directory no longer exists. This runs after the