Function register_agent_open_panes 

fn register_agent_open_panes(engine: &Arc<WshRpcEngine>, state: &AppState)

agent.open-panes: every agent pane in this instance, wherever it is. A renderer only knows the panes in its own window, so “is this agent open?” asked of a renderer misses one in a floating or other window — My agents then offered a reattach for an agent that was live, and the second pane could never run (SPEC_AGENT_SAME_PROCESS_DUPLICATE_PANE_ RECOVERY_2026_10_01.md §2 G0). Same source as agent.tracked-blocks.