refactor(tmux-subagent): stabilize polling, execution and session lifecycle with runner

src/features/tmux-subagent/attachable-session-status.ts

@@ -0,0 +1,11 @@
+const ATTACHABLE_SESSION_STATUSES = ["idle", "running"] as const
+
+export type AttachableSessionStatus = (typeof ATTACHABLE_SESSION_STATUSES)[number]
+
+export function isAttachableSessionStatus(
+  status: string | undefined,
+): status is AttachableSessionStatus {
+  return ATTACHABLE_SESSION_STATUSES.some(
+    (attachableSessionStatus) => attachableSessionStatus === status,
+  )
+}