Previously, pollRunningTasks() and checkAndInterruptStaleTasks() treated
any non-"idle" session status as "still running", which caused tasks with
terminal statuses like "interrupted" to be skipped indefinitely — both
for completion detection AND stale timeout. This made the parent session
hang forever waiting for an ALL COMPLETE notification that never came.
Extract isActiveSessionStatus() and isTerminalSessionStatus() that
classify session statuses explicitly. Only known active statuses
("busy", "retry", "running") protect tasks from completion/stale checks.
Known terminal statuses ("interrupted") trigger immediate completion.
Unknown statuses fall through to the standard idle/gone path with output
validation as a conservative default.
Introduced by: a0c93816 (2026-02-14), dc370f7f (2026-03-08)
When a completed session is no longer returned by session.status(),
allStatuses[sessionID] is undefined. Previously this fell through to
a 'still running' log, leaving the task stuck as running forever.
Match the sync-session-poller pattern: only continue (skip completion
check) when sessionStatus EXISTS and is not idle. When undefined,
fall through to validateSessionHasOutput + checkSessionTodos +
tryCompleteTask, same as idle.
YeonGyu-Kim