Durable cron jobs fire across all open sessions, not scoped to the session that created them

When a durable cron job is created in one Claude Code session, any other session open on the same machine can pick it up and fire it. This makes it difficult to keep scheduled work organized and auditable, especially when running multiple chats simultaneously.

Expected behavior: A durable cron job should fire in the session that created it, or at minimum provide a way to pin a job to a specific session.

Actual behavior: Any idle session on the machine can fire any durable job, regardless of which session scheduled it. This causes duplicate runs and makes it unpredictable which chat will execute the job.

Suggested improvement: Scope durable cron jobs to the session that created them, or add a session-pinning option so users can control which session runs a given job.