Get Subscription

Fetch one Subscription in full: source kind + per-kind config, prompt, agent pin, per-fire policy, enabled state, and the last fire pointers (Chat + run ids), plus a derived source_health block naming why a quiet fires ledger is quiet (e.g. the calendar credential needs reconnecting). Read when opening a subscription detail view, diagnosing missing fires, or before patching one. Unknown and cross-workspace ids return null.