Pi Durable checkpoints a wait and releases the invocation

What this changes for operators

• Durable host builders: back up storage before 1.4 opens it, plan the one-way cutover, split post-wait work into a new phase and supply each document’s checkpointWhen predicate. This can replace an invocation kept alive solely to wait.
• Persist the wake outside the dying process. Kill a harmless job around checkpoint commit and alarm registration, then verify it resumes once intended and reconciles any uncertain external effect. Those receipts, not a resumed transcript alone, would establish the host’s recovery.
• Measure idle resource use, wake latency and recovery interventions against the old host. Attention moves from supervising live waits to scheduling and storage custody; no current host inherits durable wakes merely by sharing Pi’s package family.