Storage products and lifecycles

“Retention” is not one switch. Each product answers a different recovery or query need and has its own budget.

Product	What it is for	Typical policy
State	Mutable reducer state needed for future blocks	durable or checkpointed
Output	Entities served by generic or processor-owned queries	latest, window, full, or none
Artifacts	Compact immutable results reusable for replay/export	bounded retention or none
Delivery	Ordered change history for external consumers	best effort, until acknowledged, or none
Checkpoints	Recovery points for processor state	automatic with a finite keep count
Undo	Unfinalized branch replacement	bounded by a reorg safety depth
Raw history	Reusable normalized source material	explicitly enabled, segmented, and bounded

The policies are orthogonal. An externalized processor can retain durable state and an acknowledgement-fenced change log while keeping no query output. A latest-value processor can retain one materialized entity with no delivery log.

Hard ceilings and backpressure

Process memory, temporary material, mapped deltas, SQLite size, artifacts, and delivery history have operator ceilings. A limit action is part of the contract: pause work, expire a best-effort consumer with reset required, or reject growth. Leani must not silently discard required delivery history to remain “healthy.”

Start from intent, not disk size

Choose what must survive a restart, what must be queryable, and what an external sink already owns. Then select a checked profile and size its budgets. See Choose an operating profile.