Module budget 

Search limits, monotone usage, and the reservation discipline (PSP-10 Definition 5, system 20, Gate AC).

Every branch action reserves resources before it starts and always consumes one nonrefundable action unit. Unused resource reservations may be released; consumed usage never decreases — there is no public decrement. A closed forest cannot reopen: closing consumes the budget by type.

Structs

ReservationRequest

One action’s resource request, reserved before the action starts.

ReservationTicket

Proof one reservation was taken; releasing unused amounts requires it.

SearchLimits

The forest’s finite limits (Definition 5). One set per forest.

SearchUsage

Monotone usage. All fields are reserved-or-consumed totals; nothing public decrements except SearchUsage::release_unused, which may only return part of a held ticket — never below what was actually consumed.

SharedSearchBudget

One forest’s usage behind a shared handle, so the branch tool loops can reserve before every action while the forest holds the same ledgered totals (Gate AC: reservations precede actions; usage never decreases; usage never persists above a limit — overflow clamps at the limit and closes the forest).