Use cases
Every program below is the same primitive: a card that carries your rulebook — merchant locks, caps and approval gates — so a rule, or a person, decides each purchase.
A program releases restricted funds to a recipient and must show a funder how every dollar was used. Rules encode the program's own policy; the trace is the report.
spend_cap · mcc_block · approval_threshold · time_window
An adjuster authorizes an advance under a policy limit. The endorsement already names covered categories, a ceiling and a period — which is a rulebook in insurance English.
mcc_block · spend_cap · time_window · per_merchant_spend_cap
A technician declares a purchase at the supply house. A webhook confirms the job is open and assigned before a card is funded, so job costing happens at declaration rather than reconciliation.
webhook_check · merchant_lock · amount_ceiling · velocity
Money goes to people who do not work for you. You keep control after it leaves your hands, and there is a way to say yes when somebody genuinely needs an exception.
merchant_lock · approval_threshold · new_merchant_review · max_uses
A named person can be surcharged personally for a distribution they cannot justify. Approving before the purchase turns the approval into the accounting line.
approval_threshold · mcc_block · spend_cap · velocity
Prior approval is already required in writing and enforced by an audit months later. The rule makes the approval the thing that funds.
webhook_check · approval_threshold · per_merchant_spend_cap
A trip needs contingency money that costs nothing if it is never used. The card carries an amount and expires the same day.
time_window · max_uses · amount_ceiling
A contractor or crew gets a card that works at one supplier, for this job, up to this amount, today — then closes itself.
merchant_lock · amount_ceiling · time_window · max_uses
Anything that tops up from a card is a purchase, and a rule can refuse it. Velocity and cooldown catch a runaway loop in seconds rather than a day.
velocity · cooldown · duplicate_charge_guard · per_merchant_spend_cap
The sharpest case, not the market. It declares what it intends to buy, waits for a verdict, and never holds a card number.
webhook_check · amount_ceiling · velocity · duplicate_charge_guard