Payments — acceptance criteria

Settling a payment

4 scenarios — these are acceptance criteria for what the service must do, not a description of what it does.

binding spec features/settle-payment.feature @ 2.0.0 — the spec of record. It states what must be; implementations converge on it, never the reverse.

Enforced by

check:version — any change must bump the artifact and service versions; a silent edit fails CI
bound by implementations in strict mode — an unbound scenario fails their build
check:intent — every schema element added to a contract must be named here
gherkin-lint

Version history

Version	First released	Service version
`2.0.0`	2026-08-27	3.0.0
`1.1.0`	2026-08-23	2.0.0
`1.0.0`	2026-08-23	1.0.0

Consume it

Agents, over MCP: get_acceptance_criteria('payments')
Raw spec: features/settle-payment.feature
Implementations pin the release tag payments/v3.0.1 in their contracts.lock and fetch read-only — the full loop is on Drive an implementation.

Settlement is terminal. Authorisation is not.

Settlement emits exactly one event

Givenan authorised payment p-1 for order o-1 of 2500 pence
Whenthe processor confirms settlement
Thena PaymentSettled event is published on payments.settled.v2
Andthe event data amount_pence is 2500

Settlement events are CloudEvents envelopes

Givenan authorised payment p-3 for order o-3 of 1000 pence
Whenthe processor confirms settlement
Thena PaymentSettled event is published on payments.settled.v2
Andthe envelope carries specversion 1.0, a unique id and a time
Andthe envelope source is /payments and its type is com.hungovercoders.payments.settled.v2
Andthe envelope subject is the payment_id, with datacontenttype application/json
Andthe data carries the payment_id, order_id, settled_at and amount_pence
Andhandlers dedupe on the envelope id

Duplicate settlement callbacks are idempotent

Givenpayment p-1 has already settled
Whenthe processor sends the settlement callback again
Thenno second PaymentSettled event is published

A reversal after authorisation does not emit settlement

Givenan authorised payment p-2
Whenthe authorisation is reversed
Thenno PaymentSettled event is published for p-2

Raw Gherkin

Feature: Settling a payment
  Settlement is terminal. Authorisation is not.

  Scenario: Settlement emits exactly one event
    Given an authorised payment "p-1" for order "o-1" of 2500 pence
    When the processor confirms settlement
    Then a "PaymentSettled" event is published on "payments.settled.v2"
    And the event data amount_pence is 2500

  Scenario: Settlement events are CloudEvents envelopes
    Given an authorised payment "p-3" for order "o-3" of 1000 pence
    When the processor confirms settlement
    Then a "PaymentSettled" event is published on "payments.settled.v2"
    And the envelope carries specversion "1.0", a unique id and a time
    And the envelope source is /payments and its type is com.hungovercoders.payments.settled.v2
    And the envelope subject is the payment_id, with datacontenttype "application/json"
    And the data carries the payment_id, order_id, settled_at and amount_pence
    And handlers dedupe on the envelope id

  Scenario: Duplicate settlement callbacks are idempotent
    Given payment "p-1" has already settled
    When the processor sends the settlement callback again
    Then no second "PaymentSettled" event is published

  Scenario: A reversal after authorisation does not emit settlement
    Given an authorised payment "p-2"
    When the authorisation is reversed
    Then no "PaymentSettled" event is published for "p-2"