The Cash Rounding API from WritersLogic Verifiable AI Agent Hub — 1 operation(s) for cash rounding.
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openapi: 3.2.0
info:
title: WritersLogic Verifiable AI Agent Hub Cash Rounding API
version: 2.0.0
description: Pay-per-call agents settled in USDC on Base via x402. Every response carries a signed provenance envelope.
contact:
name: WritersLogic
url: https://writerslogic.com/agents
email: agents@writerslogic.com
servers:
- url: https://agents.writerslogic.com
tags:
- name: Cash Rounding
paths:
/api/v1/cash-rounding:
post:
operationId: cash_rounding
summary: Cash rounding to the smallest payable coin (CHF, CAD, SEK, AUD or a caller rule)
description: 'Rounds up to 100 final cash totals to the smallest payable increment, for an agent computing what a customer actually pays in cash or the change owed. Built-in rules exist only for currencies with an official source: CHF 0.05 (Münzverordnung SR 941.101), CAD 0.05 (Government of Canada), SEK 1 (Lag 1970:1029), AUD 0.05 (Consumer Protection WA); any other currency needs a caller increment. Rounds the total only, never line items; card and electronic payments pass through unrounded where the source says so. A sub-cent tie the source does not settle returns unknown with both candidate amounts. Not a tax or invoice calculator.
Price: 0.005 USDC on Base (x402).'
x-x402-price-usdc: '0.005'
x-x402-amount: '5000'
x-payment-info:
protocols:
- x402
price:
mode: fixed
currency: USD
amount: '0.005'
x-audience: business
x-sample-url: https://agents.writerslogic.com/api/v1/samples/cash-rounding
security:
- x402: []
- apiKey: []
requestBody:
required: true
content:
application/json:
schema:
type: object
additionalProperties: false
required:
- items
properties:
items:
type: array
minItems: 1
maxItems: 100
items:
type: object
required:
- amount
properties:
amount:
type: string
pattern: ^-?\d{1,15}(\.\d{1,12})?$
maxLength: 30
description: 'Decimal string such as "-12.50" (up to 15 integer and 12 fraction digits). JSON numbers are not accepted: they are binary floats.'
currency:
type: string
pattern: ^[A-Z]{3}$
description: ISO 4217 alphabetic code, upper case.
tender:
type: string
enum:
- cash
- electronic
description: Default cash.
increment:
type: string
pattern: ^-?\d{1,15}(\.\d{1,12})?$
maxLength: 30
description: 'Caller rule: smallest payable amount in major units, e.g. "0.05". Overrides the built-in rule.'
rounding:
type: string
enum:
- half-up
- half-down
- half-even
- up
- down
- ceiling
- floor
description: 'Tie mode only: an exact tie between two payable amounts under a caller increment or a built-in rule that states no tie rule. Any other amount rounds to the nearest payable amount, and a tie rule the cited source states (SEK) wins. half-up: ties away from zero. half-down: ties toward zero. half-even: ties to the even neighbour. up: away from zero. down: toward zero. ceiling: toward +infinity. floor: toward -infinity.'
additionalProperties: false
example:
items:
- amount: '10.02'
currency: CHF
- amount: '10.03'
currency: CAD
- amount: '10.025'
currency: CHF
- amount: '49.50'
currency: SEK
responses:
'200':
description: Paid result with provenance
content:
application/json:
schema:
type: object
properties:
data:
type: object
properties:
status:
type: string
enum:
- pass
- fail
- unknown
- unsupported
description: 'pass: every rule held. fail: a rule was violated (see witnesses). unknown: the input lacks the evidence to decide. unsupported: outside what this engine covers. Missing evidence is never a pass.'
items:
type: array
items:
type: object
properties:
index:
type: integer
status:
type: string
enum:
- pass
- fail
- unknown
- unsupported
rounded:
type: string
description: Payable total; absent when status is unknown.
adjustment:
type: string
description: rounded minus amount, signed.
increment:
type: string
rule:
type: string
enum:
- built-in
- caller
- electronic-exempt
- none
source:
type: string
tieCandidates:
type: array
items:
type: string
description: Both neighbours when an exact tie is not settled by the rule.
witnesses:
type: array
items:
type: object
properties:
ruleId:
type: string
detail:
type: string
path:
type: string
description: JSON pointer or dotted path into the input.
offset:
type: integer
index:
type: integer
expected:
description: What the rule required.
actual:
description: What the input had.
versions:
type: object
description: Every semantic dependency of this answer (engine, tables and their as-of dates, tokenizer, calendar, rounding profile).
limits:
type: array
items:
type: string
deterministic:
type: boolean
description: 'Always true: pure code, no model.'
_provenance:
type: object
description: C2PA-aligned manifest and W3C VC 2.0 (eddsa-jcs-2022) issued by the hub DID; verify at POST /api/v1/verify-provenance
required:
- data
- _provenance
'400':
description: Invalid request (no payment consumed)
content:
application/json:
schema:
type: object
properties:
error:
type: string
code:
type: string
'401':
description: Invalid X-API-KEY
content:
application/json:
schema:
type: object
properties:
error:
type: string
code:
type: string
'402':
description: Payment required or invalid
content:
application/json:
schema:
type: object
description: x402 v2 PaymentRequired (also base64 in the PAYMENT-REQUIRED header)
properties:
x402Version:
type: integer
error:
type: string
code:
type: string
resource:
type: object
accepts:
type: array
items:
type: object
extensions:
type: object
'502':
description: Upstream failure; the payment is released or not settled
content:
application/json:
schema:
type: object
properties:
error:
type: string
code:
type: string
tags:
- Cash Rounding
components:
securitySchemes:
x402:
type: apiKey
in: header
name: PAYMENT-SIGNATURE
description: x402 v2 payment payload (base64) sent after a 402 challenge
apiKey:
type: apiKey
in: header
name: X-API-KEY