The Price Change Attribution API from WritersLogic Verifiable AI Agent Hub — 1 operation(s) for price change attribution.
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openapi: 3.2.0
info:
title: WritersLogic Verifiable AI Agent Hub Price Change…
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: Price Change Attribution
paths:
/api/v1/price-change-attribution:
post:
operationId: price_change_attribution
summary: Attribute a total's change to quantity, price, FX, added and removed lines…
description: 'Explains why a total moved between two versions of a quote, order or invoice (up to 300 lines each), for an agent that must say how much of the change came from quantity, unit price, exchange rate, new lines and dropped lines. Lines are matched by key. Matched lines are decomposed by sequential substitution in the declared factor order (default quantity, then price, then fx), so the effects sum to the change exactly; added and removed lines are their own effects. Rounded minor-unit effects are reconciled so they sum to the rounded total change. The order matters (price-first and quantity-first attribute the cross term differently) and is echoed back. If stated totals are supplied they are checked against the recomputed totals and the drift is reported. Not a variance explanation of why a supplier changed a price.
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/price-change-attribution
security:
- x402: []
- apiKey: []
requestBody:
required: true
content:
application/json:
schema:
type: object
additionalProperties: false
required:
- before
- after
properties:
before:
type: array
minItems: 0
maxItems: 300
items:
type: object
required:
- key
- quantity
- unitPrice
properties:
key:
type: string
minLength: 1
maxLength: 80
quantity:
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.'
unitPrice:
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.'
additionalProperties: false
after:
type: array
minItems: 0
maxItems: 300
items:
type: object
required:
- key
- quantity
- unitPrice
properties:
key:
type: string
minLength: 1
maxLength: 80
quantity:
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.'
unitPrice:
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.'
additionalProperties: false
fx:
type: object
required:
- before
- after
properties:
before:
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.'
after:
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.'
description: Multiplier from line currency to reporting currency, before and after. Default 1 and 1.
additionalProperties: false
order:
type: array
minItems: 1
maxItems: 3
items:
type: string
enum:
- quantity
- price
- fx
description: Substitution order of the factors; each at most once. Default [quantity, price, fx].
currency:
type: string
pattern: ^[A-Z]{3}$
description: ISO 4217 alphabetic code, upper case.
exponent:
type: integer
minimum: 0
maximum: 8
rounding:
type: string
enum:
- half-up
- half-down
- half-even
- up
- down
- ceiling
- floor
description: 'Default half-even. 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.'
statedBeforeTotal:
type: string
pattern: ^-?\d{1,15}(\.\d{1,12})?$
maxLength: 30
description: Optional stated total of `before` (reporting currency) to verify.
statedAfterTotal:
type: string
pattern: ^-?\d{1,15}(\.\d{1,12})?$
maxLength: 30
description: Optional stated total of `after` to verify.
example:
currency: USD
before:
- key: widget
quantity: '100'
unitPrice: '2.00'
- key: gadget
quantity: '10'
unitPrice: '9.99'
after:
- key: widget
quantity: '120'
unitPrice: '2.10'
- key: gizmo
quantity: '5'
unitPrice: '4.00'
statedBeforeTotal: '299.90'
statedAfterTotal: '272.00'
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.'
order:
type: array
items:
type: string
beforeMinor:
type: integer
afterMinor:
type: integer
deltaMinor:
type: integer
description: The exact change (after minus before) rounded once; equals the sum of byFactor and of byLine. It can differ by one unit from afterMinor minus beforeMinor, which round each total separately.
byFactor:
type: object
properties:
quantity:
type: integer
price:
type: integer
fx:
type: integer
added:
type: integer
removed:
type: integer
description: Signed minor-unit effects; they sum to deltaMinor.
byLine:
type: array
items:
type: object
properties:
key:
type: string
kind:
type: string
enum:
- changed
- added
- removed
- unchanged
deltaMinor:
type: integer
exponent:
type: integer
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:
- Price Change Attribution
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