The Cross Field Rules API from WritersLogic Verifiable AI Agent Hub — 1 operation(s) for cross field rules.
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openapi: 3.2.0
info:
title: WritersLogic Verifiable AI Agent Hub Cross Field Rules 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: Cross Field Rules
paths:
/api/v1/cross-field-rules:
post:
operationId: cross_field_rules
summary: 'Check caller-declared rules across fields of a JSON record: end after start…'
description: 'Evaluates up to 100 rules you declare over one JSON document and reports, per rule, pass, fail or unknown with the JSON pointer of every violating field and the actual value class (absent, null, empty string, value). Rule kinds: compare (>, >=, /lines/*/start). Presence is explicit (defined, non-null, non-empty) so absent, null and empty are never conflated. A missing operand yields unknown unless you choose fail or skip. For agents validating tool arguments or records beyond what a per-field schema can say. Rules are data, not code: no expressions are evaluated.
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: developer
x-sample-url: https://agents.writerslogic.com/api/v1/samples/cross-field-rules
security:
- x402: []
- apiKey: []
requestBody:
required: true
content:
application/json:
schema:
type: object
additionalProperties: false
required:
- data
- rules
properties:
data:
description: The JSON document the rules apply to.
rules:
type: array
minItems: 1
maxItems: 100
items:
type: object
additionalProperties: false
required:
- id
- kind
properties:
id:
type: string
maxLength: 80
kind:
type: string
enum:
- compare
- required-if
- forbidden-if
- exactly-one
- at-most-one
- at-least-one
- all-or-none
- sum-equals
left:
type: string
maxLength: 300
description: JSON pointer; * matches every array element.
op:
type: string
enum:
- ==
- '!='
- '>'
- '>='
- <
- <=
right:
type: string
maxLength: 300
description: JSON pointer compared with left (use value for a constant).
value:
description: Constant to compare with, or the expected total.
as:
type: string
enum:
- auto
- number
- decimal
- date
- datetime
- string
when:
type: object
additionalProperties: false
required:
- path
- op
properties:
path:
type: string
maxLength: 300
op:
type: string
enum:
- equals
- not-equals
- in
- not-in
- present
- absent
- empty
value:
description: Operand for equals, not-equals, in, not-in.
require:
type: array
maxItems: 20
items:
type: string
maxLength: 300
forbid:
type: array
maxItems: 20
items:
type: string
maxLength: 300
fields:
type: array
maxItems: 50
items:
type: string
maxLength: 300
total:
type: string
maxLength: 300
tolerance:
type: string
maxLength: 40
description: Decimal tolerance for sum-equals, default 0.
presence:
type: string
enum:
- defined
- non-null
- non-empty
description: 'What counts as present: defined (key exists), non-null (default), non-empty.'
onMissing:
type: string
enum:
- unknown
- fail
- skip
description: 'Missing or null compare operand: unknown (default), fail or skip.'
example:
data:
start: '2026-03-01'
end: '2026-02-01'
kind: card
card: '4111'
iban: null
rules:
- id: end-after-start
kind: compare
left: /end
op: '>'
right: /start
as: date
- id: card-needs-number
kind: required-if
when:
path: /kind
op: equals
value: card
require:
- /card
- id: one-payment-method
kind: exactly-one
fields:
- /card
- /iban
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.'
rules:
type: array
items:
type: object
properties:
id:
type: string
kind:
type: string
verdict:
type: string
enum:
- pass
- fail
- unknown
evaluations:
type: integer
violations:
type: array
items:
type: object
properties:
path:
type: string
detail:
type: string
actual:
description: Value or value class found.
counts:
type: object
properties:
pass:
type: integer
fail:
type: integer
unknown:
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:
- Cross Field Rules
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