The Credential Coverage API from WritersLogic Verifiable AI Agent Hub — 1 operation(s) for credential coverage.
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openapi: 3.2.0
info:
title: WritersLogic Verifiable AI Agent Hub Credential Coverage 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: Credential Coverage
paths:
/api/v1/credential-coverage:
post:
operationId: credential_coverage
summary: Do licences, certificates or insurance policies cover a required period without…
description: 'Given a required date range (a contract term, a project, a shipment window) and up to 200 credentials each valid from a date to a date (both inclusive), reports the merged covered ranges, every uncovered gap with its first and last day and length, and whether each checkpoint date is covered; a credential ending the day before the next starts is contiguous. Built for an agent verifying insurance, licences, calibration or certification continuity. It does not verify that a credential is genuine, its scope, or renewal status, and does not read the clock.
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/credential-coverage
security:
- x402: []
- apiKey: []
requestBody:
required: true
content:
application/json:
schema:
type: object
additionalProperties: false
required:
- required
- credentials
properties:
required:
type: object
required:
- start
- end
properties:
start:
type: string
pattern: ^\d{4}-\d{2}-\d{2}$
maxLength: 10
end:
type: string
pattern: ^\d{4}-\d{2}-\d{2}$
maxLength: 10
description: Inclusive last day.
credentials:
type: array
maxItems: 200
items:
type: object
required:
- id
- validFrom
- validTo
properties:
id:
type: string
maxLength: 64
validFrom:
type: string
pattern: ^\d{4}-\d{2}-\d{2}$
maxLength: 10
validTo:
type: string
pattern: ^\d{4}-\d{2}-\d{2}$
maxLength: 10
description: Inclusive last valid day.
checkpoints:
type: array
maxItems: 100
items:
type: string
pattern: ^\d{4}-\d{2}-\d{2}$
maxLength: 10
description: Specific dates that must be covered (delivery date, audit date).
toleratedGapDays:
type: integer
minimum: 0
maximum: 365
description: Gaps up to this many days are reported but do not fail (a grace period you are entitled to).
example:
required:
start: '2026-01-01'
end: '2026-12-31'
credentials:
- id: policy-1
validFrom: '2025-07-01'
validTo: '2026-06-30'
- id: policy-2
validFrom: '2026-07-02'
validTo: '2027-06-30'
checkpoints:
- '2026-07-01'
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.'
covered:
type: array
items:
type: object
properties:
from:
type: string
to:
type: string
days:
type: integer
gaps:
type: array
items:
type: object
properties:
from:
type: string
to:
type: string
days:
type: integer
tolerated:
type: boolean
checkpoints:
type: array
items:
type: object
properties:
date:
type: string
covered:
type: boolean
by:
type: array
items:
type: string
requiredDays:
type: integer
coveredDays:
type: integer
reason:
type: string
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:
- Credential Coverage
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