The Settlement Date API from WritersLogic Verifiable AI Agent Hub — 1 operation(s) for settlement date.
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openapi: 3.2.0
info:
title: WritersLogic Verifiable AI Agent Hub Settlement Date 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: Settlement Date
paths:
/api/v1/settlement-date:
post:
operationId: settlement_date
summary: 'Settlement date for a trade date: US equities T+1 on NYSE and Federal Reserve…'
description: 'Computes the settlement date for a trade date under US equities T+1 (17 CFR 240.15c6-1, compliance date 2024-05-28) counting only days when the NYSE and the Federal Reserve Banks are open, or T+n on a named or caller calendar, and checks an asserted settlement date. The settlement-day rule (NYSE and Reserve Banks both open, so Columbus Day and Veterans Day are skipped) is our inference, not a published settlement calendar, and is labelled so in versions. It does not cover other markets'' cycles, bonds/FX conventions, exemptions agreed between parties, or corporate-action dates.
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/settlement-date
security:
- x402: []
- apiKey: []
requestBody:
required: true
content:
application/json:
schema:
type: object
additionalProperties: false
required:
- settlement
- tradeDate
properties:
settlement:
type: string
enum:
- us-equities
- custom
description: 'us-equities: T+1 since 2024-05-28 on the us-equities-settlement calendar (2026-2028). custom: cycleDays on calendar/holidays/weekend.'
tradeDate:
type: string
pattern: ^\d{4}-\d{2}-\d{2}$
maxLength: 10
cycleDays:
type: integer
minimum: 0
maximum: 30
description: custom only.
calendar:
type: string
enum:
- us-federal
- us-federal-reserve
- nyse
- us-equities-settlement
- uk-england-and-wales
- uk-scotland
- uk-northern-ireland
- weekends-only
- caller
description: Named holiday calendar with a source and supported date range (outside it the answer is unsupported), weekends-only (Saturday/Sunday only), or caller (only the holidays you list).
holidays:
type: array
maxItems: 400
items:
type: string
pattern: ^\d{4}-\d{2}-\d{2}$
maxLength: 10
description: Extra non-business dates YYYY-MM-DD (company closures, a calendar we do not carry).
weekend:
type: array
maxItems: 6
items:
type: integer
minimum: 0
maximum: 6
description: Non-business weekdays, 0=Sunday..6=Saturday. Default [0, 6]; use [5, 6] for a Friday/Saturday weekend.
claimedSettlementDate:
type: string
pattern: ^\d{4}-\d{2}-\d{2}$
maxLength: 10
example:
settlement: us-equities
tradeDate: '2026-10-09'
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.'
settlementDate:
type: string
weekday:
type: string
cycleDays:
type: integer
tradeDateIsTradingDay:
type: boolean
skipped:
type: array
items:
type: object
properties:
date:
type: string
reason:
type: string
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:
- Settlement Date
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