WritersLogic Verifiable AI Agent Hub Chess Move API
The Chess Move API from WritersLogic Verifiable AI Agent Hub — 1 operation(s) for chess move.
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curl "https://apis.io/api/v1/apis/writerslogic-com:writerslogic-com-chess-move-api"
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OpenAPI Specification
openapi: 3.2.0
info:
title: WritersLogic Verifiable AI Agent Hub Chess Move 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: Chess Move
paths:
/api/v1/chess-move:
post:
operationId: chess_move
summary: Chess move legality, SAN/UCI conversion and next FEN
description: 'Checks whether a move (or a sequence of moves) is legal from a FEN position under the FIDE Laws of Chess, for agents that play, annotate or verify chess games. Accepts UCI or SAN, returns the normalized move, the new FEN, check / checkmate / stalemate / insufficient-material flags and, if asked, every legal move; an illegal move names the reason (castling_through_check, ep_exposes_king, moves_into_check, blocked, bad_promotion). Does NOT suggest or evaluate moves, detect threefold repetition (no game history), detect dead positions other than insufficient material, or support Chess960 (reported as unsupported).
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/chess-move
security:
- x402: []
- apiKey: []
requestBody:
required: true
content:
application/json:
schema:
type: object
additionalProperties: false
required:
- items
properties:
items:
type: array
items:
type: object
additionalProperties: false
required:
- fen
properties:
fen:
type: string
maxLength: 100
description: Position as a 6-field FEN, or "startpos".
move:
type: string
maxLength: 16
description: One move to check from the position, UCI (e2e4, e7e8q, e1g1) or SAN (Nf3, exd5, e8=Q, O-O).
moves:
type: array
items:
type: string
maxLength: 16
description: UCI or SAN move.
maxItems: 200
description: Moves played one after another from the position; stops at the first that is not legal. Use either move or moves.
list:
type: boolean
description: Also return every legal move (UCI and SAN) in the final position. At most 20 items per call.
expectFen:
type: string
maxLength: 100
description: 'Optional claim: the FEN you expect after the move(s). Compared on placement, side, castling and capturable en passant (4 or 6 fields).'
maxItems: 50
minItems: 1
description: 1 to 50 positions, at most 400 moves in total.
example:
items:
- fen: startpos
moves:
- e4
- e5
- Nf3
expectFen: rnbqkbnr/pppp1ppp/8/4p3/4P3/5N2/PPPP1PPP/RNBQKB1R b KQkq - 1 2
- fen: 4k3/8/8/8/8/8/5r2/4K2R w K - 0 1
move: O-O
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.'
results:
type: array
items:
type: object
properties:
index:
type: integer
status:
type: string
enum:
- pass
- fail
- unknown
- unsupported
fenValid:
type: boolean
legal:
type: boolean
description: 'Present when a move or moves were given: every move was legal.'
reason:
type: string
description: Why the item did not pass, e.g. castling_through_check, ep_exposes_king, ambiguous_san, fen.opponent_in_check.
failedMoveIndex:
type: integer
description: Index into the move sequence of the first move that was not played.
played:
type: array
items:
type: object
properties:
input:
type: string
uci:
type: string
san:
type: string
flags:
type: array
items:
type: string
description: capture, en_passant, castle, double_push, promotion, check, checkmate.
fen:
type: string
description: Position after this move.
fen:
type: string
description: Normalized FEN of the position after the last move that was played.
position:
type: object
properties:
turn:
type: string
enum:
- white
- black
inCheck:
type: boolean
checkmate:
type: boolean
stalemate:
type: boolean
insufficientMaterial:
type: boolean
description: Dead by material alone (K v K, K+minor v K, same-colour bishops only). Other dead positions are not detected.
fiftyMoveClaimable:
type: boolean
description: Halfmove clock is at least 100 (FIDE 9.3 claim). Threefold repetition is not computed.
halfmoveClock:
type: integer
fullmoveNumber:
type: integer
legalMoveCount:
type: integer
legalMoves:
type: array
items:
type: object
properties:
uci:
type: string
san:
type: string
claimMatches:
type: boolean
description: 'Present when expectFen was given: placement, side, castling and capturable en passant agree.'
description: One entry per input item, in order.
summary:
type: object
properties:
items:
type: integer
pass:
type: integer
fail:
type: integer
unknown:
type: integer
unsupported:
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:
- Chess Move
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