okx-agent-payments-protocol

name	okx-agent-payments-protocol
description	Unified payment dispatcher covering x402 (`exact` / `aggr_deferred` schemes), MPP (`charge` / `session` intents), and a2a-pay (`a2a_charge` paymentId flow). Detects HTTP 402 protocol from response headers and routes to the matching scheme/intent reference; also handles a2a paymentId mentions without a 402. Loads `references/exact.md` (x402 exact scheme — full EIP-3009 TEE or local-key fallback), `references/aggr_deferred.md` (x402 aggr_deferred scheme — Session Key Ed25519 with sessionCert), `references/charge.md` (MPP one-shot charge in transaction or hash mode, with splits), `references/session.md` (MPP channel: open + voucher loop + topUp + close, with state echo), or `references/a2a_charge.md` (a2a-pay create / pay / auto-poll status). Returns a ready-to-paste authorization header (x402 / MPP) or a tx-hash + status (a2a). Trigger words (English): '402', 'payment required', 'mpp', 'machine payment', 'pay for access', 'payment-gated', 'WWW-Authenticate: Payment', 'x402', 'x402Version', 'PAYMENT-REQUIRED', 'PAYMENT-SIGNATURE', 'X-PAYMENT', 'open channel', 'voucher', 'session payment', 'close channel', 'topup channel', 'top up channel', 'settle channel', 'settle session', 'refund channel', 'channelId', 'channel_id', 'paymentId', 'a2a_', 'a2a payment', 'create payment link', 'payment link', 'payment status'. Trigger words (Chinese): '支付通道', '关闭通道', '关闭会话', '关闭支付通道', '充值通道', '续费通道', '结算通道', '结算会话', '关单', '凭证', '会话支付', '付款链接', '创建支付', '支付状态'. Critical sensitivity rule: any user mention of close / topup / settle / voucher / refund near a `channel_id`, `0x...` channel hash, or 'session' / 'channel' context = MPP mid-session operation — load this skill, jump into `references/session.md`, do NOT search for a separate close/topup tool.
license	MIT
metadata	{"author":"okx","version":"2.0.0","homepage":"https://web3.okx.com"}

OKX Agent Payments Protocol (Dispatcher)

Unified entry point for three payment paths, distinguished by HTTP signature: accepts-based 402 (challenge in body for v1 or PAYMENT-REQUIRED header for v2), WWW-Authenticate: Payment 402 (channel-capable, with intent="charge" or "session"), and a2a-pay (paymentId-based agent-to-agent links, no 402 required). This file owns the shared steps — protocol detection, payload decode, user confirmation gate, wallet status check — then dispatches into the right scheme/intent reference.

User-facing terminology — IMPORTANT

Rule 1 — Always call it "OKX Agent Payments Protocol", and always render it bolded. Use the exact English term OKX Agent Payments Protocol in user-visible messages regardless of the user's language, and always wrap it in markdown bold (**OKX Agent Payments Protocol**) so the user sees it emphasized. Keep it as a fixed English noun phrase even inside otherwise-Chinese sentences. Reserve protocol literals and internal identifiers for CLI invocations, HTTP headers, JSON payloads, and code — never speak them to the user.

Rule 2 — Do not narrate internal protocol detection. The dispatch logic (which header was detected, which reference is being loaded, which scheme/intent was selected, TEE vs local-key path) is internal — keep it internal. The user only needs to see: (a) what is being paid, (b) what they need to confirm, (c) the result.

Rule 3 — Externally-defined protocol literals stay byte-for-byte exact. The JSON field x402Version, the HTTP headers X-PAYMENT / PAYMENT-SIGNATURE / PAYMENT-REQUIRED / WWW-Authenticate: Payment, and the reference URL https://x402.org MUST appear verbatim wherever the protocol/server requires them — these are externally defined and changing them breaks interop. CLI subcommand names (onchainos payment pay / pay-local / charge / session ... / a2a-pay ...) are this CLI's own surface and may evolve; refer to them by their current name in CLI invocations and code, but never speak them to the user (Rule 2).

Example

(中) 准备通过 **OKX Agent Payments Protocol** 完成本次支付，下面是扣款明细，请确认…… (EN) Preparing a payment via the **OKX Agent Payments Protocol**. Here are the charge details — please confirm before I proceed…

Progress narration counts as user-visible — Rules 1-3 still apply.

Long-running flows (decode → confirm → wallet check → sign → header assembly → replay) tempt status updates. Every "正在…" / "I'm now…" line is user-facing. Step labels in this SKILL.md (Step A3-Accepts, Step A3-WWW-Authenticate) and reference files (exact / aggr_deferred schemes, charge / session intents) are internal — do NOT echo them in narration.

❌ Don't say	✅ Say
"正在处理 accepts-based 流程" / "Processing the accepts-based path"	"正在通过 OKX Agent Payments Protocol 处理本次支付" / "Processing the payment via the OKX Agent Payments Protocol"
"CLI 自动选择 exact 方案" / "CLI selected the exact scheme" / "走 aggr_deferred 路径"	"签名完成" / "Signing done"
"组装 PAYMENT-SIGNATURE / X-PAYMENT 头" / "Assembling the PAYMENT-SIGNATURE header"	"正在重放请求" / "Replaying the request"
"检测到 WWW-Authenticate: Payment / PAYMENT-REQUIRED 协议" / "Detected the channel-based protocol"	(silent — go straight to the confirmation prompt)
"加载 references/exact.md" / "Loading the exact playbook"	(silent — internal routing)
"进入 session 模式 / charge 模式" / "Entering session intent"	"支付通道已开" / "Channel opened" — describe the user-visible effect, not the internal mode
"TEE 路径 / 本地 key 路径" / "Using TEE signing path"	(silent — signing path is internal)

Read ../okx-agentic-wallet/_shared/preflight.md before any onchainos command. EVM only — CAIP-2 eip155:<chainId> (run onchainos wallet chains for the list).

Reference map

Triggered by	Load
402 with PAYMENT-REQUIRED header (v2) or x402Version body field (v1), CLI returns no sessionCert	references/exact.md
402 with PAYMENT-REQUIRED header (v2) or x402Version body field (v1), CLI returns sessionCert	references/aggr_deferred.md
402 with WWW-Authenticate: Payment, intent="charge"	references/charge.md
402 with WWW-Authenticate: Payment, intent="session" (also: any mid-session op on a channel_id)	references/session.md
User mentions a paymentId / a2a_... link / "create payment link"	references/a2a_charge.md

Skill Routing

Intent	Use skill
Token prices / charts / wallet PnL / tracker activities	okx-dex-market
Token search / metadata / holders / cluster analysis	okx-dex-token
Smart money / whale / KOL signals	okx-dex-signal
Meme / pump.fun token scanning	okx-dex-trenches
Token swaps / trades / buy / sell	okx-dex-swap
Authenticated wallet (balance / send / tx history)	okx-agentic-wallet
Public address holdings	okx-wallet-portfolio
Tx broadcasting (feePayer=false hash mode)	okx-onchain-gateway
Security scanning (token / DApp / tx / signature)	okx-security

Channel mid-session ops (close / topup / settle / voucher / refund mentioned with an active channel_id, regardless of fresh 402) → stay here, jump straight into references/session.md at the matching phase. Do NOT search for a separate close-channel / topup-channel / settle-channel tool — they're all onchainos payment session ... subcommands.

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Path A: HTTP 402

Step A1: Send the original request

Make the HTTP request the user asked for. If status is not 402, return the body directly — no payment, no wallet check, no other tool calls.

Step A2: Detect the protocol

Priority 1: response.headers['WWW-Authenticate']
  starts with "Payment "        → continue at Step A3-WWW-Authenticate
Priority 2: response.headers['PAYMENT-REQUIRED']
  base64-encoded JSON           → continue at Step A3-Accepts (v2)
Priority 3: response body JSON has "x402Version"
                                → continue at Step A3-Accepts (v1)
Otherwise                       → not a supported payment protocol, stop

Both WWW-Authenticate: Payment and PAYMENT-REQUIRED/x402Version indicators present — STOP and ask the user:

The server offers two payment options via the OKX Agent Payments Protocol:

1. One-shot purchase, or streaming session (multi-request) (recommended)
2. One-shot purchase

Which would you like to use?

Internal mapping: option 1 → WWW-Authenticate: Payment path, option 2 → PAYMENT-REQUIRED/x402Version path.

Step A3-Accepts: Decode

v2 — payload is in the PAYMENT-REQUIRED response header (base64-encoded JSON):

headerValue = response.headers['PAYMENT-REQUIRED']
decoded     = JSON.parse(atob(headerValue))

v1 — payload is in the response body (direct JSON, not base64):

decoded = JSON.parse(response.body)

Extract:

accepts = decoded.accepts          // pass full array to the CLI later
option  = decoded.accepts[0]       // for display only

Save decoded for header assembly later — you will need decoded.x402Version and decoded.resource (v2).

Step A3-WWW-Authenticate: Decode

Parse the WWW-Authenticate header:

Payment id="...", realm="...", method="evm", intent="...", request="<base64url>", expires="..."

base64url-decode request to get the JSON body. Save:

intent              charge | session
amount              base units string (e.g. "1000000")
currency            ERC-20 contract address
recipient           merchant payee address
methodDetails:
  chainId           EVM chain ID (e.g. 196 for X Layer)
  escrowContract    REQUIRED for session, ABSENT for charge
  feePayer          true (transaction mode) | false (hash mode)
  splits            optional, charge only, max 10 entries
  minVoucherDelta   optional, session only
  channelId         optional, session topUp/voucher only — pre-existing channel
suggestedDeposit    optional, session only — suggested initial deposit
unitType            optional — "request" | "second" | "byte" etc.

Method check — only method="evm" is supported here. If method is "tempo", "svm", "stripe", etc. → stop and tell the user this dispatcher cannot handle it.

Challenge expiry — if expires=... (ISO-8601) is in the past, the challenge is dead: re-send the original request to get a fresh 402 before signing. Stale challenges fail with 30001 incorrect params.

Convert amount from base units to human-readable using the token's decimals (typically 6 for USDC/USD₮, 18 for native).

Step A4: Display payment details and STOP

⚠️ MANDATORY: Display details and STOP to wait for explicit user confirmation. Do NOT call onchainos wallet status or any other tool until the user confirms.

For accepts-based 402 (PAYMENT-REQUIRED header v2 / x402Version body v1):

This resource requires payment via the OKX Agent Payments Protocol:

• Network: <chain name> (<option.network>)
• Token: <token symbol> (<option.asset>)
• Amount: <human-readable amount> (from option.amount for v2, or option.maxAmountRequired for v1; convert from minimal units using token decimals)
• Pay to: <option.payTo>

Proceed with payment? (yes / no)

For WWW-Authenticate: Payment 402:

This resource requires payment via the OKX Agent Payments Protocol:

• Payment type: <one-shot purchase (charge) | streaming session (multi-request)>
• Network: <chain name> (eip155:<chainId>)
• Token: <symbol> (<currency address>)
• Amount per request: <human-readable> (atomic: <amount>)
• Pay to: <recipient>
• Who pays gas: <server (transaction mode) | you broadcast it yourself (hash mode)>
• Split recipients (one-shot only, if present): <N other parties also receive a share>
• Suggested prepaid balance (session only, if present): <human-readable>

Proceed with payment? (yes / no)

• User confirms → Step A5.
• User declines → stop. No payment, no wallet check.

Step A5: Check wallet status (only after the user explicitly confirms)

onchainos wallet status

• Logged in → Step A6.
• Not logged in (accepts-based path) → ask the user to choose between (1) wallet login (TEE signing) or (2) local private key (onchainos payment pay-local, exact scheme only). Don't read files or check env vars until the user picks.
• Not logged in (WWW-Authenticate: Payment path) → ask the user to log in via email OTP or AK. TEE-only — no local-key fallback for this path (only the accepts-based path has one).

Step A6: Hand off to the scheme/intent reference

Path	Action
accepts-based (PAYMENT-REQUIRED header v2 / x402Version body v1)	Run onchainos payment pay --accepts '<JSON.stringify(decoded.accepts)>'. When the response comes back, look at whether sessionCert is present: • sessionCert present → load references/aggr_deferred.md for header assembly + replay • sessionCert absent → load references/exact.md for header assembly + replay If the user picked the local-key fallback, run onchainos payment pay-local instead and load references/exact.md (only scheme this fallback supports).
WWW-Authenticate: Payment, intent="charge"	Load references/charge.md at "Decide mode".
WWW-Authenticate: Payment, intent="session"	Load references/session.md at "Phase S1: Open Channel" (or jump to S2 / S2b / S3 if the user is mid-session with an active channel_id).

After the reference returns the assembled X-PAYMENT / PAYMENT-SIGNATURE header or authorization_header, replay the original request and surface the response to the user. Suggest follow-ups conversationally — never expose internal field names or skill IDs.

---

Path B: a2a-pay (paymentId-based, no 402)

The user invokes this path explicitly — by mentioning a paymentId / a2a_... link, asking to "create a payment link", or asking to check a2a payment status.

Step B1: Identify the role

User says…	Load	Role
"create payment link" / "generate payment" / --amount/--recipient	references/a2a_charge.md → "Seller — Create"	Seller
Provides a paymentId / a2a_... to pay	references/a2a_charge.md → "Buyer — Pay"	Buyer
Provides a paymentId and asks for status	references/a2a_charge.md → "Status — Query"	Either

If the user says only "I want to pay" without a paymentId — STOP and ask the user to provide the seller-issued paymentId. Do not attempt anything else.

Step B2: Wallet status

Both create and pay require a live wallet session. Run onchainos wallet status:

• Logged in → proceed (load the reference and follow it).
• Not logged in → ask the user to log in via onchainos wallet login or onchainos wallet login <email>. Do NOT sign without a live session.

Step B3: Hand off to references/a2a_charge.md

The reference contains the full create/pay/status flow including the auto-poll-to-terminal logic and trust-delegation note. Buyer-side trust is delegated to the upstream caller — the buyer signs whatever the on-server challenge declares. Cross-checking the paymentId against the agreed terms is the upstream's responsibility, NOT this dispatcher's.

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Cross-cutting

Reading seller errors (WWW-Authenticate: Payment / a2a-pay)

When the seller rejects, do NOT show raw JSON or just the numeric code. Extract the human-readable explanation in priority order, use the first non-empty match:

1. body.reason (mppx, OKX TS Session)
2. body.detail (RFC 9457 ProblemDetails)
3. body.message
4. body.msg (OKX SA API)
5. body.error
6. body.title (RFC 9457 short title — fallback only)
7. fallthrough — format the whole body and add the HTTP status

Format:

❌ Seller rejected: <reason text> (code <code if present>, HTTP <status>)

Amount display

All user-facing amounts in BOTH human and atomic form: <human> (<atomic>), e.g. 0.0004 USDC (400), 1.5 ETH (1500000000000000000). Compute via amount / 10^decimals from the challenge currency token.

Token	Decimals	1 unit in minimal	Example
USDC	6	1000000	1000000 → 1.00 USDC
USDT	6	1000000	2500000 → 2.50 USDT
USDG	6	1000000	500000 → 0.50 USDG
ETH	18	1000000000000000000	10000000000000000 → 0.01 ETH

For any symbol not in the table: never assume — query okx-dex-token for the token's decimals first. If you cannot resolve them, render <minimal> <symbol> and append unknown decimals — please double-check the seller-provided amount. Do not block the flow.

Suggest next steps

After a successful payment + response, suggest conversationally:

Just completed	Suggest
Successful HTTP 402 replay	Check balance impact via okx-agentic-wallet; or make another request to the same resource
Successful a2a payment	Verify post-payment balance via okx-agentic-wallet
402 on replay (expired)	Retry with a fresh signature
Channel session in progress	Issue another voucher when the next request arrives; close the channel when done