Docs: add more resources / info

[whoabuddy]

Giant dump of info:

About Stacks

• Bitcoin L2 with 100% Bitcoin finality for smart contracts and DeFi
• Proof of Transfer (PoX) consensus anchored to Bitcoin's security
• Fast blocks (~5 seconds) with multiple Stacks blocks per Bitcoin block
• Clarity smart contracts with native Bitcoin state visibility
• sBTC for decentralized, programmable BTC; STX for gas
• Stacks Website | sBTC | Docs

x402 Ecosystem Entries

Entry	Category	Description
x402Stacks	Client-Side Integrations	TypeScript SDK (x402-stacks on npm)
x402Stacks Facilitator	Facilitators	Transaction settlement service
x402StacksScan	Infrastructure & Tooling	Ecosystem explorer and stats
AIBTC Sponsor Relay	Infrastructure & Tooling	Sponsored / gasless transaction relay
STX402	Endpoints	x402 powered registry (mainnet)
AIBTC x402 API	Endpoints	AI inference and app storage (mainnet + testnet)
x402 Biwas	Endpoints	AI-powered DeFi analytics

x402 Supported Tokens

Token	Mainnet	Testnet
STX	Native	Native
sBTC	SM3VDXK3WZZSA84XXFKAFAF15NNZX32CTSG82JFQ4.sbtc-token::sbtc-token	ST1F7QA2MDF17S807EPA36TSS8AMEFY4KA9TVGWXT.sbtc-token::sbtc-token
USDCx	SP120SBRBQJ00MCWS7TM5R8WJNTTKD5K0HFRC2CNE.usdcx::usdcx-token	Not yet deployed

Link Dump

Protocol / facilitator:

• x402 on Stacks website: https://stacksx402.com
• mainnet/testnet: https://facilitator.stacksx402.com
• health check: https://facilitator.stacksx402.com/health
• explorer/scan: https://scan.stacksx402.com
• github org: https://github.com/x402Stacks
• facilitator: https://github.com/x402Stacks/x402-stacks-facilitator
• SDK: https://github.com/tony1908/x402-stacks-sdk

Sponsored / gasless TX relay:

• github: https://github.com/aibtcdev/x402-sponsor-relay
• mainnet: https://x402-relay.aibtc.com
• mainnet docs: https://x402-relay.aibtc.com/docs
• testnet: https://x402-relay.aibtc.dev
• testnet docs: https://x402-relay.aibtc.dev/docs

stx402 endpoints:

• github: https://github.com/whoabuddy/stx402
• mainnet endpoints: https://stx402.com
• mainnet docs: https://stx402.com/docs
• mainnet dashboard: https://stx402.com/dashboard

AIBTC endpoints:

• github: https://github.com/aibtcdev/x402-api
• one-pager: docs: add one-pager explaining x402 API value proposition x402-api#22
• mainnet endpoints: https://x402.aibtc.com
• mainnet docs: https://x402.aibtc.com/docs
• mainnet dashboard: https://x402.aibtc.com/dashboard
• testnet endpoints: https://x402.aibtc.dev
• testnet docs: https://x402.aibtc.dev/docs
• testnet dashboard: https://x402.aibtc.dev/dashboard

Biwas endpoints:

• github: https://github.com/biwasxyz/x402
• mainnet endpoints: https://x402.biwas.xyz

First Integration Issue Details

Overview

Add Stacks as a third supported blockchain alongside EVM and Solana. The settlement model mirrors Solana (pre-signed transaction broadcast, not EVM-style authorization), making it a natural fit for the existing architecture. This brings three new payment tokens: STX, sBTC, and USDCx.

There's an existing Stacks x402 facilitator written in Go (x402-stacks-facilitator) and a TypeScript client/server library (x402-stacks). The goal here is to implement Stacks settlement natively in TypeScript within OpenFacilitator's core, following the same pattern as the existing EVM and Solana modules. A working crosschain example demonstrates EVM + Stacks in a single app using the x402 v2 protocol.

Stacks Settlement Model

Aspect	Detail
Settlement	Pre-signed transaction broadcast via Hiro API
Verification	Deferred to settlement — poll Hiro API for tx confirmation
Key format	Hex (secp256k1, via @stacks/transactions)
Address format	Principal — SP…/SM… (mainnet), ST…/SN… (testnet)
Token standard	SIP-010 fungible tokens (transfer contract call)
Fee payer	Sender pays by default — co-signing supported for sponsored transactions (see x402-sponsor-relay)
CAIP-2 IDs	stacks:1 (mainnet), stacks:2147483648 (testnet)

Supported tokens:

Token	Type	Mainnet Contract	Testnet Contract
STX	Native	—	—
sBTC	SIP-010	SM3VDXK3WZZSA84XXFKAFAF15NNZX32CTSG82JFQ4.sbtc-token	ST1F7QA2MDF17S807EPA36TSS8AMEFY4KA9TVGWXT.sbtc-token
USDCx	SIP-010	SP120SBRBQJ00MCWS7TM5R8WJNTTKD5K0HFRC2CNE.usdcx	ST2Y455NJPETB2SRSD0VDZP3KJE50WNHY0BN3TWY5.usdcx ¹

Settlement Implementation Details

The settlement flow has been validated against the existing Go facilitator implementation.

Hiro API endpoints needed:

• GET /extended/v1/tx/{txid} — fetch transaction details (status, recipient, amount)
• POST /v2/transactions — broadcast signed transaction bytes (Content-Type: application/octet-stream)

Free API keys with generous rate limits are available at https://platform.hiro.so.

Transaction parsing — two transaction types to handle:

• STX (native): tx_type: "token_transfer" — read token_transfer.recipient_address and token_transfer.amount directly
• SIP-010 tokens (sBTC, USDCx): tx_type: "contract_call", function_name: "transfer" — parse function args for amount (format: u1000000) and recipient/to (format: 'SP… with quote prefix)

Verification rules — after broadcast, poll until confirmed, then verify:

1. Transaction status is not failed, abort_by_response, or abort_by_post_condition
2. Transaction is confirmed (status: "success", block_height > 0)
3. Recipient matches expected address
4. Amount >= required minimum
5. Optional: sender match, memo match

Reference Implementations

Resource	Link
Stacks facilitator (Go)	https://github.com/x402Stacks/x402-stacks-facilitator
x402-stacks npm package	x402-stacks@2.0.1
Crosschain example (EVM + Stacks)	https://github.com/aibtcdev/x402-crosschain-example
stx402 (production Stacks x402 service)	https://github.com/whoabuddy/stx402
x402-api (Stacks x402 API service)	https://github.com/aibtcdev/x402-api