Stellar Hackathon

Both run on Soroban (Stellar smart contracts, Rust/WASM). Core primitive is auth-entry signing: wallets sign Soroban authorization entries so a relayer/facilitator can invoke the payment transfer atomically.

Core Protocols

x402 (Coinbase)

• Stellar x402 overview: https://developers.stellar.org/docs/build/agentic-payments/x402
• x402 Quickstart Guide: https://developers.stellar.org/docs/build/agentic-payments/x402/quickstart-guide
• Built-on-Stellar facilitator: https://developers.stellar.org/docs/build/agentic-payments/x402/built-on-stellar
• Live demo: https://stellar.org/x402-demo
• Facilitator supported networks: https://www.x402.org/facilitator/supported (stellar:testnet included)
• Coinbase x402 docs: https://docs.cdp.coinbase.com/x402/docs/welcome
• Protocol spec: https://www.x402.org/
• Test services playground: https://xlm402.com

MPP (Stripe)

• Stellar MPP overview: https://developers.stellar.org/docs/build/agentic-payments/mpp
• Charge guide (per-request, pull/push credentials): https://developers.stellar.org/docs/build/agentic-payments/mpp/charge-guide
• Session guide (unidirectional payment channels): https://developers.stellar.org/docs/build/agentic-payments/mpp/channel-guide
• Live demo: https://mpp.stellar.buzz (Node server charging 0.01 USDC/request on testnet)
• one-way-channel Soroban contract: https://github.com/stellar-experimental/one-way-channel
• Stripe MPP docs: https://docs.stripe.com/payments/machine
• Stripe MPP quickstart: https://docs.stripe.com/payments/machine/mpp/quickstart
• Protocol spec: https://mpp.dev
• Stripe product page: https://stripe.com/blog/machine-payments-protocol
• Stripe reference sample: https://github.com/stripe-samples/machine-payments

Official SDKs and Repos

Facilitators

x402 requires a facilitator service (exposes /verify, /settle, /supported). Two options:

• OpenZeppelin Relayer Plugin (run your own): https://github.com/OpenZeppelin/relayer-plugin-x402-facilitator
• OZ docs: https://docs.openzeppelin.com/relayer/1.4.x/guides/stellar-x402-facilitator-guide
• Coinbase-hosted facilitator: available for stellar:testnet

Compatible Wallets (x402 auth-entry signing required)

Freighter (browser), Albedo, Hana, HOT, Klever, OneKey. Note: Freighter mobile does NOT support x402.

Starter Templates / Reference Apps

x402

• x402 Starter Template (browser wallet): https://github.com/ElliotFriend/x402/tree/stellar-browser-wallet-example/examples/typescript/fullstack/browser-wallet-example
• 1-shot Stellar x402 app (video paywall): https://github.com/oceans404/1-shot-stellar/tree/main/x402-app
• Economic Load Balancer (multi-chain router): https://github.com/marcelosalloum/x402/tree/x402-hackathon
• Stellar Observatory (space weather via x402, MCP server): https://github.com/elliotfriend/stellar-observatory — live: https://stellar-observatory.vercel.app
• jamesbachini x402 Stellar demo (minimal local): https://github.com/jamesbachini/x402-Stellar-Demo
• x402 MCP server for agents: https://github.com/jamesbachini/x402-mcp-stellar — lets Claude Code / Codex pay for x402 services
• Sponsored agent account (give an agent a USDC wallet in <1 min, no XLM needed): https://github.com/oceans404/stellar-sponsored-agent-account — skill: https://stellar-sponsored-agent-account.onrender.com/SKILL.md

DeFi / Composition References

• AI Freighter Integration: https://github.com/carstenjacobsen/ai-freighter-integration
• AI Soroswap Integration (multi-DEX): https://github.com/carstenjacobsen/ai-soroswap-integration
• AI DeFindex Integration (yield vaults): https://github.com/carstenjacobsen/ai-defindex-integration
• AI Passkeys Integration (WebAuthn smart wallet): https://github.com/carstenjacobsen/ai-passkeys-integration
• AI Etherfuse Integration: https://github.com/carstenjacobsen/ai-etherfuse-integration
• Stellar DeFi App dashboard: https://github.com/kaankacar/stellar-defi-app (Blend, Soroswap, Phoenix, Aquarius, SDEX, Reflector)
• Ya Otter Save (fiat→stablebonds→DEX→USDC→Blend): https://github.com/briwylde08/ya-otter-save
• Anchor Starter Pack (SEP-1/6/10/12/24/31/38): https://github.com/ElliotFriend/regional-starter-pack

Stellar Dev Tooling

Soroban Building Blocks (essential reading)

• Contract Accounts: https://developers.stellar.org/docs/build/guides/contract-accounts
• Contract Authorization model: https://developers.stellar.org/docs/learn/fundamentals/contract-development/authorization
• Signing Soroban Invocations (auth-entry signing): https://developers.stellar.org/docs/build/guides/transactions/signing-soroban-invocations

AI Dev Assistance

• Stellar Dev Skill (Claude Code): https://github.com/stellar/stellar-dev-skill — invoke as stellar-dev:stellar-dev
• OpenZeppelin Skills: https://github.com/OpenZeppelin/openzeppelin-skills — /plugin marketplace add OpenZeppelin/openzeppelin-skills (includes MCP server for contract generation)
• Smart Account Kit (passkey wallets): https://github.com/kalepail/smart-account-kit
• Stellar MCP server: https://github.com/kalepail/stellar-mcp-server
• XDR MCP: https://github.com/stellar-experimental/mcp-stellar-xdr
• OpenZeppelin on Stellar (audited libs, Wizard, Relayer, Detectors): https://www.openzeppelin.com/networks/stellar
• Free AI setup guide: https://github.com/kaankacar/stellar-ai-guide-mx/blob/main/Free_AI_Setup.md

Community / Gotchas

• Stellar Hackathon FAQ: https://github.com/briwylde08/stellar-hackathon-faq
• Stellar DeFi Gotchas (400+ findings from vibe-coding runs): https://github.com/kaankacar/stellar-defi-gotchas
• Ecosystem DB (646 projects indexed): https://github.com/lumenloop/stellar-ecosystem-db — check here BEFORE building to avoid duplicating existing work
• Ecosystem Resources: https://github.com/stellar/ecosystem-resources/

Quick Decision Tree

• Need per-request micropayment for an API? → x402 Charge OR MPP Charge
• Agent makes hundreds of calls/sec? → MPP Session (payment channel)
• Need a facilitator? → Use Coinbase-hosted on testnet first, OpenZeppelin Relayer plugin for mainnet/self-host
• Need wallet in AI context? → Sponsored agent account repo (no XLM bootstrap needed)
• Unsure if something already exists? → Check Stellar Ecosystem DB first
• Need to auth a Soroban call from off-chain? → Read "Signing Soroban Invocations" + contract-authorization docs

Project Context: marc-stellar

This project is a Stellar/Soroban adaptation of the MARC Protocol (https://github.com/marc-protocol/marc), originally built on Zama fhEVM. The original uses FHE (Fully Homomorphic Encryption) to hide payment amounts on-chain. Stellar has no FHE, so the Stellar port must use a different privacy primitive. See the design doc in docs/superpowers/specs/ for the chosen approach.

Original MARC repo on disk: /Users/ram/Desktop/marc This project: /Users/ram/Desktop/marc-stellar