Meridian

Headless Stellar wallet SDK for autonomous AI agents on the x402 payment protocol.

Meridian gives AI agents the ability to discover, negotiate, and pay for HTTP APIs autonomously — no browser, no human approval, no WalletConnect popup. It handles everything from keypair management and stablecoin balance tracking to Soroban auth-entry signing, spending policy enforcement, and cross-stablecoin path payment routing.

• Complete x402 round-trip: Parse a 402 response, sign the Soroban auth entry, verify with the facilitator, and retry the original request in a single method call.
• Policy engine: Per-request, per-hour, per-day, and per-session spending limits; endpoint whitelists and blacklists.
• Cross-stablecoin routing: Resolves path payments through the Stellar DEX atomically (e.g., hold PYUSD but pay in USDC).
• Encrypted key storage: AES-256-GCM encryption at rest with pluggable storage adapters.
• Persistent spending ledger: SQLite-backed budget accounting that survives agent restarts.

Meridian is organized into five internal modules:

1. Key Manager: Secure keypair generation and AES encryption at rest.
2. Balance Tracker: Queries stablecoin and XLM reserves via Horizon.
3. Auth Signer: Constructs and signs Soroban authorization entries.
4. Policy Engine: Evaluates spending rules before every signing operation.
5. Path Resolver: Finds DEX conversion routes for asset mismatches.

• Secret keys never leave the process: Signing happens in-process inside the Key Manager.
• Every payment is gated by policy: No Soroban auth entry is signed without passing through the Policy Engine.
• Budget accounting survives restarts: The spending ledger is persisted to SQLite.

| Asset | Network | Issuer | | :--- | :--- | :--- | | USDC | Mainnet | Centre (via Stellar anchor) | | PYUSD | Mainnet | Paxos (via Stellar anchor) | | USDY | Mainnet | Ondo Finance (via Stellar anchor) | | USDC | Testnet | Testnet anchor |