[Feature 03] API Server

[onlyhyde]

Overview

Implement HTTP API server using Echo framework with /verify and /settle endpoints.

Implementation Details

Files:

• internal/api/server.go - Server setup
• internal/api/handlers.go - Request handlers
• internal/api/types.go - Request/Response types

Endpoints

Method	Path	Description
POST	/verify	Verify payment payload
POST	/settle	Execute settlement
GET	/health	Health check
GET	/.well-known/x402-facilitator	Discovery info

Request Types

VerifyRequest:

type VerifyRequest struct {
    Payload             json.RawMessage `json:"payload"`
    PaymentRequirements json.RawMessage `json:"paymentRequirements"`
}

SettleRequest:

type SettleRequest struct {
    Payload             json.RawMessage `json:"payload"`
    PaymentRequirements json.RawMessage `json:"paymentRequirements"`
}

Response Types

VerifyResponse:

type VerifyResponse struct {
    Valid   bool   `json:"valid"`
    Message string `json:"message,omitempty"`
}

SettleResponse:

type SettleResponse struct {
    Success bool   `json:"success"`
    TxHash  string `json:"txHash,omitempty"`
    Error   string `json:"error,omitempty"`
}

Acceptance Criteria

• Echo server setup with middleware (Recover, RequestID, Logger)
• POST /verify endpoint working
• POST /settle endpoint working
• GET /health endpoint
• Request validation
• Error handling with proper HTTP status codes
• Unit tests for handlers
• Integration tests

Dependencies

• [Feature 02] EVM Signer Implementation #21 EVM Signer Implementation

Branch

feature/api-server