[Feature 13] Discovery API

[onlyhyde]

Overview

Implement Well-Known discovery endpoint and supporting APIs for facilitator capabilities.

Implementation Details

Files:

• internal/api/discovery.go - Discovery types and handlers

Endpoints

Method	Path	Auth	Description
GET	/.well-known/x402-facilitator	None	Full discovery info
GET	/networks	None	Supported networks list
GET	/assets	None	Supported assets list
GET	/health	None	Health check

Discovery Response

type DiscoveryResponse struct {
    Version          string           `json:"version"`
    SupportedChains  []ChainInfo      `json:"supportedChains"`
    Endpoints        EndpointInfo     `json:"endpoints"`
    Capabilities     CapabilitiesInfo `json:"capabilities"`
    Metadata         MetadataInfo     `json:"metadata"`
}

type ChainInfo struct {
    Network         string   `json:"network"`
    ChainName       string   `json:"chainName"`
    SupportedAssets []string `json:"supportedAssets"`
    Status          string   `json:"status"`  // "active", "degraded", "inactive"
}

type CapabilitiesInfo struct {
    SupportedMechanisms []string `json:"supportedMechanisms"`
    SupportsEIP1271     bool     `json:"supportsEIP1271"`
    SupportsERC6492     bool     `json:"supportsERC6492"`
    SupportsPermit2     bool     `json:"supportsPermit2"`
}

type MetadataInfo struct {
    Name        string `json:"name"`
    Description string `json:"description,omitempty"`
    Operator    string `json:"operator,omitempty"`
    Contact     string `json:"contact,omitempty"`
    DocsURL     string `json:"docsUrl,omitempty"`
}

Chain Status Detection

• Integrate with Circuit Breaker state
• "active" when circuit is closed
• "degraded" when circuit is half-open
• "inactive" when circuit is open

Assets Endpoint

type AssetInfo struct {
    Network  string `json:"network"`
    Address  string `json:"address"`
    Symbol   string `json:"symbol"`
    Decimals int    `json:"decimals"`
    Name     string `json:"name"`
}

// GET /assets?network=eip155:8453

Acceptance Criteria

• /.well-known/x402-facilitator endpoint
• /networks endpoint
• /assets endpoint with optional network filter
• Chain status from circuit breaker
• Configurable metadata
• Unit tests
• Integration tests

Dependencies

• [Feature 03] API Server #22 API Server
• [Feature 04] Multi-Chain Configuration #23 Multi-Chain Configuration

Branch

feature/discovery-api