metamask-integration/chain138-snap/INTEGRATORS.md

Chain 138 Snap — Integrator guide

Use this Snap from your dApp to provide Chain 138 (and ALL Mainnet) network params, token list, market data, swap quotes, and bridge routes (CCIP and Trustless) inside MetaMask.

Production Snap ID

After the Snap is published to npm, use:

npm:chain138-snap

Example (wallet_invokeSnap):

await ethereum.request({
  method: 'wallet_invokeSnap',
  params: {
    snapId: 'npm:chain138-snap',
    request: { method: 'hello' },
  },
});

Required: apiBaseUrl

For market data, swap quotes, and bridge routes, the dApp must pass apiBaseUrl (your token-aggregation service base URL) in the request params:

params: {
  apiBaseUrl: 'https://your-token-aggregation-api.com',
  // optional: chainId (default 138), tokenIn, tokenOut, amountIn for swap, etc.
}

Optional URL params

You can pass these instead of or in addition to apiBaseUrl for specific data:

Param	Purpose	Used by RPCs
networksUrl	JSON URL for networks	get_networks, get_chain138_config
tokenListUrl	JSON URL for tokens	get_token_list, get_token_list_url
bridgeListUrl	JSON URL for bridge	get_bridge_routes, show_bridge_routes

Companion site env

For the companion site (this repo’s packages/site):

• Development: Uses local Snap; no SNAP_ORIGIN needed (defaults to local).
• Production: Set SNAP_ORIGIN=npm:chain138-snap and GATSBY_SNAP_API_BASE_URL to your token-aggregation base URL so the site uses the published Snap and passes apiBaseUrl to it.

RPC methods

See TESTING_INSTRUCTIONS.md for the full list: hello, get_networks, get_chain138_config, get_chain138_market_chains, get_token_list, get_token_list_url, get_oracles, show_dynamic_info, get_market_summary, show_market_data, get_bridge_routes, show_bridge_routes, get_swap_quote, show_swap_quote.