feat: Add Multichain API support

packages/examples/packages/multichain-provider/.depcheckrc.json

@@ -0,0 +1,18 @@
+{
+  "ignore-patterns": ["dist", "coverage"],
+  "ignores": [
+    "@lavamoat/allow-scripts",
+    "@lavamoat/preinstall-always-fail",
+    "@metamask/auto-changelog",
+    "@metamask/eslint-*",
+    "@types/*",
+    "@typescript-eslint/*",
+    "eslint-config-*",
+    "eslint-plugin-*",
+    "jest-silent-reporter",
+    "prettier-plugin-packagejson",
+    "ts-node",
+    "typedoc",
+    "typescript"
+  ]
+}

packages/examples/packages/multichain-provider/CHANGELOG.md

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+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+[Unreleased]: https://github.com/MetaMask/snaps/

packages/examples/packages/multichain-provider/LICENSE.APACHE2

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packages/examples/packages/multichain-provider/LICENSE.MIT0

@@ -0,0 +1,16 @@
+MIT No Attribution
+
+Copyright 2026 Consensys Software Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this
+software and associated documentation files (the "Software"), to deal in the Software
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+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

packages/examples/packages/multichain-provider/README.md

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+# `@metamask/multichain-provider-example-snap`
+
+This Snap demonstrates the use of the `endowment:multichain-provider` permission.
+
+The permission grants the Snap access to CAIP-25 provider methods via `snap.request`.
+
+## Snap manifest
+
+Along with other permissions, the manifest of this snap includes the
+`endowment:multichain-provider` permission:
+
+```json
+{
+  "initialPermissions": {
+    "endowment:mulitchain-provider": {}
+  }
+}
+```
+
+This permission does not require any additional configuration.
+
+## Snap usage
+
+This snap exposes an `onRpcRequest` handler, which supports the following
+JSON-RPC methods:
+
+- `createSession`: Create the multichain API session.
+- `revokeSession`: Revoke the current multichain API session.
+- `getChainId`: Get the current Ethereum chain ID as a string.
+- `getAccounts`: Get the accounts for the selected scope.
+- `signMessage`: Sign a message using an Ethereum or Solana account.
+- `signTypedData`: Sign a struct using an Ethereum account.
+- `getGenesisHash`: Get the genesis hash for the selected scope.
+
+For more information, you can refer to
+[the end-to-end tests](./src/index.test.ts).

packages/examples/packages/multichain-provider/jest.config.js

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+const deepmerge = require('deepmerge');
+
+const baseConfig = require('../../../../jest.config.base');
+
+module.exports = deepmerge(baseConfig, {
+  preset: '@metamask/snaps-jest',
+
+  // `@metamask/snaps-jest` currently doesn't support collecting
+  // coverage information.
+  collectCoverage: false,
+
+  // This is required for the tests to run inside the `MetaMask/snaps`
+  // repository. You don't need this in your own project.
+  moduleNameMapper: {
+    '^@metamask/(.+)/production/jsx-runtime': [
+      '<rootDir>/../../../$1/src/jsx/production/jsx-runtime',
+      '<rootDir>/../../../../node_modules/@metamask/$1/jsx/production/jsx-runtime',
+      '<rootDir>/node_modules/@metamask/$1/jsx/production/jsx-runtime',
+    ],
+    '^@metamask/(.+)/jsx': [
+      '<rootDir>/../../../$1/src/jsx',
+      '<rootDir>/../../../../node_modules/@metamask/$1/jsx',
+      '<rootDir>/node_modules/@metamask/$1/jsx',
+    ],
+    '^@metamask/(.+)/node$': [
+      '<rootDir>/../../../$1/src/node',
+      '<rootDir>/../../../../node_modules/@metamask/$1/node',
+      '<rootDir>/node_modules/@metamask/$1/node',
+    ],
+    '^@metamask/(.+)$': [
+      '<rootDir>/../../../$1/src',
+      '<rootDir>/../../../../node_modules/@metamask/$1',
+      '<rootDir>/node_modules/@metamask/$1',
+    ],
+  },
+});

packages/examples/packages/multichain-provider/package.json

@@ -0,0 +1,74 @@
+{
+  "name": "@metamask/multichain-provider-example-snap",
+  "version": "0.0.0",
+  "description": "MetaMask example Snap demonstrating the use of the Multichain Provider API and `endowment:multichain-provider` permission",
+  "keywords": [
+    "MetaMask",
+    "Snaps",
+    "Ethereum"
+  ],
+  "homepage": "https://github.com/MetaMask/snaps/tree/main/packages/examples/packages/multichain-provider#readme",
+  "bugs": {
+    "url": "https://github.com/MetaMask/snaps/issues"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/MetaMask/snaps.git"
+  },
+  "license": "(MIT-0 OR Apache-2.0)",
+  "sideEffects": false,
+  "main": "./dist/bundle.js",
+  "files": [
+    "dist",
+    "snap.manifest.json"
+  ],
+  "scripts": {
+    "build": "mm-snap build",
+    "build:clean": "yarn clean && yarn build",
+    "changelog:update": "../../../../scripts/update-changelog.sh @metamask/multichain-provider-example-snap",
+    "changelog:validate": "../../../../scripts/validate-changelog.sh @metamask/multichain-provider-example-snap",
+    "clean": "rimraf \"dist\"",
+    "lint": "yarn lint:eslint && yarn lint:misc --check && yarn changelog:validate && yarn lint:dependencies",
+    "lint:ci": "yarn lint",
+    "lint:dependencies": "depcheck",
+    "lint:eslint": "eslint . --cache",
+    "lint:fix": "yarn lint:eslint --fix && yarn lint:misc --write",
+    "lint:misc": "prettier --no-error-on-unmatched-pattern --log-level warn \"**/*.json\" \"**/*.md\" \"**/*.html\" \"!CHANGELOG.md\" \"!snap.manifest.json\" --ignore-path ../../../../.gitignore",
+    "publish:preview": "yarn npm publish --tag preview",
+    "since-latest-release": "../../../../scripts/since-latest-release.sh",
+    "start": "mm-snap watch",
+    "test": "jest --reporters=jest-silent-reporter",
+    "test:clean": "jest --clearCache",
+    "test:verbose": "jest --verbose",
+    "test:watch": "jest --watch"
+  },
+  "dependencies": {
+    "@metamask/snaps-sdk": "workspace:^",
+    "@metamask/utils": "^11.9.0"
+  },
+  "devDependencies": {
+    "@jest/globals": "^29.5.0",
+    "@lavamoat/allow-scripts": "^3.4.1",
+    "@metamask/auto-changelog": "^5.0.2",
+    "@metamask/snaps-cli": "workspace:^",
+    "@metamask/snaps-jest": "workspace:^",
+    "@swc/core": "1.11.31",
+    "@swc/jest": "^0.2.38",
+    "@types/node": "18.14.2",
+    "deepmerge": "^4.2.2",
+    "depcheck": "^1.4.7",
+    "eslint": "^9.11.0",
+    "jest": "^29.0.2",
+    "jest-silent-reporter": "^0.6.0",
+    "prettier": "^3.3.3",
+    "ts-node": "^10.9.1",
+    "typescript": "~5.3.3"
+  },
+  "engines": {
+    "node": "^20 || >=22"
+  },
+  "publishConfig": {
+    "access": "public",
+    "registry": "https://registry.npmjs.org/"
+  }
+}