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feat(ApplicationState): init controller #7808

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7ff3a8a
feat(ApplicationState): init controller
Kriys94 Feb 2, 2026
06a874b
fix: code
Kriys94 Feb 3, 2026
5b9c3c7
chore: rename to ClientStateController
Kriys94 Feb 5, 2026
3620a98
fix: clean
Kriys94 Feb 5, 2026
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1 change: 1 addition & 0 deletions .github/CODEOWNERS
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/packages/eip-5792-middleware @MetaMask/wallet-integrations

## Core Platform Team
/packages/client-state-controller @MetaMask/core-platform
/packages/base-controller @MetaMask/core-platform
/packages/build-utils @MetaMask/core-platform
/packages/composable-controller @MetaMask/core-platform
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24 changes: 24 additions & 0 deletions packages/client-state-controller/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]

### Changed

- **BREAKING:** Selectors are now exported under `clientStateControllerSelectors` instead of as standalone functions. Use `clientStateControllerSelectors.selectIsClientOpen(state)` instead of `selectIsClientOpen(state)`.

### Added

- Initial release of `@metamask/client-state-controller` (renamed from `@metamask/application-state-controller`)
- `ClientStateController` for managing client (UI) open/closed state
- `ClientStateController:setClientOpen` messenger action for platform code to call
- `ClientStateController:stateChange` event for controllers to subscribe to lifecycle changes
- `isClientOpen` state property (not persisted - always starts as `false`)
- `clientStateControllerSelectors.selectIsClientOpen` selector for derived state access
- Full TypeScript support with exported types

[Unreleased]: https://github.com/MetaMask/core/
21 changes: 21 additions & 0 deletions packages/client-state-controller/LICENSE
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MIT License

Copyright (c) 2026 MetaMask

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 without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
218 changes: 218 additions & 0 deletions packages/client-state-controller/README.md
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# `@metamask/client-state-controller`

Tracks and manages the lifecycle state of MetaMask as a client.

## Overview

The `ClientStateController` provides a centralized way for controllers to respond to application lifecycle changes. Platform code calls `ClientStateController:setClientOpen` via messenger, and other controllers subscribe to `stateChange` events.

**Use this state and events together with other lifecycle signals** (e.g. `KeyringController:unlock` / `KeyringController:lock`). Whether the client is "open" is only one condition; you often also need the keyring unlocked (user has completed onboarding / is logged in) before starting network requests or sensitive work. See [Using with other lifecycle state](#using-with-other-lifecycle-state-eg-keyring-unlocklock) below.

## Important: Usage guidelines and warnings

**Do not subscribe to updates for all kinds of data as soon as the client opens.** When MetaMask opens, the current screen may not need every type of data. Starting subscriptions, polling, or network requests for everything when `isClientOpen` becomes true is not a good long-term strategy and can lead to:

- Unnecessary network traffic and battery use
- **Requests before onboarding is complete** — we have run into problems in the past with making network requests before users complete onboarding; the same issues can recur if consumers start all their updates as soon as the client is "open"
- Poor performance and scalability as more features are added

**Use this controller responsibly:**

- Start only the subscriptions, polling, or requests that are **needed for the current screen or flow**
- Do **not** start network-dependent or heavy behavior solely because `ClientStateController:stateChange` reported `isClientOpen: true`
- Consider **deferring** non-critical updates until the user has completed onboarding or reached a screen that needs that data
- Prefer starting and stopping per feature or per screen (e.g., when a component mounts that needs the data) rather than globally when the client opens
- **Combine with Keyring unlock/lock:** Think about using `ClientStateController` state together with `KeyringController:unlock` and `KeyringController:lock` (or equivalent). Only start work when it is appropriate for both client visibility and wallet state (e.g. client open **and** keyring unlocked).
- **Prefer pause/resume over stop/start for polling:** When reacting to client open/close, prefer pausing and resuming polling (so you can resume without full re-initialization) rather than stopping and starting from scratch. Use the selector when subscribing (see example below).

## Installation

`yarn add @metamask/client-state-controller`

or

`npm install @metamask/client-state-controller`

## Usage

### Basic Setup

```typescript
import { Messenger } from '@metamask/messenger';
import {
ClientStateController,
ClientStateControllerActions,
ClientStateControllerEvents,
} from '@metamask/client-state-controller';

const rootMessenger = new Messenger<
'Root',
ClientStateControllerActions,
ClientStateControllerEvents
>({ namespace: 'Root' });

const controllerMessenger = new Messenger({
namespace: 'ClientStateController',
parent: rootMessenger,
});

const clientStateController = new ClientStateController({
messenger: controllerMessenger,
});
```

### Platform Integration (Extension)

```typescript
// In MetamaskController
class MetamaskController {
// Platform calls this when UI opens/closes
set isClientOpen(open) {
this.controllerMessenger.call(
'ClientStateController:setClientOpen',
open,
);
}
}
```

### Platform Integration (React Native)

```typescript
import { AppState } from 'react-native';

// In Engine initialization
AppState.addEventListener('change', (state) => {
controllerMessenger.call(
'ClientStateController:setClientOpen',
state === 'active',
);
});
```

### Consumer Controller

Use `ClientStateController:stateChange` only for behavior that **must** run when the client is open or closed (e.g., pausing/resuming a single critical background task). Do not use it to start all possible updates; see [Usage guidelines and warnings](#important-usage-guidelines-and-warnings) above.

**Use the selector** when subscribing so the handler receives a single derived value (e.g. `isClientOpen`), and **prefer pause/resume** over stop/start for polling so you can resume without full re-initialization.

```typescript
import { clientStateControllerSelectors } from '@metamask/client-state-controller';

class TokenBalancesController extends BaseController {
constructor({ messenger }) {
super({ messenger, ... });

// Subscribe with a selector so the handler receives isClientOpen (boolean).
// Prefer pause/resume so polling can be resumed without full re-initialization.
this.messenger.subscribe(
'ClientStateController:stateChange',
(isClientOpen) => {
if (isClientOpen) {
this.resumePolling();
} else {
this.pausePolling();
}
},
(state) => clientStateControllerSelectors.selectIsClientOpen(state),
);
}

resumePolling() {
// Start polling if previously paused, otherwise do nothing
}

pausePolling() {
// Mark that polling is paused so resumePolling can restart it later,
// and ensure that polling is stopped
}
}
```

Note: `stateChange` emits `[state, patches]`; the selector receives the full payload and returns the value passed to the handler (here, `isClientOpen`).

### Using with other lifecycle state (e.g. Keyring unlock/lock)

Client open/close alone is usually not enough to decide when to start or stop work. Combine `ClientStateController:stateChange` with other lifecycle events and state, such as:

- **KeyringController:unlock** / **KeyringController:lock** — whether the wallet is unlocked (user has completed onboarding / is logged in)
- Any other controller that expresses "ready for background work" or "user session active"

Only start subscriptions, polling, or network requests when **both** the client is open and the keyring (or equivalent) is unlocked. Stop or pause when the client closes **or** the keyring locks.

```typescript
import { clientStateControllerSelectors } from '@metamask/client-state-controller';

class SomeDataController extends BaseController {
#clientOpen = false;
#keyringUnlocked = false;

constructor({ messenger }) {
super({ messenger, ... });

messenger.subscribe(
'ClientStateController:stateChange',
(isClientOpen) => {
this.#clientOpen = isClientOpen;
this.updateActive();
},
(state) => clientStateControllerSelectors.selectIsClientOpen(state),
);

messenger.subscribe('KeyringController:unlock', () => {
this.#keyringUnlocked = true;
this.updateActive();
});

messenger.subscribe('KeyringController:lock', () => {
this.#keyringUnlocked = false;
this.updateActive();
});
}

updateActive() {
const shouldRun = this.#clientOpen && this.#keyringUnlocked;
if (shouldRun) {
this.resume();
} else {
this.pause();
}
}
}
```

## API Reference

### State

| Property | Type | Description |
| -------------- | --------- | ------------------------------------------ |
| `isClientOpen` | `boolean` | Whether the client (UI) is currently open. |

Note: State is not persisted. It always starts as `false`.

### Actions

| Action | Parameters | Description |
| ----------------------------------------- | --------------- | -------------------------------- |
| `ClientStateController:getState` | none | Returns current state. |
| `ClientStateController:setClientOpen` | `open: boolean` | Sets whether the client is open. |

### Events

| Event | Payload | Description |
| -------------------------------------- | ------------------ | ---------------------------- |
| `ClientStateController:stateChange` | `[state, patches]` | Standard state change event. |

### Selectors

```typescript
import { clientStateControllerSelectors } from '@metamask/client-state-controller';

const state = messenger.call('ClientStateController:getState');
const isOpen = clientStateControllerSelectors.selectIsClientOpen(state);
```

## Contributing

This package is part of a monorepo. Instructions for contributing can be found in the [monorepo README](https://github.com/MetaMask/core#readme).
24 changes: 24 additions & 0 deletions packages/client-state-controller/jest.config.js
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/*
* For a detailed explanation regarding each configuration property and type check, visit:
* https://jestjs.io/docs/configuration
*/

const merge = require('deepmerge');
const path = require('path');

const baseConfig = require('../../jest.config.packages');

const displayName = path.basename(__dirname);

module.exports = merge(baseConfig, {
displayName,
coveragePathIgnorePatterns: [],
coverageThreshold: {
global: {
branches: 100,
functions: 100,
lines: 100,
statements: 100,
},
},
});
72 changes: 72 additions & 0 deletions packages/client-state-controller/package.json
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{
"name": "@metamask/client-state-controller",
"version": "0.0.0",
"description": "Tracks and manages the lifecycle state of MetaMask as a client.",
"keywords": [
"MetaMask",
"Ethereum"
],
"homepage": "https://github.com/MetaMask/core/tree/main/packages/client-state-controller#readme",
"bugs": {
"url": "https://github.com/MetaMask/core/issues"
},
"repository": {
"type": "git",
"url": "https://github.com/MetaMask/core.git"
},
"license": "MIT",
"sideEffects": false,
"exports": {
".": {
"import": {
"types": "./dist/index.d.mts",
"default": "./dist/index.mjs"
},
"require": {
"types": "./dist/index.d.cts",
"default": "./dist/index.cjs"
}
},
"./package.json": "./package.json"
},
"main": "./dist/index.cjs",
"types": "./dist/index.d.cts",
"files": [
"dist/"
],
"scripts": {
"build": "ts-bridge --project tsconfig.build.json --verbose --clean --no-references",
"build:all": "ts-bridge --project tsconfig.build.json --verbose --clean",
"build:docs": "typedoc",
"changelog:update": "../../scripts/update-changelog.sh @metamask/client-state-controller",
"changelog:validate": "../../scripts/validate-changelog.sh @metamask/client-state-controller",
"publish:preview": "yarn npm publish --tag preview",
"since-latest-release": "../../scripts/since-latest-release.sh",
"test": "NODE_OPTIONS=--experimental-vm-modules jest --reporters=jest-silent-reporter",
"test:clean": "NODE_OPTIONS=--experimental-vm-modules jest --clearCache",
"test:verbose": "NODE_OPTIONS=--experimental-vm-modules jest --verbose",
"test:watch": "NODE_OPTIONS=--experimental-vm-modules jest --watch"
},
"dependencies": {
"@metamask/base-controller": "^9.0.0",
"@metamask/messenger": "^0.3.0"
},
"devDependencies": {
"@metamask/auto-changelog": "^3.4.4",
"@ts-bridge/cli": "^0.6.4",
"@types/jest": "^27.5.2",
"deepmerge": "^4.2.2",
"jest": "^27.5.1",
"ts-jest": "^27.1.5",
"typedoc": "^0.24.8",
"typedoc-plugin-missing-exports": "^2.0.0",
"typescript": "~5.3.3"
},
"engines": {
"node": "^18.18 || >=20"
},
"publishConfig": {
"access": "public",
"registry": "https://registry.npmjs.org/"
}
}
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