Main Process Architecture Guide: Dependency Injection Pattern (DIP)

When to use this skill

Use this skill when you want to:

• Create or refactor Electron main process modules using the Dependency Injection pattern
• Design testable services, IPC handlers, and window managers with constructor-injected dependencies
• Share provider interfaces across modules and break circular dependencies using the provider pattern
• Establish consistent module and file structure, DI provider registration, and naming conventions
• Onboard contributors to main-process architecture patterns and coding standards

Overview

The main process architecture is built on a Dependency Injection Container pattern, utilizing TypeScript decorators and metadata reflection. This architecture enables modular, testable, and maintainable Electron main process code.

Key Technologies

• TypeScript with decorators and metadata reflection
• Dependency Injection Container for managing service lifecycle
• Module-based architecture for separation of concerns
• IPC Communication between main and renderer processes
• Window Management with lifecycle hooks

Architecture Goals

1. Modularity: Each feature is isolated in its own module
2. Testability: Dependencies are injected, making mocking straightforward
3. Scalability: Easy to add new modules without affecting existing code
4. Type Safety: Full TypeScript support with strong typing
5. Separation of Concerns: Clear boundaries between services, IPC, windows, and data

---

Core Principles

1. Dependency Injection (DI)

All dependencies are injected through constructors, never instantiated directly within classes.

Anti-Pattern (Don't do this):

@Injectable()
export class BadService {
  private authService = new AuthService(); // ❌ Direct instantiation
}

Correct Pattern:

@Injectable()
export class GoodService {
  constructor(private authService: AuthService) {} // ✅ Injected dependency
}

2. Single Responsibility Principle

Each service, IPC handler, and window manager should have one clear responsibility.

3. Provider Pattern for Cross-Module Access

When one module needs functionality from another module, use the Provider Pattern to expose only the necessary interface.

4. Module Encapsulation

Modules export only what other modules need via the exports array in @RgModule.

---

Architecture Layers

1. app.ts (Bootstrap) initializes every module through bootstrapModules so that the DI container and metadata decorators can hydrate the application graph.
2. Module Layer (@RgModule) defines metadata such as imports, providers, ipc, windows, and exports, giving structure to each feature module.
3. Service Layer, IPC Handlers, and Window Managers represent the main entry points for business logic, renderer communication, and BrowserWindow lifecycle hooks within a module.
4. Shared Utilities ($shared, config) provide cross-cutting helpers that can be used by services, IPC handlers, and windows to share configuration, storage, and utility functions.

---

Module System

Module Structure

Every feature module follows this structure:

module-name/
├── module.ts          # Module definition with @RgModule decorator
├── service.ts         # Business logic (optional, can be multiple services)
├── ipc.ts             # IPC communication handlers (optional)
├── window.ts          # BrowserWindow management (optional)
├── tokens.ts          # Dependency injection tokens (optional)
├── types.ts           # TypeScript type definitions (optional)
└── services/          # Additional services (optional)
    ├── service-a.ts
    └── service-b.ts

Module Definition Template

import { RgModule } from "../@core/decorators/rg-module.js";
import { SomeService } from "./service.js";
import { SomeIpc } from "./ipc.js";
import { SomeWindow } from "./window.js";

@RgModule({
  imports: [], // Other modules this module depends on
  providers: [], // Services, factories, and values to register
  ipc: [], // IPC handlers
  windows: [], // Window managers
  exports: [], // Services to expose to other modules
})
export class SomeModule {}

Module Metadata Properties

• imports (Class[]): Modules to import so their exported providers become available in this module.
• providers (Provider[]): Services, factories, or values registered in the DI container for this module.
• ipc (Class[]): IPC handler classes decorated with @IpcHandler() to manage renderer/main communication.
• windows (Class[]): Window manager classes decorated with @WindowManager() that control BrowserWindow lifecycles.
• exports (Class[]): Providers that this module exposes to any module that imports it.

---

Decorators Reference

@RgModule

Defines a module and its dependencies.

Usage:

@RgModule({
  imports: [RestApiModule, CryptoModule],
  providers: [UserService],
  ipc: [UserIpc],
  windows: [],
  exports: [UserService],
})
export class UserModule {}

@Injectable

Marks a class as injectable into the DI container.

Usage:

@Injectable()
export class UserService {
  constructor(
    @Inject(USER_REST_API_PROVIDER)
    private restApiProvider: TUserRestApiProvider
  ) {}

  async fetchUser(id: string): Promise<TUser | undefined> {
    // Implementation
  }
}

@Inject

Injects a dependency using a token (Symbol).

Usage:

@Injectable()
export class SomeService {
  constructor(@Inject(SOME_TOKEN) private dependency: TSomeType) {}
}

@IpcHandler

Marks a class as an IPC communication handler.

Usage:

@IpcHandler()
export class UserIpc implements TIpcHandlerInterface {
  constructor(private userService: UserService) {}

  async onInit({ getWindow }: TParamOnInit<TWindows["main"]>) {
    const mainWindow = getWindow("window:main");

    ipcMainOn("fetchUser", async (event, userId: string) => {
      const user = await this.userService.fetchUser(userId);
      event.reply("fetchUser", user);
    });
  }
}

Lifecycle:

• onInit() is called when the module is bootstrapped

@WindowManager

Defines a window manager with configuration.

Usage:

@WindowManager<TWindows["main"]>({
  hash: "window:main",
  isCache: true,
  options: {
    width: 800,
    height: 600,
    show: false,
    resizable: true,
  },
})
export class MainWindow implements TWindowManager {
  constructor(@Inject(SOME_PROVIDER) private someProvider: TSomeProvider) {}

  onWebContentsDidFinishLoad(window: BrowserWindow): void {
    // Called after window content finishes loading
  }
}

Lifecycle Methods:

• onWebContentsDidFinishLoad(window) - Called when web contents finish loading

---

File Structure Conventions

1. module.ts - Module Definition

Purpose: Declare module metadata and wire dependencies.

Template:

import { RgModule } from "../@core/decorators/rg-module.js";
import { DependencyModule } from "../dependency/module.js";
import { DependencyService } from "../dependency/service.js";
import { FeatureService } from "./service.js";
import { FeatureIpc } from "./ipc.js";
import { FEATURE_DEPENDENCY_PROVIDER } from "./tokens.js";
import type { TFeatureDependencyProvider } from "./types.js";

@RgModule({
  imports: [DependencyModule],
  ipc: [FeatureIpc],
  providers: [
    FeatureService,
    {
      provide: FEATURE_DEPENDENCY_PROVIDER,
      useFactory: (
        depService: DependencyService
      ): TFeatureDependencyProvider => ({
        someMethod: (args) => depService.someMethod(args),
      }),
      inject: [DependencyService],
    },
  ],
  exports: [FeatureService],
})
export class FeatureModule {}

2. service.ts - Business Logic

Purpose: Implement core business logic and data operations.

Template:

import { Injectable } from "../@core/decorators/injectable.js";
import { Inject } from "../@core/decorators/inject.js";
import { FEATURE_DEPENDENCY_PROVIDER } from "./tokens.js";
import type { TFeatureDependencyProvider } from "./types.js";

@Injectable()
export class FeatureService {
  constructor(
    @Inject(FEATURE_DEPENDENCY_PROVIDER)
    private dependencyProvider: TFeatureDependencyProvider
  ) {}

  async performAction(input: string): Promise<TResult | undefined> {
    const result = await this.dependencyProvider.someMethod(input);

    if (result.error !== undefined) {
      console.error("Error:", result.error);
      return undefined;
    }

    return result.data;
  }
}

3. ipc.ts - IPC Communication

Purpose: Handle IPC messages between main and renderer processes.

Template:

import { ipcMainOn } from "../$shared/utils.js";
import { IpcHandler } from "../@core/decorators/ipc-handler.js";
import type {
  TIpcHandlerInterface,
  TParamOnInit,
} from "../@core/types/ipc-handler.js";
import { FeatureService } from "./service.js";

@IpcHandler()
export class FeatureIpc implements TIpcHandlerInterface {
  constructor(private featureService: FeatureService) {}

  async onInit({ getWindow }: TParamOnInit<TWindows["main"]>) {
    const mainWindow = getWindow("window:main");

    ipcMainOn("featureAction", async (event, payload: TPayload) => {
      const result = await this.featureService.performAction(payload.input);
      event.reply("featureAction", result);
    });
  }
}

4. window.ts - Window Management

Purpose: Manage BrowserWindow lifecycle and interactions.

Template:

import { BrowserWindow } from "electron";
import { WindowManager } from "../@core/decorators/window-manager.js";
import { Inject } from "../@core/decorators/inject.js";
import { isDev } from "../$shared/utils.js";
import type { TWindowManager } from "../types.js";
import { FEATURE_PROVIDER } from "./tokens.js";
import type { TFeatureProvider } from "./types.js";

@WindowManager<TWindows["feature"]>({
  hash: "window:feature",
  isCache: true,
  options: {
    width: 500,
    height: 400,
    show: false,
    resizable: isDev(),
  },
})
export class FeatureWindow implements TWindowManager {
  constructor(@Inject(FEATURE_PROVIDER) private provider: TFeatureProvider) {}

  onWebContentsDidFinishLoad(window: BrowserWindow): void {
    // Initialize window after content loads
    this.provider.initialize(window);
  }
}

5. tokens.ts - DI Tokens

Purpose: Define unique symbols for dependency injection.

Template:

export const FEATURE_PROVIDER = Symbol("FEATURE_PROVIDER");
export const FEATURE_DEPENDENCY_PROVIDER = Symbol(
  "FEATURE_DEPENDENCY_PROVIDER"
);

6. types.ts - Type Definitions

Purpose: Define TypeScript types and interfaces.

Template:

import type { BrowserWindow } from "electron";

export type TFeatureProvider = {
  initialize: (window: BrowserWindow) => void;
  cleanup: () => void;
};

export type TFeatureDependencyProvider = {
  someMethod: (input: string) => Promise<TResult>;
};

export type TResult = {
  data?: any;
  error?: {
    message: string;
    code?: string;
  };
};

---

Code Generation Patterns

Pattern 1: Simple Module (Service Only)

Use Case: Utility services with no IPC or windows.

Example: CryptoModule, MenuModule, TrayModule

Structure:

// module.ts
@RgModule({
  providers: [CryptoService],
  exports: [CryptoService],
})
export class CryptoModule {}

// service.ts
@Injectable()
export class CryptoService {
  async encrypt(key: string, data: string): Promise<string> {
    // Implementation
  }

  async decrypt(key: string, encrypted: string): Promise<string> {
    // Implementation
  }
}

Pattern 2: Module with Dependencies

Use Case: Service that depends on other modules.

Example: AuthModule, UserModule

Structure:

// module.ts
@RgModule({
  imports: [RestApiModule],
  providers: [
    AuthService,
    {
      provide: AUTH_REST_API_PROVIDER,
      useFactory: (restApiService: RestApiService): TAuthRestApiProvider => ({
        get: (endpoint, options) => restApiService.get(endpoint, options),
      }),
      inject: [RestApiService],
    },
  ],
  exports: [AuthService],
})
export class AuthModule {}

// tokens.ts
export const AUTH_REST_API_PROVIDER = Symbol("AUTH_REST_API_PROVIDER");

// types.ts
export type TAuthRestApiProvider = {
  get: <T>(endpoint: string, options?: any) => Promise<TApiResponse<T>>;
};

// service.ts
@Injectable()
export class AuthService {
  constructor(
    @Inject(AUTH_REST_API_PROVIDER)
    private restApiProvider: TAuthRestApiProvider
  ) {}

  async login(credentials: TCredentials): Promise<TUser | undefined> {
    const response = await this.restApiProvider.get("/auth/login");
    return response.data;
  }
}

Pattern 3: Module with IPC Communication

Use Case: Feature that communicates with renderer process.

Example: NotificationModule, UserModule

Structure:

// module.ts
@RgModule({
  ipc: [NotificationIpc],
  providers: [NotificationService],
  exports: [NotificationService],
})
export class NotificationModule {}

// ipc.ts
@IpcHandler()
export class NotificationIpc implements TIpcHandlerInterface {
  constructor(private notificationService: NotificationService) {}

  async onInit({ getWindow }: TParamOnInit<TWindows["main"]>) {
    ipcMainOn(
      "showNotification",
      async (event, options: TNotificationOptions) => {
        this.notificationService.setNotification(options);
        event.reply("showNotification", { success: true });
      }
    );
  }
}

Pattern 4: Module with Window Management

Use Case: Feature that creates and manages BrowserWindows.

Example: AppModule, ResourcesModule

Structure:

// module.ts
@RgModule({
  imports: [MenuModule, TrayModule],
  ipc: [AppIpc],
  windows: [AppWindow],
  providers: [
    AppService,
    {
      provide: MENU_PROVIDER,
      useFactory: (menuService: MenuService): TMenuProvider => ({
        buildMenu: (items) => menuService.buildMenu(items),
      }),
      inject: [MenuService],
    },
  ],
})
export class AppModule {}

// window.ts
@WindowManager<TWindows["main"]>({
  hash: "window:main",
  isCache: true,
  options: {
    width: 800,
    height: 600,
    show: false,
  },
})
export class AppWindow implements TWindowManager {
  constructor(@Inject(MENU_PROVIDER) private menuProvider: TMenuProvider) {}

  onWebContentsDidFinishLoad(window: BrowserWindow): void {
    this.menuProvider.buildMenu();
    window.show();
  }
}

// ipc.ts
@IpcHandler()
export class AppIpc implements TIpcHandlerInterface {
  constructor(private appService: AppService) {}

  async onInit({ getWindow }: TParamOnInit<TWindows["main"]>) {
    const mainWindow = getWindow("window:main");
    const window = await mainWindow.create();

    ipcMainOn("closeApp", () => {
      window?.close();
    });
  }
}

Pattern 5: Complex Module with Sub-Services

Use Case: Large modules with multiple services.

Example: ResourcesModule, UpdaterModule

Structure:

resources/
├── module.ts
├── ipc/
│   ├── actions.ts
│   └── open.ts
├── services/
│   ├── resources.ts
│   ├── cacheWindows.ts
│   └── types.ts
├── windows/
│   ├── add.ts
│   ├── update.ts
│   └── delete.ts
├── tokens.ts
└── types.ts

// module.ts
@RgModule({
  imports: [RestApiModule, CryptoModule, TrayModule],
  ipc: [ResourcesActionsIpc, ResourcesOpenIpc],
  windows: [UpdateWindow, AddWindow, DeleteWindow],
  providers: [
    ResourcesService,
    CacheWindowsService,
    {
      provide: RESOURCES_REST_API_PROVIDER,
      useFactory: (
        restApiService: RestApiService
      ): TResourcesRestApiProvider => ({
        get: (endpoint, options) => restApiService.get(endpoint, options),
        post: (endpoint, data, options) =>
          restApiService.post(endpoint, data, options),
        put: (endpoint, data, options) =>
          restApiService.put(endpoint, data, options),
        delete: (endpoint, options) => restApiService.delete(endpoint, options),
      }),
      inject: [RestApiService],
    },
    {
      provide: RESOURCES_CRYPTO_PROVIDER,
      useFactory: (cryptoService: CryptoService): TResourcesCryptoProvider => ({
        encrypt: (key, value) => cryptoService.encrypt(key, value),
        decrypt: (key, vault) => cryptoService.decrypt(key, vault),
      }),
      inject: [CryptoService],
    },
  ],
  exports: [ResourcesService],
})
export class ResourcesModule {}

// services/resources.ts
@Injectable()
export class ResourcesService {
  constructor(
    @Inject(RESOURCES_REST_API_PROVIDER)
    private restApiProvider: TResourcesRestApiProvider
  ) {}

  async byId(id: string): Promise<TResource | undefined> {
    const response = await this.restApiProvider.get(`/resources/${id}`);
    return response.data;
  }

  async create(data: TResourceData): Promise<TResource | undefined> {
    const response = await this.restApiProvider.post("/resources", data);
    return response.data;
  }
}

---

Provider Pattern

Why Use Providers?

Providers create abstraction layers between modules, exposing only necessary functionality while hiding implementation details.

Provider Definition Pattern

1. Create Token:

// tokens.ts
export const SERVICE_PROVIDER = Symbol("SERVICE_PROVIDER");

2. Define Provider Type:

// types.ts
export type TServiceProvider = {
  methodA: (arg: string) => Promise<TResult>;
  methodB: () => void;
};

3. Register in Module:

// module.ts
@RgModule({
  imports: [DependencyModule],
  providers: [
    {
      provide: SERVICE_PROVIDER,
      useFactory: (depService: DependencyService): TServiceProvider => ({
        methodA: (arg) => depService.methodA(arg),
        methodB: () => depService.methodB(),
      }),
      inject: [DependencyService],
    },
  ],
})
export class FeatureModule {}

4. Inject in Consumer:

// service.ts
@Injectable()
export class ConsumerService {
  constructor(@Inject(SERVICE_PROVIDER) private provider: TServiceProvider) {}

  async useProvider(): Promise<void> {
    await this.provider.methodA("input");
    this.provider.methodB();
  }
}

Provider Types

1. Class Provider (Default)

providers: [MyService];
// Equivalent to:
providers: [
  {
    provide: MyService,
    useClass: MyService,
  },
];

2. Factory Provider

providers: [
  {
    provide: MY_TOKEN,
    useFactory: (dep: Dependency): TMyType => ({
      method: () => dep.doSomething(),
    }),
    inject: [Dependency],
  },
];

3. Value Provider

providers: [
  {
    provide: CONFIG_TOKEN,
    useValue: {
      apiUrl: "https://api.example.com",
      timeout: 5000,
    },
  },
];

---

Complete Examples

Example 1: Create a New "Settings" Module

Goal: Create a module that manages application settings with IPC communication.

Step 1: Create Directory Structure

src/main/settings/
├── module.ts
├── service.ts
├── ipc.ts
├── tokens.ts
└── types.ts

Step 2: Define Types

// types.ts
export type TSettings = {
  theme: "light" | "dark";
  language: string;
  autoUpdate: boolean;
};

export type TUpdateSettingsPayload = Partial<TSettings>;

Step 3: Create Service

// service.ts
import { Injectable } from "../@core/decorators/injectable.js";
import { getElectronStorage, setElectronStorage } from "../$shared/store.js";

@Injectable()
export class SettingsService {
  constructor() {}

  getSettings(): TSettings {
    const settings = getElectronStorage("settings");

    return (
      settings ?? {
        theme: "light",
        language: "en",
        autoUpdate: true,
      }
    );
  }

  updateSettings(updates: TUpdateSettingsPayload): TSettings {
    const currentSettings = this.getSettings();
    const newSettings = { ...currentSettings, ...updates };

    setElectronStorage("settings", newSettings);

    return newSettings;
  }
}

Step 4: Create IPC Handler

// ipc.ts
import { ipcMainOn } from "../$shared/utils.js";
import { IpcHandler } from "../@core/decorators/ipc-handler.js";
import type {
  TIpcHandlerInterface,
  TParamOnInit,
} from "../@core/types/ipc-handler.js";
import { SettingsService } from "./service.js";
import type { TUpdateSettingsPayload } from "./types.js";

@IpcHandler()
export class SettingsIpc implements TIpcHandlerInterface {
  constructor(private settingsService: SettingsService) {}

  async onInit({ getWindow }: TParamOnInit<TWindows["main"]>) {
    ipcMainOn("getSettings", (event) => {
      const settings = this.settingsService.getSettings();
      event.reply("getSettings", settings);
    });

    ipcMainOn("updateSettings", (event, payload: TUpdateSettingsPayload) => {
      const settings = this.settingsService.updateSettings(payload);
      event.reply("updateSettings", settings);
    });
  }
}

Step 5: Create Module

// module.ts
import { RgModule } from "../@core/decorators/rg-module.js";
import { SettingsService } from "./service.js";
import { SettingsIpc } from "./ipc.js";

@RgModule({
  ipc: [SettingsIpc],
  providers: [SettingsService],
  exports: [SettingsService],
})
export class SettingsModule {}

Step 6: Register in app.ts

// app.ts
import { SettingsModule } from "./settings/module.js";

app.on("ready", async () => {
  await bootstrapModules([
    AppPreloadModule,
    AppModule,
    SettingsModule, // Add here
    // ... other modules
  ]);
});

Example 2: Module with External API Integration

Goal: Create a Weather module that fetches weather data from an external API.

Step 1: Create Structure

src/main/weather/
├── module.ts
├── service.ts
├── ipc.ts
├── tokens.ts
└── types.ts

Step 2: Define Types

// types.ts
export type TWeatherData = {
  temperature: number;
  condition: string;
  humidity: number;
  location: string;
};

export type TWeatherRestApiProvider = {
  get: <T>(endpoint: string, options?: any) => Promise<TApiResponse<T>>;
};

type TApiResponse<T> = {
  data?: T;
  error?: {
    message: string;
    code?: string;
  };
  status: number;
};

Step 3: Create Tokens

// tokens.ts
export const WEATHER_REST_API_PROVIDER = Symbol("WEATHER_REST_API_PROVIDER");

Step 4: Create Service

// service.ts
import { Injectable } from "../@core/decorators/injectable.js";
import { Inject } from "../@core/decorators/inject.js";
import { WEATHER_REST_API_PROVIDER } from "./tokens.js";
import type { TWeatherRestApiProvider, TWeatherData } from "./types.js";

@Injectable()
export class WeatherService {
  constructor(
    @Inject(WEATHER_REST_API_PROVIDER)
    private restApiProvider: TWeatherRestApiProvider
  ) {}

  async getWeather(city: string): Promise<TWeatherData | undefined> {
    const response = await this.restApiProvider.get<TWeatherData>(
      `https://api.weather.com/v1/weather?city=${city}`,
      {
        headers: {
          "Content-Type": "application/json",
        },
      }
    );

    if (response.error !== undefined) {
      console.error("Weather API Error:", response.error);
      return undefined;
    }

    return response.data;
  }
}

Step 5: Create IPC Handler

// ipc.ts
import { ipcMainOn } from "../$shared/utils.js";
import { IpcHandler } from "../@core/decorators/ipc-handler.js";
import type {
  TIpcHandlerInterface,
  TParamOnInit,
} from "../@core/types/ipc-handler.js";
import { WeatherService } from "./service.js";

@IpcHandler()
export class WeatherIpc implements TIpcHandlerInterface {
  constructor(private weatherService: WeatherService) {}

  async onInit({ getWindow }: TParamOnInit<TWindows["main"]>) {
    ipcMainOn("getWeather", async (event, city: string) => {
      const weather = await this.weatherService.getWeather(city);
      event.reply("getWeather", weather);
    });
  }
}

Step 6: Create Module with Provider

// module.ts
import { RgModule } from "../@core/decorators/rg-module.js";
import { RestApiModule } from "../rest-api/module.js";
import { RestApiService } from "../rest-api/service.js";
import { WeatherService } from "./service.js";
import { WeatherIpc } from "./ipc.js";
import { WEATHER_REST_API_PROVIDER } from "./tokens.js";
import type { TWeatherRestApiProvider } from "./types.js";

@RgModule({
  imports: [RestApiModule],
  ipc: [WeatherIpc],
  providers: [
    WeatherService,
    {
      provide: WEATHER_REST_API_PROVIDER,
      useFactory: (
        restApiService: RestApiService
      ): TWeatherRestApiProvider => ({
        get: (endpoint, options) => restApiService.get(endpoint, options),
      }),
      inject: [RestApiService],
    },
  ],
  exports: [WeatherService],
})
export class WeatherModule {}

Example 3: Module with Window Management

Goal: Create a Preferences window module.

Step 1: Create Structure

src/main/preferences/
├── module.ts
├── service.ts
├── ipc.ts
├── window.ts
├── tokens.ts
└── types.ts

Step 2: Update Window Types

// src/main/config.ts (add to windows object)
export const windows: TWindows = {
  // ... existing windows
  preferences: "window:preferences",
};

Step 3: Define Types

// types.ts
import type { BrowserWindow } from "electron";

export type TPreferencesProvider = {
  openPreferences: () => void;
  closePreferences: () => void;
};

Step 4: Create Tokens

// tokens.ts
export const PREFERENCES_PROVIDER = Symbol("PREFERENCES_PROVIDER");

Step 5: Create Service

// service.ts
import { Injectable } from "../@core/decorators/injectable.js";
import { getWindow } from "../@core/control-window/receive.js";

@Injectable()
export class PreferencesService {
  constructor() {}

  async openPreferences(): Promise<void> {
    const preferencesWindow =
      getWindow<TWindows["preferences"]>("window:preferences");

    if (preferencesWindow !== undefined) {
      const window = await preferencesWindow.create();
      window?.show();
    }
  }

  closePreferences(): void {
    const preferencesWindow =
      getWindow<TWindows["preferences"]>("window:preferences");

    if (preferencesWindow !== undefined) {
      preferencesWindow.hide();
    }
  }
}

Step 6: Create Window Manager

// window.ts
import { BrowserWindow } from "electron";
import { WindowManager } from "../@core/decorators/window-manager.js";
import { isDev } from "../$shared/utils.js";
import type { TWindowManager } from "../types.js";

@WindowManager<TWindows["preferences"]>({
  hash: "window:preferences",
  isCache: true,
  options: {
    width: 600,
    height: 500,
    show: false,
    resizable: isDev(),
    title: "Preferences",
  },
})
export class PreferencesWindow implements TWindowManager {
  constructor() {}

  onWebContentsDidFinishLoad(window: BrowserWindow): void {
    // Initialize preferences window
    console.log("Preferences window loaded");
  }
}

Step 7: Create IPC Handler

// ipc.ts
import { ipcMainOn } from "../$shared/utils.js";
import { IpcHandler } from "../@core/decorators/ipc-handler.js";
import type {
  TIpcHandlerInterface,
  TParamOnInit,
} from "../@core/types/ipc-handler.js";
import { PreferencesService } from "./service.js";

@IpcHandler()
export class PreferencesIpc implements TIpcHandlerInterface {
  constructor(private preferencesService: PreferencesService) {}

  async onInit({ getWindow }: TParamOnInit<TWindows["main"]>) {
    ipcMainOn("openPreferences", async () => {
      await this.preferencesService.openPreferences();
    });

    ipcMainOn("closePreferences", () => {
      this.preferencesService.closePreferences();
    });
  }
}

Step 8: Create Module

// module.ts
import { RgModule } from "../@core/decorators/rg-module.js";
import { PreferencesService } from "./service.js";
import { PreferencesIpc } from "./ipc.js";
import { PreferencesWindow } from "./window.js";

@RgModule({
  ipc: [PreferencesIpc],
  windows: [PreferencesWindow],
  providers: [PreferencesService],
  exports: [PreferencesService],
})
export class PreferencesModule {}

---

Best Practices

1. Module Organization

✅ Do:

• Keep modules focused on a single feature or domain
• Use sub-services for complex modules
• Export only what other modules need
• Import only required modules

❌ Don't:

• Create circular dependencies between modules
• Export everything from a module
• Mix unrelated functionality in one module

2. Service Design

✅ Do:

• Inject all dependencies via constructor
• Use @Injectable() decorator on all services
• Keep services stateless when possible
• Return undefined on errors with logging
• Use TypeScript types for all parameters and return values

❌ Don't:

• Instantiate services directly (new MyService())
• Store mutable state in services without careful consideration
• Throw errors without handling them
• Use any type

3. Provider Pattern

✅ Do:

• Create provider interfaces that expose minimal API surface
• Use descriptive names for provider tokens
• Document provider type interfaces
• Use factory providers for cross-module dependencies

❌ Don't:

• Expose entire services across module boundaries
• Create providers without type definitions
• Use string tokens (use Symbols instead)

4. IPC Communication

✅ Do:

• Define clear IPC channel names
• Type all IPC payloads
• Handle errors gracefully
• Use ipcMainOn helper for type safety
• Reply to all IPC calls

❌ Don't:

• Use generic channel names like "data" or "message"
• Send untyped data over IPC
• Forget to handle errors
• Create memory leaks by not removing listeners

5. Window Management

✅ Do:

• Use descriptive window hash names
• Set appropriate default window options
• Implement onWebContentsDidFinishLoad for initialization
• Use isCache: true for singleton windows
• Hide windows instead of destroying when reusable

❌ Don't:

• Create multiple instances of singleton windows
• Show windows before content is loaded
• Hardcode window dimensions (use config)
• Forget to clean up window resources

6. Error Handling

✅ Do:

• Return undefined on errors
• Log errors with context
• Use dialog.showMessageBox for critical errors
• Validate input before processing
• Handle async errors with try-catch

❌ Don't:

• Silently swallow errors
• Use error codes without messages
• Crash the app on recoverable errors

7. Type Safety

✅ Do:

• Define all types in types.ts
• Use strict TypeScript compiler options
• Type all function parameters and returns
• Use discriminated unions for state
• Export types for cross-module usage

❌ Don't:

• Use any type
• Skip type definitions
• Use implicit types
• Create type inconsistencies

8. Naming Conventions

✅ Do:

• Use PascalCase for class names
• Use camelCase for method and variable names
• Use UPPER_SNAKE_CASE for constants and tokens
• Prefix types with T (e.g., TUser, TSettings)
• Suffix modules with Module
• Suffix services with Service
• Suffix IPC handlers with Ipc
• Suffix windows with Window

❌ Don't:

• Mix naming conventions
• Use abbreviations without context
• Create ambiguous names

9. File Organization

✅ Do:

• Keep related files together in module folders
• Use services/ subfolder for multiple services
• Use ipc/ subfolder for multiple IPC handlers
• Use windows/ subfolder for multiple windows
• Use index files sparingly

❌ Don't:

• Create deeply nested folder structures
• Mix module files with core framework files
• Create circular file dependencies

10. Dependency Management

✅ Do:

• Declare all module dependencies in imports
• Use provider pattern for cross-module access
• Register services in the correct module
• Export services that other modules need

❌ Don't:

• Access services from unimported modules
• Create tight coupling between modules
• Import modules unnecessarily

---

Common Patterns Summary

1. Simple Utility Module (e.g., CryptoModule)

@RgModule({
  providers: [UtilityService],
  exports: [UtilityService],
})
export class UtilityModule {}

2. Module with External Dependency (e.g., AuthModule)

@RgModule({
  imports: [DependencyModule],
  providers: [
    FeatureService,
    {
      provide: FEATURE_PROVIDER,
      useFactory: (dep: DependencyService) => ({
        method: () => dep.method(),
      }),
      inject: [DependencyService],
    },
  ],
  exports: [FeatureService],
})
export class FeatureModule {}

3. Module with IPC (e.g., NotificationModule)

@RgModule({
  ipc: [FeatureIpc],
  providers: [FeatureService],
  exports: [FeatureService],
})
export class FeatureModule {}

4. Module with Window (e.g., AppModule)

@RgModule({
  imports: [DependencyModule],
  ipc: [FeatureIpc],
  windows: [FeatureWindow],
  providers: [FeatureService],
})
export class FeatureModule {}

5. Complex Module (e.g., ResourcesModule, UpdaterModule)

@RgModule({
  imports: [Dep1Module, Dep2Module, Dep3Module],
  ipc: [Feature1Ipc, Feature2Ipc],
  windows: [Window1, Window2],
  providers: [
    Service1,
    Service2,
    Service3,
    { provide: PROVIDER_1, useFactory: ..., inject: [...] },
    { provide: PROVIDER_2, useFactory: ..., inject: [...] },
  ],
  exports: [Service1],
})
export class ComplexModule {}

---

Troubleshooting

Issue: "Cannot inject undefined"

Cause: Service is not registered in module providers or dependency module is not imported.

Solution:

1. Ensure service is in providers array
2. Check that dependency module is in imports array
3. Verify exported services in dependency modules

Issue: "Circular dependency detected"

Cause: Two modules import each other.

Solution:

1. Refactor shared functionality into a third module
2. Use provider pattern to break circular dependency
3. Reconsider module boundaries

Issue: "Window is undefined"

Cause: Window not registered in module or hash mismatch.

Solution:

1. Add window class to windows array in @RgModule
2. Verify hash in @WindowManager matches usage
3. Check window is registered in config.ts

Issue: "IPC handler not called"

Cause: IPC handler not registered or channel name mismatch.

Solution:

1. Add IPC handler to ipc array in @RgModule
2. Verify channel names match between main and renderer
3. Ensure onInit is implemented

---

Conclusion

This architecture provides a robust, scalable foundation for Electron main process development using Dependency Injection and modular design. By following these patterns and best practices, you can create maintainable, testable, and well-organized code.

Key Takeaways:

1. Use decorators (@RgModule, @Injectable, @IpcHandler, @WindowManager) for metadata-driven architecture
2. Inject dependencies via constructors, never instantiate directly
3. Use providers to expose functionality across module boundaries
4. Follow file conventions for consistent codebase structure
5. Type everything for maximum type safety
6. Keep modules focused on single responsibilities
7. Handle errors gracefully with appropriate user feedback

When generating new code, always follow these patterns to maintain architectural consistency.