feat(#379): Register MatrixService in BridgeModule with conditional loading

- Add CHAT_PROVIDERS injection token for bridge-agnostic access
- Conditional loading based on env vars (DISCORD_BOT_TOKEN, MATRIX_ACCESS_TOKEN)
- Both bridges can run simultaneously
- No crash if neither bridge is configured
- Tests verify all configuration combinations

Refs #379

apps/api/src/bridge/bridge.constants.ts

@@ -0,0 +1,15 @@
+/**
+ * Bridge Module Constants
+ *
+ * Injection tokens for the bridge module.
+ */
+
+/**
+ * Injection token for the array of active IChatProvider instances.
+ *
+ * Use this token to inject all configured chat providers:
+ * ```
+ * @Inject(CHAT_PROVIDERS) private readonly chatProviders: IChatProvider[]
+ * ```
+ */
+export const CHAT_PROVIDERS = "CHAT_PROVIDERS";

apps/api/src/bridge/bridge.module.spec.ts

@@ -1,10 +1,13 @@
 import { Test, TestingModule } from "@nestjs/testing";
 import { BridgeModule } from "./bridge.module";
 import { DiscordService } from "./discord/discord.service";
+import { MatrixService } from "./matrix/matrix.service";
 import { StitcherService } from "../stitcher/stitcher.service";
 import { PrismaService } from "../prisma/prisma.service";
 import { BullMqService } from "../bullmq/bullmq.service";
-import { describe, it, expect, beforeEach, vi } from "vitest";
+import { CHAT_PROVIDERS } from "./bridge.constants";
+import type { IChatProvider } from "./interfaces";
+import { describe, it, expect, beforeEach, afterEach, vi } from "vitest";
 
 // Mock discord.js
 const mockReadyCallbacks: Array<() => void> = [];
@@ -53,20 +56,93 @@ vi.mock("discord.js", () => {
   };
 });
 
-describe("BridgeModule", () => {
-  let module: TestingModule;
+// Mock matrix-bot-sdk
+vi.mock("matrix-bot-sdk", () => {
+  return {
+    MatrixClient: class MockMatrixClient {
+      start = vi.fn().mockResolvedValue(undefined);
+      stop = vi.fn();
+      on = vi.fn();
+      sendMessage = vi.fn().mockResolvedValue("$mock-event-id");
+    },
+    SimpleFsStorageProvider: class MockStorage {
+      constructor(_path: string) {
+        // no-op
+      }
+    },
+    AutojoinRoomsMixin: {
+      setupOnClient: vi.fn(),
+    },
+  };
+});
 
-  beforeEach(async () => {
-    // Set environment variables
-    process.env.DISCORD_BOT_TOKEN = "test-token";
-    process.env.DISCORD_GUILD_ID = "test-guild-id";
-    process.env.DISCORD_CONTROL_CHANNEL_ID = "test-channel-id";
+/**
+ * Saved environment variables to restore after each test
+ */
+interface SavedEnvVars {
+  DISCORD_BOT_TOKEN?: string;
+  DISCORD_GUILD_ID?: string;
+  DISCORD_CONTROL_CHANNEL_ID?: string;
+  MATRIX_ACCESS_TOKEN?: string;
+  MATRIX_HOMESERVER_URL?: string;
+  MATRIX_BOT_USER_ID?: string;
+  MATRIX_CONTROL_ROOM_ID?: string;
+  MATRIX_WORKSPACE_ID?: string;
+  ENCRYPTION_KEY?: string;
+}
+
+describe("BridgeModule", () => {
+  let savedEnv: SavedEnvVars;
+
+  beforeEach(() => {
+    // Save current env vars
+    savedEnv = {
+      DISCORD_BOT_TOKEN: process.env.DISCORD_BOT_TOKEN,
+      DISCORD_GUILD_ID: process.env.DISCORD_GUILD_ID,
+      DISCORD_CONTROL_CHANNEL_ID: process.env.DISCORD_CONTROL_CHANNEL_ID,
+      MATRIX_ACCESS_TOKEN: process.env.MATRIX_ACCESS_TOKEN,
+      MATRIX_HOMESERVER_URL: process.env.MATRIX_HOMESERVER_URL,
+      MATRIX_BOT_USER_ID: process.env.MATRIX_BOT_USER_ID,
+      MATRIX_CONTROL_ROOM_ID: process.env.MATRIX_CONTROL_ROOM_ID,
+      MATRIX_WORKSPACE_ID: process.env.MATRIX_WORKSPACE_ID,
+      ENCRYPTION_KEY: process.env.ENCRYPTION_KEY,
+    };
+
+    // Clear all bridge env vars
+    delete process.env.DISCORD_BOT_TOKEN;
+    delete process.env.DISCORD_GUILD_ID;
+    delete process.env.DISCORD_CONTROL_CHANNEL_ID;
+    delete process.env.MATRIX_ACCESS_TOKEN;
+    delete process.env.MATRIX_HOMESERVER_URL;
+    delete process.env.MATRIX_BOT_USER_ID;
+    delete process.env.MATRIX_CONTROL_ROOM_ID;
+    delete process.env.MATRIX_WORKSPACE_ID;
+
+    // Set encryption key (needed by StitcherService)
     process.env.ENCRYPTION_KEY = "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef";
 
     // Clear ready callbacks
     mockReadyCallbacks.length = 0;
 
-    module = await Test.createTestingModule({
+    vi.clearAllMocks();
+  });
+
+  afterEach(() => {
+    // Restore env vars
+    for (const [key, value] of Object.entries(savedEnv)) {
+      if (value === undefined) {
+        delete process.env[key];
+      } else {
+        process.env[key] = value;
+      }
+    }
+  });
+
+  /**
+   * Helper to compile a test module with BridgeModule
+   */
+  async function compileModule(): Promise<TestingModule> {
+    return Test.createTestingModule({
       imports: [BridgeModule],
     })
       .overrideProvider(PrismaService)
@@ -74,24 +150,144 @@ describe("BridgeModule", () => {
       .overrideProvider(BullMqService)
       .useValue({})
       .compile();
+  }
 
-    // Clear all mocks
-    vi.clearAllMocks();
+  /**
+   * Helper to set Discord env vars
+   */
+  function setDiscordEnv(): void {
+    process.env.DISCORD_BOT_TOKEN = "test-discord-token";
+    process.env.DISCORD_GUILD_ID = "test-guild-id";
+    process.env.DISCORD_CONTROL_CHANNEL_ID = "test-channel-id";
+  }
+
+  /**
+   * Helper to set Matrix env vars
+   */
+  function setMatrixEnv(): void {
+    process.env.MATRIX_ACCESS_TOKEN = "test-matrix-token";
+    process.env.MATRIX_HOMESERVER_URL = "https://matrix.example.com";
+    process.env.MATRIX_BOT_USER_ID = "@bot:example.com";
+    process.env.MATRIX_CONTROL_ROOM_ID = "!room:example.com";
+    process.env.MATRIX_WORKSPACE_ID = "test-workspace-id";
+  }
+
+  describe("with both Discord and Matrix configured", () => {
+    let module: TestingModule;
+
+    beforeEach(async () => {
+      setDiscordEnv();
+      setMatrixEnv();
+      module = await compileModule();
+    });
+
+    it("should compile the module", () => {
+      expect(module).toBeDefined();
+    });
+
+    it("should provide DiscordService", () => {
+      const discordService = module.get<DiscordService>(DiscordService);
+      expect(discordService).toBeDefined();
+      expect(discordService).toBeInstanceOf(DiscordService);
+    });
+
+    it("should provide MatrixService", () => {
+      const matrixService = module.get<MatrixService>(MatrixService);
+      expect(matrixService).toBeDefined();
+      expect(matrixService).toBeInstanceOf(MatrixService);
+    });
+
+    it("should provide CHAT_PROVIDERS with both providers", () => {
+      const chatProviders = module.get<IChatProvider[]>(CHAT_PROVIDERS);
+      expect(chatProviders).toBeDefined();
+      expect(chatProviders).toHaveLength(2);
+      expect(chatProviders[0]).toBeInstanceOf(DiscordService);
+      expect(chatProviders[1]).toBeInstanceOf(MatrixService);
+    });
+
+    it("should provide StitcherService via StitcherModule", () => {
+      const stitcherService = module.get<StitcherService>(StitcherService);
+      expect(stitcherService).toBeDefined();
+      expect(stitcherService).toBeInstanceOf(StitcherService);
+    });
   });
 
-  it("should be defined", () => {
-    expect(module).toBeDefined();
+  describe("with only Discord configured", () => {
+    let module: TestingModule;
+
+    beforeEach(async () => {
+      setDiscordEnv();
+      module = await compileModule();
+    });
+
+    it("should compile the module", () => {
+      expect(module).toBeDefined();
+    });
+
+    it("should provide DiscordService", () => {
+      const discordService = module.get<DiscordService>(DiscordService);
+      expect(discordService).toBeDefined();
+      expect(discordService).toBeInstanceOf(DiscordService);
+    });
+
+    it("should provide CHAT_PROVIDERS with only Discord", () => {
+      const chatProviders = module.get<IChatProvider[]>(CHAT_PROVIDERS);
+      expect(chatProviders).toBeDefined();
+      expect(chatProviders).toHaveLength(1);
+      expect(chatProviders[0]).toBeInstanceOf(DiscordService);
+    });
   });
 
-  it("should provide DiscordService", () => {
-    const discordService = module.get<DiscordService>(DiscordService);
-    expect(discordService).toBeDefined();
-    expect(discordService).toBeInstanceOf(DiscordService);
+  describe("with only Matrix configured", () => {
+    let module: TestingModule;
+
+    beforeEach(async () => {
+      setMatrixEnv();
+      module = await compileModule();
+    });
+
+    it("should compile the module", () => {
+      expect(module).toBeDefined();
+    });
+
+    it("should provide MatrixService", () => {
+      const matrixService = module.get<MatrixService>(MatrixService);
+      expect(matrixService).toBeDefined();
+      expect(matrixService).toBeInstanceOf(MatrixService);
+    });
+
+    it("should provide CHAT_PROVIDERS with only Matrix", () => {
+      const chatProviders = module.get<IChatProvider[]>(CHAT_PROVIDERS);
+      expect(chatProviders).toBeDefined();
+      expect(chatProviders).toHaveLength(1);
+      expect(chatProviders[0]).toBeInstanceOf(MatrixService);
+    });
   });
 
-  it("should provide StitcherService", () => {
-    const stitcherService = module.get<StitcherService>(StitcherService);
-    expect(stitcherService).toBeDefined();
-    expect(stitcherService).toBeInstanceOf(StitcherService);
+  describe("with neither bridge configured", () => {
+    let module: TestingModule;
+
+    beforeEach(async () => {
+      // No env vars set for either bridge
+      module = await compileModule();
+    });
+
+    it("should compile the module without errors", () => {
+      expect(module).toBeDefined();
+    });
+
+    it("should provide CHAT_PROVIDERS as an empty array", () => {
+      const chatProviders = module.get<IChatProvider[]>(CHAT_PROVIDERS);
+      expect(chatProviders).toBeDefined();
+      expect(chatProviders).toHaveLength(0);
+      expect(Array.isArray(chatProviders)).toBe(true);
+    });
+  });
+
+  describe("CHAT_PROVIDERS token", () => {
+    it("should be a string constant", () => {
+      expect(CHAT_PROVIDERS).toBe("CHAT_PROVIDERS");
+      expect(typeof CHAT_PROVIDERS).toBe("string");
+    });
   });
 });

apps/api/src/bridge/bridge.module.ts

@@ -1,16 +1,55 @@
-import { Module } from "@nestjs/common";
+import { Logger, Module } from "@nestjs/common";
 import { DiscordService } from "./discord/discord.service";
+import { MatrixService } from "./matrix/matrix.service";
 import { StitcherModule } from "../stitcher/stitcher.module";
+import { CHAT_PROVIDERS } from "./bridge.constants";
+import type { IChatProvider } from "./interfaces";
+
+const logger = new Logger("BridgeModule");
 
 /**
  * Bridge Module - Chat platform integrations
  *
- * Provides integration with chat platforms (Discord, Slack, Matrix, etc.)
+ * Provides integration with chat platforms (Discord, Matrix, etc.)
  * for controlling Mosaic Stack via chat commands.
+ *
+ * Both services are always registered as providers, but the CHAT_PROVIDERS
+ * injection token only includes bridges whose environment variables are set:
+ * - Discord: included when DISCORD_BOT_TOKEN is set
+ * - Matrix: included when MATRIX_ACCESS_TOKEN is set
+ *
+ * Both bridges can run simultaneously, and no error occurs if neither is configured.
+ * Consumers should inject CHAT_PROVIDERS for bridge-agnostic access to all active providers.
  */
 @Module({
   imports: [StitcherModule],
-  providers: [DiscordService],
-  exports: [DiscordService],
+  providers: [
+    DiscordService,
+    MatrixService,
+    {
+      provide: CHAT_PROVIDERS,
+      useFactory: (discord: DiscordService, matrix: MatrixService): IChatProvider[] => {
+        const providers: IChatProvider[] = [];
+
+        if (process.env.DISCORD_BOT_TOKEN) {
+          providers.push(discord);
+          logger.log("Discord bridge enabled (DISCORD_BOT_TOKEN detected)");
+        }
+
+        if (process.env.MATRIX_ACCESS_TOKEN) {
+          providers.push(matrix);
+          logger.log("Matrix bridge enabled (MATRIX_ACCESS_TOKEN detected)");
+        }
+
+        if (providers.length === 0) {
+          logger.warn("No chat bridges configured. Set DISCORD_BOT_TOKEN or MATRIX_ACCESS_TOKEN.");
+        }
+
+        return providers;
+      },
+      inject: [DiscordService, MatrixService],
+    },
+  ],
+  exports: [DiscordService, MatrixService, CHAT_PROVIDERS],
 })
 export class BridgeModule {}