feat: Discord slash command handling via HTTP interactions

.changeset/tender-falcons-design.md

@@ -0,0 +1,5 @@
+---
+"@chat-adapter/discord": minor
+---
+
+Add support for slash command interactions — `onSlashCommand` handlers are now invoked when a Discord user triggers an application command, and the deferred "thinking" response is resolved automatically via the interaction token.

packages/adapter-discord/src/index.test.ts

@@ -4,9 +4,9 @@
 
 import { generateKeyPairSync, sign } from "node:crypto";
 import { ValidationError } from "@chat-adapter/shared";
-import type { Logger } from "chat";
+import type { ChatInstance, Logger, StateAdapter } from "chat";
 import { InteractionType } from "discord-api-types/v10";
-import { describe, expect, it, vi } from "vitest";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { createDiscordAdapter, DiscordAdapter } from "./index";
 import { DiscordFormatConverter } from "./markdown";
 
@@ -67,6 +67,52 @@ function createWebhookRequest(
   });
 }
 
+function createMockState(): StateAdapter & { cache: Map<string, unknown> } {
+  const cache = new Map<string, unknown>();
+  return {
+    cache,
+    connect: vi.fn().mockResolvedValue(undefined),
+    disconnect: vi.fn().mockResolvedValue(undefined),
+    subscribe: vi.fn().mockResolvedValue(undefined),
+    unsubscribe: vi.fn().mockResolvedValue(undefined),
+    isSubscribed: vi.fn().mockResolvedValue(false),
+    acquireLock: vi.fn().mockResolvedValue(null),
+    releaseLock: vi.fn().mockResolvedValue(undefined),
+    extendLock: vi.fn().mockResolvedValue(true),
+    get: vi
+      .fn()
+      .mockImplementation((key: string) =>
+        Promise.resolve(cache.get(key) ?? null)
+      ),
+    set: vi.fn().mockImplementation((key: string, value: unknown) => {
+      cache.set(key, value);
+      return Promise.resolve();
+    }),
+    delete: vi.fn().mockImplementation((key: string) => {
+      cache.delete(key);
+      return Promise.resolve();
+    }),
+  };
+}
+
+function createMockChatInstance(state: StateAdapter): ChatInstance {
+  return {
+    processMessage: vi.fn(),
+    handleIncomingMessage: vi.fn().mockResolvedValue(undefined),
+    processReaction: vi.fn(),
+    processAction: vi.fn(),
+    processAppHomeOpened: vi.fn(),
+    processAssistantContextChanged: vi.fn(),
+    processAssistantThreadStarted: vi.fn(),
+    processModalSubmit: vi.fn().mockResolvedValue(undefined),
+    processModalClose: vi.fn(),
+    processSlashCommand: vi.fn(),
+    getState: () => state,
+    getUserName: () => "test-bot",
+    getLogger: () => mockLogger,
+  };
+}
+
 // ============================================================================
 // Factory Function Tests
 // ============================================================================
@@ -374,38 +420,146 @@ describe("handleWebhook - APPLICATION_COMMAND", () => {
     logger: mockLogger,
   });
 
-  it("handles slash command interaction", async () => {
-    const body = JSON.stringify({
-      type: InteractionType.ApplicationCommand,
-      id: "interaction123",
-      application_id: "test-app-id",
-      token: "interaction-token",
-      version: 1,
-      guild_id: "guild123",
-      channel_id: "channel456",
-      member: {
-        user: {
-          id: "user789",
-          username: "testuser",
-          discriminator: "0001",
-        },
-        roles: [],
-        joined_at: "2021-01-01T00:00:00.000Z",
-      },
-      data: {
-        id: "cmd123",
-        name: "test",
-        type: 1,
+  const mockState = createMockState();
+  const mockChat = createMockChatInstance(mockState);
+
+  adapter.initialize(mockChat);
+
+  const slashCommandBody = JSON.stringify({
+    type: InteractionType.ApplicationCommand,
+    id: "interaction123",
+    application_id: "test-app-id",
+    token: "interaction-token",
+    version: 1,
+    guild_id: "guild123",
+    channel_id: "channel456",
+    member: {
+      user: {
+        id: "user789",
+        username: "testuser",
+        discriminator: "0001",
       },
-    });
-    const request = createWebhookRequest(body);
+      roles: [],
+      joined_at: "2021-01-01T00:00:00.000Z",
+    },
+    data: {
+      id: "cmd123",
+      name: "test",
+      type: 1,
+    },
+  });
 
+  it("ACKs with DeferredChannelMessageWithSource", async () => {
+    const request = createWebhookRequest(slashCommandBody);
     const response = await adapter.handleWebhook(request);
     expect(response.status).toBe(200);
-
     const responseBody = await response.json();
     expect(responseBody).toEqual({ type: 5 }); // DeferredChannelMessageWithSource
   });
+
+  it("invokes processSlashCommand with correct event", async () => {
+    const processSlashCommand = mockChat.processSlashCommand as ReturnType<
+      typeof vi.fn
+    >;
+    processSlashCommand.mockClear();
+    const request = createWebhookRequest(slashCommandBody);
+    await adapter.handleWebhook(request);
+
+    expect(processSlashCommand).toHaveBeenCalledOnce();
+    const [event] = processSlashCommand.mock.calls[0] as [
+      Record<string, unknown>,
+    ];
+    expect(event.command).toBe("/test");
+    expect(event.channelId).toBe("discord:guild123:channel456");
+    expect(event.triggerId).toBe("interaction-token");
+    expect((event.user as { userId: string }).userId).toBe("user789");
+    expect(event.raw).toMatchObject({ id: "interaction123" });
+  });
+});
+
+// ============================================================================
+// postChannelMessage - Interaction Token Resolution Tests
+// ============================================================================
+
+describe("postChannelMessage - interaction token resolution", () => {
+  const channelId = "discord:guild123:channel456";
+  const stateKey = `discord:interaction-token:${channelId}`;
+  const msgResponse = { id: "msg-1", channel_id: "channel456" };
+
+  let adapter: InstanceType<typeof DiscordAdapter>;
+  let mockState: ReturnType<typeof createMockState>;
+
+  beforeEach(() => {
+    adapter = createDiscordAdapter({
+      botToken: "test-bot-token",
+      publicKey: testPublicKey,
+      applicationId: "test-app-id",
+      logger: mockLogger,
+    });
+    mockState = createMockState();
+    adapter.initialize(createMockChatInstance(mockState));
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it("PATCHes @original with JSON when token is in state", async () => {
+    await mockState.set(stateKey, "my-token");
+    vi.spyOn(global, "fetch").mockResolvedValue(
+      new Response(JSON.stringify(msgResponse), { status: 200 })
+    );
+
+    const result = await adapter.postChannelMessage(channelId, "Hello!");
+
+    const [url, init] = vi.mocked(fetch).mock.calls[0] as [string, RequestInit];
+    expect(url).toContain("/webhooks/test-app-id/my-token/messages/@original");
+    expect(init.method).toBe("PATCH");
+    expect(init.body).not.toBeInstanceOf(FormData);
+    expect(result.id).toBe("msg-1");
+    expect(await mockState.get(stateKey)).toBeNull();
+  });
+
+  it("PATCHes @original with multipart when token is in state and files are present", async () => {
+    await mockState.set(stateKey, "my-token");
+    vi.spyOn(global, "fetch").mockResolvedValue(
+      new Response(JSON.stringify(msgResponse), { status: 200 })
+    );
+
+    await adapter.postChannelMessage(channelId, {
+      raw: "Here is a file",
+      files: [
+        {
+          filename: "test.txt",
+          data: Buffer.from("hello"),
+          mimeType: "text/plain",
+        },
+      ],
+    });
+
+    const [url, init] = vi.mocked(fetch).mock.calls[0] as [string, RequestInit];
+    expect(url).toContain("/webhooks/test-app-id/my-token/messages/@original");
+    expect(init.method).toBe("PATCH");
+    expect(init.body).toBeInstanceOf(FormData);
+    expect(await mockState.get(stateKey)).toBeNull();
+  });
+
+  it("deletes token and falls back to channel POST when PATCH fails", async () => {
+    await mockState.set(stateKey, "bad-token");
+    vi.spyOn(global, "fetch")
+      .mockResolvedValueOnce(new Response("Server Error", { status: 500 }))
+      .mockResolvedValueOnce(
+        new Response(JSON.stringify(msgResponse), { status: 200 })
+      );
+
+    const result = await adapter.postChannelMessage(channelId, "Hello!");
+
+    expect(vi.mocked(fetch)).toHaveBeenCalledTimes(2);
+    const [secondUrl] = vi.mocked(fetch).mock.calls[1] as [string, RequestInit];
+    expect(secondUrl).toContain("/channels/channel456/messages");
+    expect(result.id).toBe("msg-1");
+    expect(await mockState.get(stateKey)).toBeNull();
+  });
 });
 
 // ============================================================================