Discord: fix forum thread starters

src/discord/monitor.tool-result.test.ts

@@ -1,6 +1,7 @@
 import type { Client } from "@buape/carbon";
 import { ChannelType, MessageType } from "@buape/carbon";
 import { beforeEach, describe, expect, it, vi } from "vitest";
+import { Routes } from "discord-api-types/v10";
 
 const sendMock = vi.fn();
 const reactMock = vi.fn();
@@ -381,6 +382,112 @@ describe("discord tool result dispatch", () => {
     expect(capturedCtx?.ThreadLabel).toContain("Discord thread #general");
   });
 
+  it("treats forum threads as distinct sessions without channel payloads", async () => {
+    const { createDiscordMessageHandler } = await import("./monitor.js");
+    let capturedCtx:
+      | {
+          SessionKey?: string;
+          ParentSessionKey?: string;
+          ThreadStarterBody?: string;
+          ThreadLabel?: string;
+        }
+      | undefined;
+    dispatchMock.mockImplementationOnce(async ({ ctx, dispatcher }) => {
+      capturedCtx = ctx;
+      dispatcher.sendFinalReply({ text: "hi" });
+      return { queuedFinal: true, counts: { final: 1 } };
+    });
+
+    const cfg = {
+      agent: { model: "anthropic/claude-opus-4-5", workspace: "/tmp/clawd" },
+      session: { store: "/tmp/clawdbot-sessions.json" },
+      discord: {
+        dm: { enabled: true, policy: "open" },
+        guilds: { "*": { requireMention: false } },
+      },
+      routing: { allowFrom: [] },
+    } as ReturnType<typeof import("../config/config.js").loadConfig>;
+
+    const handler = createDiscordMessageHandler({
+      cfg,
+      discordConfig: cfg.discord,
+      accountId: "default",
+      token: "token",
+      runtime: {
+        log: vi.fn(),
+        error: vi.fn(),
+        exit: (code: number): never => {
+          throw new Error(`exit ${code}`);
+        },
+      },
+      botUserId: "bot-id",
+      guildHistories: new Map(),
+      historyLimit: 0,
+      mediaMaxBytes: 10_000,
+      textLimit: 2000,
+      replyToMode: "off",
+      dmEnabled: true,
+      groupDmEnabled: false,
+      guildEntries: { "*": { requireMention: false } },
+    });
+
+    const fetchChannel = vi
+      .fn()
+      .mockResolvedValueOnce({
+        type: ChannelType.PublicThread,
+        name: "topic-1",
+        parentId: "forum-1",
+      })
+      .mockResolvedValueOnce({
+        type: ChannelType.GuildForum,
+        name: "support",
+      });
+    const restGet = vi.fn().mockResolvedValue({
+      content: "starter message",
+      author: { id: "u1", username: "Alice", discriminator: "0001" },
+      timestamp: new Date().toISOString(),
+    });
+    const client = {
+      fetchChannel,
+      rest: {
+        get: restGet,
+      },
+    } as unknown as Client;
+
+    await handler(
+      {
+        message: {
+          id: "m6",
+          content: "thread reply",
+          channelId: "t1",
+          timestamp: new Date().toISOString(),
+          type: MessageType.Default,
+          attachments: [],
+          embeds: [],
+          mentionedEveryone: false,
+          mentionedUsers: [],
+          mentionedRoles: [],
+          author: { id: "u2", bot: false, username: "Bob", tag: "Bob#2" },
+        },
+        author: { id: "u2", bot: false, username: "Bob", tag: "Bob#2" },
+        member: { displayName: "Bob" },
+        guild: { id: "g1", name: "Guild" },
+        guild_id: "g1",
+      },
+      client,
+    );
+
+    expect(capturedCtx?.SessionKey).toBe("agent:main:discord:channel:t1");
+    expect(capturedCtx?.ParentSessionKey).toBe(
+      "agent:main:discord:channel:forum-1",
+    );
+    expect(capturedCtx?.ThreadStarterBody).toContain("starter message");
+    expect(capturedCtx?.ThreadLabel).toContain("Discord thread #support");
+    expect(restGet).toHaveBeenCalledWith(
+      Routes.channelMessage("t1", "t1"),
+    );
+  });
+
   it("scopes thread sessions to the routed agent", async () => {
     const { createDiscordMessageHandler } = await import("./monitor.js");
 

src/discord/monitor.ts

@@ -139,14 +139,22 @@ async function resolveDiscordThreadStarter(params: {
   channel: DiscordThreadChannel;
   client: Client;
   parentId?: string;
+  parentType?: ChannelType;
 }): Promise<DiscordThreadStarter | null> {
   const cacheKey = params.channel.id;
   const cached = DISCORD_THREAD_STARTER_CACHE.get(cacheKey);
   if (cached) return cached;
   try {
-    if (!params.parentId) return null;
+    const parentType = params.parentType;
+    const isForumParent =
+      parentType === ChannelType.GuildForum ||
+      parentType === ChannelType.GuildMedia;
+    const messageChannelId = isForumParent
+      ? params.channel.id
+      : params.parentId;
+    if (!messageChannelId) return null;
     const starter = (await params.client.rest.get(
-      Routes.channelMessage(params.parentId, params.channel.id),
+      Routes.channelMessage(messageChannelId, params.channel.id),
     )) as {
       content?: string | null;
       embeds?: Array<{ description?: string | null }>;
@@ -226,6 +234,14 @@ export type DiscordMessageHandler = (
   client: Client,
 ) => Promise<void>;
 
+function isDiscordThreadType(type: ChannelType | undefined): boolean {
+  return (
+    type === ChannelType.PublicThread ||
+    type === ChannelType.PrivateThread ||
+    type === ChannelType.AnnouncementThread
+  );
+}
+
 export function resolveDiscordReplyTarget(opts: {
   replyToMode: ReplyToMode;
   replyToId?: string;
@@ -666,12 +682,32 @@ export function createDiscordMessageHandler(params: {
         message.channel &&
         "isThread" in message.channel &&
         message.channel.isThread();
+      const isThreadByType =
+        isGuildMessage && isDiscordThreadType(channelInfo?.type);
       const threadChannel = isThreadChannel
         ? (message.channel as DiscordThreadChannel)
-        : null;
+        : isThreadByType
+          ? {
+              id: message.channelId,
+              name: channelInfo?.name ?? undefined,
+              parentId: channelInfo?.parentId ?? undefined,
+            }
+          : null;
       const threadParentId =
-        threadChannel?.parentId ?? threadChannel?.parent?.id ?? undefined;
+        threadChannel?.parentId ??
-      const threadParentName = threadChannel?.parent?.name;
+        threadChannel?.parent?.id ??
+        channelInfo?.parentId ??
+        undefined;
+      let threadParentName = threadChannel?.parent?.name;
+      let threadParentType: ChannelType | undefined;
+      if (threadChannel && threadParentId) {
+        const parentInfo = await resolveDiscordChannelInfo(
+          client,
+          threadParentId,
+        );
+        threadParentName = threadParentName ?? parentInfo?.name;
+        threadParentType = parentInfo?.type;
+      }
       const threadName = threadChannel?.name;
       const configChannelName = threadParentName ?? channelName;
       const configChannelSlug = configChannelName
@@ -935,6 +971,7 @@ export function createDiscordMessageHandler(params: {
           channel: threadChannel,
           client,
           parentId: threadParentId,
+          parentType: threadParentType,
         });
         if (starter?.text) {
           const starterEnvelope = formatThreadStarterEnvelope({
@@ -1684,13 +1721,17 @@ async function deliverDiscordReply(params: {
 async function resolveDiscordChannelInfo(
   client: Client,
   channelId: string,
-): Promise<{ type: ChannelType; name?: string; topic?: string } | null> {
+): Promise<
+  { type: ChannelType; name?: string; topic?: string; parentId?: string } | null
+> {
   try {
     const channel = await client.fetchChannel(channelId);
     if (!channel) return null;
     const name = "name" in channel ? (channel.name ?? undefined) : undefined;
     const topic = "topic" in channel ? (channel.topic ?? undefined) : undefined;
-    return { type: channel.type, name, topic };
+    const parentId =
+      "parentId" in channel ? (channel.parentId ?? undefined) : undefined;
+    return { type: channel.type, name, topic, parentId };
   } catch (err) {
     logVerbose(`discord: failed to fetch channel ${channelId}: ${String(err)}`);
     return null;