fix(discord): fallback thread parent lookup when parentId missing

src/discord/monitor/threading.parent-info.test.ts

@@ -0,0 +1,47 @@
+import { ChannelType } from "@buape/carbon";
+import { describe, expect, it, vi } from "vitest";
+import { resolveDiscordThreadParentInfo } from "./threading.js";
+
+describe("resolveDiscordThreadParentInfo", () => {
+  it("falls back to fetched thread parentId when parentId is missing in payload", async () => {
+    const fetchChannel = vi.fn(async (channelId: string) => {
+      if (channelId === "thread-1") {
+        return {
+          id: "thread-1",
+          type: ChannelType.PublicThread,
+          name: "thread-name",
+          parentId: "parent-1",
+        };
+      }
+      if (channelId === "parent-1") {
+        return {
+          id: "parent-1",
+          type: ChannelType.GuildText,
+          name: "parent-name",
+        };
+      }
+      return null;
+    });
+
+    const client = {
+      fetchChannel,
+    } as unknown as import("@buape/carbon").Client;
+
+    const result = await resolveDiscordThreadParentInfo({
+      client,
+      threadChannel: {
+        id: "thread-1",
+        parentId: undefined,
+      },
+      channelInfo: null,
+    });
+
+    expect(fetchChannel).toHaveBeenCalledWith("thread-1");
+    expect(fetchChannel).toHaveBeenCalledWith("parent-1");
+    expect(result).toEqual({
+      id: "parent-1",
+      name: "parent-name",
+      type: ChannelType.GuildText,
+    });
+  });
+});

src/discord/monitor/threading.ts

@@ -131,8 +131,12 @@ export async function resolveDiscordThreadParentInfo(params: {
   channelInfo: import("./message-utils.js").DiscordChannelInfo | null;
 }): Promise<DiscordThreadParentInfo> {
   const { threadChannel, channelInfo, client } = params;
-  const parentId =
+  let parentId =
     threadChannel.parentId ?? threadChannel.parent?.id ?? channelInfo?.parentId ?? undefined;
+  if (!parentId && threadChannel.id) {
+    const threadInfo = await resolveDiscordChannelInfo(client, threadChannel.id);
+    parentId = threadInfo?.parentId ?? undefined;
+  }
   if (!parentId) {
     return {};
   }