diff --git a/src/telegram/bot-message-context.dm-topic-threadid.test.ts b/src/telegram/bot-message-context.dm-topic-threadid.test.ts
new file mode 100644
index 0000000000..ffef2f592c
--- /dev/null
+++ b/src/telegram/bot-message-context.dm-topic-threadid.test.ts
@@ -0,0 +1,169 @@
+import { describe, expect, it, vi, beforeEach } from "vitest";
+import { buildTelegramMessageContext } from "./bot-message-context.js";
+
+// Mock recordInboundSession to capture updateLastRoute parameter
+const recordInboundSessionMock = vi.fn().mockResolvedValue(undefined);
+vi.mock("../channels/session.js", () => ({
+  recordInboundSession: (...args: unknown[]) => recordInboundSessionMock(...args),
+}));
+
+describe("buildTelegramMessageContext DM topic threadId in deliveryContext (#8891)", () => {
+  const baseConfig = {
+    agents: { defaults: { model: "anthropic/claude-opus-4-5", workspace: "/tmp/openclaw" } },
+    channels: { telegram: {} },
+    messages: { groupChat: { mentionPatterns: [] } },
+  } as never;
+
+  beforeEach(() => {
+    recordInboundSessionMock.mockClear();
+  });
+
+  it("passes threadId to updateLastRoute for DM topics", async () => {
+    const ctx = await buildTelegramMessageContext({
+      primaryCtx: {
+        message: {
+          message_id: 1,
+          chat: { id: 1234, type: "private" },
+          date: 1700000000,
+          text: "hello",
+          message_thread_id: 42, // DM Topic ID
+          from: { id: 42, first_name: "Alice" },
+        },
+        me: { id: 7, username: "bot" },
+      } as never,
+      allMedia: [],
+      storeAllowFrom: [],
+      options: {},
+      bot: {
+        api: {
+          sendChatAction: vi.fn(),
+          setMessageReaction: vi.fn(),
+        },
+      } as never,
+      cfg: baseConfig,
+      account: { accountId: "default" } as never,
+      historyLimit: 0,
+      groupHistories: new Map(),
+      dmPolicy: "open",
+      allowFrom: [],
+      groupAllowFrom: [],
+      ackReactionScope: "off",
+      logger: { info: vi.fn() },
+      resolveGroupActivation: () => undefined,
+      resolveGroupRequireMention: () => false,
+      resolveTelegramGroupConfig: () => ({
+        groupConfig: { requireMention: false },
+        topicConfig: undefined,
+      }),
+    });
+
+    expect(ctx).not.toBeNull();
+    expect(recordInboundSessionMock).toHaveBeenCalled();
+
+    // Check that updateLastRoute includes threadId
+    const callArgs = recordInboundSessionMock.mock.calls[0]?.[0] as {
+      updateLastRoute?: { threadId?: string };
+    };
+    expect(callArgs?.updateLastRoute).toBeDefined();
+    expect(callArgs?.updateLastRoute?.threadId).toBe("42");
+  });
+
+  it("does not pass threadId for regular DM without topic", async () => {
+    const ctx = await buildTelegramMessageContext({
+      primaryCtx: {
+        message: {
+          message_id: 1,
+          chat: { id: 1234, type: "private" },
+          date: 1700000000,
+          text: "hello",
+          // No message_thread_id
+          from: { id: 42, first_name: "Alice" },
+        },
+        me: { id: 7, username: "bot" },
+      } as never,
+      allMedia: [],
+      storeAllowFrom: [],
+      options: {},
+      bot: {
+        api: {
+          sendChatAction: vi.fn(),
+          setMessageReaction: vi.fn(),
+        },
+      } as never,
+      cfg: baseConfig,
+      account: { accountId: "default" } as never,
+      historyLimit: 0,
+      groupHistories: new Map(),
+      dmPolicy: "open",
+      allowFrom: [],
+      groupAllowFrom: [],
+      ackReactionScope: "off",
+      logger: { info: vi.fn() },
+      resolveGroupActivation: () => undefined,
+      resolveGroupRequireMention: () => false,
+      resolveTelegramGroupConfig: () => ({
+        groupConfig: { requireMention: false },
+        topicConfig: undefined,
+      }),
+    });
+
+    expect(ctx).not.toBeNull();
+    expect(recordInboundSessionMock).toHaveBeenCalled();
+
+    // Check that updateLastRoute does NOT include threadId
+    const callArgs = recordInboundSessionMock.mock.calls[0]?.[0] as {
+      updateLastRoute?: { threadId?: string };
+    };
+    expect(callArgs?.updateLastRoute).toBeDefined();
+    expect(callArgs?.updateLastRoute?.threadId).toBeUndefined();
+  });
+
+  it("does not set updateLastRoute for group messages", async () => {
+    const ctx = await buildTelegramMessageContext({
+      primaryCtx: {
+        message: {
+          message_id: 1,
+          chat: { id: -1001234567890, type: "supergroup", title: "Test Group" },
+          date: 1700000000,
+          text: "@bot hello",
+          message_thread_id: 99,
+          from: { id: 42, first_name: "Alice" },
+        },
+        me: { id: 7, username: "bot" },
+      } as never,
+      allMedia: [],
+      storeAllowFrom: [],
+      options: { forceWasMentioned: true },
+      bot: {
+        api: {
+          sendChatAction: vi.fn(),
+          setMessageReaction: vi.fn(),
+        },
+      } as never,
+      cfg: baseConfig,
+      account: { accountId: "default" } as never,
+      historyLimit: 0,
+      groupHistories: new Map(),
+      dmPolicy: "open",
+      allowFrom: [],
+      groupAllowFrom: [],
+      ackReactionScope: "off",
+      logger: { info: vi.fn() },
+      resolveGroupActivation: () => true,
+      resolveGroupRequireMention: () => false,
+      resolveTelegramGroupConfig: () => ({
+        groupConfig: { requireMention: false },
+        topicConfig: undefined,
+      }),
+    });
+
+    expect(ctx).not.toBeNull();
+    expect(recordInboundSessionMock).toHaveBeenCalled();
+
+    // Check that updateLastRoute is undefined for groups
+    const callArgs = recordInboundSessionMock.mock.calls[0]?.[0] as {
+      updateLastRoute?: unknown;
+    };
+    expect(callArgs?.updateLastRoute).toBeUndefined();
+  });
+});