diff --git a/src/config/sessions.test.ts b/src/config/sessions.test.ts
index 0f867e93077..c6f92246e02 100644
--- a/src/config/sessions.test.ts
+++ b/src/config/sessions.test.ts
@@ -176,7 +176,7 @@ describe("sessions", () => {
     });
   });
 
-  it("updateLastRoute clears threadId when deliveryContext explicitly omits it", async () => {
+  it("updateLastRoute clears threadId when explicit route omits threadId", async () => {
     const mainSessionKey = "agent:main:main";
     const dir = await fs.mkdtemp(path.join(os.tmpdir(), "openclaw-sessions-"));
     const storePath = path.join(dir, "sessions.json");
@@ -209,7 +209,6 @@ describe("sessions", () => {
       deliveryContext: {
         channel: "telegram",
         to: "222",
-        threadId: undefined,
       },
     });
 
diff --git a/src/config/sessions/store.ts b/src/config/sessions/store.ts
index 8f9ebf1d03a..a7fe48e1444 100644
--- a/src/config/sessions/store.ts
+++ b/src/config/sessions/store.ts
@@ -440,10 +440,21 @@ export async function updateLastRoute(params: {
     });
     const mergedInput = mergeDeliveryContext(explicitContext, inlineContext);
     const explicitDeliveryContext = params.deliveryContext;
-    const clearThreadFromFallback =
+    const explicitThreadFromDeliveryContext =
       explicitDeliveryContext != null &&
-      Object.prototype.hasOwnProperty.call(explicitDeliveryContext, "threadId") &&
-      explicitDeliveryContext.threadId == null;
+      Object.prototype.hasOwnProperty.call(explicitDeliveryContext, "threadId")
+        ? explicitDeliveryContext.threadId
+        : undefined;
+    const explicitThreadValue =
+      explicitThreadFromDeliveryContext ??
+      (threadId != null && threadId !== "" ? threadId : undefined);
+    const explicitRouteProvided = Boolean(
+      explicitContext?.channel ||
+      explicitContext?.to ||
+      inlineContext?.channel ||
+      inlineContext?.to,
+    );
+    const clearThreadFromFallback = explicitRouteProvided && explicitThreadValue == null;
     const fallbackContext = clearThreadFromFallback
       ? removeThreadFromDeliveryContext(deliveryContextFromSession(existing))
       : deliveryContextFromSession(existing);
diff --git a/src/telegram/send.returns-undefined-empty-input.test.ts b/src/telegram/send.returns-undefined-empty-input.test.ts
index d6c71c44d59..a93a1e41b66 100644
--- a/src/telegram/send.returns-undefined-empty-input.test.ts
+++ b/src/telegram/send.returns-undefined-empty-input.test.ts
@@ -508,6 +508,23 @@ describe("sendMessageTelegram", () => {
     expect(res.messageId).toBe("58");
   });
 
+  it("does not retry thread-not-found when no message_thread_id was provided", async () => {
+    const chatId = "123";
+    const threadErr = new Error("400: Bad Request: message thread not found");
+    const sendMessage = vi.fn().mockRejectedValueOnce(threadErr);
+    const api = { sendMessage } as unknown as {
+      sendMessage: typeof sendMessage;
+    };
+
+    await expect(
+      sendMessageTelegram(chatId, "hello forum", {
+        token: "tok",
+        api,
+      }),
+    ).rejects.toThrow("message thread not found");
+    expect(sendMessage).toHaveBeenCalledTimes(1);
+  });
+
   it("sets disable_notification when silent is true", async () => {
     const chatId = "123";
     const sendMessage = vi.fn().mockResolvedValue({
diff --git a/src/telegram/send.ts b/src/telegram/send.ts
index 570f68aa73b..3d1d32bb82a 100644
--- a/src/telegram/send.ts
+++ b/src/telegram/send.ts
@@ -179,7 +179,17 @@ function isTelegramThreadNotFoundError(err: unknown): boolean {
 }
 
 function hasMessageThreadIdParam(params?: Record<string, unknown>): boolean {
-  return Boolean(params && Object.hasOwn(params, "message_thread_id"));
+  if (!params) {
+    return false;
+  }
+  const value = params.message_thread_id;
+  if (typeof value === "number") {
+    return Number.isFinite(value);
+  }
+  if (typeof value === "string") {
+    return value.trim().length > 0;
+  }
+  return false;
 }
 
 function removeMessageThreadIdParam(