From 463493aa283422e865b9f69b0e8d5ab5a8a34c87 Mon Sep 17 00:00:00 2001
From: chinar-amrutkar <chinar.amrutkar@gmail.com>
Date: Sun, 3 May 2026 16:16:19 +0100
Subject: [PATCH] fix(telegram): suppress stale replies when dispatch is
 superseded

When a newer inbound message arrives while an older dispatch is still
processing, buffered final answers from the old dispatch could be
delivered into the new message's thread.

Add `bufferedGeneration` to `BufferedFinalAnswer` to track which
abort fence generation buffered the answer. `takeBufferedFinalAnswer`
now rejects buffered answers whose generation doesn't match the
current dispatch's generation, preventing stale content delivery.

Fixes #76642
---
 extensions/telegram/src/bot-message-dispatch.ts      |  3 ++-
 .../telegram/src/reasoning-lane-coordinator.ts       | 12 +++++++++++-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/extensions/telegram/src/bot-message-dispatch.ts b/extensions/telegram/src/bot-message-dispatch.ts
index ac7c1b1aa7c..2c988229c6c 100644
--- a/extensions/telegram/src/bot-message-dispatch.ts
+++ b/extensions/telegram/src/bot-message-dispatch.ts
@@ -907,7 +907,7 @@ export const dispatchTelegramMessage = async ({
                     const _hasMedia = reply.hasMedia;
 
                     const flushBufferedFinalAnswer = async () => {
-                      const buffered = reasoningStepState.takeBufferedFinalAnswer();
+                      const buffered = reasoningStepState.takeBufferedFinalAnswer(abortFenceGeneration);
                       if (!buffered) {
                         return;
                       }
@@ -935,6 +935,7 @@ export const dispatchTelegramMessage = async ({
                         reasoningStepState.bufferFinalAnswer({
                           payload,
                           text: segment.text,
+                          bufferedGeneration: abortFenceGeneration,
                         });
                         continue;
                       }
diff --git a/extensions/telegram/src/reasoning-lane-coordinator.ts b/extensions/telegram/src/reasoning-lane-coordinator.ts
index 447b60dd1d0..182de6202cd 100644
--- a/extensions/telegram/src/reasoning-lane-coordinator.ts
+++ b/extensions/telegram/src/reasoning-lane-coordinator.ts
@@ -93,6 +93,7 @@ export function splitTelegramReasoningText(text?: string): TelegramReasoningSpli
 type BufferedFinalAnswer = {
   payload: ReplyPayload;
   text: string;
+  bufferedGeneration?: number;
 };
 
 export function createTelegramReasoningStepState() {
@@ -117,7 +118,16 @@ export function createTelegramReasoningStepState() {
     bufferedFinalAnswer = value;
   };
 
-  const takeBufferedFinalAnswer = (): BufferedFinalAnswer | undefined => {
+  const takeBufferedFinalAnswer = (
+    currentGeneration?: number,
+  ): BufferedFinalAnswer | undefined => {
+    if (
+      currentGeneration !== undefined &&
+      bufferedFinalAnswer?.bufferedGeneration !== undefined &&
+      bufferedFinalAnswer.bufferedGeneration !== currentGeneration
+    ) {
+      return undefined;
+    }
     const value = bufferedFinalAnswer;
     bufferedFinalAnswer = undefined;
     return value;