fix: keep IM session streams subscribed across desktop views

Telegram and desktop can attach to the same session while a turn is streaming. The WebSocket handler now tracks output callbacks per client and broadcasts session messages instead of replacing the previous subscriber. Telegram thinking deltas are accumulated before editing the placeholder so the preview does not collapse to the latest tiny chunk.

Constraint: Desktop and IM adapters may observe the same active session concurrently
Rejected: Keep a single session output callback | a later desktop view can steal Telegram's live content and completion events
Confidence: high
Scope-risk: moderate
Directive: Do not collapse session output callbacks back to one callback without a multi-client streaming regression
Tested: bun run check:server (828 pass); bun run check:adapters (358 pass); git diff --check
Not-tested: Live Telegram Bot API smoke against the packaged app

adapters/telegram/__tests__/telegram.test.ts

@@ -2,6 +2,7 @@ import { describe, it, expect } from 'bun:test'
 import { splitMessage, formatPermissionRequest, truncateInput, escapeMarkdownV2 } from '../../common/format.js'
 import { parsePermitCallbackData } from '../../common/permission.js'
 import {
+  buildTelegramThinkingUpdate,
   formatTelegramOutboundText,
   formatTelegramStreamingText,
   planTelegramStreamingUpdate,
@@ -96,6 +97,23 @@ describe('Telegram message formatting', () => {
     })
   })
 
+  describe('Telegram thinking updates', () => {
+    it('accumulates thinking deltas before formatting the preview', () => {
+      const first = buildTelegramThinkingUpdate('', 'The user')
+      const second = buildTelegramThinkingUpdate(first.fullText, ' wants a long answer')
+
+      expect(second.fullText).toBe('The user wants a long answer')
+      expect(second.messageText).toBe('💭 The user wants a long answer...')
+    })
+
+    it('caps long thinking previews while keeping the full accumulated text', () => {
+      const result = buildTelegramThinkingUpdate('abcdef', 'ghij', 6)
+
+      expect(result.fullText).toBe('abcdefghij')
+      expect(result.messageText).toBe('💭 abcdef...')
+    })
+  })
+
   describe('permission request formatting', () => {
     it('formats Bash command request', () => {
       const result = formatPermissionRequest('Bash', { command: 'npm test' }, 'abcde')

adapters/telegram/format.ts

@@ -11,6 +11,26 @@ export function formatTelegramStreamingText(text: string): string {
   return `${formatTelegramOutboundText(text)} ▍`
 }
 
+const DEFAULT_THINKING_PREVIEW_LIMIT = 1000
+
+export type TelegramThinkingUpdate = {
+  fullText: string
+  messageText: string
+}
+
+export function buildTelegramThinkingUpdate(
+  currentText: string,
+  deltaText: string,
+  previewLimit = DEFAULT_THINKING_PREVIEW_LIMIT,
+): TelegramThinkingUpdate {
+  const fullText = currentText + deltaText
+  const preview = fullText.slice(0, Math.max(0, previewLimit)).trimStart()
+  return {
+    fullText,
+    messageText: preview ? `💭 ${preview}...` : '💭 思考中...',
+  }
+}
+
 export type TelegramStreamingUpdate = {
   sealedChunks: string[]
   activeChunk: string

adapters/telegram/index.ts

@@ -19,6 +19,7 @@ import {
   splitMessage,
 } from '../common/format.js'
 import {
+  buildTelegramThinkingUpdate,
   formatTelegramOutboundText,
   formatTelegramStreamingText,
   planTelegramStreamingUpdate,
@@ -68,6 +69,7 @@ attachmentStore.gc().catch((err) => {
 const placeholders = new Map<string, { chatId: string; messageId: number }>()
 // Track accumulated text per chat for streaming
 const accumulatedText = new Map<string, string>()
+const accumulatedThinkingText = new Map<string, string>()
 // Message buffers per chat
 const buffers = new Map<string, MessageBuffer>()
 // Track chats waiting for project selection
@@ -118,6 +120,7 @@ function getRuntimeState(chatId: string): ChatRuntimeState {
 function clearTransientChatState(chatId: string): void {
   placeholders.delete(chatId)
   accumulatedText.delete(chatId)
+  accumulatedThinkingText.delete(chatId)
   buffers.get(chatId)?.reset()
   const runtime = getRuntimeState(chatId)
   runtime.state = 'idle'
@@ -408,11 +411,13 @@ async function handleServerMessage(chatId: string, msg: ServerMessage): Promise<
         const sent = await bot.api.sendMessage(numericChatId, '💭 思考中...')
         placeholders.set(chatId, { chatId, messageId: sent.message_id })
         accumulatedText.set(chatId, '')
+        accumulatedThinkingText.set(chatId, '')
       }
       break
 
     case 'content_start':
       if (msg.blockType === 'text') {
+        accumulatedThinkingText.delete(chatId)
         if (!placeholders.has(chatId)) {
           const sent = await bot.api.sendMessage(numericChatId, '▍')
           placeholders.set(chatId, { chatId, messageId: sent.message_id })
@@ -443,6 +448,7 @@ async function handleServerMessage(chatId: string, msg: ServerMessage): Promise<
 
     case 'content_delta':
       if (msg.text) {
+        accumulatedThinkingText.delete(chatId)
         buf.append(msg.text)
         const newUploads = getTgWatcher(chatId).feed(msg.text)
         for (const pending of newUploads) {
@@ -453,11 +459,16 @@ async function handleServerMessage(chatId: string, msg: ServerMessage): Promise<
 
     case 'thinking':
       if (placeholders.has(chatId)) {
+        const update = buildTelegramThinkingUpdate(
+          accumulatedThinkingText.get(chatId) ?? '',
+          msg.text,
+        )
+        accumulatedThinkingText.set(chatId, update.fullText)
         try {
           await bot.api.editMessageText(
             numericChatId,
             placeholders.get(chatId)!.messageId,
-            `💭 ${msg.text.slice(0, 200)}...`,
+            update.messageText,
           )
         } catch { /* ignore */ }
       }
@@ -506,6 +517,7 @@ async function handleServerMessage(chatId: string, msg: ServerMessage): Promise<
         }
         placeholders.delete(chatId)
         accumulatedText.delete(chatId)
+        accumulatedThinkingText.delete(chatId)
         buffers.get(chatId)?.reset()
       }
       break
@@ -513,6 +525,7 @@ async function handleServerMessage(chatId: string, msg: ServerMessage): Promise<
     case 'error':
       runtime.state = 'idle'
       runtime.verb = undefined
+      accumulatedThinkingText.delete(chatId)
       // Auto-recover from stale thinking block signatures by creating a fresh session.
       // This happens when the API key or provider changed since the session was created.
       if (msg.message && /Invalid.*signature.*thinking/i.test(msg.message)) {

src/server/__tests__/conversations.test.ts

@@ -2528,6 +2528,84 @@ describe('WebSocket Chat Integration', () => {
     })
   })
 
+  it('should stream one active turn to multiple connected clients', async () => {
+    await withMockStreamDelay(150, async () => {
+      const sessionId = `chat-multi-client-${crypto.randomUUID()}`
+      const firstMessages: any[] = []
+      const secondMessages: any[] = []
+
+      await new Promise<void>((resolve, reject) => {
+        let secondConnected = false
+        let firstComplete = false
+        let secondComplete = false
+        let ws2: WebSocket | null = null
+
+        const timeout = setTimeout(() => {
+          ws1.close()
+          ws2?.close()
+          reject(new Error(`Timed out waiting for both clients to complete for session ${sessionId}`))
+        }, 10_000)
+
+        const cleanup = () => {
+          if (!firstComplete || !secondComplete) return
+          clearTimeout(timeout)
+          ws1.close()
+          ws2?.close()
+          resolve()
+        }
+
+        const handleFailure = (message: string) => {
+          clearTimeout(timeout)
+          ws1.close()
+          ws2?.close()
+          reject(new Error(message))
+        }
+
+        const ws1 = new WebSocket(`${wsUrl}/ws/${sessionId}`)
+        ws1.onmessage = (event) => {
+          const msg = JSON.parse(event.data as string)
+          firstMessages.push(msg)
+
+          if (msg.type === 'connected') {
+            ws1.send(JSON.stringify({ type: 'user_message', content: 'multi client stream' }))
+            return
+          }
+
+          if (msg.type === 'thinking' && !secondConnected) {
+            secondConnected = true
+            ws2 = new WebSocket(`${wsUrl}/ws/${sessionId}`)
+            ws2.onmessage = (secondEvent) => {
+              const secondMsg = JSON.parse(secondEvent.data as string)
+              secondMessages.push(secondMsg)
+              if (secondMsg.type === 'error') {
+                handleFailure(secondMsg.message)
+                return
+              }
+              if (secondMsg.type === 'message_complete') {
+                secondComplete = true
+                cleanup()
+              }
+            }
+            ws2.onerror = () => handleFailure(`Second WebSocket error for session ${sessionId}`)
+          }
+
+          if (msg.type === 'message_complete') {
+            firstComplete = true
+            cleanup()
+          }
+        }
+
+        ws1.onerror = () => handleFailure(`First WebSocket error for session ${sessionId}`)
+      })
+
+      expect(firstMessages.some((msg) => msg.type === 'content_delta')).toBe(true)
+      expect(firstMessages.some((msg) => msg.type === 'message_complete')).toBe(true)
+      expect(secondMessages.some((msg) => msg.type === 'connected')).toBe(true)
+      expect(secondMessages.some((msg) => msg.type === 'content_delta')).toBe(true)
+      expect(secondMessages.some((msg) => msg.type === 'message_complete')).toBe(true)
+    })
+  })
+
   it('should keep using the selected runtime config across the whole session until changed', async () => {
     const providerService = new ProviderService()
     const providerA = await providerService.addProvider({

src/server/ws/handler.ts

@@ -107,8 +107,16 @@ export type WebSocketData = {
   serverHost: string
 }
 
-// Active WebSocket sessions
+// Active WebSocket clients, grouped by session. Desktop, H5, and IM adapters can
-const activeSessions = new Map<string, ServerWebSocket<WebSocketData>>()
+// legitimately watch the same running session at the same time.
+const activeSessions = new Map<string, Set<ServerWebSocket<WebSocketData>>>()
+const clientOutputCallbacks = new Map<
+  ServerWebSocket<WebSocketData>,
+  {
+    sessionId: string
+    callback: (cliMsg: any) => void
+  }
+>()
 
 export const handleWebSocket = {
   open(ws: ServerWebSocket<WebSocketData>) {
@@ -135,11 +143,11 @@ export const handleWebSocket = {
       sessionCleanupTimers.delete(sessionId)
     }
 
-    activeSessions.set(sessionId, ws)
+    addActiveClient(sessionId, ws)
     if (prewarmedSessions.has(sessionId)) {
       bindPrewarmMetadataCapture(sessionId)
     } else {
-      rebindSessionOutput(sessionId, ws)
+      bindClientSessionOutput(sessionId, ws)
     }
 
     const msg: ServerMessage = { type: 'connected', sessionId }
@@ -218,19 +226,23 @@ export const handleWebSocket = {
     }
 
     console.log(`[WS] Client disconnected from session: ${sessionId} (${code}: ${reason})`)
-    if (activeSessions.get(sessionId) !== ws) {
+    if (!removeActiveClient(sessionId, ws)) {
       console.log(`[WS] Ignoring stale client disconnect for session: ${sessionId}`)
       return
     }
+    removeClientOutputCallback(ws)
+
+    if (hasActiveClients(sessionId)) {
+      return
+    }
+
     computerUseApprovalService.cancelSession(sessionId)
-    activeSessions.delete(sessionId)
-    conversationService.clearOutputCallbacks(sessionId)
 
     // Schedule delayed cleanup: if the client doesn't reconnect within 30 seconds,
     // stop the CLI subprocess to avoid leaking resources.
     const cleanupTimer = setTimeout(() => {
       sessionCleanupTimers.delete(sessionId)
-      if (!activeSessions.has(sessionId)) {
+      if (!hasActiveClients(sessionId)) {
         console.log(`[WS] Session ${sessionId} not reconnected after 30s, stopping CLI subprocess`)
         conversationService.stopSession(sessionId)
         cleanupSessionRuntimeState(sessionId)
@@ -340,7 +352,7 @@ async function handleUserMessage(
   const shouldForwardCurrentTurnLocalCommand =
     createCurrentTurnLocalCommandForwarder(desktopSlashCommand)
 
-  rebindSessionOutput(sessionId, ws, {
+  bindAllClientSessionOutputs(sessionId, {
     shouldForward: (cliMsg) => {
       if (userMessageSent || (cliMsg.type === 'result' && cliMsg.is_error)) {
         return true
@@ -1679,7 +1691,56 @@ function isCompactSummaryMessageContent(content: unknown): content is string {
   )
 }
 
-function rebindSessionOutput(
+function addActiveClient(
+  sessionId: string,
+  ws: ServerWebSocket<WebSocketData>,
+): void {
+  let clients = activeSessions.get(sessionId)
+  if (!clients) {
+    clients = new Set()
+    activeSessions.set(sessionId, clients)
+  }
+  clients.add(ws)
+}
+
+function removeActiveClient(
+  sessionId: string,
+  ws: ServerWebSocket<WebSocketData>,
+): boolean {
+  const clients = activeSessions.get(sessionId)
+  if (!clients?.has(ws)) return false
+  clients.delete(ws)
+  if (clients.size === 0) {
+    activeSessions.delete(sessionId)
+  }
+  return true
+}
+
+function hasActiveClients(sessionId: string): boolean {
+  return (activeSessions.get(sessionId)?.size ?? 0) > 0
+}
+
+function removeClientOutputCallback(ws: ServerWebSocket<WebSocketData>): void {
+  const entry = clientOutputCallbacks.get(ws)
+  if (!entry) return
+  conversationService.removeOutputCallback(entry.sessionId, entry.callback)
+  clientOutputCallbacks.delete(ws)
+}
+
+function bindAllClientSessionOutputs(
+  sessionId: string,
+  options?: {
+    shouldForward?: (cliMsg: any) => boolean
+  },
+): void {
+  const clients = activeSessions.get(sessionId)
+  if (!clients) return
+  for (const ws of clients) {
+    bindClientSessionOutput(sessionId, ws, options)
+  }
+}
+
+function bindClientSessionOutput(
   sessionId: string,
   ws: ServerWebSocket<WebSocketData>,
   options?: {
@@ -1688,8 +1749,9 @@ function rebindSessionOutput(
 ) {
   if (!conversationService.hasSession(sessionId)) return
 
-  conversationService.clearOutputCallbacks(sessionId)
+  removeClientOutputCallback(ws)
-  conversationService.onOutput(sessionId, (cliMsg) => {
+
+  const callback = (cliMsg: any) => {
     if (options?.shouldForward && !options.shouldForward(cliMsg)) {
       return
     }
@@ -1702,7 +1764,10 @@ function rebindSessionOutput(
     if (cliMsg.type === 'result') {
       triggerTitleGeneration(ws, sessionId)
     }
-  })
+  }
+
+  clientOutputCallbacks.set(ws, { sessionId, callback })
+  conversationService.onOutput(sessionId, callback)
 }
 
 type RuntimeSettings = {
@@ -1926,9 +1991,12 @@ async function waitForRuntimeTransitionBeforeUserTurn(
  * Send a message to a specific session's WebSocket (for use by services)
  */
 export function sendToSession(sessionId: string, message: ServerMessage): boolean {
-  const ws = activeSessions.get(sessionId)
+  const clients = activeSessions.get(sessionId)
-  if (!ws) return false
+  if (!clients || clients.size === 0) return false
-  ws.send(JSON.stringify(message))
+  const payload = JSON.stringify(message)
+  for (const ws of clients) {
+    ws.send(payload)
+  }
   return true
 }
 
@@ -1991,11 +2059,14 @@ export function closeSessionConnection(sessionId: string, reason = 'session clos
   conversationService.clearOutputCallbacks(sessionId)
   cleanupSessionRuntimeState(sessionId)
 
-  const ws = activeSessions.get(sessionId)
+  const clients = activeSessions.get(sessionId)
-  if (!ws) return false
+  if (!clients || clients.size === 0) return false
 
   activeSessions.delete(sessionId)
+  for (const ws of clients) {
+    clientOutputCallbacks.delete(ws)
     ws.close(1000, reason)
+  }
   return true
 }
 
@@ -2007,6 +2078,7 @@ export function __resetWebSocketHandlerStateForTests(): void {
   for (const timer of sessionCleanupTimers.values()) clearTimeout(timer)
   for (const timer of prewarmIdleTimers.values()) clearTimeout(timer)
   activeSessions.clear()
+  clientOutputCallbacks.clear()
   sessionCleanupTimers.clear()
   prewarmIdleTimers.clear()
 }