fix(explicit-user-abort): separate explicit user abort semantics (#3776)

* fix(explicit-user-abort): separate explicit user abort semantics

* address comments

* more

apps/sim/app/workspace/[workspaceId]/home/hooks/use-chat.ts

@@ -92,6 +92,9 @@ const DEPLOY_TOOL_NAMES = new Set(['deploy_api', 'deploy_chat', 'deploy_mcp', 'r
 const RECONNECT_TAIL_ERROR =
   'Live reconnect failed before the stream finished. The latest response may be incomplete.'
 const TERMINAL_STREAM_STATUSES = new Set(['complete', 'error', 'cancelled'])
+const MAX_RECONNECT_ATTEMPTS = 10
+const RECONNECT_BASE_DELAY_MS = 1000
+const RECONNECT_MAX_DELAY_MS = 30_000
 
 interface StreamEventEnvelope {
   eventId: number
@@ -1565,6 +1568,7 @@ export function useChat(
     (options?: { error?: boolean }) => {
       sendingRef.current = false
       setIsSending(false)
+      setIsReconnecting(false)
       abortControllerRef.current = null
       invalidateChatQueries()
 
@@ -1609,6 +1613,47 @@ export function useChat(
   )
   finalizeRef.current = finalize
 
+  const resumeOrFinalize = useCallback(
+    async (opts: {
+      streamId: string
+      assistantId: string
+      gen: number
+      fromEventId: number
+      snapshot?: StreamSnapshot | null
+      signal?: AbortSignal
+    }): Promise<void> => {
+      const { streamId, assistantId, gen, fromEventId, snapshot, signal } = opts
+
+      const batch =
+        snapshot ??
+        (await (async () => {
+          const b = await fetchStreamBatch(streamId, fromEventId, signal)
+          if (streamGenRef.current !== gen) return null
+          return { events: b.events, status: b.status } as StreamSnapshot
+        })())
+
+      if (!batch || streamGenRef.current !== gen) return
+
+      if (isTerminalStreamStatus(batch.status)) {
+        finalize(batch.status === 'error' ? { error: true } : undefined)
+        return
+      }
+
+      const reconnectResult = await attachToExistingStream({
+        streamId,
+        assistantId,
+        expectedGen: gen,
+        snapshot: batch,
+        initialLastEventId: batch.events[batch.events.length - 1]?.eventId ?? fromEventId,
+      })
+
+      if (streamGenRef.current === gen && !reconnectResult.aborted) {
+        finalize(reconnectResult.error ? { error: true } : undefined)
+      }
+    },
+    [fetchStreamBatch, attachToExistingStream, finalize]
+  )
+
   const sendMessage = useCallback(
     async (message: string, fileAttachments?: FileAttachmentForApi[], contexts?: ChatContext[]) => {
       if (!message.trim() || !workspaceId) return
@@ -1745,44 +1790,13 @@ export function useChat(
             return
           }
 
-          const batch = await fetchStreamBatch(
-            userMessageId,
-            termination.lastEventId,
-            abortController.signal
-          )
-          if (streamGenRef.current !== gen) {
-            return
-          }
-          if (isTerminalStreamStatus(batch.status)) {
-            finalize(batch.status === 'error' ? { error: true } : undefined)
-            return
-          }
-
-          logger.warn(
-            'Primary stream ended without terminal event, attempting in-place reconnect',
-            {
-              streamId: userMessageId,
-              lastEventId: termination.lastEventId,
-              streamStatus: batch.status,
-              sawDoneEvent: termination.sawDoneEvent,
-            }
-          )
-
-          const reconnectResult = await attachToExistingStream({
+          await resumeOrFinalize({
             streamId: userMessageId,
             assistantId,
-            expectedGen: gen,
-            snapshot: {
-              events: batch.events,
-              status: batch.status,
-            },
-            initialLastEventId:
-              batch.events[batch.events.length - 1]?.eventId ?? termination.lastEventId,
+            gen,
+            fromEventId: termination.lastEventId,
+            signal: abortController.signal,
           })
-
-          if (streamGenRef.current === gen && !reconnectResult.aborted) {
-            finalize(reconnectResult.error ? { error: true } : undefined)
-          }
         }
       } catch (err) {
         if (err instanceof Error && err.name === 'AbortError') return
@@ -1827,17 +1841,13 @@ export function useChat(
               .find((m) => m.role === 'assistant')
             const recoveryAssistantId = lastAssistantMsg?.id ?? assistantId
 
-            const reconnectResult = await attachToExistingStream({
+            await resumeOrFinalize({
               streamId: pendingRecovery.streamId,
               assistantId: recoveryAssistantId,
-              expectedGen: gen,
+              gen,
+              fromEventId: lastEventIdRef.current,
               snapshot: pendingRecovery.snapshot,
-              initialLastEventId: lastEventIdRef.current,
             })
-
-            if (streamGenRef.current === gen && !reconnectResult.aborted) {
-              finalize(reconnectResult.error ? { error: true } : undefined)
-            }
             return
           } catch (recoveryError) {
             logger.warn('Failed to recover active stream after conflict', {
@@ -1847,6 +1857,53 @@ export function useChat(
           }
         }
 
+        const activeStreamId = streamIdRef.current
+        if (activeStreamId && streamGenRef.current === gen) {
+          for (let attempt = 0; attempt < MAX_RECONNECT_ATTEMPTS; attempt++) {
+            if (streamGenRef.current !== gen) return
+            if (abortControllerRef.current?.signal.aborted) return
+
+            const delayMs = Math.min(RECONNECT_BASE_DELAY_MS * 2 ** attempt, RECONNECT_MAX_DELAY_MS)
+            logger.info('Reconnect attempt after network error', {
+              streamId: activeStreamId,
+              attempt: attempt + 1,
+              maxAttempts: MAX_RECONNECT_ATTEMPTS,
+              delayMs,
+              error: errorMessage,
+            })
+
+            setIsReconnecting(true)
+            await new Promise((resolve) => setTimeout(resolve, delayMs))
+
+            if (streamGenRef.current !== gen) return
+            if (abortControllerRef.current?.signal.aborted) return
+
+            try {
+              await resumeOrFinalize({
+                streamId: activeStreamId,
+                assistantId,
+                gen,
+                fromEventId: lastEventIdRef.current,
+                signal: abortController.signal,
+              })
+              return
+            } catch (reconnectErr) {
+              if (reconnectErr instanceof Error && reconnectErr.name === 'AbortError') return
+              logger.warn('Reconnect attempt failed', {
+                streamId: activeStreamId,
+                attempt: attempt + 1,
+                error: reconnectErr instanceof Error ? reconnectErr.message : String(reconnectErr),
+              })
+            }
+          }
+
+          logger.error('All reconnect attempts exhausted', {
+            streamId: activeStreamId,
+            maxAttempts: MAX_RECONNECT_ATTEMPTS,
+          })
+          setIsReconnecting(false)
+        }
+
         setError(errorMessage)
         if (streamGenRef.current === gen) {
           finalize({ error: true })
@@ -1859,7 +1916,7 @@ export function useChat(
       queryClient,
       processSSEStream,
       finalize,
-      attachToExistingStream,
+      resumeOrFinalize,
       preparePendingStreamRecovery,
     ]
   )

apps/sim/lib/copilot/chat-streaming.ts

@@ -23,9 +23,12 @@ const CHAT_STREAM_LOCK_TTL_SECONDS = 2 * 60 * 60
 const STREAM_ABORT_TTL_SECONDS = 10 * 60
 const STREAM_ABORT_POLL_MS = 1000
 
-// Registry of in-flight Sim→Go streams so the explicit abort endpoint can
-// reach them. Keyed by streamId, cleaned up when the stream completes.
-const activeStreams = new Map<string, AbortController>()
+interface ActiveStreamEntry {
+  abortController: AbortController
+  userStopController: AbortController
+}
+
+const activeStreams = new Map<string, ActiveStreamEntry>()
 
 // Tracks in-flight streams by chatId so that a subsequent request for the
 // same chat can force-abort the previous stream and wait for it to settle
@@ -184,9 +187,10 @@ export async function abortActiveStream(streamId: string): Promise<boolean> {
       })
     }
   }
-  const controller = activeStreams.get(streamId)
-  if (!controller) return published
-  controller.abort()
+  const entry = activeStreams.get(streamId)
+  if (!entry) return published
+  entry.userStopController.abort()
+  entry.abortController.abort()
   activeStreams.delete(streamId)
   return true
 }
@@ -285,7 +289,8 @@ export function createSSEStream(params: StreamingOrchestrationParams): ReadableS
   let eventWriter: ReturnType<typeof createStreamEventWriter> | null = null
   let clientDisconnected = false
   const abortController = new AbortController()
-  activeStreams.set(streamId, abortController)
+  const userStopController = new AbortController()
+  activeStreams.set(streamId, { abortController, userStopController })
 
   if (chatId && !pendingChatStreamAlreadyRegistered) {
     registerPendingChatStream(chatId, streamId)
@@ -348,6 +353,7 @@ export function createSSEStream(params: StreamingOrchestrationParams): ReadableS
             try {
               const shouldAbort = await redis.get(getStreamAbortKey(streamId))
               if (shouldAbort && !abortController.signal.aborted) {
+                userStopController.abort()
                 abortController.abort()
                 await redis.del(getStreamAbortKey(streamId))
               }
@@ -449,6 +455,7 @@ export function createSSEStream(params: StreamingOrchestrationParams): ReadableS
           executionId,
           runId,
           abortSignal: abortController.signal,
+          userStopSignal: userStopController.signal,
           onEvent: async (event) => {
             await pushEvent(event)
           },

apps/sim/lib/copilot/orchestrator/index.ts

@@ -116,6 +116,7 @@ export async function orchestrateCopilotStream(
   execContext.executionId = executionId
   execContext.runId = runId
   execContext.abortSignal = options.abortSignal
+  execContext.userStopSignal = options.userStopSignal
 
   const payloadMsgId = requestPayload?.messageId
   const messageId = typeof payloadMsgId === 'string' ? payloadMsgId : crypto.randomUUID()

apps/sim/lib/copilot/orchestrator/sse/handlers/handlers.test.ts

@@ -120,7 +120,9 @@ describe('sse-handlers tool lifecycle', () => {
 
   it('marks an in-flight tool as cancelled when aborted mid-execution', async () => {
     const abortController = new AbortController()
+    const userStopController = new AbortController()
     execContext.abortSignal = abortController.signal
+    execContext.userStopSignal = userStopController.signal
 
     executeToolServerSide.mockImplementationOnce(
       () =>
@@ -137,9 +139,15 @@ describe('sse-handlers tool lifecycle', () => {
       } as any,
       context,
       execContext,
-      { interactive: false, timeout: 1000, abortSignal: abortController.signal }
+      {
+        interactive: false,
+        timeout: 1000,
+        abortSignal: abortController.signal,
+        userStopSignal: userStopController.signal,
+      }
     )
 
+    userStopController.abort()
     abortController.abort()
     await new Promise((resolve) => setTimeout(resolve, 10))
 

apps/sim/lib/copilot/orchestrator/sse/handlers/tool-execution.ts

@@ -240,9 +240,13 @@ function abortRequested(
   execContext: ExecutionContext,
   options?: OrchestratorOptions
 ): boolean {
-  return Boolean(
-    options?.abortSignal?.aborted || execContext.abortSignal?.aborted || context.wasAborted
-  )
+  if (options?.userStopSignal?.aborted || execContext.userStopSignal?.aborted) {
+    return true
+  }
+  if (context.wasAborted) {
+    return true
+  }
+  return false
 }
 
 function cancelledCompletion(message: string): AsyncToolCompletion {

apps/sim/lib/copilot/orchestrator/tool-executor/index.ts

@@ -1269,6 +1269,7 @@ async function executeServerToolDirect(
       chatId: context.chatId,
       messageId: context.messageId,
       abortSignal: context.abortSignal,
+      userStopSignal: context.userStopSignal,
     })
 
     const resultRecord =

apps/sim/lib/copilot/orchestrator/types.ts

@@ -164,6 +164,8 @@ export interface OrchestratorOptions {
   onComplete?: (result: OrchestratorResult) => void | Promise<void>
   onError?: (error: Error) => void | Promise<void>
   abortSignal?: AbortSignal
+  /** Fires only on explicit user stop, never on passive transport disconnect. */
+  userStopSignal?: AbortSignal
   interactive?: boolean
 }
 
@@ -199,6 +201,8 @@ export interface ExecutionContext {
   executionId?: string
   runId?: string
   abortSignal?: AbortSignal
+  /** Fires only on explicit user stop, never on passive transport disconnect. */
+  userStopSignal?: AbortSignal
   userTimezone?: string
   userPermission?: string
   decryptedEnvVars?: Record<string, string>

apps/sim/lib/copilot/tools/server/base-tool.ts

@@ -7,13 +7,15 @@ export interface ServerToolContext {
   chatId?: string
   messageId?: string
   abortSignal?: AbortSignal
+  /** Fires only on explicit user stop, never on passive transport disconnect. */
+  userStopSignal?: AbortSignal
 }
 
 export function assertServerToolNotAborted(
   context?: ServerToolContext,
   message = 'Request aborted before tool mutation could be applied.'
 ): void {
-  if (context?.abortSignal?.aborted) {
+  if (context?.userStopSignal?.aborted) {
     throw new Error(message)
   }
 }