fix(mothership): run workflow tools (run from block, run until block)

apps/sim/app/api/copilot/chat/route.ts

@@ -14,6 +14,7 @@ import {
 } from '@/lib/copilot/chat-streaming'
 import { COPILOT_REQUEST_MODES } from '@/lib/copilot/models'
 import { orchestrateCopilotStream } from '@/lib/copilot/orchestrator'
+import { getStreamMeta, readStreamEvents } from '@/lib/copilot/orchestrator/stream/buffer'
 import {
   authenticateCopilotRequestSessionOnly,
   createBadRequestResponse,
@@ -454,6 +455,30 @@ export async function GET(req: NextRequest) {
         return NextResponse.json({ success: false, error: 'Chat not found' }, { status: 404 })
       }
 
+      let streamSnapshot: {
+        events: Array<{ eventId: number; streamId: string; event: Record<string, unknown> }>
+        status: string
+      } | null = null
+
+      if (chat.conversationId) {
+        try {
+          const [meta, events] = await Promise.all([
+            getStreamMeta(chat.conversationId),
+            readStreamEvents(chat.conversationId, 0),
+          ])
+          streamSnapshot = {
+            events: events || [],
+            status: meta?.status || 'unknown',
+          }
+        } catch (err) {
+          logger.warn('Failed to read stream snapshot for chat', {
+            chatId,
+            conversationId: chat.conversationId,
+            error: err instanceof Error ? err.message : String(err),
+          })
+        }
+      }
+
       const transformedChat = {
         id: chat.id,
         title: chat.title,
@@ -466,6 +491,7 @@ export async function GET(req: NextRequest) {
         resources: Array.isArray(chat.resources) ? chat.resources : [],
         createdAt: chat.createdAt,
         updatedAt: chat.updatedAt,
+        ...(streamSnapshot ? { streamSnapshot } : {}),
       }
 
       logger.info(`Retrieved chat ${chatId}`)

apps/sim/app/workspace/[workspaceId]/home/home.tsx

@@ -178,6 +178,7 @@ export function Home({ chatId }: HomeProps = {}) {
   const {
     messages,
     isSending,
+    isReconnecting,
     sendMessage,
     stopGeneration,
     resolvedChatId,
@@ -330,7 +331,7 @@ export function Home({ chatId }: HomeProps = {}) {
     return () => ro.disconnect()
   }, [hasMessages])
 
-  if (!hasMessages && chatId && isLoadingHistory) {
+  if (chatId && (isLoadingHistory || isReconnecting)) {
     return (
       <ChatSkeleton>
         <UserInput

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

@@ -45,6 +45,7 @@ import type {
 export interface UseChatReturn {
   messages: ChatMessage[]
   isSending: boolean
+  isReconnecting: boolean
   error: string | null
   resolvedChatId: string | undefined
   sendMessage: (
@@ -250,6 +251,7 @@ export function useChat(
   const queryClient = useQueryClient()
   const [messages, setMessages] = useState<ChatMessage[]>([])
   const [isSending, setIsSending] = useState(false)
+  const [isReconnecting, setIsReconnecting] = useState(false)
   const [error, setError] = useState<string | null>(null)
   const [resolvedChatId, setResolvedChatId] = useState<string | undefined>(initialChatId)
   const [resources, setResources] = useState<MothershipResource[]>([])
@@ -268,6 +270,10 @@ export function useChat(
   }, [messageQueue])
 
   const sendMessageRef = useRef<UseChatReturn['sendMessage']>(async () => {})
+  const processSSEStreamRef = useRef<
+    (reader: ReadableStreamDefaultReader<Uint8Array>, assistantId: string) => Promise<void>
+  >(async () => {})
+  const finalizeRef = useRef<(options?: { error?: boolean }) => void>(() => {})
 
   const abortControllerRef = useRef<AbortController | null>(null)
   const chatIdRef = useRef<string | undefined>(initialChatId)
@@ -329,6 +335,7 @@ export function useChat(
     setMessages([])
     setError(null)
     setIsSending(false)
+    setIsReconnecting(false)
     setResources([])
     setActiveResourceId(null)
     setMessageQueue([])
@@ -346,6 +353,7 @@ export function useChat(
     setMessages([])
     setError(null)
     setIsSending(false)
+    setIsReconnecting(false)
     setResources([])
     setActiveResourceId(null)
     setMessageQueue([])
@@ -365,6 +373,95 @@ export function useChat(
         ensureWorkflowInRegistry(resource.id, resource.title, workspaceId)
       }
     }
+
+    // Kick off stream reconnection immediately if there's an active stream.
+    // The stream snapshot was fetched in parallel with the chat history (same
+    // API call), so there's no extra round-trip.
+    const activeStreamId = chatHistory.activeStreamId
+    const snapshot = chatHistory.streamSnapshot
+    if (activeStreamId && !sendingRef.current) {
+      const gen = ++streamGenRef.current
+      const abortController = new AbortController()
+      abortControllerRef.current = abortController
+      streamIdRef.current = activeStreamId
+      sendingRef.current = true
+      setIsReconnecting(true)
+
+      const assistantId = crypto.randomUUID()
+
+      const reconnect = async () => {
+        try {
+          const encoder = new TextEncoder()
+
+          const batchEvents = snapshot?.events ?? []
+          const streamStatus = snapshot?.status ?? ''
+
+          if (!snapshot || (batchEvents.length === 0 && streamStatus === 'unknown')) {
+            // No snapshot available — stream buffer expired. Clean up.
+            const cid = chatIdRef.current
+            if (cid) {
+              fetch('/api/mothership/chat/stop', {
+                method: 'POST',
+                headers: { 'Content-Type': 'application/json' },
+                body: JSON.stringify({ chatId: cid, streamId: activeStreamId, content: '' }),
+              }).catch(() => {})
+            }
+            return
+          }
+
+          setIsSending(true)
+          setIsReconnecting(false)
+
+          const lastEventId =
+            batchEvents.length > 0 ? batchEvents[batchEvents.length - 1].eventId : 0
+          const isStreamDone = streamStatus === 'complete' || streamStatus === 'error'
+
+          const combinedStream = new ReadableStream<Uint8Array>({
+            async start(controller) {
+              if (batchEvents.length > 0) {
+                const sseText = batchEvents
+                  .map((e) => `data: ${JSON.stringify(e.event)}\n`)
+                  .join('\n')
+                controller.enqueue(encoder.encode(`${sseText}\n`))
+              }
+
+              if (!isStreamDone) {
+                try {
+                  const sseRes = await fetch(
+                    `/api/copilot/chat/stream?streamId=${activeStreamId}&from=${lastEventId}`,
+                    { signal: abortController.signal }
+                  )
+                  if (sseRes.ok && sseRes.body) {
+                    const reader = sseRes.body.getReader()
+                    while (true) {
+                      const { done, value } = await reader.read()
+                      if (done) break
+                      controller.enqueue(value)
+                    }
+                  }
+                } catch (err) {
+                  if (!(err instanceof Error && err.name === 'AbortError')) {
+                    logger.warn('SSE tail failed during reconnect', err)
+                  }
+                }
+              }
+
+              controller.close()
+            },
+          })
+
+          await processSSEStreamRef.current(combinedStream.getReader(), assistantId)
+        } catch (err) {
+          if (err instanceof Error && err.name === 'AbortError') return
+        } finally {
+          setIsReconnecting(false)
+          if (streamGenRef.current === gen) {
+            finalizeRef.current()
+          }
+        }
+      }
+      reconnect()
+    }
   }, [chatHistory, workspaceId])
 
   useEffect(() => {
@@ -405,11 +502,14 @@ export function useChat(
 
       const flush = () => {
         streamingBlocksRef.current = [...blocks]
-        setMessages((prev) =>
-          prev.map((m) =>
-            m.id === assistantId ? { ...m, content: runningText, contentBlocks: [...blocks] } : m
-          )
-        )
+        const snapshot = { content: runningText, contentBlocks: [...blocks] }
+        setMessages((prev) => {
+          const idx = prev.findIndex((m) => m.id === assistantId)
+          if (idx >= 0) {
+            return prev.map((m) => (m.id === assistantId ? { ...m, ...snapshot } : m))
+          }
+          return [...prev, { id: assistantId, role: 'assistant' as const, ...snapshot }]
+        })
       }
 
       while (true) {
@@ -662,6 +762,9 @@ export function useChat(
     },
     [workspaceId, queryClient, addResource, removeResource]
   )
+  useLayoutEffect(() => {
+    processSSEStreamRef.current = processSSEStream
+  })
 
   const persistPartialResponse = useCallback(async () => {
     const chatId = chatIdRef.current
@@ -750,50 +853,9 @@ export function useChat(
     },
     [invalidateChatQueries]
   )
-
-  useEffect(() => {
-    const activeStreamId = chatHistory?.activeStreamId
-    if (!activeStreamId || !appliedChatIdRef.current || sendingRef.current) return
-
-    const gen = ++streamGenRef.current
-    const abortController = new AbortController()
-    abortControllerRef.current = abortController
-    sendingRef.current = true
-    setIsSending(true)
-
-    const assistantId = crypto.randomUUID()
-    setMessages((prev) => [
-      ...prev,
-      {
-        id: assistantId,
-        role: 'assistant' as const,
-        content: '',
-        contentBlocks: [],
-      },
-    ])
-
-    const reconnect = async () => {
-      try {
-        const response = await fetch(`/api/copilot/chat/stream?streamId=${activeStreamId}&from=0`, {
-          signal: abortController.signal,
-        })
-        if (!response.ok || !response.body) return
-        await processSSEStream(response.body.getReader(), assistantId)
-      } catch (err) {
-        if (err instanceof Error && err.name === 'AbortError') return
-      } finally {
-        if (streamGenRef.current === gen) {
-          finalize()
-        }
-      }
-    }
-    reconnect()
-
-    return () => {
-      abortController.abort()
-      appliedChatIdRef.current = undefined
-    }
-  }, [chatHistory?.activeStreamId, processSSEStream, finalize])
+  useLayoutEffect(() => {
+    finalizeRef.current = finalize
+  })
 
   const sendMessage = useCallback(
     async (message: string, fileAttachments?: FileAttachmentForApi[], contexts?: ChatContext[]) => {
@@ -937,7 +999,11 @@ export function useChat(
     if (sendingRef.current) {
       await persistPartialResponse()
     }
-    const sid = streamIdRef.current
+    const sid =
+      streamIdRef.current ||
+      queryClient.getQueryData<TaskChatHistory>(taskKeys.detail(chatIdRef.current))
+        ?.activeStreamId ||
+      undefined
     streamGenRef.current++
     abortControllerRef.current?.abort()
     abortControllerRef.current = null
@@ -1054,6 +1120,7 @@ export function useChat(
   return {
     messages,
     isSending,
+    isReconnecting,
     error,
     resolvedChatId,
     sendMessage,