fix(chat): carry attachments through the stored handoff lane too

The unclaimed-event fallback excluded attachment sends and restored
them under the disposed mount's pending key. The persisted handoff now
carries fileAttachments (they are plain references to already-uploaded
files), the home consumer forwards them, and the recovery branch always
hands off — no stranded lane remains.

Author: j15z

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

@@ -370,7 +370,7 @@ export function Home({ chatId, userName, userId, tableViewsEnabled }: HomeProps)
     const handoff = MothershipHandoffStorage.consume(workspaceId)
     if (!handoff) return
     if (handoff.message) {
-      sendMessage(handoff.message, undefined, handoff.contexts)
+      sendMessage(handoff.message, handoff.fileAttachments, handoff.contexts)
       return
     }
     const contexts = handoff.contexts ?? []

apps/sim/app/workspace/[workspaceId]/home/hooks/use-chat.mount-send.test.tsx

@@ -178,10 +178,17 @@ describe('useChat mount-settling send recovery', () => {
   })
 
   it('re-persists an aborted chatless send as a handoff for the next mount', async () => {
+    const attachment = {
+      id: 'file-2',
+      key: 'uploads/file-2',
+      filename: 'report.pdf',
+      media_type: 'application/pdf',
+      size: 99,
+    }
     const { getResult, unmount } = renderUseChat()
 
     await act(async () => {
-      void getResult().sendMessage('hello from the palette')
+      void getResult().sendMessage('hello from the palette', [attachment])
     })
     await waitFor(() => state.postCalls === 1)
 
@@ -197,7 +204,9 @@ describe('useChat mount-settling send recovery', () => {
     await waitFor(() => window.localStorage.getItem('sim_mothership_handoff') !== null)
 
     expect(allQueuedMessages()).toHaveLength(0)
-    expect(MothershipHandoffStorage.consume('ws-1')?.message).toBe('hello from the palette')
+    const handoff = MothershipHandoffStorage.consume('ws-1')
+    expect(handoff?.message).toBe('hello from the palette')
+    expect(handoff?.fileAttachments).toEqual([attachment])
   })
 
   it('does not re-queue a send the server already received', async () => {

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

@@ -4506,26 +4506,22 @@ export function useChat(
            the cleanup that aborted this send belongs to a full remount — a
            queue restore would orphan the message under the dead instance's
            key. Deliver to the replacement surface instead: its send listener
-           is live by the time this microtask executes, and the event carries
-           attachments. When nothing claims it (a real navigation away), a
-           one-shot handoff covers attachment-less sends for the next mount;
-           attachment payloads exceed what the handoff carries and fall back to
-           the queue restore. Chat-bound sends always keep the queue restore
-           (their key is the stable chat id). */
+           is live by the time this microtask executes. When nothing claims the
+           event (a real navigation away), a one-shot handoff covers the next
+           mount; both lanes carry attachments. Chat-bound sends keep the queue
+           restore — their key is the stable chat id. */
         if (recoverableCleanupAbort && dispatchChatKey.startsWith(PENDING_CHAT_KEY_PREFIX)) {
-          if (sendMothershipMessage(msg.content, msg.contexts, msg.fileAttachments)) {
-            return
-          }
-          if (!msg.fileAttachments?.length) {
+          if (!sendMothershipMessage(msg.content, msg.contexts, msg.fileAttachments)) {
             MothershipHandoffStorage.store(
               {
                 message: msg.content,
                 ...(msg.contexts?.length ? { contexts: msg.contexts } : {}),
+                ...(msg.fileAttachments?.length ? { fileAttachments: msg.fileAttachments } : {}),
               },
               workspaceId
             )
-            return
           }
+          return
         }
         useMothershipQueueStore.getState().insertAt(dispatchChatKey, originalIndex, msg)
       }

apps/sim/lib/core/utils/browser-storage.ts

@@ -4,6 +4,7 @@
  */
 
 import { createLogger } from '@sim/logger'
+import type { FileAttachmentForApi } from '@/app/workspace/[workspaceId]/home/types'
 import type { ChatContext } from '@/stores/panel'
 
 const logger = createLogger('BrowserStorage')
@@ -307,6 +308,8 @@ export interface MothershipHandoff {
   message?: string
   /** Structured contexts to attach — e.g. a `logs` mention tagging a run. */
   contexts?: ChatContext[]
+  /** Already-uploaded attachment references riding along with the message. */
+  fileAttachments?: FileAttachmentForApi[]
 }
 
 interface StoredHandoff extends MothershipHandoff {
@@ -353,6 +356,7 @@ export class MothershipHandoffStorage {
       contexts: message
         ? contexts
         : [...MothershipHandoffStorage.pendingContexts(workspaceId), ...contexts],
+      ...(handoff.fileAttachments?.length ? { fileAttachments: handoff.fileAttachments } : {}),
       workspaceId,
       timestamp: Date.now(),
     })
@@ -409,7 +413,13 @@ export class MothershipHandoffStorage {
       return null
     }
 
-    return { ...(data.message ? { message: data.message } : {}), contexts }
+    return {
+      ...(data.message ? { message: data.message } : {}),
+      contexts,
+      ...(Array.isArray(data.fileAttachments) && data.fileAttachments.length > 0
+        ? { fileAttachments: data.fileAttachments }
+        : {}),
+    }
   }
 
   static clear(): boolean {