diff --git a/chat-sdk/src/attachments.ts b/chat-sdk/src/attachments.ts
index 328c9076fa..00492b2162 100644
--- a/chat-sdk/src/attachments.ts
+++ b/chat-sdk/src/attachments.ts
@@ -106,10 +106,11 @@ export async function uploadAttachments(
     )
     const uploaded = results.flatMap((r) => (r.status === 'fulfilled' ? [r.value] : []))
     const reasons = results.flatMap((r) => (r.status === 'rejected' ? [r.reason] : []))
-    if (reasons.length === 0) return uploaded
+    // A stop that lands once every upload has answered still withdraws the batch.
+    if (reasons.length === 0 && !signal?.aborted) return uploaded
     await Promise.all(uploaded.map((u) => api.deleteFile(u.s3).catch(() => {})))
     // The failure that started it, not the aborts it caused in the other uploads.
-    throw reasons.find((reason) => !isAbortError(reason)) ?? reasons[0]
+    throw reasons.find((reason) => !isAbortError(reason)) ?? reasons[0] ?? abortError()
   } finally {
     signal?.removeEventListener('abort', abortBatch)
   }
diff --git a/chat-sdk/src/chat.ts b/chat-sdk/src/chat.ts
index 12d7cdf802..c673768d1f 100644
--- a/chat-sdk/src/chat.ts
+++ b/chat-sdk/src/chat.ts
@@ -22,6 +22,7 @@ import {
   conversationTitle,
   errorResultMessage,
   extractChatAnswer,
+  abortError,
   isAbortError,
   isErrorResult,
   now,
@@ -167,6 +168,8 @@ class ChatImpl implements Chat {
           })
         }
       }
+      // Nothing may start once stop() or a conversation switch has withdrawn the turn.
+      if (turn.controller.signal.aborted) throw abortError()
       turn.started = true
       // Listed only once the run is asked for: a send that never runs (an upload that failed
       // or was stopped) then has no conversation entry to take back.
diff --git a/chat-sdk/test/attachments.test.ts b/chat-sdk/test/attachments.test.ts
index e93a10f4be..0960b0dd11 100644
--- a/chat-sdk/test/attachments.test.ts
+++ b/chat-sdk/test/attachments.test.ts
@@ -413,4 +413,31 @@ describe('sendMessage with attachments', () => {
     expect(call.url.searchParams.get('file_key')).toMatch(/\/0\/contract\.pdf$/)
     expect(call.url.searchParams.get('content_type')).toBe('application/pdf')
   })
+
+  test('stop() after the uploads land but before the run starts deletes them and runs nothing', async () => {
+    const { fetch, calls } = fetchMock(
+      upload,
+      (c) =>
+        c.method === 'DELETE' && c.url.pathname === '/api/w/ws/job_helpers/delete_s3_file'
+          ? json('deleted')
+          : undefined,
+      run,
+      answer
+    )
+    const chat = createChat(options(fetch))
+    const sending = chat.sendMessage('read this', {
+      attachments: [{ name: 'contract.pdf', data: pdf }],
+      attachmentsInput: { name: 'files', multiple: true }
+    })
+    // The upload responds at once; Stop lands before the send resumes after it.
+    while (uploads(calls).length === 0) await Promise.resolve()
+    await chat.stop()
+    await expect(sending).rejects.toMatchObject({ name: 'AbortError' })
+    expect(runs(calls)).toHaveLength(0)
+    const key = uploads(calls)[0].url.searchParams.get('file_key')
+    expect(
+      calls.filter((c) => c.method === 'DELETE').map((c) => c.url.searchParams.get('file_key'))
+    ).toEqual([key])
+    expect(chat.getState()).toMatchObject({ status: 'idle', messages: [], conversations: [] })
+  })
 })