[Bug] Background session creation fails to acknowledge on frontend after successful session creation

Bug Description
I see an issue when I try to create a background session where it does actually create the session, but it doesn't ack it properly on the frontend.

& I'd like you to implement this change:

<...> 

 You can reference @STATE_OF_PLAY.md and @WORKING_NOTES.md for context on the problem space.
  ⎿  Read STATE_OF_PLAY.md (372 lines)
  ⎿  Read WORKING_NOTES.md (289 lines)
  ⎿  Failed to create background session: Failed to upload session history (message 1/6). Try running /login and signing in with a claude.ai account (not Console).

Environment Info

• Platform: darwin
• Terminal: iTerm.app
• Version: 2.0.75
• Feedback ID:

Errors

[{"error":"Error: NON-FATAL: Lock acquisition failed for /Users/earljstsauver/.local/share/claude/versions/2.0.75 (expected in multi-process scenarios)\n    at XZR (/$bunfs/root/claude:2430:2165)\n    at bUA (/$bunfs/root/claude:2430:1885)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-01-06T08:23:03.437Z"},{"error":"Error\n    at ak (/$bunfs/root/claude:59:1144)\n    at <anonymous> (/$bunfs/root/claude:60:10093)\n    at emit (node:events:92:22)\n    at endReadableNT (internal:streams/readable:861:50)\n    at processTicksAndRejections (native:7:39)\n    at request (/$bunfs/root/claude:62:2149)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-01-06T08:23:03.438Z"},{"error":"Error\n    at <anonymous> (/$bunfs/root/claude:60:10681)\n    at emit (node:events:92:22)\n    at <anonymous> (/$bunfs/root/claude:59:5642)\n    at request (/$bunfs/root/claude:62:2149)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-01-06T08:34:45.608Z"},{"error":"Error: Request was aborted.\n    at makeRequest (/$bunfs/root/claude:801:3940)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-01-06T08:43:17.483Z"},{"error":"Error\n    at E (/$bunfs/root/claude:60:4953)\n    at abort (unknown)\n    at NN (/$bunfs/root/claude:2657:65668)\n    at <anonymous> (/$bunfs/root/claude:2577:6039)\n    at <anonymous> (/$bunfs/root/claude:323:2520)\n    at H (/$bunfs/root/claude:323:3365)\n    at emit (/$bunfs/root/claude:315:1468)\n    at PwD (/$bunfs/root/claude:320:4585)\n    at <anonymous> (/$bunfs/root/claude:202:109032)\n    at processInput (/$bunfs/root/claude:322:659)\n    at request (/$bunfs/root/claude:62:2149)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-01-06T08:49:16.551Z"},{"error":"Error\n    at ak (/$bunfs/root/claude:59:1144)\n    at <anonymous> (/$bunfs/root/claude:60:10093)\n    at emit (node:events:92:22)\n    at endReadableNT (internal:streams/readable:861:50)\n    at processTicksAndRejections (native:7:39)\n    at request (/$bunfs/root/claude:62:2149)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-01-06T08:52:30.010Z"}]