## Why
Resuming another session must keep drafts, queued follow-ups, and interrupted steer retries with their original thread. Submitted input whose delivery is still uncertain must wait for matching receipts before the queue can advance.
## What changed
- Pause submissions while draining outgoing events, then capture input before switching threads or backends.
- Restore saved input through a shared resume path, reconcile receipts from resumed history and buffered events, preserve active-turn state, and dispatch eligible queued input when the resumed thread is idle.
- Preserve whether a draft's leading `!` is literal text or a shell command.
- Reject `!` shell commands in Cloud conversations with an error and clear the pending submission so the next prompt can proceed.
## Testing
Add regression coverage for session round trips with buffered completion and interruption events, receipt reconciliation across read-only and writable resumes, draft shell mode, and submitting a prompt after a rejected Cloud shell command.
GitOrigin-RevId: 9a823a398a371e689b8ae743de494323ae95ef57
Benjamin Carlsson
5183e1dcb2