## Why
The command center previously refused to open tasks managed by another app server, preventing users from viewing their saved history.
## What changed
- Fall back to a frozen, read-only history snapshot when attaching fails because another server owns the task. Preserve drafts and skip buffered request replay and paused-goal prompts while viewing.
- Keep the snapshot when reopening the displayed task, and allow explicit retry to attach once the other server releases it.
- Allow pasting into the command center while a read-only conversation is displayed, while keeping the conversation composer protected.
- Box the TUI startup future to keep it out of the CLI caller's frame.
## Testing
Add coverage for read-only history, draft and selection preservation, retry before and after ownership release, and history-read failure without leaving the current conversation. Assert that opening a read-only task does not start a turn and that the TUI startup future remains below 64 KiB.
GitOrigin-RevId: f1bdb5b2d9182079de4e53346a56742a4a02a1c7
Eric Traut
7efb0262d6