Synced from monorepo

Changes:
- Detect the herdr multiplexer
- Mark /gboom as non-production code
- Bound peak memory when loading a large session
- Add a subagent lifecycle soak bounding threads, fds, and heap
- Stream inherited replay to bound fork memory
- Copy full plan from plan approval with y
- Stop armed signature verification from deleting the managed-deny smoke policy
- Add source-tagged terminal version telemetry
- Show the UI instantly and fetch models and settings in the background
- Session test helpers
- computer_reason on the ConversationHistoryDone trailer

crates/codegen/xai-grok-pager/docs/user-guide/19-plan-mode.md

@@ -77,6 +77,7 @@ Scroll the plan with the arrow keys or `j`/`k`. The action bar shows these short
 | `a`      | Approve the plan and start building. With pending comments, this reads `approve w/ comments` and sends them alongside the approval. |
 | `s`      | Request changes. Focus moves to the prompt so you can type revision notes; press `Enter` to send them. |
 | `c`      | Comment on the selected line or line range.                                                          |
+| `y`      | Copy the full plan to the clipboard.                                                                 |
 | `q`      | Quit plan -- abandon the plan without approving and turn plan mode off.                              |
 
 Press `Tab` to move focus between the plan preview and the prompt.