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-pty-harness/src/pty.rs

@@ -574,6 +574,7 @@ const HOST_TERMINAL_ENV_VARS: &[&str] = &[
     "CMUX_SOCKET_PATH",
     "CMUX_PANEL_ID",
     "CMUX_BUNDLE_ID",
+    "HERDR_ENV",
     // Embedded editor markers (embedded_editor_from_env).
     "NVIM",
     "NVIM_LISTEN_ADDRESS",