fix: apply the review items for #688 at merge

disarmTuiSwitchGuard matches the closed `#{client_tty},<tty>}` form, so a TUI on /dev/pts/4 no longer removes the hook armed for a second TUI on /dev/pts/41 (unit test plus a real-tmux case)
beginAttachHandoff arms the one-shot attach hook as its last tmux call before spawnSync, after the switch keys and the per-session dressing loop, with an order assertion in tui-app.test.ts and a sentence in the invariants paragraph
docs/remote-sessions.md and the buildRemoteLaunchCommand JSDoc show `remain-on-exit failed` at the end of the remote create chain

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/architecture-invariants.md

@@ -18,7 +18,7 @@ Implementation detail extracted from `CLAUDE.md` so that file stays small enough
 
 ### The prefix table on Codeman's socket holds only send-prefix
 
-**Browser tabs are tmux clients, so tmux's prefix table must not reach `switch-client`** (`src/tmux-prefix-table.ts`, called from `createSession` before `respawn-pane`, and from `reconcileSessions()` at boot whenever the socket lists a pane, so sessions that survived an upgrade are covered). Every keystroke typed into a browser terminal reaches the `tmux attach-session` client behind it, and app.js deliberately lets Ctrl+B through to the terminal (readline, Claude Code's "ctrl+b ctrl+b"). With tmux's stock prefix table, Ctrl+B then `(` `)` `L` `s` `w` moved that client onto ANOTHER session, which the tab then showed and typed into under the original's label; `d` detached it, `$` renamed the session, `:` opened tmux's prompt. So the table is reduced to `<prefix> send-prefix` (the socket's configured prefix, read with `show-options -gv prefix`), once per tmux server in practice: the reset only runs while `list-keys -T prefix` shows anything else. The same reduction is applied when Codeman creates the nested tmux behind a Docker case (`-L codeman-docker`) or an owned remote session (`-L codeman-remote`). Those servers set `prefix C-q` and used to keep tmux's stock prefix table, so inside the pane Ctrl+Q then `)` `(` `s` `w` or `L` ran `switch-client` / `choose-tree` on the inner server and moved its client onto a sibling session. `nestedPrefixTableResetCommands()` (bind `C-q send-prefix`, then `unbind-key -a -T prefix`, then bind it again, so a user config that left the prefix table empty cannot make `unbind-key -a` abort the `\;` chain) is appended to both create chains, before `remain-on-exit failed` on the remote chain so a remote tmux that rejects `failed` cannot drop it. Those sockets are dedicated to Codeman, so the server-global table is the right scope. A non-owned remote attach joins another Codeman's `-L codeman` and does not run it. ⚠️ Keep `send-prefix`: Claude Code inside tmux backgrounds a command with "ctrl+b ctrl+b". ⚠️ Never touch the `root` table, and tolerate (and re-bind after a reset) `C-<letter> detach-client`: `codeman tui`'s attach claims F1 and Alt+1..9 in `root` and the held-Ctrl alias `C-d` in `prefix` (`beginAttachHandoff`), and a session created mid-attach must not take that way out away. ⚠️ Key tables are server-wide. F1 and the held-Ctrl `C-d` still detach every client for the length of an attach (a way out, not a session move). **`M-1`..`M-9` do not move other clients.** `bindSwitchKey` binds them to `if-shell -F` (`tuiSwitchGuard`) so `switch-client` runs only when `#{client_tty}` is the TUI's terminal and `#{client_pid}` equals `@codeman-tui-pid`. A one-shot `client-attached[90]` hook (`tuiSwitchAttachHook`) sets that option as the TUI's client attaches, then removes itself. A browser tab does not match, including Esc followed by a digit within `escape-time` (500 ms on tmux 3.4), which arrives as the same `M-<digit>`. If the TUI is killed before `restore()`, the binding can remain, but the stored pid is the dead client and the hook will not re-arm a pty that reuses the number, so the key does nothing. `restore()` removes the keys only while they still name this tty, and the next attach that claims the strip releases any of these bindings first. A second TUI attach replaces the keys (one binding per key). Escape-time on Codeman's socket stays at tmux's default: lowering it would change Esc delivery for every pane, and the guard already refuses other clients. ⚠️ The consequence for every terminal attach: `Ctrl+B d` does not exist on this socket. Anything that attaches a user's terminal claims its own way out for the attach, as `beginAttachHandoff` and `scripts/tmux-manager.sh` (F1 in `root`) do, and never advertises tmux's stock chord. Tests: `test/tmux-prefix-table.test.ts` (real tmux on a private socket, driven through a pty attach client, including the nested `C-q` table), `test/tui/tui-switch-guard.test.ts` (the guarded Alt keys against a second client), the wiring in `test/tmux-manager.test.ts`, the script in `test/tmux-manager-script-attach.test.ts`.
+**Browser tabs are tmux clients, so tmux's prefix table must not reach `switch-client`** (`src/tmux-prefix-table.ts`, called from `createSession` before `respawn-pane`, and from `reconcileSessions()` at boot whenever the socket lists a pane, so sessions that survived an upgrade are covered). Every keystroke typed into a browser terminal reaches the `tmux attach-session` client behind it, and app.js deliberately lets Ctrl+B through to the terminal (readline, Claude Code's "ctrl+b ctrl+b"). With tmux's stock prefix table, Ctrl+B then `(` `)` `L` `s` `w` moved that client onto ANOTHER session, which the tab then showed and typed into under the original's label; `d` detached it, `$` renamed the session, `:` opened tmux's prompt. So the table is reduced to `<prefix> send-prefix` (the socket's configured prefix, read with `show-options -gv prefix`), once per tmux server in practice: the reset only runs while `list-keys -T prefix` shows anything else. The same reduction is applied when Codeman creates the nested tmux behind a Docker case (`-L codeman-docker`) or an owned remote session (`-L codeman-remote`). Those servers set `prefix C-q` and used to keep tmux's stock prefix table, so inside the pane Ctrl+Q then `)` `(` `s` `w` or `L` ran `switch-client` / `choose-tree` on the inner server and moved its client onto a sibling session. `nestedPrefixTableResetCommands()` (bind `C-q send-prefix`, then `unbind-key -a -T prefix`, then bind it again, so a user config that left the prefix table empty cannot make `unbind-key -a` abort the `\;` chain) is appended to both create chains, before `remain-on-exit failed` on the remote chain so a remote tmux that rejects `failed` cannot drop it. Those sockets are dedicated to Codeman, so the server-global table is the right scope. A non-owned remote attach joins another Codeman's `-L codeman` and does not run it. ⚠️ Keep `send-prefix`: Claude Code inside tmux backgrounds a command with "ctrl+b ctrl+b". ⚠️ Never touch the `root` table, and tolerate (and re-bind after a reset) `C-<letter> detach-client`: `codeman tui`'s attach claims F1 and Alt+1..9 in `root` and the held-Ctrl alias `C-d` in `prefix` (`beginAttachHandoff`), and a session created mid-attach must not take that way out away. ⚠️ Key tables are server-wide. F1 and the held-Ctrl `C-d` still detach every client for the length of an attach (a way out, not a session move). **`M-1`..`M-9` do not move other clients.** `bindSwitchKey` binds them to `if-shell -F` (`tuiSwitchGuard`) so `switch-client` runs only when `#{client_tty}` is the TUI's terminal and `#{client_pid}` equals `@codeman-tui-pid`. A one-shot `client-attached[90]` hook (`tuiSwitchAttachHook`) sets that option as the TUI's client attaches, then removes itself. It is armed as the handoff's last tmux call before `spawnSync`, after the keys and the per-session bars, so only a TUI killed during the attach's own startup can leave that hook armed for its tty. A browser tab does not match, including Esc followed by a digit within `escape-time` (500 ms on tmux 3.4), which arrives as the same `M-<digit>`. If the TUI is killed before `restore()`, the binding can remain, but the stored pid is the dead client and the hook will not re-arm a pty that reuses the number, so the key does nothing. `restore()` removes the keys only while they still name this tty, and the next attach that claims the strip releases any of these bindings first. A second TUI attach replaces the keys (one binding per key). Escape-time on Codeman's socket stays at tmux's default: lowering it would change Esc delivery for every pane, and the guard already refuses other clients. ⚠️ The consequence for every terminal attach: `Ctrl+B d` does not exist on this socket. Anything that attaches a user's terminal claims its own way out for the attach, as `beginAttachHandoff` and `scripts/tmux-manager.sh` (F1 in `root`) do, and never advertises tmux's stock chord. Tests: `test/tmux-prefix-table.test.ts` (real tmux on a private socket, driven through a pty attach client, including the nested `C-q` table), `test/tui/tui-switch-guard.test.ts` (the guarded Alt keys against a second client), the wiring in `test/tmux-manager.test.ts`, the script in `test/tmux-manager-script-attach.test.ts`.
 
 ### Reverse-proxy base path
 

docs/remote-sessions.md

@@ -96,7 +96,8 @@ ssh -o BatchMode=yes -t <connection-args> user@host \
      set -t codeman-ssh-<id8> prefix C-q \; set -s escape-time 0 \; \
      set -t codeman-ssh-<id8> window-size latest \; \
      bind-key -T prefix C-q send-prefix \; unbind-key -a -T prefix \; \
-     bind-key -T prefix C-q send-prefix'
+     bind-key -T prefix C-q send-prefix \; \
+     set -t codeman-ssh-<id8> remain-on-exit failed'
 ```
 
 Key points: