Use grouped tmux sessions for independent window navigation#21
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Use grouped tmux sessions for independent window navigation#21
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Replace `tmux attach-session` with `tmux new-session -t` when reattaching to an existing session. This creates a grouped session that shares windows but allows each terminal to independently select the active window. The `destroy-unattached` option ensures grouped sessions are cleaned up when the terminal disconnects.
The semicolon command separator in os.execvp doesn't work reliably with tmux. Instead, create the grouped session detached with a PID-based unique name, set destroy-unattached on it, then attach.
Setting destroy-unattached on a detached session causes tmux to destroy it immediately. Use a client-attached hook instead so the option is set only after the client connects, avoiding the race condition.
Use tmux display-message to get the session ID of the process's own session instead of picking the first attached one. In grouped session setups, multiple sessions are attached simultaneously, and the old approach would always find the original session, causing window operations (open editor, terminal, claude) to switch the active window in the wrong terminal.
The forestui process runs in the original session's pane, so display-message always returned the original session ID regardless of which grouped session the user is viewing from. Instead, use list-clients sorted by client_activity to find the most recently active client's session — that's the terminal the user just interacted with. Remove session caching since the active client can change between grouped sessions at any time.
Override status-left on grouped sessions to show the base session name (e.g. forestui-forest) instead of the internal PID-suffixed name (e.g. forestui-forest-23116). The grouped session is an implementation detail that should be transparent to the user.
1. Fix shell injection via unquoted forest_path (shlex.quote) 2. Replace select-window existence check with read-only list-windows to avoid switching the active window in the original session 3. Scope list-clients to our session_group so unrelated tmux sessions don't cause forestui to resolve to the wrong session 4. Use destroy-unattached keep-last instead of on, preventing the last session in the group from being destroyed 5. Use show-options -gv for status-left to get just the value without option name prefix or quoting 6. Add error handling for grouped session creation with fallback to direct attach
The existence check used exact match on "forestui", missing dev mode windows named "forestui-dev-HHMM". This caused a second terminal to spawn a duplicate forestui process instead of just attaching.
strip() was removing a trailing space that's part of the tmux
status-left template, causing the separator between the session name
and the first window tab to disappear. Use rstrip('\n') to only
remove the subprocess newline.
Provides a skill that lets Claude launch forestui in headless virtual terminals via tu, visually verify UI behavior, and interact with the running app. Supports multi-terminal testing with isolated tmux servers for verifying grouped session behavior.
The user is likely running their own tmux/forestui session. Without TMUX_TMPDIR isolation the agent would interfere with their live session.
tmux's -t flag does prefix matching by default, so has-session -t forestui-forest would match orphaned grouped sessions like forestui-forest-12345. The = prefix forces exact match on all session targets: has-session, list-windows, new-window, new-session.
Plain text screenshots lose colors and highlighting, making it impossible to tell which tmux window is active. PNG mode captures the full terminal with color for accurate visual verification.
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Summary
tmux attach-sessionwith grouped sessions (tmux new-session -t) so each terminal can independently navigate tmux windowsclient-attachedhook to defer settingdestroy-unattached, since setting it on a detached session destroys it immediatelyCloses #20
Test plan
forestuiin terminal A — creates the original tmux sessionforestuiin terminal B — creates a grouped session (verify withtmux list-sessions)