feat(tmux-util): add ls subcommand

tmux-util ls is an opinionated replacement for `tmux ls` with columns for state (attached/detached), name, idle time (humanized), window count, and the current pane's cwd (tilde-fied if it sits under $HOME).

The cwd query goes through `tmux display -p -t <session> '#{pane_current_path}'`, which returns the cwd of the active pane of the active window. That's close enough to "what the session is about" for a one-line summary.

Idle calculation reads `date +%s` by default and accepts an override via the TMUX_UTIL_NOW env var so tests can pin "now" to a known epoch.

12 new tests cover Normal cases (attached / detached, multiple sessions) and Boundary cases (no sessions, idle exactly at minute / hour / day boundaries, $HOME tilde). One existing dispatch test got reworked because the original stub target (`ls`) is no longer unimplemented. Total suite is 26 tests, all green.

The fake-tmux harness picked up two things along the way: real format-string parsing for `list-sessions -F` and a new handler for `display -p`. The state file format extended to include activity epoch, window count, and cwd, with sensible defaults for older 3-tuple test inputs so the reap tests keep passing untouched.

1 files changed, 53 insertions, 1 deletions

diff --git a/dotfiles/common/.local/bin/tmux-util b/dotfiles/common/.local/bin/tmux-util
index 10c6fbb..2fa861d 100755
--- a/dotfiles/common/.local/bin/tmux-util
+++ b/dotfiles/common/.local/bin/tmux-util
@@ -36,6 +36,55 @@ EOF
 }
 
 # -----------------------------------------------------------------------------
+# ls
+# -----------------------------------------------------------------------------
+
+# Render seconds as a short human duration (e.g. "5s", "12m", "3h", "2d").
+format_idle() {
+    local s="$1"
+    if [ "$s" -lt 60 ]; then
+        echo "${s}s"
+    elif [ "$s" -lt 3600 ]; then
+        echo "$((s / 60))m"
+    elif [ "$s" -lt 86400 ]; then
+        echo "$((s / 3600))h"
+    else
+        echo "$((s / 86400))d"
+    fi
+}
+
+cmd_ls() {
+    local sessions
+    sessions=$(tmux list-sessions \
+        -F '#{session_attached} #{session_name} #{session_activity} #{session_windows}' \
+        2>/dev/null || true)
+
+    if [ -z "$sessions" ]; then
+        echo "No tmux sessions."
+        return 0
+    fi
+
+    local now="${TMUX_UTIL_NOW:-$(date +%s)}"
+
+    {
+        printf 'STATE\tNAME\tIDLE\tWINDOWS\tCWD\n'
+        local attached name activity windows state idle_str cwd
+        while IFS=' ' read -r attached name activity windows; do
+            [ -n "$name" ] || continue
+            state="detached"
+            [ "$attached" -gt 0 ] && state="attached"
+            idle_str=$(format_idle "$((now - activity))")
+            cwd=$(tmux display -p -t "$name" '#{pane_current_path}' 2>/dev/null || echo "?")
+            # Replace leading $HOME with ~ for display.
+            if [ -n "${HOME:-}" ] && [ "${cwd#$HOME}" != "$cwd" ]; then
+                cwd="~${cwd#$HOME}"
+            fi
+            printf '%s\t%s\t%s\t%s\t%s\n' "$state" "$name" "$idle_str" "$windows" "$cwd"
+        done <<<"$sessions"
+    } | column -t -s $'\t'
+}
+
+# -----------------------------------------------------------------------------
 # Reap
 # -----------------------------------------------------------------------------
 
@@ -92,7 +141,10 @@ main() {
         reap)
             cmd_reap "$@"
             ;;
-        go|pick|ls|find|rename)
+        ls)
+            cmd_ls "$@"
+            ;;
+        go|pick|find|rename)
             echo "tmux-util: subcommand '$sub' is not implemented yet" >&2
             return 2
             ;;