feat(tmux-util): add find subcommand

tmux-util find <pattern> walks every pane across every session, queries each pane's foreground command (`#{pane_current_command}`), and prints the location of any pane whose command matches the pattern. Output format: `<session>:<window>.<pane> <command>`, one per line.

Pattern is a basic ERE (passed through `grep -E`), so anchors and alternation work. Substring matching is the common case.

Exit code:
- 0 with output: matches found
- 1 with no output: no matches (lets you script around it)
- 2 with usage on stderr: missing or empty pattern

7 new tests cover Normal cases (single match, multi-match across sessions, format verification) and Boundary cases (no matches, no sessions, missing pattern, empty pattern). fake-tmux now parses pid:cmd entries in the state file so panes can carry a synthetic command name. Total suite: 39 tests, all green.

1 files changed, 31 insertions, 5 deletions

diff --git a/tests/tmux-util/fake-tmux b/tests/tmux-util/fake-tmux
index 163ea24..b5a1e61 100755
--- a/tests/tmux-util/fake-tmux
+++ b/tests/tmux-util/fake-tmux
@@ -38,6 +38,19 @@ render_format() {
     echo "$out"
 }
 
+# Render a tmux format string against one pane's fields.
+# Args: format, name, pid, cmd, idx, cwd
+render_pane_format() {
+    local out="$1" name="$2" pid="$3" cmd="$4" idx="$5" cwd="$6"
+    out="${out//\#\{pane_pid\}/$pid}"
+    out="${out//\#\{pane_current_command\}/$cmd}"
+    out="${out//\#\{pane_current_path\}/$cwd}"
+    out="${out//\#\{session_name\}/$name}"
+    out="${out//\#\{window_index\}/0}"
+    out="${out//\#\{pane_index\}/$idx}"
+    echo "$out"
+}
+
 case "$cmd" in
     list-sessions)
         fmt=""
@@ -54,20 +67,33 @@ case "$cmd" in
         done
         ;;
     list-panes)
+        all=0
+        fmt=""
         session=""
         while [ "$#" -gt 0 ]; do
             case "$1" in
                 -t) shift; session="$1"; shift ;;
-                -F) shift; [ "$#" -gt 0 ] && shift ;;
+                -F) shift; fmt="${1:-}"; shift ;;
                 -s) shift ;;
+                -a) all=1; shift ;;
                 *)  shift ;;
             esac
         done
-        read_state | while IFS=' ' read -r name attached pids _rest; do
-            if [ "$name" = "$session" ]; then
-                [ "$pids" = "-" ] || echo "$pids" | tr ',' '\n'
-                exit 0
+        [ -n "$fmt" ] || fmt='#{pane_pid}'
+        read_state | while IFS=' ' read -r name attached pids activity windows cwd; do
+            [ -n "$name" ] || continue
+            if [ "$all" -eq 0 ] && [ "$name" != "$session" ]; then
+                continue
             fi
+            [ "$pids" = "-" ] && continue
+            idx=0
+            for entry in $(echo "$pids" | tr ',' ' '); do
+                pid="${entry%%:*}"
+                cmd="${entry##*:}"
+                [ "$cmd" = "$entry" ] && cmd="shell"
+                render_pane_format "$fmt" "$name" "$pid" "$cmd" "$idx" "${cwd:-/tmp}"
+                idx=$((idx + 1))
+            done
         done
         ;;
     display)