feat(c5): add tmux pipe-pane session logging

Starts tmux pipe-pane capture for the current pane whenever fish
launches inside a tmux session. Each shell gets a timestamped log
in SCROLLBACK_HISTORY_DIR. Toggling __fish_config_op_logging stops
or restarts the pipe in all open fish shells via the existing
--on-variable event handlers.

functions/__fish_config_sync_logging.fish

@@ -6,8 +6,9 @@
 #
 # DESCRIPTION
 #   Synchronises C5 logging state: creates or removes the Kitty sentinel
-#   file ($XDG_CONFIG_HOME/fish/.logging_disabled) and generates or removes
-#   the paru/yay AUR-helper log wrappers based on the combined value of
+#   file ($XDG_CONFIG_HOME/fish/.logging_disabled), generates or removes the
+#   paru/yay AUR-helper log wrappers, and starts or stops tmux pipe-pane
+#   capture for the current pane — all based on the combined value of
 #   __fish_config_opinionated (master) and __fish_config_op_logging (C5).
 #   Called by --on-variable event handlers whenever either variable changes.
 #   Safe to call at any time; wrapper removal only affects files bearing
@@ -32,6 +33,15 @@ function __fish_config_sync_logging --description 'Sync C5 logging state: sentin
         # Logging enabled: remove sentinel and regenerate wrappers if binaries exist
         rm -f $sentinel
 
+        # Restart tmux pipe-pane for the current pane if inside tmux
+        if set -q TMUX
+            set -l log_dir (set -q SCROLLBACK_HISTORY_DIR; and echo $SCROLLBACK_HISTORY_DIR; or echo "$HOME/.terminal_history")
+            set -l pane_id (tmux display-message -p '#{session_name}-w#{window_index}-p#{pane_index}' 2>/dev/null)
+            set -l timestamp (date "+%Y-%m-%d_%H-%M-%S")
+            mkdir -p $log_dir
+            tmux pipe-pane "cat >> $log_dir/tmux_${pane_id}_${timestamp}.log" 2>/dev/null
+        end
+
         if test -x /usr/bin/paru
             mkdir -p (dirname $paru_wrapper)
             printf '%s\n' \
@@ -95,5 +105,10 @@ function __fish_config_sync_logging --description 'Sync C5 logging state: sentin
             and grep -q "# yay-wrapper-version:" $yay_wrapper 2>/dev/null
             rm -f $yay_wrapper
         end
+
+        # Stop tmux pipe-pane for the current pane if inside tmux
+        if set -q TMUX
+            tmux pipe-pane 2>/dev/null
+        end
     end
 end