fix: support native touch input on Wayland

mpv 0.40 on Wayland doesn't update mouse-pos during touch drags.
Add touch-pos property observer for reliable gesture tracking and
document the --native-touch=yes requirement.

scripts/touch-gestures.lua

@@ -9,6 +9,10 @@
     * Configurable gesture zones, pixels-per-step sensitivity, per-control step sizes, and optional inverted direction.
     * Shows OSD feedback after each adjustment.
 
+  Requirements:
+    * mpv 0.39+ recommended for native touch support.
+    * On Wayland, run mpv with `--native-touch=yes` for reliable touch tracking.
+
   Configuration:
     Edit the `config` table below to tune zone widths, step sizes, and OSD duration; script-opts files are ignored.
 ]]
@@ -293,6 +297,9 @@ local function apply_steps(kind, steps)
   end
 end
 
+local poll_timer = nil
+local update_gesture
+
 local function reset_state()
   if state.active and config.log_debug then
     dbg(string.format("end gesture zone=%s accum=%.2f", tostring(state.zone), state.accum))
@@ -305,6 +312,24 @@ local function reset_state()
   state.last_y = 0
   state.start_x = 0
   state.start_y = 0
+  if poll_timer then
+    poll_timer:kill()
+    poll_timer = nil
+  end
+end
+
+local function poll_position()
+  local pos = mp.get_property_native("mouse-pos")
+  if pos and pos.x and pos.y then
+    update_gesture(nil, pos)
+  end
+end
+
+local function start_poll_timer()
+  if poll_timer then
+    poll_timer:kill()
+  end
+  poll_timer = mp.add_periodic_timer(0.016, poll_position)
 end
 
 local function begin_gesture_tracking(pos)
@@ -319,6 +344,7 @@ local function begin_gesture_tracking(pos)
   state.cached_volume_pct = nil
   state.cached_brightness_pct = nil
   dbg(string.format("begin tracking at (%.0f,%.0f)", pos.x, pos.y))
+  start_poll_timer()
 end
 
 local function lock_axis(axis, zone)
@@ -328,7 +354,7 @@ local function lock_axis(axis, zone)
   dbg(string.format("locked axis=%s zone=%s", axis, tostring(zone)))
 end
 
-local function update_gesture(_, pos)
+update_gesture = function(_, pos)
   if not pos or not pos.x or not pos.y then
     return
   end
@@ -477,6 +503,27 @@ end
 
 mp.add_forced_key_binding("mouse_btn0", "touch-gestures", handle_touch, { complex = true })
 mp.observe_property("mouse-pos", "native", update_gesture)
+mp.observe_property("touch-pos", "native", function(_, touch)
+  if touch and #touch > 0 then
+    local pos = { x = touch[1].x, y = touch[1].y }
+    if not state.active then
+      if not in_excluded_zone(pos) then
+        begin_gesture_tracking(pos)
+      end
+    else
+      update_gesture(nil, pos)
+    end
+  else
+    if state.active then
+      if not state.axis then
+        forwarding_click = true
+        mp.commandv("keypress", "mouse_btn0")
+        forwarding_click = false
+      end
+      reset_state()
+    end
+  end
+end)
 
 mp.register_event("shutdown", function()
   reset_state()