quest: hotkeys bind by physical key, folding in the X11 keycode grab

quest/m1/README.md

@@ -24,5 +24,5 @@ than opening an m2 for them.
 ## Required
 
 - [Viewer-side composition](/quest/m1/compose/README.md) - sources as their own tracks plus a layout track, composed by viewers and by a server
-- [Keypad keys bind as hotkeys](/quest/m1/hotkeys-keypad.md) - scene and action keys on the keypad, apart from the main row
+- [Hotkeys bind by physical key](/quest/m1/hotkeys-keypad.md) - keypad keys apart from the main row, any X11 key, and every binding across layout changes
 - [Scene graph view](/quest/m1/scene-graph.md) - a node view of picture and audio scenes, their routing, volume, pan, and waveforms

quest/m1/hotkeys-keypad.md

@@ -1,20 +1,51 @@
-# [S] Keypad keys bind as hotkeys
+# [M] Hotkeys bind by physical key
 
 ## Goal
 
-The operator binds keypad keys (`Numpad0` to `Numpad9`, the keypad
-operators, and keypad Enter) to studio actions, and they fire system-wide on
-macOS, Windows, X11, and the Wayland portal, apart from the main-row keys
-with the same symbol. Streamers often put scenes on the keypad.
+A hotkey is the physical key the operator pressed, on every platform:
+- Keypad keys (`Numpad0` to `Numpad9`, the keypad operators, and keypad
+  Enter) bind apart from the main-row keys with the same symbol, and fire
+  system-wide on macOS, Windows, X11, and the Wayland portal. Streamers often
+  put scenes on the keypad.
+- On X11, any key binds, including one that types a letter outside A to Z
+  (such as ö on a German layout) and one winit cannot name.
+- A keyboard layout change leaves every binding on its key without a restart:
+  on X11 no held grab strands, and on Windows no binding moves to the key the
+  new layout gives its virtual key.
 
 ## Plan
 
 From [moq-dev/studio#61](https://github.com/moq-dev/studio/pull/61), which
-refuses keypad keys rather than binding them; picked 2026-11-06 (maintainer,
-/quest-plan) as its own quest so #61 lands as reviewed.
+refuses keypad keys and non-A-to-Z X11 letters, registers through the layout
+in use when the studio starts or a key is bound, and asks for a restart after
+an X11 layout change. Picked 2026-11-06 (maintainer, /quest-plan): keypad keys
+as their own quest so #61 landed as reviewed, and the X11 keycode grab folded
+in, since both rework the same grab path.
 
-- Carry winit's physical `KeyCode` (or the key's keypad location) through
-  `Binding`, so `Numpad1` and `Digit1` stay distinct.
-- Register global-hotkey's `Numpad*` codes on macOS, Windows, and X11, and
-  ask the GlobalShortcuts portal for `KP_*` keysyms on Wayland.
-- `README.md` drops the note that keypad keys are refused.
+- Carry winit's `PhysicalKey` through `Binding`, taken from the window's
+  winit key event rather than egui's, so `Numpad1` and `Digit1` stay distinct
+  and a key winit leaves `Unidentified` keeps its native code. egui-winit
+  drops a key it can name neither logically nor physically, so the Hotkeys
+  panel cannot take it from egui. This replaces the keypad twin tracking in
+  `rs/moq-studio/src/hotkeys/keypad.rs`.
+- On X11, the studio grabs by keycode itself (XGrabKey through x11rb, which
+  `layout.rs` already reads the keyboard mapping with) instead of through
+  global-hotkey, which grabs by keysym and looks it up again in the current
+  layout on release (see `Layout::releases` in `layout.rs`). The keycode is
+  winit's Linux scancode plus 8 (`PhysicalKeyExtScancode::to_scancode`), for
+  a named key and an `Unidentified` one alike, so releasing a grab needs no
+  lookup and the restart note goes.
+- On Windows, `RegisterHotKey` matches the virtual key the active layout gives
+  the pressed key, so `layout.rs` maps each binding's scancode to a virtual key
+  through that layout. The studio registers every binding again when that
+  layout changes, not only when a binding does, as `hear` does now.
+  Unregistering is by id, so nothing can strand. Recommended: read the
+  foreground window's layout, which the system translates the key with, since
+  a game usually has focus.
+- Register global-hotkey's `Numpad*` codes on macOS and Windows, and ask the
+  GlobalShortcuts portal for `KP_*` keysyms on Wayland. macOS registers by key
+  position, so a layout change moves nothing there. A key winit leaves
+  `Unidentified` is refused outside X11, saying global-hotkey cannot name it.
+- `README.md`'s Hotkeys section drops the keypad refusal, the X11 letter
+  refusal, the restart note, and the layout read when the studio starts or a
+  key is bound.