feat(input): raw device layer — multi-key held state, analog, mouse, gamepad, touch, full-state replay (#50)

The raw device layer the input proposal sketched, over the action maps +
record/replay of #7. Beyond one key per frame, gameplay can read:

- Multiple simultaneous held keys: Input.key_down / key_pressed / key_released,
  with clean rising/falling edges (hold left AND jump).
- Analog from keys: Input.axis(neg, pos) and a normalized Input.vector(l,r,u,d)
  (diagonals scaled by 1/sqrt(2)), plus Input.strength(action).
- Mouse: Input.mouse_x/y, mouse_dx/dy (per-frame delta), mouse_down(btn), wheel.
- Gamepads: Input.pad_connected/pad_button/pad_axis (SDL-order buttons, -1..1
  sticks); touch: Input.touch_count/touch_x/touch_y.

The held set is fed by the platform when windowed — cocoa.ll now tracks
keyDown/keyUp into a 256-bit held-key bitset (win_held) and the mouse
buttons/wheel (win_mouse), gated so headless builds DCE the native calls — and
by the Input.press / Input.set_mouse / Input.set_pad / Input.set_touch injection
on every target (Godot-style action injection: replays, AI, network-fed input).
Input.record / replay now snapshot the full per-frame device state (held set +
mouse), extending #7's single-key tape.

Everything is integer and deterministic, so the same inputs reproduce the same
frame on every run and headless. The gamepad/touch native hardware bindings
(GameController.framework / NSTouch) feed the same injected state and are the one
remaining platform-glue follow-up; the software layer, semantics and replay are
complete and driven deterministically today.

Worked example + regression: examples/library/input_device.ludic
(1 1 0 1 0 1 71 -71 5 1 3 1 2 1 0 0 1, injection-driven headless). 23 new
docs/language/input pages. Full suite 78 passed, self-host C-free fixpoint
intact, no golden drift; cocoa.ll assembles and a windowed build links.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

selfhost/backend/emit_call.ludic

@@ -190,6 +190,31 @@ function emit_ns_call(ns: pointer, meth: pointer, e: Node) -> Val {
     if (meth == "pressed") { bare = "input_pressed" }
     if (meth == "record")  { bare = "input_record" }
     if (meth == "replay")  { bare = "input_replay" }
+    # device layer (#50): multi-key held state, analog axes/vectors, mouse,
+    # gamepads, touch — reached as ordinary @fn_input_* calls into input.ludic.
+    if (meth == "key_down")     { bare = "input_key_down";     push(labels, "key") }
+    if (meth == "key_pressed")  { bare = "input_key_pressed";  push(labels, "key") }
+    if (meth == "key_released") { bare = "input_key_released"; push(labels, "key") }
+    if (meth == "press")        { bare = "input_press";        push(labels, "key") }
+    if (meth == "release")      { bare = "input_release";      push(labels, "key") }
+    if (meth == "axis")         { bare = "input_axis";         push(labels, "neg"); push(labels, "pos") }
+    if (meth == "vector")       { bare = "input_vector";       push(labels, "left"); push(labels, "right"); push(labels, "up"); push(labels, "down") }
+    if (meth == "strength")     { bare = "input_strength";     push(labels, "action") }
+    if (meth == "mouse_x")      { bare = "input_mouse_x" }
+    if (meth == "mouse_y")      { bare = "input_mouse_y" }
+    if (meth == "mouse_dx")     { bare = "input_mouse_dx" }
+    if (meth == "mouse_dy")     { bare = "input_mouse_dy" }
+    if (meth == "mouse_down")   { bare = "input_mouse_down";   push(labels, "button") }
+    if (meth == "wheel")        { bare = "input_wheel" }
+    if (meth == "set_mouse")    { bare = "input_set_mouse";    push(labels, "x"); push(labels, "y"); push(labels, "buttons"); push(labels, "wheel") }
+    if (meth == "pad_connected"){ bare = "input_pad_connected"; push(labels, "pad") }
+    if (meth == "pad_button")   { bare = "input_pad_button";   push(labels, "pad"); push(labels, "button") }
+    if (meth == "pad_axis")     { bare = "input_pad_axis";     push(labels, "pad"); push(labels, "axis") }
+    if (meth == "set_pad")      { bare = "input_set_pad";      push(labels, "pad"); push(labels, "connected"); push(labels, "buttons"); push(labels, "lx"); push(labels, "ly"); push(labels, "rx"); push(labels, "ry") }
+    if (meth == "touch_count")  { bare = "input_touch_count" }
+    if (meth == "touch_x")      { bare = "input_touch_x";      push(labels, "index") }
+    if (meth == "touch_y")      { bare = "input_touch_y";      push(labels, "index") }
+    if (meth == "set_touch")    { bare = "input_set_touch";    push(labels, "index"); push(labels, "x"); push(labels, "y"); push(labels, "active") }
   }
   # Phase 3: the bare reflection / networking / process builtins, namespaced.
   # Each is a pure alias — the callee is rewritten to the bare name below.

selfhost/backend/emit_head.ludic

@@ -63,6 +63,8 @@ function emit_header() -> void {
   emith("declare void @win_present(ptr, i32, i32)\n")
   emith("declare i32 @win_running()\n")
   emith("declare void @win_close()\n")
+  emith("declare void @win_held(ptr)\n")
+  emith("declare void @win_mouse(ptr)\n")
   emith("@__stderrp = external global ptr\n")
   emith("@__stdoutp = external global ptr\n")
   emith("@.fmt_int = private unnamed_addr constant [4 x i8] c\"%d\\0A\\00\"\n")

selfhost/backend/emit_intrin2.ludic

@@ -11,6 +11,7 @@ function is_intrinsic2(name: pointer) -> bool {
   if (name == "is_windowed") or (name == "game_title") { return true }
   if (name == "win_open") or (name == "win_poll") or (name == "win_present") { return true }
   if (name == "win_running") or (name == "win_close") { return true }
+  if (name == "win_held") or (name == "win_mouse") { return true }   # #50 device layer
   return false
 }
 
@@ -49,5 +50,10 @@ function emit_intrinsic2(name: pointer, e: Node) -> Val {
     return val("0", "void")
   }
   if (name == "win_close") { emit("  call void @win_close()\n");  return val("0", "void") }
+  # #50 — fill a caller buffer with the platform device state (windowed only,
+  # DCE'd headless). win_held: an 8-word held-key bitset; win_mouse: [x, y,
+  # button-mask, wheel-delta].
+  if (name == "win_held")  { let a = arg_code(e, 0);  emit("  call void @win_held(ptr ");  emit(a);  emit(")\n");  return val("0", "void") }
+  if (name == "win_mouse") { let a = arg_code(e, 0);  emit("  call void @win_mouse(ptr ");  emit(a);  emit(")\n");  return val("0", "void") }
   return val("0", "void")
 }

selfhost/frontend/parse.ludic

@@ -183,6 +183,9 @@ function p_postfix() -> Node {
       # Input.* action-map / record-replay methods (#7) -> splice input.ludic.
       # Input.key stays bare (no runtime), so gate on the new methods only.
       if e.a.kind == E_ID and e.a.s == "Input" and (e.s == "bind" or e.s == "rebind" or e.s == "poll" or e.s == "down" or e.s == "pressed" or e.s == "record" or e.s == "replay") { g_uses_input = true }
+      # #50 device layer — any of the multi-key / analog / mouse / gamepad / touch
+      # methods also splices input.ludic (Input.key stays bare, no runtime).
+      if e.a.kind == E_ID and e.a.s == "Input" and (e.s == "key_down" or e.s == "key_pressed" or e.s == "key_released" or e.s == "press" or e.s == "release" or e.s == "axis" or e.s == "vector" or e.s == "strength" or e.s == "mouse_x" or e.s == "mouse_y" or e.s == "mouse_dx" or e.s == "mouse_dy" or e.s == "mouse_down" or e.s == "wheel" or e.s == "set_mouse" or e.s == "pad_connected" or e.s == "pad_button" or e.s == "pad_axis" or e.s == "set_pad" or e.s == "touch_count" or e.s == "touch_x" or e.s == "touch_y" or e.s == "set_touch") { g_uses_input = true }
       # Anim.play/clip/on_frame/fired + Motion.to (#48): the ergonomic writes over
       # the SpriteAnim/Motion components live in systems.ludic and use the world
       # table, so splice it and force the reflection ABI even if the game leaves