feat: switch text to UTF-8; add Unicode key events, dead keys & Czech layout; fix numpad navigation; add NumLock support

programs/include/Api/Syscall.hpp

@@ -271,6 +271,12 @@ namespace montauk::abi {
     static constexpr uint64_t SYS_CONSENT_NEXT         = 192;  // (ConsentRequest*) -> 1 delivered, 0 none queued
     static constexpr uint64_t SYS_CONSENT_REPLY        = 193;  // (requestId, CONSENT_ALLOW/DENY) -> 0, -1 stale id
 
+    /* Unicode key events. Size-versioned: the caller passes sizeof(its
+       KeyEvent); the kernel copies min(size, its own) bytes and zero-fills the
+       rest, so the struct can grow without another syscall. */
+    static constexpr uint64_t SYS_GETKEY_EX            = 194;  // (KeyEvent*, size) -> 0; blocks like SYS_GETKEY
+    static constexpr uint64_t SYS_CHILDIO_WRITEKEY_EX  = 195;  // (childPid, const KeyEvent*, size) -> status
+
     /* Kernel-owned process capabilities. User identities may namespace
        per-user resources, but never participate in authorization decisions. */
     static constexpr uint64_t CAP_PROCESS_ADMIN = 1ULL << 0;
@@ -531,7 +537,10 @@ namespace montauk::abi {
         uint32_t    buildNumber;   // monotonic kernel build number
     };
 
-    struct KeyEvent {
+    // Legacy 9-byte key event, read by SYS_GETKEY and written by
+    // SYS_CHILDIO_WRITEKEY. Kept so binaries built before codepoints still work.
+    // `ascii` is a Windows-1252 byte.
+    struct KeyEventV1 {
         uint8_t scancode;
         char    ascii;
         bool    pressed;
@@ -547,6 +556,32 @@ namespace montauk::abi {
         bool    extended;
     };
 
+    // Key event with the Unicode text it types (SYS_GETKEY_EX,
+    // SYS_CHILDIO_WRITEKEY_EX, WinEvent). Its first 9 bytes ARE a KeyEventV1, so
+    // a legacy reader sees a valid event. `codepoint` is the character the key
+    // produces (0 for control/navigation keys and dead keys). `ascii` is its
+    // Windows-1252 byte, or KEY_ASCII_SUBSTITUTE when 1252 has none.
+    struct KeyEvent {
+        uint8_t  scancode;
+        char     ascii;
+        bool     pressed;
+        bool     shift;
+        bool     ctrl;
+        bool     alt;
+        bool     capslock;
+        bool     altgr;
+        bool     extended;
+        uint8_t  _reserved[3];
+        uint32_t codepoint;
+    };
+    static_assert(sizeof(KeyEventV1) == 9, "KeyEventV1 is frozen ABI");
+    static_assert(sizeof(KeyEvent) == 16, "KeyEvent must fit the WinEvent union");
+
+    // ASCII SUB: `ascii` of a text key whose character has no Windows-1252 byte.
+    // A control character, so legacy code that only accepts ascii >= 0x20 skips
+    // it, while code testing `ascii == 0` for navigation keys is not confused.
+    static constexpr char KEY_ASCII_SUBSTITUTE = 0x1A;
+
     struct MouseState {
         int32_t  x;
         int32_t  y;
@@ -584,12 +619,13 @@ namespace montauk::abi {
         uint8_t type;     // 0=key, 1=mouse, 2=resize, 3=close, 4=scale
         uint8_t _pad[3];
         union {
-            KeyEvent key;
+            KeyEvent key;   // 16 bytes: the union was already that size (mouse)
             struct { int32_t x, y, scroll; uint8_t buttons, prev_buttons; } mouse;
             struct { int32_t w, h; } resize;
             struct { int32_t scale; } scale;
         };
     };
+    static_assert(sizeof(WinEvent) == 20, "WinEvent layout is shared with existing binaries");
 
     struct WinInfo {
         int32_t  id;