fix(eui-neo): pin the Windows API floor and name kernel32 for app-main

Auditing the one TU the `app-main` feature adds — which nothing in this index
compiled until tests/examples/eui-neo-app-main existed — turned up two
Windows-only requirements it carries:

* core/app/frame_pacing.h calls CreateWaitableTimerExW, and both mingw-w64's
  winbase.h and the Windows SDK guard that declaration behind
  `#if _WIN32_WINNT >= 0x0600`. The header sets no floor of its own, so it
  inherits the toolchain default, and mingw-w64 has historically defaulted as
  low as 0x502. Pin 0x0A00 in cflags + cxxflags rather than depend on which
  default the runner's llvm ships — that is effectively what upstream builds
  against via the MSVC SDK, and a command-line define is respected by
  _mingw.h's `#ifndef` guard. Every other Windows API in the package is
  pre-Vista, which is why this never surfaced.

* the same header reaches CreateWaitableTimerExW / SetWaitableTimer /
  WaitForSingleObject / CloseHandle, so name -lkernel32. It is in every sane
  default lib set, but the surrounding comment is specifically about mcpp not
  inheriting CMake's CMAKE_C_STANDARD_LIBRARIES, so spelling it out is
  consistent and free.

timeBeginPeriod (winmm) and MonitorFromWindow / GetMonitorInfoW /
EnumDisplaySettingsW (user32) were already covered; glfw3native.h ships in
compat.glfw's include/GLFW/.

Linux is unaffected (the flags are inside the `windows` section) and all three
eui-neo members re-verified green there.

Author: Sunrisepeak

.agents/docs/2026-07-30-eui-neo-window-and-app-main-members.md

@@ -188,10 +188,25 @@ the build+link half of both members on those platforms is asserted by the
 `workspace (macos)` / `workspace (windows)` legs, not locally. Two things are new
 there and worth watching on the first run:
 
-* `glfw_app_main.cpp` has never been compiled on any platform. Its Windows half
-  (`<mmsystem.h>`, `GLFW_EXPOSE_NATIVE_WIN32`, `glfw3native.h`, `timeBeginPeriod`,
-  `MonitorFromWindow`, `EnumDisplaySettingsW`) needs `-lwinmm` and `-luser32`, both
-  already in the descriptor's `windows.ldflags`.
+* `glfw_app_main.cpp` has never been compiled on any platform, so its Windows half
+  is newly exercised. Two descriptor additions came out of auditing it, both
+  Windows-only and both for that TU alone:
+
+  * **`-D_WIN32_WINNT=0x0A00`** (cflags + cxxflags). `core/app/frame_pacing.h`
+    calls `CreateWaitableTimerExW`, which mingw-w64's `winbase.h` and the Windows
+    SDK both guard behind `#if _WIN32_WINNT >= 0x0600`. The header sets no floor of
+    its own and mingw-w64 has historically defaulted as low as `0x502`, so the
+    build would depend on which default the runner's llvm ships. Everything else in
+    the package only reaches pre-Vista APIs, which is why it never came up.
+  * **`-lkernel32`**. `frame_pacing.h` reaches `CreateWaitableTimerExW` /
+    `SetWaitableTimer` / `WaitForSingleObject` / `CloseHandle`. kernel32 is in
+    every sane default lib set, so this is belt-and-braces — but the surrounding
+    comment in the descriptor is precisely about mcpp not inheriting CMake's
+    `CMAKE_C_STANDARD_LIBRARIES`, so naming it is consistent and free.
+
+  `timeBeginPeriod` (winmm) and `MonitorFromWindow` / `GetMonitorInfoW` /
+  `EnumDisplaySettingsW` (user32) were already covered by the existing list;
+  `glfw3native.h` ships in compat.glfw's `include/GLFW/`.
 * these are the first members to link `compat.glfw` off Linux from their **own** code
   rather than through `compat.eui-neo`, which exercises the macOS
   `Cocoa`/`IOKit`/`CoreFoundation` frameworks and the Windows `-lgdi32` from a

pkgs/e/compat.eui-neo.lua

@@ -309,7 +309,20 @@ package = {
             -- through eui_neo.h), hence both lists; EUI_TRAY_WINAPI only gates
             -- tray_bridge.c, but keeping the pair symmetrical is cheaper than
             -- re-deriving which is which.
-            cflags  = { "-DEUI_TRAY_WINAPI=1", "-DNOMINMAX" },
+            --
+            -- `_WIN32_WINNT` is for the `app-main` feature's TU, which nothing
+            -- compiled until tests/examples/eui-neo-app-main existed:
+            -- core/app/frame_pacing.h calls CreateWaitableTimerExW, and both
+            -- mingw-w64's winbase.h and the Windows SDK guard that declaration
+            -- behind `#if _WIN32_WINNT >= 0x0600`. The header sets no floor of
+            -- its own, so it inherits the toolchain default — mingw-w64 has
+            -- historically defaulted as low as 0x502. Pin the floor rather than
+            -- depend on which default the runner's llvm ships; 0x0A00 is what
+            -- upstream effectively builds against via the MSVC SDK, and a
+            -- command-line define is respected by _mingw.h's `#ifndef` guard.
+            -- The rest of the package only reaches pre-Vista APIs, which is why
+            -- this never came up before.
+            cflags  = { "-DEUI_TRAY_WINAPI=1", "-DNOMINMAX", "-D_WIN32_WINNT=0x0A00" },
             -- Upstream builds at CMAKE_CXX_STANDARD 17; this index's floor is
             -- c++23, and one Windows-only line does not survive the move:
             -- `parseWindowsSelection()` in core/platform/platform.cpp pushes
@@ -326,7 +339,8 @@ package = {
             -- already sits eight lines above and does the right thing); until
             -- then this keeps us on a real upstream release tag rather than a
             -- fork carrying the patch.
-            cxxflags = { "-DEUI_TRAY_WINAPI=1", "-DNOMINMAX", "-fno-char8_t" },
+            cxxflags = { "-DEUI_TRAY_WINAPI=1", "-DNOMINMAX", "-fno-char8_t",
+                         "-D_WIN32_WINNT=0x0A00" },
             -- Upstream lists winmm/urlmon/shell32/user32/imm32/pdh and stops
             -- there, because CMake's MSVC default `CMAKE_C_STANDARD_LIBRARIES`
             -- already drags in kernel32/user32/gdi32/shell32/ole32/comdlg32/…
@@ -337,10 +351,20 @@ package = {
             -- URLDownloadToFileA and ShellExecuteA are covered by the upstream
             -- list.) Like the char8_t break above, this only showed up once the
             -- mcpp#233 collision stopped dropping the TU.
+            --
+            -- kernel32 for the `app-main` TU: core/app/frame_pacing.h reaches
+            -- CreateWaitableTimerExW / SetWaitableTimer / WaitForSingleObject /
+            -- CloseHandle, and glfw_app_main.cpp reaches timeBeginPeriod (winmm,
+            -- already listed) plus MonitorFromWindow / GetMonitorInfoW /
+            -- EnumDisplaySettingsW (user32, already listed). kernel32 is part of
+            -- every sane Windows default lib set, so this is belt-and-braces for
+            -- the one TU in this package that had never been compiled — naming
+            -- it costs nothing and the comment above is precisely about mcpp not
+            -- inheriting CMake's defaults.
             ldflags = {
                 "-lwinmm", "-lurlmon", "-lshell32",
                 "-luser32", "-limm32", "-lpdh", "-lole32",
-                "-lcomdlg32",
+                "-lcomdlg32", "-lkernel32",
             },
         },