D952: macOS black window when started with the display asleep - VSync through CGL, not SDL3's display-link wait

docs/porting-notes.md

@@ -676,6 +676,8 @@ through a converter or a runtime bswap fixup reads scrambled.
 - **CPU-built RDP triangles need float vertices, not `Vtx` (D245).** Where GE builds RDP edge/texture coefficients on the CPU (sky/water), 32-bit S/T and positions are normal; squeezing them through s16 `tc`/`ob` costs visible precision on horizon-scale geometry. Use `G_FLOATVTX_EXT` (`port/include/floatvtx.h`).
 - **A first-run-only preset is skipped forever by any earlier launch that created the ini, and window keys are not an "untouched" signal (D283).** Seeding values *before* `configLoad()` only works when no `ge007.ini` exists; one launch in a different environment (SteamOS Desktop Mode has no `STEAMOS`) writes a plain ini and the preset never runs. Apply presets *after* the load, record a one-shot flag key, and gate on keys the user must change deliberately (`Video.Fullscreen`, `Window.Maximized`) — `Window.Width/Height` are rewritten from the live window on every clean exit (`videoSaveWindowState`), so "still at default" never holds for them.
 
+**SDL3 on macOS: a GL swap with VSync can wait forever (D952).** SDL3's Cocoa backend implements the GL swap interval itself: `SDL_GL_SwapWindow` waits, with no timeout, for a tick from a `CVDisplayLink` that SDL creates and starts once, with the context. If that link never runs (seen when the game starts while the display is asleep), the first swap never returns: black window, zero frames, every other thread waiting behind the render thread. Tells: `sample` shows `Cocoa_GL_SwapWindow -> SDL_WaitCondition*` on the render thread and the process has no `CVDisplayLink` thread. Fix pattern: leave SDL's interval at 0 and set `kCGLCPSwapInterval` on the context with `CGLSetParameter`, which waits in the driver (SDL2's behaviour). Reproduce with `pmset displaysleepnow` before launching.
+
 ## D. N64 hardware idioms fast3d does not emulate
 
 - **Appending a port-owned 2D overlay to the game frame: hook inside