[macOS] Fix SDL threading issues and add full macOS support

.gitattributes

@@ -0,0 +1,4 @@
+* text=auto eol=lf
+*.sln text eol=crlf
+*.vcxproj text eol=crlf
+*.vcxproj.filters text eol=crlf

.gitignore

@@ -1,16 +1,19 @@
-/config.h
-
-*.SnipesGame
-
-# Visual C++
-/*.vcxproj.user
-/*.suo
-/ipch
-/Release
-/Debug
-/SDL Release
-/SDL Debug
-
-# GNUmakefile
-/snipes
-/snipes.exe
+/config.h
+
+*.SnipesGame
+
+# Visual C++
+/*.vcxproj.user
+/*.suo
+/ipch
+/Release
+/Debug
+/SDL Release
+/SDL Debug
+
+# GNUmakefile
+/snipes
+/snipes.exe
+
+# Font
+SnipesConsole.ttf

AGENTS.md

@@ -0,0 +1,40 @@
+# AGENTS.md
+
+This file provides additional technical guidance for AI agents and automated tools when working with the Snipes codebase.
+
+## Quick Reference for Agents
+
+### Code Style Guidelines
+- Follow existing code conventions in each file
+- Use tabs for indentation in C++ files
+- Maintain 80-character line width where practical
+- Preserve original game logic exactly when making fixes
+
+### Platform-Specific Considerations
+
+#### macOS
+- SDL operations must run on the main thread
+- Use `SDL_MAIN_HANDLED` macro
+- Font fallback system searches system fonts if custom font unavailable
+
+#### Windows
+- Both SDL and console builds must remain functional
+- Visual Studio solution supports multiple configurations
+- Console build uses Windows-specific APIs in `windows/` directory
+
+#### Linux/POSIX
+- SDL build is primary target
+- Ensure POSIX compliance for portability
+- Test with various distributions when possible
+
+### Testing Guidelines
+- Preserve 100% game logic compatibility with original
+- Test both windowed and fullscreen modes
+- Verify replay file compatibility
+- Check keyboard input with different layouts
+
+### Common Pitfalls to Avoid
+- Don't modify core game logic in Snipes.cpp unless fixing documented bugs
+- Maintain platform abstraction layer boundaries
+- Keep SDL-specific code in `sdl/` directory
+- Don't break Windows console build when adding SDL features

README.md

@@ -10,7 +10,7 @@ For more information, see the [vogons.org forum thread](https://www.vogons.org/v
 
 SDL builds require the SDL2 and SDL2_ttf libraries.
 
-On startup, the SDL build will attempt to load a custom font, which can be obtained separately from [here](http://kingbird.myphotos.cc/ee22d44076adb8a34d8e20df4be3730a/SnipesConsole.ttf).
+On startup, the SDL build will attempt to load a custom font, which can be obtained separately from [here](http://kingbird.myphotos.cc/ee22d44076adb8a34d8e20df4be3730a/SnipesConsole.ttf). The custom font is required for authentic visuals. If unavailable, the game will fall back to system fonts with a warning that visuals will differ from the original.
 
 #### With Visual Studio
 
@@ -23,6 +23,8 @@ On startup, the SDL build will attempt to load a custom font, which can be obtai
 1. (Optional) Copy `config-sample.h` to `config.h`, and edit as desired
 2. Run `make` to compile an SDL build.
 
+The SDL build works on Linux, Windows, and macOS.
+
 For Arch Linux, you can use the [snipes-git](https://aur.archlinux.org/packages/snipes-git/) AUR package.
 
 ### Replay recording