feat: add Windows support via ConPTY

Add Windows platform support to ghostling using the ConPTY API for
pseudo-terminal emulation.  The implementation lives entirely in
main.c alongside the existing Unix code, gated by #ifdef _WIN32.

Key changes:
- ConPTY-based pty spawning with shell auto-detection (pwsh > powershell > cmd)
- Threaded pipe reader for ConPTY output (PeekNamedPipe is unreliable)
- --shell <path> flag for explicit shell selection on all platforms
- GUI subsystem build to prevent console window on Windows
- Windows CI job on windows-latest
- Bump ghostty to include import-lib OUTPUT fix (ghostty-org/ghostty#11794)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: deblasis

.github/workflows/test.yml

@@ -59,3 +59,22 @@ jobs:
         run: |
           nix develop -c cmake -B build -G Ninja
           nix develop -c cmake --build build
+
+  build-windows:
+    runs-on: windows-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
+
+      - name: Setup Zig
+        uses: mlugg/setup-zig@v2
+        with:
+          version: 0.15.2
+
+      - name: Setup Ninja
+        uses: seanmiddleditch/gha-setup-ninja@7e868db0f3406270dd46e1dac26c65f621456723 # master
+
+      - name: Build
+        run: |
+          cmake -B build -G Ninja
+          cmake --build build

CMakeLists.txt

@@ -28,9 +28,11 @@ endif()
 # The Ghostty CMakeLists.txt delegates to `zig build lib-vt` to produce the
 # shared library. See https://ghostty.org/docs/install/build for the
 # required Zig version.
+# TODO: point back to ghostty-org/ghostty once the import-lib OUTPUT fix
+# lands upstream (see: https://github.com/ghostty-org/ghostty/pull/11794).
 FetchContent_Declare(ghostty
-  GIT_REPOSITORY https://github.com/ghostty-org/ghostty.git
-  GIT_TAG ecc55b94c803789762682065ab68f227447909c5
+  GIT_REPOSITORY https://github.com/deblasis/ghostty.git
+  GIT_TAG 7d31d9b57f7064f74cd8a098189d2f9248ef4dd5
 )
 FetchContent_MakeAvailable(ghostty)
 
@@ -56,9 +58,25 @@ target_compile_features(${PROJECT_NAME} PRIVATE c_std_11)
 target_include_directories(${PROJECT_NAME} PRIVATE "${CMAKE_BINARY_DIR}")
 target_link_libraries(${PROJECT_NAME} raylib ghostty-vt)
 
+# Build as a GUI subsystem app on Windows so we don't get a console window.
+# Without this, the child shell inherits our console and writes there instead
+# of through the ConPTY pipe.  We keep main() as the entry point.
+if(WIN32)
+  set_target_properties(${PROJECT_NAME} PROPERTIES WIN32_EXECUTABLE TRUE)
+  # MSVC/Clang need an explicit entry point override to keep main() as the
+  # entry point in a GUI subsystem app.  MinGW handles this automatically.
+  if(MSVC OR (CMAKE_C_COMPILER_ID STREQUAL "Clang" AND NOT MINGW))
+    target_link_options(${PROJECT_NAME} PRIVATE "LINKER:/ENTRY:mainCRTStartup")
+  endif()
+endif()
+
 # macOS requires these system frameworks for raylib's windowing/input/rendering.
 if (APPLE)
   target_link_libraries(${PROJECT_NAME} "-framework IOKit")
   target_link_libraries(${PROJECT_NAME} "-framework Cocoa")
   target_link_libraries(${PROJECT_NAME} "-framework OpenGL")
 endif()
+
+# Windows: ConPTY APIs (used for terminal emulation) are provided by kernel32.lib,
+# which is linked implicitly by default on all Windows compilers (MSVC, MinGW-w64, Clang).
+# No explicit target_link_libraries() call is needed for Windows.

README.md

@@ -4,8 +4,7 @@ Ghostling is a demo project meant to highlight a minimum
 functional terminal built on the libghostty C API in a
 [single C file](https://github.com/ghostty-org/ghostling/blob/main/main.c).
 
-The example uses Raylib for windowing and rendering. It is single-threaded
-(although libghostty-vt supports threading) and uses a 2D graphics renderer
+The example uses Raylib for windowing and rendering. It uses a 2D graphics renderer
 instead of a direct GPU renderer like the primary [Ghostty](https://ghostty.org) GUI. This is to
 showcase the flexibility of libghostty and how it can be used in a variety of
 contexts.
@@ -64,11 +63,6 @@ These features aren't properly exposed by libghostty-vt yet but will be:
 - OSC clipboard support
 - OSC title setting
 
-These are things that could work but haven't been tested or aren't
-implemented in Ghostling itself:
-
-- Windows support (libghostty-vt supports Windows)
-
 This list is incomplete and we'll add things as we find them.
 
 ### What You Won't Ever Get
@@ -112,9 +106,13 @@ Requirements:
 ```sh
 cmake -B build -G Ninja
 cmake --build build
-./build/ghostling
+./build/ghostling          # Linux / macOS
+.\build\ghostling.exe      # Windows
 ```
 
+On Windows, ghostling uses ConPTY and auto-detects the best available
+shell (pwsh > powershell > cmd). Use `--shell <path>` to override.
+
 > [!WARNING]
 >
 > Debug builds are VERY SLOW since Ghostty included a lot of extra