Move the build_backend script to tools folder.

tools/build_backend.py

@@ -0,0 +1,100 @@
+"""Custom build backend that builds libaegis with Zig before building the Python package."""
+
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+from setuptools import build_meta as _orig
+
+
+def _check_zig_available():
+    """Check if Zig is installed and available."""
+    if shutil.which("zig") is None:
+        raise RuntimeError(
+            "\n" + "=" * 70 + "\n"
+            "ERROR: Zig compiler not found!\n"
+            "\n"
+            "Building pyaegis requires the Zig compiler to build the libaegis\n"
+            "static library. Please install Zig before building this package.\n"
+            "\n"
+            "Installation instructions:\n"
+            "  - Visit: https://ziglang.org/download/\n"
+            "  - Or use a package manager:\n"
+            "    * macOS:   brew install zig\n"
+            "    * Linux:   See https://github.com/ziglang/zig/wiki/Install-Zig-from-a-Package-Manager\n"
+            "    * Windows: choco install zig  or  scoop install zig\n"
+            "\n"
+            "After installing Zig, please try building again.\n" + "=" * 70 + "\n"
+        )
+
+
+def _build_libaegis():
+    """Build libaegis static library with Zig."""
+    # Check Zig availability first
+    _check_zig_available()
+
+    libaegis_dir = Path(__file__).parent.parent / "libaegis"
+    if not libaegis_dir.exists():
+        raise FileNotFoundError(
+            f"libaegis directory not found at {libaegis_dir}. "
+            "Cannot build static library."
+        )
+
+    print("Building libaegis static library with Zig...")
+    try:
+        subprocess.run(
+            ["zig", "build", "-Drelease"],
+            cwd=libaegis_dir,
+            check=True,
+            capture_output=False,
+        )
+        print("Successfully built libaegis static library")
+    except subprocess.CalledProcessError as e:
+        print(
+            f"\nError: Zig build failed with exit code {e.returncode}\n"
+            f"Command: {' '.join(e.cmd)}\n",
+            file=sys.stderr,
+        )
+        raise
+
+
+# Expose all the standard build backend hooks
+def get_requires_for_build_wheel(config_settings=None):
+    """Return build requirements and ensure libaegis is built first."""
+    _build_libaegis()
+    return _orig.get_requires_for_build_wheel(config_settings)
+
+
+def get_requires_for_build_sdist(config_settings=None):
+    """Return build requirements for sdist and ensure libaegis is built first."""
+    _build_libaegis()
+    return _orig.get_requires_for_build_sdist(config_settings)
+
+
+_orig_prepare_metadata_for_build_wheel = _orig.prepare_metadata_for_build_wheel
+_orig_build_sdist = _orig.build_sdist
+
+
+def prepare_metadata_for_build_wheel(metadata_directory, config_settings=None):
+    """Prepare metadata and ensure libaegis is built (some frontends call this early)."""
+    _build_libaegis()
+    return _orig_prepare_metadata_for_build_wheel(metadata_directory, config_settings)
+
+
+def build_sdist(sdist_directory, config_settings=None):
+    """Build sdist, building libaegis first so the sdist can include built artifacts if needed."""
+    _build_libaegis()
+    return _orig_build_sdist(sdist_directory, config_settings)
+
+
+def build_wheel(wheel_directory, config_settings=None, metadata_directory=None):
+    """Build wheel with libaegis built first."""
+    _build_libaegis()
+    return _orig.build_wheel(wheel_directory, config_settings, metadata_directory)
+
+
+def build_editable(wheel_directory, config_settings=None, metadata_directory=None):
+    """Build editable install with libaegis built first."""
+    _build_libaegis()
+    return _orig.build_editable(wheel_directory, config_settings, metadata_directory)