Utility module for accessing frontend in backend code.

passkey/util/frontend.py

@@ -0,0 +1,60 @@
+from importlib import resources
+from pathlib import Path
+
+__all__ = ["path", "file", "run_dev"]
+
+
+def _resolve_static_dir() -> Path:
+    # Try packaged path via importlib.resources (works for wheel/installed).
+    try:  # pragma: no cover - trivial path resolution
+        pkg_dir = resources.files("passkey") / "frontend-build"
+        fs_path = Path(str(pkg_dir))
+        if fs_path.is_dir():
+            return fs_path
+    except Exception:  # pragma: no cover - defensive
+        pass
+    # Fallback for editable/development before build.
+    return Path(__file__).parent.parent / "frontend-build"
+
+
+path: Path = _resolve_static_dir()
+
+
+def file(*parts: str) -> Path:
+    """Return a child path under the static root."""
+    return path.joinpath(*parts)
+
+
+def run_dev():
+    """Spawn the frontend dev server (bun or npm) as a background process."""
+    import atexit
+    import shutil
+    import signal
+    import subprocess
+
+    devpath = Path(__file__).parent.parent.parent / "frontend"
+    if not (devpath / "package.json").exists():
+        raise RuntimeError(
+            "Dev frontend is only available when running from git."
+            if "site-packages" in devpath.parts
+            else f"Frontend source code not found at {devpath}"
+        )
+    bun = shutil.which("bun")
+    npm = shutil.which("npm") if bun is None else None
+    if not bun and not npm:
+        raise RuntimeError("Neither bun nor npm found on PATH for dev server")
+    cmd: list[str] = [bun, "--bun", "run", "dev"] if bun else [npm, "run", "dev"]  # type: ignore[list-item]
+    proc = subprocess.Popen(cmd, cwd=str(devpath))
+
+    def _terminate():
+        if proc.poll() is None:
+            proc.terminate()
+
+    atexit.register(_terminate)
+
+    def _signal_handler(signum, frame):
+        _terminate()
+        raise SystemExit(0)
+
+    for sig in (signal.SIGINT, signal.SIGTERM):
+        signal.signal(sig, _signal_handler)