Add auth2api

pkgs/auth2api/package.nix

@@ -0,0 +1,44 @@
+{
+  lib,
+  buildNpmPackage,
+  nodejs_20,
+  makeWrapper,
+  sources,
+}:
+
+buildNpmPackage {
+  pname = "auth2api";
+  version = sources.auth2api.version;
+  src = sources.auth2api.src;
+
+  nodejs = nodejs_20;
+
+  npmDepsHash = "sha256-lHwY5MQ0nRoOPcURzmJCiXiUxEx9ZwZJSWKbkD4ZuIA=";
+
+  # Patch to allow running with an empty api-keys list (unauthenticated).
+  # Safe because the service binds to 127.0.0.1 by default.
+  patches = [ ./no-auth.patch ];
+
+  # auth2api's build script is `tsc` (TypeScript compile → dist/)
+  # devDeps (typescript, tsx) are needed for the build; buildNpmPackage
+  # prunes them automatically after the build step completes.
+  npmBuildScript = "build";
+
+  nativeBuildInputs = [ makeWrapper ];
+
+  # buildNpmPackage installs the package under $out/lib/node_modules/auth2api/.
+  # Wire up a $out/bin/auth2api wrapper pointing at the compiled entry-point.
+  postInstall = ''
+    makeWrapper ${nodejs_20}/bin/node $out/bin/auth2api \
+      --add-flags "$out/lib/node_modules/auth2api/dist/index.js"
+  '';
+
+  meta = {
+    description = "Lightweight Claude OAuth to OpenAI-compatible API proxy";
+    homepage = "https://github.com/AmazingAng/auth2api";
+    license = lib.licenses.mit;
+    maintainers = [ ];
+    platforms = lib.platforms.linux;
+    mainProgram = "auth2api";
+  };
+}