feat: add API prefix for prefixes in url

api_service.py

@@ -10,8 +10,31 @@ from fastapi import FastAPI, Query
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse
 
+
+
 app = FastAPI(title="Signature Validation API")
 
+# Optional path prefix support: when behind a reverse-proxy that uses a
+# URL prefix (eg. `https://api.example.tld/library/...`) set `API_PREFIX` to
+# that prefix (example: `/library`) so incoming requests are rewritten to the
+# application root. This keeps route definitions unchanged while supporting
+# both proxied and direct deployments.
+_api_prefix_raw = os.getenv("API_PREFIX", "").strip()
+api_prefix = ""
+if _api_prefix_raw:
+    if not _api_prefix_raw.startswith("/"):
+        _api_prefix_raw = "/" + _api_prefix_raw
+    api_prefix = _api_prefix_raw.rstrip("/")
+
+
+@app.middleware("http")
+async def _strip_api_prefix(request, call_next):
+    if api_prefix and request.url.path.startswith(api_prefix):
+        new_path = request.url.path[len(api_prefix) :]
+        request.scope["path"] = new_path or "/"
+        request.scope["root_path"] = api_prefix
+    return await call_next(request)
+
 # Allow PHP application to call this API
 app.add_middleware(
     CORSMiddleware,