imag vector generation with dimentionality reduction

app/main.py

@@ -14,10 +14,12 @@ import threading
 from contextlib import asynccontextmanager
 from pathlib import Path
 
-from fastapi import FastAPI, HTTPException
+from fastapi import FastAPI, HTTPException, Request
+from fastapi.exceptions import RequestValidationError
+from fastapi.encoders import jsonable_encoder
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.staticfiles import StaticFiles
-from fastapi.responses import FileResponse
+from fastapi.responses import FileResponse, JSONResponse
 
 from app.infrastructure.persistence import restore_bundled_assets
 from app.infrastructure.settings import (
@@ -213,6 +215,27 @@ app.add_middleware(
     allow_headers=["*"],
 )
 
+
+def _json_safe(value):
+    """Replace floats JSON cannot carry (NaN, +/-inf) so an error can be sent."""
+    if isinstance(value, float) and (value != value or value in (float("inf"), float("-inf"))):
+        return str(value)
+    if isinstance(value, dict):
+        return {k: _json_safe(v) for k, v in value.items()}
+    if isinstance(value, (list, tuple)):
+        return [_json_safe(v) for v in value]
+    return value
+
+
+@app.exception_handler(RequestValidationError)
+async def _validation_error_as_422(request: Request, exc: RequestValidationError) -> JSONResponse:
+    """FastAPI's own 422 body echoes the rejected input. Python's JSON parser
+    accepts `NaN` on the way in, pydantic rejects it, and the echo then fails
+    to serialise - so a client that sent one NaN in a float field got a 500
+    instead of the 422 that names the field. Found by the image-vector
+    search, where the body is 1024 floats; applies to every route."""
+    return JSONResponse(status_code=422, content={"detail": _json_safe(jsonable_encoder(exc.errors()))})
+
 # A wrong origin list fails only in the browser, as an opaque "blocked by CORS"
 # with a perfectly healthy 200 in the server log - so state the effective list
 # at startup, where it can actually be compared against the frontend's URL.