check for doubles

main.py

@@ -216,10 +216,25 @@ async def delete_book_api(book_id: int):
 
 @app.get("/api/debug/calibre_books")
 async def debug_calibre_books():
-    """Return raw listbooks sample so we can verify field names and structure."""
+    """Show raw Calibre-Web listbooks response shape so we can identify field names."""
     cfg = config.load()
-    books = fetch_all_books(cfg.calibre)
+    from uploader import CalibreClient
-    return {"total": len(books), "sample": books[:5]}
+    client = CalibreClient(cfg.calibre)
+    client._ensure_auth()
+    resp = client._session.get(
+        f"{cfg.calibre.url}/ajax/listbooks",
+        params={"draw": 1, "start": 0, "length": 5, "sort": "title", "order": "asc"},
+        timeout=30,
+    )
+    data = resp.json()
+    non_list = {k: v for k, v in data.items() if not isinstance(v, list)}
+    list_keys = {k: len(v) for k, v in data.items() if isinstance(v, list)}
+    return {
+        "http_status": resp.status_code,
+        "top_level_keys": list(data.keys()),
+        "non_list_fields": non_list,
+        "list_fields_lengths": list_keys,
+    }
 
 
 # --- Data reset ---