fix(mcp): provide data arg to RecordNotFoundError; preserve BYOK has_user_credential on decryption failure

- delete_user_credential now constructs RecordNotFoundError with the
  required 'data' kwarg so the proxy delete endpoints continue to
  receive a typed exception instead of a TypeError-induced 500.
- _annotate_user_credential_flags falls back to row-existence when a
  credential row cannot be decrypted (e.g. after salt-key rotation), so
  BYOK servers do not regress to has_user_credential=False when the
  row is in fact stored.

Co-authored-by: Yassin Kortam <yassin@berri.ai>

litellm/proxy/_experimental/mcp_server/db.py

@@ -680,11 +680,20 @@ async def delete_user_credential(
         where={"user_id_server_id": {"user_id": user_id, "server_id": server_id}}
     )
     if existing is None:
-        raise RecordNotFoundError()
+        raise RecordNotFoundError(
+            data={"error": {"message": "no BYOK credential row", "meta": {}}}
+        )
     if _decode_user_fields_payload(existing.credential_b64) is not None:
         # Treat as "no BYOK credential present" so the endpoint reports
         # has_credential=False without clobbering the user-fields row.
-        raise RecordNotFoundError()
+        raise RecordNotFoundError(
+            data={
+                "error": {
+                    "message": "row holds user-fields payload, not a BYOK credential",
+                    "meta": {},
+                }
+            }
+        )
     await prisma_client.db.litellm_mcpusercredentials.delete(
         where={"user_id_server_id": {"user_id": user_id, "server_id": server_id}}
     )

litellm/proxy/management_endpoints/mcp_management_endpoints.py

@@ -882,12 +882,14 @@ if MCP_AVAILABLE:
             # Decrypt once and classify, instead of paying the crypto
             # cost twice (once for user-fields detection, once for BYOK).
             decoded = _decode_user_credential(row.credential_b64)
-            if not decoded:
-                continue
-            payload = _parse_user_fields_plaintext(decoded)
+            payload = _parse_user_fields_plaintext(decoded) if decoded else None
             if payload is not None:
                 user_fields_by_server[row.server_id] = payload
             else:
+                # Either a BYOK credential or an undecryptable row (e.g.
+                # after a salt-key rotation). Either way, a credential row
+                # exists for this (user, server), so surface it as present
+                # instead of silently telling the user to reconnect.
                 byok_set.add(row.server_id)
         for server in servers:
             if getattr(server, "is_byok", False):