fix: align default model names with SDK defaults (#6704)

server/main.py

@@ -19,7 +19,6 @@ from errors import (
 from fastapi import Depends, FastAPI, HTTPException, Query, Request
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse, RedirectResponse
-from mem0.exceptions import ValidationError as Mem0ValidationError
 from models import RequestLog, User
 from pydantic import BaseModel, Field
 from rate_limit import limiter
@@ -39,6 +38,8 @@ from slowapi import _rate_limit_exceeded_handler
 from slowapi.errors import RateLimitExceeded
 from sqlalchemy import func, select
 
+from mem0.exceptions import ValidationError as Mem0ValidationError
+
 load_dotenv()
 
 install_request_id_logging()
@@ -113,7 +114,7 @@ POSTGRES_COLLECTION_NAME = os.environ.get("POSTGRES_COLLECTION_NAME", "memories"
 
 OPENAI_API_KEY = os.environ.get("OPENAI_API_KEY")
 HISTORY_DB_PATH = os.environ.get("HISTORY_DB_PATH", "/app/history/history.db")
-DEFAULT_LLM_MODEL = os.environ.get("MEM0_DEFAULT_LLM_MODEL", "gpt-4.1-nano-2025-04-14")
+DEFAULT_LLM_MODEL = os.environ.get("MEM0_DEFAULT_LLM_MODEL", "gpt-5-mini")
 DEFAULT_EMBEDDER_MODEL = os.environ.get("MEM0_DEFAULT_EMBEDDER_MODEL", "text-embedding-3-small")
 
 DEFAULT_CONFIG = {