diff --git a/app/main.py b/app/main.py
index 6ef3d91..e3ab516 100644
--- a/app/main.py
+++ b/app/main.py
@@ -1,7 +1,6 @@
 from contextlib import asynccontextmanager
 from pathlib import Path
 
-import asyncpg
 from fastapi import Depends, FastAPI, Request
 from fastapi.responses import HTMLResponse
 from fastapi.templating import Jinja2Templates
@@ -23,7 +22,6 @@ from app.middleware.profiler import ProfilingMiddleware
 from app.redis import get_redis
 from app.services.auth import AuthBearer
 from app.services.chat_agent import build_chat_agent
-from app.services.chat_session import ChatSessionManager
 
 templates = Jinja2Templates(directory=Path(__file__).parent.parent / "templates")
 
@@ -32,7 +30,7 @@ templates = Jinja2Templates(directory=Path(__file__).parent.parent / "templates"
 async def lifespan(app: FastAPI):
     app.logger = get_logger()
     app.redis = await get_redis()
-    postgres_dsn = global_settings.postgres_url.unicode_string()
+    global_settings.postgres_url.unicode_string()
     # Chat service: initialize the pluggable model-client adapter. The session
     # manager is now a singleton and will be auto-instantiated on first access.
     # See app/services/chat_agent.py to swap the local stub for a real model
diff --git a/app/services/chat_agent.py b/app/services/chat_agent.py
index 994af9d..7ef5725 100644
--- a/app/services/chat_agent.py
+++ b/app/services/chat_agent.py
@@ -72,7 +72,7 @@ class LocalEchoAgent:
         return None
 
 
-def _validate_base_url(instance: OllamaChatAgent, attribute: attrs.Attribute, value: str) -> None:
+def _validate_base_url(_instance: OllamaChatAgent, _attribute: attrs.Attribute, value: str) -> None:
     """Validate that base_url is a valid HTTP(S) URL.
 
     Args:
@@ -92,7 +92,7 @@ def _validate_base_url(instance: OllamaChatAgent, attribute: attrs.Attribute, va
         raise ValueError(msg)
 
 
-def _validate_timeout(instance: OllamaChatAgent, attribute: attrs.Attribute, value: float) -> None:
+def _validate_timeout(_instance: OllamaChatAgent, _attribute: attrs.Attribute, value: float) -> None:
     """Validate that timeout is positive.
 
     Args:
diff --git a/tests/test_ollama_chat_agent_attrs.py b/tests/test_ollama_chat_agent_attrs.py
index 4fac694..19250f2 100644
--- a/tests/test_ollama_chat_agent_attrs.py
+++ b/tests/test_ollama_chat_agent_attrs.py
@@ -2,8 +2,8 @@
 import httpx
 import pytest
 
-from app.services.chat_agent import OllamaChatAgent, LocalEchoAgent, build_chat_agent
 from app.config import ChatConfig
+from app.services.chat_agent import LocalEchoAgent, OllamaChatAgent, build_chat_agent
 
 
 class TestOllamaChatAgentAttrsFeatures: