diff --git a/asgi_app.py b/asgi_app.py
index 14bce87..0e54a1c 100644
--- a/asgi_app.py
+++ b/asgi_app.py
@@ -139,22 +139,54 @@ async def mcp_protocol_handler(request: Request):
     token = auth_header.split(" ")[1]
     try:
         # Validate Clerk JWT token (required)
-        from clerk_backend_api import Clerk
-        clerk = Clerk(bearer_auth=os.getenv("CLERK_SECRET_KEY"))
-        jwt_claims = clerk.jwt_templates.verify_token(token)
-        user_id = jwt_claims.get("sub")
+        from clerk_backend_api import Clerk, models
+        import jwt
         
-        if not user_id:
-            logger.error("JWT token validation failed - no user_id in claims")
+        # First, decode JWT token without verification to get session_id
+        try:
+            decoded_token = jwt.decode(token, options={"verify_signature": False})
+            session_id = decoded_token.get("sid") or decoded_token.get("session_id")
+        except Exception as e:
+            logger.error(f"JWT token decoding failed: {e}")
             raise HTTPException(
                 status_code=401,
-                detail="Invalid token - no user_id in claims"
+                detail="Invalid JWT token format"
             )
         
-        logger.info(f"Bearer JWT token validated for user: {user_id}")
-        # Add user info to request state
-        request.state.user_id = user_id
-        request.state.token_scopes = jwt_claims.get("scopes", ["read", "search"])
+        if not session_id:
+            logger.error("No session_id found in JWT token")
+            raise HTTPException(
+                status_code=401,
+                detail="Invalid token - no session_id in claims"
+            )
+        
+        # Now verify the session with Clerk
+        clerk = Clerk(bearer_auth=os.getenv("CLERK_SECRET_KEY"))
+        
+        try:
+            # Use deprecated but working sessions.verify method
+            session = clerk.sessions.verify(session_id=session_id, token=token)
+            user_id = session.user_id if session else None
+            
+            if not user_id:
+                logger.error("Session verification failed - no user_id")
+                raise HTTPException(
+                    status_code=401,
+                    detail="Invalid session - no user_id"
+                )
+            
+            logger.info(f"Bearer JWT token validated for user: {user_id}")
+            # Add user info to request state
+            request.state.user_id = user_id
+            request.state.session_id = session_id
+            request.state.token_scopes = ["read", "search"]  # Default scopes
+            
+        except models.ClerkErrors as e:
+            logger.error(f"Clerk session verification failed: {e}")
+            raise HTTPException(
+                status_code=401,
+                detail="Session verification failed"
+            )
         
     except HTTPException:
         # Re-raise HTTPException as-is
diff --git a/mcp_auth_http_simple.py b/mcp_auth_http_simple.py
index 1b651ab..87b2d51 100644
--- a/mcp_auth_http_simple.py
+++ b/mcp_auth_http_simple.py
@@ -189,6 +189,62 @@ async def register_client(request: Request):
         "token_endpoint_auth_method": "none"
     })
 
+@router.post("/auth/callback")
+async def oauth_callback_post(request: Request):
+    """OAuth callback POST endpoint for token exchange"""
+    
+    # Parse form data (standard OAuth token exchange format)
+    form_data = await request.form()
+    grant_type = form_data.get("grant_type")
+    code = form_data.get("code")
+    redirect_uri = form_data.get("redirect_uri")
+    client_id = form_data.get("client_id")
+    code_verifier = form_data.get("code_verifier")
+    
+    logger.info(f"OAuth callback POST - grant_type: {grant_type}")
+    logger.info(f"Code: {code[:20] if code else 'None'}...")
+    logger.info(f"Client ID: {client_id}")
+    logger.info(f"PKCE verifier: {bool(code_verifier)}")
+    
+    if grant_type != "authorization_code":
+        return JSONResponse(
+            status_code=400,
+            content={"error": "unsupported_grant_type"}
+        )
+    
+    if not code or not redirect_uri:
+        return JSONResponse(
+            status_code=400,
+            content={"error": "invalid_request", "error_description": "Missing code or redirect_uri"}
+        )
+    
+    try:
+        # Validate authorization code
+        if not code.startswith("clerk_auth_"):
+            return JSONResponse(
+                status_code=400,
+                content={"error": "invalid_grant", "error_description": "Invalid authorization code"}
+            )
+        
+        # TODO: In production, validate code against stored session
+        # For now, we'll return a placeholder response
+        
+        # Generate or retrieve actual Clerk JWT token
+        # This should be the actual JWT token from Clerk authentication
+        return JSONResponse({
+            "access_token": "PLACEHOLDER_CLERK_JWT_TOKEN",
+            "token_type": "Bearer",
+            "expires_in": 3600,
+            "scope": "read search"
+        })
+        
+    except Exception as e:
+        logger.exception(f"OAuth callback POST failed: {e}")
+        return JSONResponse(
+            status_code=500,
+            content={"error": "server_error", "error_description": str(e)}
+        )
+
 @router.post("/token")
 async def token_endpoint(request: Request):
     """OAuth 2.1 Token Endpoint - exchanges code for Clerk JWT"""