diff --git a/Makefile b/Makefile
index 70588ba..573988f 100644
--- a/Makefile
+++ b/Makefile
@@ -187,7 +187,12 @@ dev:
 	echo "✓ LangGraph server started on localhost:2024"; \
 	echo "Starting Gateway API..."; \
 	cd backend && uv run uvicorn src.gateway.app:app --host 0.0.0.0 --port 8001 > ../logs/gateway.log 2>&1 & \
-	sleep 2; \
+	sleep 3; \
+	if ! lsof -i :8001 -sTCP:LISTEN -t >/dev/null 2>&1; then \
+		echo "✗ Gateway API failed to start. Last log output:"; \
+		tail -30 logs/gateway.log; \
+		cleanup; \
+	fi; \
 	echo "✓ Gateway API started on localhost:8001"; \
 	echo "Starting Frontend..."; \
 	cd frontend && pnpm run dev > ../logs/frontend.log 2>&1 & \
diff --git a/backend/src/agents/lead_agent/agent.py b/backend/src/agents/lead_agent/agent.py
index 5877a71..7775cd1 100644
--- a/backend/src/agents/lead_agent/agent.py
+++ b/backend/src/agents/lead_agent/agent.py
@@ -12,6 +12,7 @@ from src.agents.middlewares.title_middleware import TitleMiddleware
 from src.agents.middlewares.uploads_middleware import UploadsMiddleware
 from src.agents.middlewares.view_image_middleware import ViewImageMiddleware
 from src.agents.thread_state import ThreadState
+from src.config.app_config import get_app_config
 from src.config.summarization_config import get_summarization_config
 from src.models import create_chat_model
 from src.sandbox.middleware import SandboxMiddleware
@@ -213,7 +214,6 @@ def _build_middlewares(config: RunnableConfig):
 
     # Add ViewImageMiddleware only if the current model supports vision
     model_name = config.get("configurable", {}).get("model_name") or config.get("configurable", {}).get("model")
-    from src.config import get_app_config
 
     app_config = get_app_config()
     # If no model_name specified, use the first model (default)
diff --git a/backend/src/config/app_config.py b/backend/src/config/app_config.py
index f438315..3c219d9 100644
--- a/backend/src/config/app_config.py
+++ b/backend/src/config/app_config.py
@@ -113,7 +113,10 @@ class AppConfig(BaseModel):
         """
         if isinstance(config, str):
             if config.startswith("$"):
-                return os.getenv(config[1:], config)
+                env_value = os.getenv(config[1:])
+                if env_value is None:
+                    raise ValueError(f"Environment variable {config[1:]} not found for config value {config}")
+                return env_value
             return config
         elif isinstance(config, dict):
             return {k: cls.resolve_env_variables(v) for k, v in config.items()}
diff --git a/backend/src/config/extensions_config.py b/backend/src/config/extensions_config.py
index 61e2668..8b8f3e4 100644
--- a/backend/src/config/extensions_config.py
+++ b/backend/src/config/extensions_config.py
@@ -130,9 +130,10 @@ class ExtensionsConfig(BaseModel):
         for key, value in config.items():
             if isinstance(value, str):
                 if value.startswith("$"):
-                    env_value = os.getenv(value[1:], None)
-                    if env_value is not None:
-                        config[key] = env_value
+                    env_value = os.getenv(value[1:])
+                    if env_value is None:
+                        raise ValueError(f"Environment variable {value[1:]} not found for config value {value}")
+                    config[key] = env_value
                 else:
                     config[key] = value
             elif isinstance(value, dict):
diff --git a/backend/src/gateway/app.py b/backend/src/gateway/app.py
index 617e15d..f8643a0 100644
--- a/backend/src/gateway/app.py
+++ b/backend/src/gateway/app.py
@@ -1,9 +1,11 @@
 import logging
+import sys
 from collections.abc import AsyncGenerator
 from contextlib import asynccontextmanager
 
 from fastapi import FastAPI
 
+from src.config.app_config import get_app_config
 from src.gateway.config import get_gateway_config
 from src.gateway.routers import artifacts, mcp, memory, models, skills, uploads
 
@@ -20,6 +22,14 @@ logger = logging.getLogger(__name__)
 @asynccontextmanager
 async def lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
     """Application lifespan handler."""
+
+    # Load config and check necessary environment variables at startup
+    try:
+        get_app_config()
+        logger.info("Configuration loaded successfully")
+    except Exception as e:
+        logger.error(f"Failed to load configuration: {e}")
+        sys.exit(1)
     config = get_gateway_config()
     logger.info(f"Starting API Gateway on {config.host}:{config.port}")