fix: validate API keys at provider init to prevent 403 'authorization missing'

When NVIDIA_NIM_API_KEY or OPENROUTER_API_KEY is empty or not set,
the proxy forwarded requests without a valid Authorization header,
causing providers to return 403 with 'Header of type authorization
was missing'.

Now fail fast with HTTP 503 and a clear message telling users to add
the key to .env, with links to obtain keys.

Fixes #29

Co-authored-by: Ali Khokhar <alishahryar2@gmail.com>

api/dependencies.py

@@ -2,6 +2,7 @@
 
 from typing import Optional
 
+from fastapi import HTTPException
 from loguru import logger
 
 from config.settings import Settings, get_settings as _get_settings, NVIDIA_NIM_BASE_URL
@@ -24,6 +25,17 @@ def get_provider() -> BaseProvider:
         settings = get_settings()
 
         if settings.provider_type == "nvidia_nim":
+            if (
+                not settings.nvidia_nim_api_key
+                or not settings.nvidia_nim_api_key.strip()
+            ):
+                raise HTTPException(
+                    status_code=503,
+                    detail=(
+                        "NVIDIA_NIM_API_KEY is not set. Add it to your .env file. "
+                        "Get a key at https://build.nvidia.com/settings/api-keys"
+                    ),
+                )
             from providers.nvidia_nim import NvidiaNimProvider
 
             config = ProviderConfig(
@@ -38,6 +50,17 @@ def get_provider() -> BaseProvider:
             _provider = NvidiaNimProvider(config, nim_settings=settings.nim)
             logger.info("Provider initialized: %s", settings.provider_type)
         elif settings.provider_type == "open_router":
+            if (
+                not settings.open_router_api_key
+                or not settings.open_router_api_key.strip()
+            ):
+                raise HTTPException(
+                    status_code=503,
+                    detail=(
+                        "OPENROUTER_API_KEY is not set. Add it to your .env file. "
+                        "Get a key at https://openrouter.ai/keys"
+                    ),
+                )
             from providers.open_router import OpenRouterProvider
 
             config = ProviderConfig(

tests/api/test_dependencies.py

@@ -1,4 +1,5 @@
 import pytest
+from fastapi import HTTPException
 from unittest.mock import AsyncMock, MagicMock, patch
 from api.dependencies import get_provider, get_settings, cleanup_provider
 from providers.lmstudio import LMStudioProvider
@@ -143,6 +144,50 @@ async def test_get_provider_passes_http_timeouts_from_settings():
         assert timeout.connect == 5.0
 
 
+@pytest.mark.asyncio
+async def test_get_provider_nvidia_nim_missing_api_key():
+    """NVIDIA NIM with empty API key raises HTTPException 503."""
+    with patch("api.dependencies.get_settings") as mock_settings:
+        mock_settings.return_value = _make_mock_settings(nvidia_nim_api_key="")
+
+        with pytest.raises(HTTPException) as exc_info:
+            get_provider()
+
+        assert exc_info.value.status_code == 503
+        assert "NVIDIA_NIM_API_KEY" in exc_info.value.detail
+        assert "build.nvidia.com" in exc_info.value.detail
+
+
+@pytest.mark.asyncio
+async def test_get_provider_nvidia_nim_whitespace_only_api_key():
+    """NVIDIA NIM with whitespace-only API key raises HTTPException 503."""
+    with patch("api.dependencies.get_settings") as mock_settings:
+        mock_settings.return_value = _make_mock_settings(nvidia_nim_api_key="   ")
+
+        with pytest.raises(HTTPException) as exc_info:
+            get_provider()
+
+        assert exc_info.value.status_code == 503
+        assert "NVIDIA_NIM_API_KEY" in exc_info.value.detail
+
+
+@pytest.mark.asyncio
+async def test_get_provider_open_router_missing_api_key():
+    """OpenRouter with empty API key raises HTTPException 503."""
+    with patch("api.dependencies.get_settings") as mock_settings:
+        mock_settings.return_value = _make_mock_settings(
+            provider_type="open_router",
+            open_router_api_key="",
+        )
+
+        with pytest.raises(HTTPException) as exc_info:
+            get_provider()
+
+        assert exc_info.value.status_code == 503
+        assert "OPENROUTER_API_KEY" in exc_info.value.detail
+        assert "openrouter.ai" in exc_info.value.detail
+
+
 @pytest.mark.asyncio
 async def test_get_provider_unknown_type():
     """Test that unknown provider_type raises ValueError."""