Add Redis fallback to NoOpCache

app/presentation/api/v1/endpoints.py

@@ -56,7 +56,17 @@ async def get_query_use_case() -> QueryProcessingUseCase:
     )
     llm = GeminiLLM(api_key=settings.gemini_api_key, model_name=settings.gemini_model)
     prompt_builder = DefaultPromptBuilder()
-    cache = RedisCache(redis_url=settings.redis_url)
+    
+    # Use NoOpCache if Redis unavailable
+    try:
+        from app.infrastructure.cache.redis_cache import RedisCache
+        cache = RedisCache(redis_url=settings.redis_url)
+        # Test connection
+        await cache.get("test_key")
+    except Exception:
+        logger.warning("redis_unavailable", msg="Falling back to NoOpCache")
+        from app.infrastructure.cache.noop_cache import NoOpCache
+        cache = NoOpCache()
 
     # For now, using a simple reranker (in production use cross-encoder)
     from app.infrastructure.external.simple_reranker import SimpleReranker