feat: add rag backend and review access fixes

fastapi_modules/fastapi_leaudit/rag_engine/chroma_client.py

@@ -0,0 +1,40 @@
+from __future__ import annotations
+
+from typing import Any
+
+from fastapi_modules.fastapi_leaudit.rag_engine.config import RAG_CONFIG
+
+_instance: Any | None = None
+
+
+def init_chroma() -> Any:
+    global _instance
+    if _instance is not None:
+        return _instance
+
+    import chromadb  # lazy import to avoid hard failure before feature is enabled
+    import chromadb.config
+
+    host = RAG_CONFIG["CHROMA_HOST"]
+    if host:
+        token = RAG_CONFIG.get("CHROMA_TOKEN", "")
+        header = RAG_CONFIG.get("CHROMA_AUTH_HEADER", "X-Chroma-Token")
+        settings = (
+            chromadb.config.Settings(
+                chroma_client_auth_provider="chromadb.auth.token_authn.TokenAuthClientProvider",
+                chroma_client_auth_credentials=token,
+                chroma_auth_token_transport_header=header,
+            )
+            if token
+            else chromadb.config.Settings()
+        )
+        _instance = chromadb.HttpClient(host=host, port=RAG_CONFIG["CHROMA_PORT"], settings=settings)
+    else:
+        _instance = chromadb.PersistentClient(path=RAG_CONFIG["CHROMA_PERSIST_DIR"])
+    return _instance
+
+
+def get_chroma() -> Any:
+    if _instance is None:
+        return init_chroma()
+    return _instance