## Problem

In a cascaded LiteLLM proxy topology (upstream proxy routing to a downstream LiteLLM proxy), two categories of operational metadata are silently dropped before the HTTP call reaches the downstream proxy: user-supplied tags and `litellm_session_id`.

When a client sends `{"metadata": {"tags": ["project-x", "team-a"]}}` to the upstream proxy, those tags are accumulated in `litellm_params["metadata"]["requester_metadata"]` during the upstream pipeline. `LiteLLMProxyChatConfig.transform_request()` builds the outbound request body from only `model`, `messages`, and `optional_params`, never inspecting `litellm_params`. The downstream proxy therefore receives no tags, and per-tag budget rules or spend attributions configured there are never evaluated.

`litellm_session_id` suffers the same fate. When a client includes `extra_body.litellm_session_id` for multi-turn session continuity, the upstream proxy extracts it into `litellm_params["litellm_session_id"]`. The transform discards it, so the downstream proxy creates sessions without the caller's intended identifier. Both issues are silent at runtime; no error is raised, the call succeeds, but the downstream proxy behaves as if…