#32112 Proxy: non-standard request param sent once is permanently re-injected into ALL subsequent requests to that deployment (in-memory state poisoning)
### What happened
On the LiteLLM proxy (v1.81.16, `openai/` custom provider entries pointing at llama.cpp `llama-server` backends), **a single request that includes a non-standard body parameter permanently contaminates the proxy's in-memory state for that deployment: the parameter is silently re-injected into every subsequent request to that model — from any client — until the proxy is restarted.**
We hit this in production: one client sent `dry_multiplier: 0.8` (a llama.cpp sampler param) in its request body. That client was later fixed to stop sending it — but the proxy kept injecting `dry_multiplier: 0.8` into all requests for that model for the rest of the day. Because DRY penalizes repeated token sequences, this silently corrupted code generation (repeated identifiers got mangled mid-file, e.g. `LEFT_ASSOCIATIVE` → `LEFT_ASSOCIAIVE`, and commas/brackets were dropped in long files, causing syntax errors). It was extremely hard to trace because the on-disk config was clean and only the *arriving* request body (observed via llama-server's `/slots`) showed the extra param.
### 4-step reproduction
Backend: llama.cpp `llama-server` (any model), config entry:
```yaml model_list…