### What happened?

With `ollama_chat/*` + streaming + tools, **every** tool call delta is emitted with `index=0`. When a model emits 2+ tool calls in one turn, any client that accumulates `arguments` by `index` (the OpenAI streaming convention) merges them into a single malformed tool call:

``` {"path": "a.rs"}{"path": "b.rs"} ```

That string then goes into the client's conversation history as `tool_calls[0].function.arguments`. On the **next** turn it is sent back to the proxy, where `OllamaChatConfig.transform_request` calls a bare `json.loads()` on it ([`ollama/chat/transformation.py#L268`](https://github.com/BerriAI/litellm/blob/main/litellm/llms/ollama/chat/transformation.py#L268)) and raises. The proxy surfaces it as a 500:

``` litellm.APIConnectionError: Extra data: line 1 column 29 (char 28) File "/app/.venv/lib/python3.13/site-packages/litellm/main.py", line 5522, in completion response = _complete_ollama_chat(_dispatch_ctx) ```

Two things make this painful to diagnose:

1. The error surfaces **one turn after** the turn that corrupted the history. 2. It is reported as `APIConnectionError` (unmapped exceptions fall through to it), so it reads like a network probl…