Gemini 3.1 history_config

Client SDKs
1

# LiveKit Gemini 3.1 Vertex history_config bug

Hi LiveKit team,

We are testing Gemini 3.1 Flash Live on Vertex AI through `livekit-plugins-google==1.5.4` and hit a connection failure caused by `history_config` being sent on the Vertex path.

## Environment

- `livekit-agents==1.5.4`

- `livekit-plugins-google==1.5.4`

- `google-genai==1.73.1`

- Vertex AI enabled

- Model: `gemini-3.1-flash-live-preview`

## Current behavior

For Gemini 3.1, the plugin marks chat context as non-mutable and builds the connect config with:

```python

history_config=types.HistoryConfig(initial_history_in_client_content=True)

if not self._realtime_model.capabilities.mutable_chat_context

else None

```

On Vertex AI, `google-genai` rejects that field with:

```text

ValueError: history_config parameter is not supported in Vertex AI.

```

This prevents the session from connecting at all.

## Why this seems wrong

Gemini 3.1 on LiveKit already has documented mid-session limitations such as `generate_reply()`, `update_instructions()`, and `update_chat_ctx()` not being supported. That is fine.

The problem here is earlier than those limitations: the plugin currently sends a config field that Vertex explicitly does not support, so basic voice sessions fail before the model can even start.

## Suggested fix

In `livekit/plugins/google/realtime/realtime_api.py`, avoid sending `history_config` on the Vertex path.

Something along these lines should fix it:

```python

history_config = None

if not self._opts.vertexai and not self._realtime_model.capabilities.mutable_chat_context:

history_config = types.HistoryConfig(initial_history_in_client_content=True)

```

Then use that value in `types.LiveConnectConfig(…)`.

## Expected behavior

- Gemini 3.1 on Vertex should connect successfully.

- The known 3.1 mid-session limitations can still remain enforced.

- The plugin should not send provider-incompatible config fields when `vertexai=True`.

## Notes

We applied a local wrapper on our side that clears `history_config` only for Vertex + Gemini 3.1, and that is the workaround we are using for now.

If helpful, I can also send a minimal reproduction snippet.

2

I’m not familiar with history_config, looking at the code, I thought it was internal.

If helpful, I can also send a minimal reproduction snippet.

Yes, please.

3

Ya basically vertex hasn’t released gemini 3.1 live api yet. At least not for me. Not sure if Livekit will fix that issue or has already when its released.