zed Agent Panel: Can't talk to Gemini 2.5 Pro over OpenRouter: "Error interacting with language model: data did not match any variant of untagged enum ResponseStreamResult"

Summary

Tried talking to Gemini 2.5 Pro Preview via OpenRouter and got this. It used to work.

Description

Steps to trigger the problem:

Update your settings to include the following (have Zed setup with OpenRouter per this discussion: https://github.com/zed-industries/zed/discussions/16576 ):

  "language_models": {
    "openai": {
      "api_url": "https://openrouter.ai/api/v1",
      "available_models": [
        {
          "name": "openai/o4-mini",
          "display_name": "o4-mini (OpenRouter)",
          "max_tokens": 200000
        },
        {
          "name": "openai/o4-mini-high",
          "display_name": "o4-mini-high (OpenRouter)",
          "max_tokens": 200000
        },
        {
          "name": "openai/o3",
          "display_name": "o3 (OpenRouter)",
          "max_tokens": 200000
        },
        {
          "name": "openai/gpt-4.5-preview",
          "display_name": "GPT-4.5 (Preview) (OpenRouter)",
          "max_tokens": 128000
        },
        {
          "name": "google/gemini-2.5-pro-preview",
          "display_name": "Gemini 2.5 Pro Preview (OpenRouter)",
          "max_tokens": 1048576
        },
        {
          "name": "anthropic/claude-sonnet-4",
          "display_name": "Claude Sonnet 4 (OpenRouter)",
          "max_tokens": 200000
        },
        {
          "name": "anthropic/claude-sonnet-4:thinking",
          "display_name": "Claude Sonnet 4 Thinking (OpenRouter)",
          "max_tokens": 200000
        },
        {
          "name": "anthropic/claude-opus-4",
          "display_name": "Claude Opus 4 (OpenRouter)",
          "max_tokens": 200000
        }
      ],
      "version": "1"
    }
  },

Actual Behavior:

It thinks for a while (probably charging me credits..) and then gives this error instead of giving any output.

Expected Behavior:

For conversations to work. EDIT: It seems this is a problem just with Gemini 2.5 Pro Preview. Other OpenRouter models, at least o4-mini that I tested, seem to work.