Gemma models return reasoning in `<thought>` tags – UI does not format/hide them

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#321,918 1 comment 0 reactions 1 assignee View on GitHub

@justschen is already working on this.

Since Jun 18, 2026.

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Description

When using Gemma models (e.g., gemma-4-27b-a4b-it, gemma-4-21b-it) via the Google AI API , the model includes its reasoning/chain-of-thought inside <thought>...</thought> tags. The extension currently only strips or formats tags like <think> or <thinking>, leaving <thought> content rendered as plain text, which clutters the chat UI and breaks the intended clean display.

Environment:

  • Copilot Chat Extension Version: 0.54.0
  • VS Code Version:
  • OS Version: windows 11
  • Feature: Ask/Edit mode (both)
  • Selected model: Gemma 4 31B and 27B (via custom endpoint)

Steps to Reproduce:

  1. Configure the extension to use the Google AI API with a Gemma model.
  2. Send a prompt that triggers reasoning (e.g., a math problem or coding puzzle).
  3. Observe the response – the model outputs a <thought> block containing its internal reasoning, followed by the final answer.
  4. The <thought> content appears as raw text in the chat panel, not collapsed or styled.

Expected Behavior:
The extension should treat <thought> tags similarly to <think>/<thinking> – i.e., either hide them entirely (since they are internal reasoning) or render them in a collapsible/separate section with a distinct style (e.g., grayed out, collapsed by default). This would keep the final answer clean and readable.

Actual Behavior:
The entire <thought> block is displayed verbatim, making the response messy and harder to parse, especially for lengthy reasoning.

Workaround (for now):
I cloned the copilot repo and applied support for .

Here is before

Image

Here is after

Image

Additional Context:
This affects all Gemma models served by Google . The model’s official documentation confirms it uses <thought> for internal reasoning. Many other tools (e.g., Ollama, LM Studio) already support stripping these tags, so it would be great if this extension could do the same.

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