[Bug] MiniMax responses show duplicate text in GUI but not in CLI

[lucasjingcn]

Bug Description

When using MiniMax models (M2.5 or M2.1) through a custom gateway proxy, the text response displays twice in the OpenCode GUI, but works correctly (displays once) in the CLI.

Steps to Reproduce

1. Set up a proxy gateway that forwards requests to MiniMax API (Anthropic-compatible format)
2. Configure OpenCode to use this gateway as the provider
3. Send a message to MiniMax model
4. Observe the response in GUI vs CLI

Expected Behavior

The text should display only once, regardless of whether using GUI or CLI.

Actual Behavior

• CLI: Text displays correctly (once)
• GUI: Text displays twice (duplicate)

Additional Info

• Tested with both MiniMax-M2.5 and MiniMax-M2.1 models
• The gateway returns correct JSON response (verified with curl)
• Direct API calls to MiniMax work correctly
• The issue only occurs when going through the gateway in GUI mode

Environment

• OpenCode version: [latest]
• OS: macOS
• Provider: MiniMax via custom gateway

Screenshots

GUI showing duplicate text:
[attach screenshot here]

CLI showing correct single text:
[attach screenshot here]

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• Streaming content duplication during LLM streaming in desktop/web UI #14822: Streaming content duplication during LLM streaming in desktop/web UI — same symptom of text appearing duplicated in GUI during streaming
• [Bug] Web UI: Duplicate text rendering during streaming due to dual render path race condition in session-turn.tsx #14280: [Bug] Web UI: Duplicate text rendering during streaming — same symptom of text doubled in the web/GUI, with root cause analysis in session-turn.tsx
• Some AI text is printed twice or more times #14623: Some AI text is printed twice or more times — same duplication behavior in the UI

These issues describe the same core problem (text rendered twice in the GUI/desktop UI but not in CLI). The root cause may already be identified or in progress. Please review those issues and consider whether this is the same bug before proceeding.

[github-actions]

To stay organized issues are automatically closed after 60 days of no activity. If the issue is still relevant please open a new one.