desktop: model tooltip shows "reasoning not supported" for every model #50557

Summary

The desktop app model tooltip always shows "Reasoning: not supported" — even for models that clearly support reasoning. The tooltip reads model.capabilities.reasoning, but the V2 Model.Capabilities schema only defines tools, input, and output (additionalProperties: false), so that field is never present in server data.

Environment

• opencode version: 2.0.12
• Desktop app: 2.0.12 (Windows x64, Electron build)
• OS: Windows 11 (NT 10.0.26200)
• Shell: cmd.exe
• Install/channel: release
• Active plugins: ./plugin/config-audit.js

Reproduction

1. Desktop app 2.0.12 with model opencode-go/deepseek-v4.1-flash.
2. Open the model tooltip in the model picker.
3. It reports "Reasoning: not supported".

Expected Behavior

Models that support reasoning should report "Reasoning: allowed". deepseek-v4.1-flash exposes compatibility.reasoningField: "reasoning_content" and reasoning variants low/high/max.

Actual Behavior

The tooltip reports "not supported". Because the checked field does not exist in the API schema, no model can ever be reported as reasoning-capable.

Additional Context

Desktop bundle logic (extracted from app.asar):

c = () => e.model.capabilities
  ? (e.model.capabilities.reasoning ? t(`model.tooltip.reasoning.allowed`) : t(`model.tooltip.reasoning.none`))
  : (e.model.reasoning ? t(`model.tooltip.reasoning.allowed`) : t(`model.tooltip.reasoning.none`))

Server data (GET /api/model, opencode-go/deepseek-v4.1-flash):

{
  "capabilities": { "tools": true, "input": ["text", "image"], "output": ["text"] },
  "compatibility": { "reasoningField": "reasoning_content" },
  "variants": [{ "id": "low" }, { "id": "high" }, { "id": "max" }]
}

Model.Capabilities in the OpenAPI spec: { tools, input, output } with additionalProperties: false.

Suggested fix: derive reasoning support from the model's variants (reasoning-effort) or compatibility.reasoningField, instead of a capabilities.reasoning field the schema does not allow.