I did read the code. OpenCode uses your global `small_model` (https://github.com/anomalyco/opencode/blob/dev/packages/open...) or title agent (https://github.com/anomalyco/opencode/blob/51e310c9/packages...)

OpenCode Zen is their own service provider; they see your prompt the same way OpenAI and Anthropic do. Somebody has to see your code, unless you host your models yourself.