When you send your first message and opencode generates a title automatically, it uses the free opencode/gpt-5-nano model from the OpenCode Zen provider at https://opencode.ai/zen/v1
Ask AI to look at the code for you
We don't have any proof they're not logging everything, by default we should assume they are
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.