ANTHROPIC_BASE_URL / ANTHROPIC_API_KEY / ANTHROPIC_MODEL
OpenHarness speaks the Anthropic Messages protocol, so three environment variables are enough — or choose the Anthropic-compatible provider profile inside oh setup. Set ANTHROPIC_MODEL explicitly to an id from the catalogue: dated Anthropic names such as claude-haiku-4-5-20251001 are not served here. Give it a generous output budget, since thinking-capable models spend part of max_tokens before any text appears.
export ANTHROPIC_BASE_URL="https://starseaapi.com" export ANTHROPIC_API_KEY="sk-your-key" export ANTHROPIC_MODEL="deepseek-v4.1-flash" oh # or: oh -p "..." --output-format json