Short answer: for a marketplace SaaS chatbot that reviews code changes, choose the runtime pattern that records tenant, route, model, token usage, and fallback reason in one usage event; one credential and automatic fallback are useful, but neither matters if a team can't explain each tenant's bill. Start with the accounting boundary, not the provider list. A direct integration preserves maximum control, a self-hosted gateway centralizes routing while keeping operations in-house, and a manage...