Three Cost Attribution Models for Multi-Tenant Chatbot APIs Explained

When building a marketplace SaaS chatbot that reviews code changes, choosing the right runtime pattern is critical for accurately attributing costs to individual tenants. Three main approaches exist: direct provider integration, a self-hosted gateway, and a managed broker, each with distinct trade-offs around control, operational burden, and billing transparency. Regardless of the pattern chosen, every API call must emit a complete usage record — including tenant ID, model used, token count, and fallback reason — even when a request shifts to a secondary model. A reliable evaluation should test all three patterns against the same fixture, covering normal responses, rate-limit errors, and timeouts, ensuring tenant attribution is never lost across attempts. The core principle is to define the accounting boundary first, since a single shared credential or automatic fallback adds little value if engineering teams cannot reconstruct each tenant's charges.