Model Substitution Window

Model Substitution Window treats every frontier model dependency as a timed option, not a permanent commitment. The framework holds that the value of a multi-model orchestration layer is realized only when a provider's pricing or capability shifts, and that shift is the moment an agency can renegotiate scope. Anthropic's Claude Haiku 5.5 arrived at $0.10 per million input tokens with a 1 million token context window, a roughly 90% cut against prior small-model pricing, which resets the cost baseline for high-volume client work like document summarization and campaign analysis. Agencies that abstracted model calls behind a gateway can pass that saving into margin or into a lower retainer bid within days. Agencies that hardcoded one vendor absorb the change on the client's timeline instead of their own. The window closes when the next contract or statement of work is signed.