Claude Fable 5 runs safety classifiers on requests and during generation, returning refusal stop reasons.

The important change is operational: refused work has a machine-readable stop reason and no charge before output.

For builders, the beta fallbacks parameter reruns refused requests on another model and bills at fallback rates.

• Jun 11, 2026OpenAI modelcard diff shows the API docs navigation content removed.
• Jun 11, 2026OpenAI pricing page removed visible API pricing content for GPT-5.5, GPT-5.4, and realtime.
• Jun 11, 2026Anthropic launched Claude Fable 5 and Claude Mythos 5 with 1M context and 128k max output.

This is the world we build in. It moves this fast. We move with it.