Previously the announced drop-dead date was October 22, 2025. The date was silently postponed to October 29 (by writing a new date in the documentation) a day or two before that.

Previous market (resolved NO): https://manifold.markets/SorenBjornstad/claude-sonnet-35-and-36-unavailable. This market will be resolved in the same manner as that one, except of course for the date:

This market resolves to YES if Claude Sonnet 3.5 and 3.6 (i.e., “claude-3-5-sonnet-20240620” and “claude-3-5-sonnet-20241022”) models are unusable through the Anthropic API on October 30, 2025, one day after the newly documented retirement date (for reasons other than transient error). It resolves to NO if either or both models remain accessible through the API on that date for any reason.

See https://docs.anthropic.com/en/docs/about-claude/model-deprecations for current announced dates and historical announcements.