Resolution criteria

• Resolves YES if Anthropic publicly releases a model explicitly named “Claude Sonnet 4.5” on or before October 13, 2025 at 11:59:59 pm Pacific Time, evidenced by any of the following:

  • An official Anthropic news/blog post or models page naming “Claude Sonnet 4.5.” (anthropic.com)

  • The Anthropic API or docs list a model with ID/alias beginning with claude-sonnet-4-5-… or claude-sonnet-4-5. (docs.anthropic.com)

  • Official listings on Amazon Bedrock or Google Vertex AI that use the exact “Claude Sonnet 4.5” name. (docs.anthropic.com)

• Resolves NO if the above is not met by the deadline.

• Not counted: different names (e.g., “Sonnet 4.1” or “Sonnet 5”), third‑party/partner mentions without Anthropic using “Claude Sonnet 4.5,” leaks/rumors, or private/internal betas not reflected in Anthropic’s public docs/API. (docs.anthropic.com)

Background

• As of September 29, 2025, the latest Sonnet listed by Anthropic is Claude Sonnet 4 (model ID claude-sonnet-4-20250514). (docs.anthropic.com)

• Claude 4 (including Sonnet 4) launched May 22, 2025; Anthropic has since issued a minor “4.1” update for Opus, but not for Sonnet. (techcrunch.com)

• Recent enterprise integrations (e.g., Microsoft 365 Copilot) reference Sonnet 4 and Opus 4.1, with no mention of a Sonnet 4.5 to date. (reuters.com)

Considerations

• Anthropic’s naming uses snapshot-style model IDs and occasional minor versions (e.g., Opus 4.1). This market requires the exact string “Claude Sonnet 4.5”; adjacent releases (Sonnet 4.1/5.0) would not qualify. (docs.anthropic.com)