You'll notice Notable
No documentation found
The model list, aliases and defaults can now come from a signed remote catalog document rather than only from app releases.
Claude Code can now fetch, cache, and verify a signed remote "model catalog" document from https://downloads.claude.ai/model-catalog/v1/catalog.json (or a custom/managed URL). Signatures use RSASSA-PKCS1-v1_5-SHA512 checked against trust roots, with a hard-coded release-signing public key named claude-code-release-signing-key, and a compiled-in seed document is used as a fallback before the first successful fetch. This lets the model list, aliases, and defaults be updated server-side rather than only through app releases, with tamper protection from the signature check.
Names in the bundleCLAUDE_CODE_MODEL_CATALOG_URL
Two sources agreeTwo things we can check say the same as this entry.
Anthropic's release notes agree
Added s in /effort to change effort for the current session only, matching /model
The name it cites is new in this build
New in this build: CLAUDE_CODE_MODEL_CATALOG_URL