Sonnet 4.6 (1M context) replaces Sonnet 4.5 on Max plan—switch via /model. Startup gets 5 perf wins; git worktree isolation for agents; WASM memory leaks fixed for long sessions.
--worktree (-w) flag to start Claude in an isolated git worktreeConfigChange hook event that fires when configuration files change during a session, enabling enterprise security auditing and optional blocking of settings changes.-p) by skipping unnecessary API calls during startupplugin enable and plugin disable to auto-detect the correct scope when --scope is not specified, instead of always defaulting to user scope/config — memo comparators now correctly detect verbose changesdisableAllHooks setting to respect managed settings hierarchy — non-managed settings can no longer disable managed hooks set by policy (#26637)--resume session picker showing raw XML tags for sessions that start with commands like /clear. Now correctly falls through to the session ID fallback.isolation: "worktree" for working in a temporary git worktreebackground: true to always run as a background tasksettings.json for default configurationCLAUDE_CODE_SIMPLE) now includes the file edit tool in addition to the Bash tool, allowing direct file editing in simple mode.supportsEffort, supportedEffortLevels, and supportsAdaptiveThinking fields so consumers can discover model capabilities.