2.1.49 — Claude code - Product release notes & changelog tool

Improved MCP OAuth authentication with step-up auth support and discovery caching, reducing redundant network requests during server connections
Added --worktree (-w) flag to start Claude in an isolated git worktree
Subagents support isolation: "worktree" for working in a temporary git worktree
Added Ctrl+F keybinding to kill background agents (two-press confirmation)
Agent definitions support background: true to always run as a background task
Plugins can ship settings.json for default configuration
Fixed file-not-found errors to suggest corrected paths when the model drops the repo folder
Fixed Ctrl+C and ESC being silently ignored when background agents are running and the main thread is idle. Pressing twice within 3 seconds now kills all background agents.
Fixed prompt suggestion cache regression that reduced cache hit rates.
Fixed plugin enable and plugin disable to auto-detect the correct scope when --scope is not specified, instead of always defaulting to user scope
Simple mode (CLAUDE_CODE_SIMPLE) now includes the file edit tool in addition to the Bash tool, allowing direct file editing in simple mode.
Permission suggestions are now populated when safety checks trigger an ask response, enabling SDK consumers to display permission options
Sonnet 4.5 with 1M context is being removed from the Max plan in favor of our frontier Sonnet 4.6 model, which now has 1M context. Please switch in /model.
Fixed verbose mode not updating thinking block display when toggled via /config — memo comparators now correctly detect verbose changes
Fixed unbounded WASM memory growth during long sessions by periodically resetting the tree-sitter parser
Fixed potential rendering issues caused by stale yoga layout references
Improved performance in non-interactive mode (-p) by skipping unnecessary API calls during startup
Improved performance by caching authentication failures for HTTP and SSE MCP servers, avoiding repeated connection attempts to servers requiring auth
Fixed unbounded memory growth during long-running sessions caused by Yoga WASM linear memory never shrinking
SDK model info now includes supportsEffort, supportedEffortLevels, and supportsAdaptiveThinking fields so consumers can discover model capabilities.
Added ConfigChange hook event that fires when configuration files change during a session, enabling enterprise security auditing and optional blocking of settings changes.
Improved startup performance by caching MCP auth failures to avoid redundant connection attempts
Improved startup performance by reducing HTTP calls for analytics token counting
Improved startup performance by batching MCP tool token counting into a single API call
Fixed disableAllHooks setting to respect managed settings hierarchy — non-managed settings can no longer disable managed hooks set by policy (#26637)
Fixed --resume session picker showing raw XML tags for sessions that start with commands like /clear. Now correctly falls through to the session ID fallback.
Improved permission prompts for path safety and working directory blocks to show the reason for the restriction instead of a bare prompt with no context