Claude Code 2.1.166
This release adds fallback model configuration for handling API unavailability, glob pattern support in deny rules for tools, hardened cross-session messaging security, improved thinking token controls across models, and numerous bug fixes including terminal rendering issues, image processing errors, and session stability improvements.
- Added
fallbackModelsetting to configure up to three fallback models tried in order when the primary model is overloaded or unavailable;--fallback-modelnow also applies to interactive sessions - Added glob pattern support in deny rule tool-name position (
"*"denies all tools); allow rules reject non-MCP globs, and unknown tool names in deny rules warn at startup - Hardened cross-session messaging: messages relayed via
SendMessagefrom other Claude sessions no longer carry user authority — receivers refuse relayed permission requests, and auto mode blocks them MAX_THINKING_TOKENS=0,--thinking disabled, and the per-model thinking toggle now disable thinking on models that think by default via the Claude API (3P providers unchanged)- Claude Code now retries a turn once on the fallback model when the API rejects an unexpected non-retryable error; auth, rate-limit, request-size, and transport errors still surface immediately
claude updatenow announces the target version before downloading instead of going silentclaude agents: typing a URL into the list now filters to the session whose first prompt contained it- Fixed a recurring "image could not be processed" error and extra token usage when an unprocessable image was sent in a session
- Fixed remote sessions becoming permanently stuck when a brief backend disruption occurred during worker registration at startup
- Fixed flickering in JetBrains IDE terminals (IntelliJ, PyCharm, WebStorm, etc.) on 2026.1+ by enabling synchronized output
- Fixed Shift+non-ASCII characters (e.g. Shift+ä → Ä) being dropped in terminals using the Kitty keyboard protocol (WezTerm, Ghostty, kitty)
- Fixed PowerShell command validation occasionally hanging far past its time budget on Windows when a killed process's children held its output pipes
- Fixed orphaned
claude --bg-pty-hostprocesses spinning at 100% CPU after the daemon dies while connected on macOS - Fixed voice mode requiring
/loginto clear a stale auth check after toggling/voice - Fixed managed settings with an invalid entry silently disabling enforcement of their remaining valid policies
- Fixed managed-settings
allowedMcpServers/deniedMcpServerspredicates not matching when they use${VAR}references - Fixed background agent sessions that entered a git worktree crash-looping with "No conversation found" when reopened from
claude agents - Fixed duplicated thinking text in the Ctrl+O transcript view while streaming
- Fixed
/doctorshowing a contradictory failed "Not inside a remote session" check when run inside a remote session - Fixed the cursor sticking at the end of the first line when typing a multiline prompt in the
claude agentsdispatch and reply inputs - Fixed blank lines appearing between background agent rows in the task list on terminals without Unicode support
Source: original entry ↗
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