This comprehensive changelog tracks Claude Code’s rapid evolution since its preview launch in February 2025. Each version brings significant improvements based on user feedback and real-world usage patterns.
Claude Fable 5 is now available — “a Mythos-class model that we’ve made safe for general use. Fable’s capabilities exceed those of any model we’ve ever made generally available.” Update to version 2.1.170 for access; switch with /model fable (model ID claude-fable-5).
$10 / $50 per million tokens — exactly 2× Opus 4.8 — with a 1M context window, 128K max output, effort levels up to max (including xhigh), and adaptive thinking only.
Included on Pro, Max, Team, and seat-based Enterprise plans from June 9 through June 22, 2026; from June 23, 2026 further use requires usage credits.
Fixed sessions not saving transcripts (and not appearing in --resume) when launched from the VS Code integrated terminal.
v2.1.169 - June 8, 2026
--safe-mode, /cd & Bundled-Skill Controls
--safe-mode flag + CLAUDE_CODE_SAFE_MODE env var — start with all customizations (CLAUDE.md, plugins, skills, hooks, MCP servers) disabled, for troubleshooting
/cd — move the session to a new working directory without breaking the prompt cache
disableBundledSkills setting + CLAUDE_CODE_DISABLE_BUNDLED_SKILLS env var — hide bundled skills, workflows, and built-in slash commands
Self-hosted runner gains a post-session lifecycle hook — runs after the session ends, before workspace deletion, so you can snapshot uncommitted work or export logs
fallbackModel setting (and --fallback-model now in interactive sessions) — configure up to three fallback models tried in order when the primary is overloaded or unavailable; Claude Code also retries a turn once on the fallback when the API returns an unexpected non-retryable error (auth, rate-limit, request-size, and transport errors still surface immediately)
Glob patterns in deny rules — the tool-name position now accepts globs, so "*" 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 SendMessage from another Claude session 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 toggle now disable thinking on models that think by default (via the Claude API)
claude update announces the target version before downloading; claude agents filters the list as you type a session URL
v2.1.167–168 followed with reliability fixes (JetBrains terminal flicker on 2026.1+, Kitty-protocol Shift keys, voice mode, managed settings)
/plugin list with --enabled/--disabled filters; requiredMinimumVersion / requiredMaximumVersion managed settings refuse startup outside an approved version range and point users to a sanctioned build
claude agents --json now reports waitingFor (what a blocked session is waiting on); dispatching from the state-grouped view starts in the directory the view was opened from
/effort confirms when your chosen level will persist as the default for new sessions
Clicking a slash command in autocomplete now fills it into the prompt instead of running it immediately — press Enter to run
Remote Control shows as a persistent footer pill; Windsurf renamed to Devin Desktop across /ide, /terminal-setup, and /scroll-speed
/btw gains a “c to copy” shortcut (raw markdown); Stop and SubagentStop hooks can return hookSpecificOutput.additionalContext
v2.1.160–161 - June 2, 2026
ultracode Trigger Keyword & Config-Write Guards
The dynamic-workflow trigger keyword is now ultracode (renamed from workflow) and is highlighted in violet in the prompt input — the bare word “workflow” no longer triggers a run, though asking for one in your own words still does. See Dynamic Workflows.
Config-write guards — a prompt now appears before writing to shell startup files (.zshenv, .zlogin, .bash_login) and ~/.config/git/; acceptEdits mode also prompts before writing execution-granting build configs (.npmrc, .yarnrc*, bunfig.toml, .bazelrc, .pre-commit-config.yaml, .devcontainer/)
Edit no longer needs a separate Read after a single-file grep/egrep/fgrep — the grep satisfies the read-before-edit check
/mcp collapses claude.ai connectors you’ve never signed into; a failed Bash call in a parallel batch no longer cancels the others
OTEL_RESOURCE_ATTRIBUTES values are emitted as metric labels, so you can slice usage by custom dimensions like team or repo
.claude/skills Plugin Auto-Load & Auto Mode on Cloud Providers
Plugins in .claude/skills load automatically — no marketplace required; claude plugin init <name> scaffolds a new one, and /plugin arguments autocomplete
EnterWorktree can switch between Claude-managed worktrees mid-session; the agent field in settings.json is now honored for dispatched claude agents sessions
Auto mode on Amazon Bedrock, Google Vertex, and Microsoft Foundry for Opus 4.7 and Opus 4.8 — opt in with CLAUDE_CODE_ENABLE_AUTO_MODE=1
Fixed an Opus 4.8 issue where modified thinking blocks led to API errors
v2.1.154 - May 28, 2026
Claude Opus 4.8, Dynamic Workflows & ultracode
Claude Opus 4.8 is now available — Anthropic’s new flagship model, around four times less likely than Opus 4.7 to leave flaws in its own code unflagged. Pricing is unchanged at $5 / $25 per million tokens, and xhigh effort is the new default.
Dynamic workflows (research preview) — ask Claude to create a workflow and it orchestrates work across tens to hundreds of subagents in the background, verifying outputs before reporting back. Watch active runs with the new /workflows command.
ultracode — run /effort ultracode to combine xhigh reasoning with automatic workflow orchestration; Claude decides when a task warrants a workflow. It lasts the session — drop back with /effort high for routine work.
Fast mode on Opus 4.8 is now far cheaper: 2× the standard rate for 2.5× the speed.
Lean system prompt is now the default for every model except Haiku, Sonnet, and Opus 4.7 and earlier.
/simplify redesigned — runs a cleanup-only review (reuse, simplification, efficiency, altitude) and applies the fixes.
Effort slider relabeled from “Speed” / “Intelligence” to “Faster” / “Smarter”.
v2.1.152 - May 27, 2026
/code-review --fix & Skill Tool Controls
/code-review --fix applies the review’s findings to your working tree after the review — surfacing reuse, simplification, and efficiency cleanups.
Skills and slash commands can set disallowed-tools in frontmatter to remove tools from the model for that command.
Added /reload-skills; SessionStart hooks can now return reloadSkills: true.
v2.1.147 - May 21, 2026
/simplify → /code-review with Effort Levels
Renamed /simplify to /code-review and added effort levels (e.g. /code-review high).
--strict-mcp-config improvements for subagent MCP servers.
Streaming tool execution is now enabled by default across all platforms.
v2.1.145 - May 19, 2026
claude agents --json, Plugin Discovery
Added claude agents --json for scripting and automation.
The Agent tool now includes agent_id and parent_agent_id in OpenTelemetry spans.
/plugin Discover shows a plugin’s commands, agents, skills, hooks, and MCP/LSP servers before you install it.
v2.1.144 - May 19, 2026
/resume for Background Sessions
/resume now supports background sessions — sessions started with claude --bg or from the agent view are marked with a bg label.
Background sessions show their elapsed duration on completion (e.g. “Agent completed · 3h 2m 5s”).
Supervisor now reconnects to detached sessions after auto-update without losing in-flight work
Peek panel: paste an image to attach a screenshot to the reply you send to a blocked session
New claude respawn --all flag restarts every stopped session in one shot — pairs well with morning login after laptop sleep
Filter syntax in the dispatch input: s:blocked matches everything waiting on you (needs input + ready for review PRs)
Fixed ← shortcut occasionally backgrounding the wrong session when multiple peek panels were open
Fixed claude rm <id> failing to clean up empty .claude/worktrees/ parents
Fixed agent view ignoring disableAgentView: true set only in managed settings
v2.1.139 - May 11, 2026
/goal, Agent View Research Preview, Background Sessions
/goal sets a completion condition; Claude keeps working across turns until a small fast model confirms it. Aliases stop/off/reset/none/cancel for /goal clear. Up to 4,000-char conditions. Works in -p and Remote Control.
Agent view (claude agents) — research preview of a full-terminal dashboard for every background session: dispatch, peek, attach, detach, all sessions hosted by a per-user supervisor process
New shell commands: claude --bg "<prompt>", claude attach <id>, claude logs <id>, claude stop <id>, claude respawn <id>, claude rm <id>
New in-session commands: /bg / /background (background the current session), /stop (end a session from inside it), /tasks (list in-flight work that would block backgrounding)
← on an empty prompt in any Claude Code session backgrounds it and opens agent view with that row pre-selected (toggleable in /config)
Fixed credential save crash on Linux/Windows corrupting ~/.claude/.credentials.json
Fixed /fork writing full parent conversation per fork (now uses pointer + lazy hydrate)
v2.1.117 - April 22, 2026
Native bfs/ugrep on macOS/Linux, Parallel MCP Startup
Native macOS/Linux builds replace Glob/Grep tools with embedded bfs and ugrep available through the Bash tool — faster searches without the tool round-trip (Windows and npm builds unchanged)
Improved /model: selections persist across restarts even when the project pins a different model; startup header shows when the active model comes from a project/managed-settings pin
Faster startup when both local and claude.ai MCP servers are configured (concurrent connect default)
/resume on stale, large sessions now offers to summarize before re-reading
OpenTelemetry: user_prompt events include command_name/command_source; cost.usage, token.usage, api_request, api_error include effort when supported
Advisor Tool (experimental): dialog now carries an “experimental” label; no more stuck “result content could not be processed” errors
cleanupPeriodDays retention sweep now covers ~/.claude/tasks/, shell-snapshots/, and backups/
Default effort for Pro/Max on Opus 4.6 and Sonnet 4.6 is now high (was medium)
Fixed Opus 4.7 sessions showing inflated /context percentages — Claude Code was computing against 200K instead of native 1M
Fixed Bedrock application-inference-profile requests failing with 400 when backed by Opus 4.7 with thinking disabled
Fixed WebFetch hanging on very large HTML pages by truncating input before HTML→markdown conversion
v2.1.116 - April 20, 2026
Faster /resume, Thinking Spinner Progress
/resume on large sessions is significantly faster (up to 67% on 40MB+ sessions)
Faster MCP startup with multiple stdio servers; resources/templates/list is deferred to first @-mention
Smoother fullscreen scrolling in VS Code / Cursor / Windsurf terminals — /terminal-setup now configures editor scroll sensitivity
/doctor can now be opened while Claude is responding
Security: sandbox auto-allow no longer bypasses dangerous-path check for rm/rmdir on /, $HOME, or critical system directories
Claude Code now uses https://downloads.claude.ai/claude-code-releases
Fixed Devanagari and other Indic scripts rendering with broken column alignment
Fixed Ctrl+- not triggering undo in Kitty keyboard protocol terminals (iTerm2, Ghostty, WezTerm, Windows Terminal)
Fixed /branch rejecting conversations with transcripts larger than 50MB
Fixed intermittent API 400 “cache control TTL ordering” errors
v2.1.114 - April 18, 2026
Permission Dialog Crash Fix
Fixed a crash in the permission dialog when an agent teams teammate requested tool permission
v2.1.113 - April 17, 2026
Native CLI Binary, Sandbox Hardening
CLI now spawns a native Claude Code binary (via per-platform optional dependency) instead of bundled JavaScript
Added sandbox.network.deniedDomains to block specific domains even when a broader allowedDomains wildcard permits them
Fullscreen: Shift+↑/↓ scrolls the viewport when extending a selection past visible edge
Ctrl+A / Ctrl+E now move to start/end of current logical line in multiline input (readline behavior)
Windows: Ctrl+Backspace now deletes the previous word
Improved /loop: Esc cancels pending wakeups
Improved /ultrareview: faster launch, parallelized checks, diffstat in launch dialog
Subagents that stall mid-stream now fail with a clear error after 10 minutes instead of hanging
Security: macOS /private/{etc,var,tmp,home} paths treated as dangerous removal targets under Bash(rm:*)
Security: Bash deny rules now match commands wrapped in env/sudo/watch/ionice/setsid
Security: Bash(find:*) allow rules no longer auto-approve find -exec/-delete
Fixed thinking.type.enabled is not supported 400 error when using Opus 4.7 via Bedrock Application Inference Profile ARN
Fixed Bash dangerouslyDisableSandbox running commands outside the sandbox without a permission prompt
v2.1.112 - April 16, 2026
Opus 4.7 Availability Fix
Fixed “claude-opus-4-7 is temporarily unavailable” for auto mode
v2.1.111 - April 16, 2026
Claude Opus 4.7 + xhigh effort + /ultrareview
Claude Opus 4.7 xhigh effort level now available — tune speed vs. intelligence via /effort, --effort, or the model picker; other models fall back to high
Auto mode now available for Max subscribers when using Opus 4.7
/effort opens an interactive slider when called without arguments
Fixed claude -w <name> failing with “already exists” after stale worktree cleanup
Fixed subagents in isolated worktrees being denied Read/Edit access to files inside their own worktree
Fixed RemoteTrigger tool’s run action sending an empty body
v2.1.100 - April 10, 2026
Paste Improvements, Plugin Dependency Resolution
Faster paste handling and better CRLF handling in long pastes
Plugin dependency auto-install during marketplace add
Performance fixes across SDK subprocess cleanup
v2.1.98 - April 9, 2026
Google Vertex Setup Wizard, Perforce Mode, Monitor Tool
Added interactive Google Vertex AI setup wizard from the login screen — guides through GCP auth, project/region config, credential verification, model pinning
Added CLAUDE_CODE_PERFORCE_MODE env var — Edit/Write/NotebookEdit fail on read-only files with a p4 edit hint instead of silently overwriting
Added Monitor tool for streaming events from background scripts
Added subprocess sandboxing with PID namespace isolation on Linux via CLAUDE_CODE_SUBPROCESS_ENV_SCRUB, plus CLAUDE_CODE_SCRIPT_CAPS to cap per-session script invocations
Added --exclude-dynamic-system-prompt-sections flag to print mode for cross-user cache improvement
Added workspace.git_worktree to the status line JSON when inside a linked git worktree
Added W3C TRACEPARENT env var to Bash tool subprocesses when OTEL tracing is enabled
Fixed a Bash tool permission bypass where backslash-escaped flags could be auto-allowed as read-only leading to arbitrary code execution
Fixed --dangerously-skip-permissions being silently downgraded to accept-edits mode
Fixed managed-settings allow rules remaining active after admin removed them until restart
Improved /agents with tabbed layout: Running tab + Library tab with Run agent / View running instance
v2.1.97 - April 8, 2026
NO_FLICKER Focus View, Cedar Highlighting
Added focus view toggle (Ctrl+O) in NO_FLICKER mode showing prompt, one-line tool summary with edit diffstats, and final response
Added refreshInterval status line setting to re-run the command every N seconds
Added ● N running indicator in /agents next to agent types with live subagent instances
Added syntax highlighting for Cedar policy files (.cedar, .cedarpolicy)
Fixed MCP HTTP/SSE connections accumulating ~50 MB/hr of unreleased buffers on reconnect
Improved image handling: pasted and attached images compressed to same token budget as Read-tool images
Improved sandbox: sandbox.network.allowMachLookup now takes effect on macOS
Improved Bridge sessions to show local git repo, branch, and cwd on claude.ai session card
Fixed CJK/@-mention completion after punctuation; Japanese/Chinese input no longer requires space before / or @
v2.1.96 - April 8, 2026
Bedrock Auth Hotfix
Fixed Bedrock requests failing with 403 "Authorization header is missing" when using AWS_BEARER_TOKEN_BEDROCK or CLAUDE_CODE_SKIP_BEDROCK_AUTH (regression in 2.1.94)
v2.1.94 - April 7, 2026
Mantle-backed Bedrock, Higher Default Effort
Added support for Amazon Bedrock powered by Mantle — set CLAUDE_CODE_USE_MANTLE=1
Changed default effort level from medium to high for API-key, Bedrock/Vertex/Foundry, Team, and Enterprise users
Added compact Slacked #channel header with clickable channel link for Slack MCP send-message calls
Added keep-coding-instructions frontmatter for plugin output styles
Added hookSpecificOutput.sessionTitle to UserPromptSubmit hooks
Plugin skills declared via "skills": ["./"] now use the skill’s frontmatter name
Fixed agents stuck after 429 with long Retry-After
Fixed Console login on macOS silently failing with “Not logged in” when keychain is locked
Improved --resume to resume sessions from other worktrees of the same repo directly
v2.1.92 - April 4, 2026
forceRemoteSettingsRefresh, Bedrock Setup Wizard
Added forceRemoteSettingsRefresh policy setting — CLI blocks startup until remote managed settings are freshly fetched (fail-closed)
Added interactive Bedrock setup wizard from the login screen’s “3rd-party platform” option
Added per-model and cache-hit breakdown to /cost for subscription users
/release-notes is now an interactive version picker
Remote Control session names use your hostname as the default prefix (e.g. myhost-graceful-unicorn)
Removed /tag command
Removed /vim command (toggle vim mode via /config → Editor mode)
Improved Write tool diff computation speed for large files (60% faster on files with tabs/&/$)
Linux sandbox now ships the apply-seccomp helper in both npm and native builds
Fixed subagent spawning permanently failing with “Could not determine pane count” after tmux window churn
v2.1.91 - April 2, 2026
MCP Result Size Override, Plugin bin/
Added MCP tool result persistence override via _meta["anthropic/maxResultSizeChars"] (up to 500K)
Added disableSkillShellExecution setting to disable inline shell execution in skills and slash commands
Plugins can now ship executables under bin/ and invoke them as bare commands from the Bash tool
Added support for multi-line prompts in claude-cli://open?q= deep links (encoded newlines %0A no longer rejected)
Fixed transcript chain breaks on --resume that could lose history when async transcript writes fail silently
Fixed plan mode in remote sessions losing track of the plan file after a container restart
Conditional hooks: Added if field for hooks using permission rule syntax (e.g., Bash(git *)) to filter when they run, reducing process spawning overhead
MCP OAuth RFC 9728: MCP OAuth now follows Protected Resource Metadata discovery to find the authorization server
Added CLAUDE_CODE_MCP_SERVER_NAME and CLAUDE_CODE_MCP_SERVER_URL env vars to MCP headersHelper scripts
Added .jj and .sl to VCS directory exclusion lists so Grep and file autocomplete skip Jujutsu/Sapling metadata
MEMORY.md index now truncates at 25KB as well as 200 lines
Read tool uses compact line-number format and deduplicates unchanged re-reads, reducing token usage
Plugins blocked by organization policy can no longer be installed or enabled
Fixed --resume failing with orphan tool_result blocks on sessions created before v2.1.85
Fixed /compact failing when the conversation has grown too large for the compact request itself
VSCode: Fixed extension defaulting Max plan users to Sonnet after OAuth token refresh
v2.1.83-84 - March 25-26, 2026
Transcript Search, Plugin Options & PowerShell
Transcript search: Press / in transcript mode (Ctrl+O) to search, n/N to step through matches
managed-settings.d/ drop-in directory: Separate teams can deploy independent policy fragments that merge alphabetically
Plugin options: manifest.userConfig allows plugins to prompt for configuration at enable time, with sensitive: true values stored in keychain
PowerShell tool for Windows as an opt-in preview
Added CwdChanged and FileChanged hook events for reactive environment management
Added TaskCreated hook that fires when a task is created via TaskCreate
Added sandbox.failIfUnavailable setting to exit with error when sandbox cannot start
Pasted images now insert [Image #N] chip at cursor for positional reference
Rules and skills paths: frontmatter now accepts a YAML list of globs
MCP tool descriptions and server instructions capped at 2KB to prevent context bloat
Token counts ≥1M now display as “1.5m” instead of “1512.6k”
Added idle-return prompt nudging users after 75+ minutes to /clear
Agents can declare initialPrompt in frontmatter to auto-submit a first turn
VSCode: Added rate limit warning banner with usage percentage and reset time
v2.1.81 - March 22, 2026
Bare Mode & Channels
--bare flag for scripted -p calls — skips hooks, LSP, plugin sync, and skill directory walks; requires ANTHROPIC_API_KEY; auto-memory fully disabled
--channels permission relay — channel servers that declare the permission capability can forward tool approval prompts to your phone
Resuming a session that was in a worktree now switches back to that worktree
MCP read/search tool calls collapse into a single Queried <server> line (expand with Ctrl+O)
Improved plugin freshness — ref-tracked plugins now re-clone on every load
v2.1.37: Fixed an issue where /fast was not immediately available after enabling /extra-usage
v2.1.36: Fast mode is now available for Opus 4.6 — same model, faster output. Toggle with /fast
v2.1.34 - February 17, 2026
Agent Teams & Sandbox Fixes
Fixed a crash when agent teams setting changed between renders
Fixed a bug where commands excluded from sandboxing (via sandbox.excludedCommands or dangerouslyDisableSandbox) could bypass the Bash ask permission rule when autoAllowBashIfSandboxed was enabled
v2.1.33 - February 15, 2026
Agent Hooks & VSCode Remote Sessions
Added TeammateIdle and TaskCompleted hook events for multi-agent workflows
Added memory frontmatter field for agents — persistent memory with user, project, or local scope
Added support for restricting sub-agents via Task(agent_type) syntax in agent “tools” frontmatter
Added plugin name to skill descriptions and /skills menu for better discoverability
VSCode: Added support for remote sessions, allowing OAuth users to browse and resume sessions from claude.ai
VSCode: Added git branch and message count to the session picker, with search by branch name
Fixed multiple issues: thinking interruption, API proxy 404 fallback, proxy env var propagation, /resume XML markup display
v2.1.32 - February 12, 2026
Claude Opus 4.6 & Agent Teams
Claude Opus 4.6 is now available!
Agent Teams research preview — multi-agent collaboration (set CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1)
Automatic Memories — Claude now records and recalls memories as it works
Summarize from here — partial conversation summarization via message selector
Skills from .claude/skills/ in additional directories (--add-dir) now loaded automatically
Skill character budget scales with context window (2% of context)
