Anthropic Release Notes

• Opus 4.8 is here! Now defaults to high effort · /effort xhigh for your hardest tasks
• Introducing dynamic workflows: ask Claude to create a workflow and it orchestrates work across tens to hundreds of agents in the background, so you can take on larger, more complex tasks. Run /workflows to view your runs
• Fast mode on Opus 4.8 is now available at a fraction of its previous cost: 2x the standard rate for 2.5x the speed
• The lean system prompt is now the default for all models except Haiku, Sonnet, and Opus 4.7 and earlier
• Claude now reserves the multiple-choice question prompt for decisions it genuinely cannot make itself, instead of asking when it already has enough context to proceed
• /simplify now runs a cleanup-only review (reuse, simplification, efficiency, altitude) and applies the fixes, instead of running the full /code-review --fix bug-hunting review
• Renamed the /effort slider labels from "Speed"/"Intelligence" to "Faster"/"Smarter" for clarity
• claude agents: type ! <command> to run a shell command as a background session you can attach to and detach from. Also available as claude --bg --exec '<command>'
• claude agents: /logout now signs you out instead of being sent to a background session
• ←← to open the agents view now works on Bedrock, Vertex, Foundry, and with telemetry disabled …

• Added skipLfs option to github/git plugin marketplace sources to skip Git LFS downloads during clone and update
• Claude Code now shows a one-time notice when your npm global install can't auto-update; /doctor lists the fixes
• Status line commands now receive COLUMNS and LINES environment variables so scripts can size output to the terminal width
• claude agents: autocomplete in the dispatch input now suggests native slash commands and bundled skills, not just project skills
• claude agents: PR column now shows PR #N for a single PR or N PRs for multiple
• claude doctor now shows the result of your last update attempt
• Combined the separate "needs authentication" startup notifications for MCP servers and connectors into a single message
• macOS: background agents now appear as "Claude Code" in Privacy & Security and keep their permission grants across upgrades
• Fixed stateful MCP servers without the optional GET SSE stream reconnect-looping on tools/list (regression in v2.1.147)
• Fixed a regression where a custom API gateway could receive the user's Anthropic OAuth credential instead of the gateway's own token
• Fixed subagent (Agent tool) frontmatter MCP servers ignoring --strict-mcp-config, --bare, remote mode, enterprise managed MCP config, and managed-settings MCP server allow/deny policies …

• We've launched Claude Opus 4.8 (claude-opus-4-8), our most capable model. Claude Opus 4.8 supports a 1M token context window by default on the Claude API, Amazon Bedrock, Google Cloud, and Microsoft Foundry, 128k max output tokens, and the same set of tools and platform features as Claude Opus 4.7. See the migration guide for baseline settings, features, and migration guidance.
• We've launched mid-conversation system messages. On Claude Opus 4.8, you can send role: "system" messages after a user turn (subject to placement rules) in the messages array, preserving prompt cache hits when instructions change during a long-running session. No beta header is required.
• The stop_details field on refusal responses is now publicly documented; it returns a category (cyber, bio, or null) and a human-readable explanation, so your application can route different classes of refusal to the right next step. No beta header is required. …

Claude Opus 4.8 launch

We’ve upgraded Claude Opus to a new version. Claude Opus 4.8 shows improvements over Opus 4.7 in coding, agentic skills, reasoning, and practical knowledge work tasks. For more information, see our blog post: Introducing Claude Opus 4.8.

Enterprise plans can manage connector access with custom roles

We added connector permissions to extend the existing custom roles framework and allow administrators to control which connectors, and which individual tools on those connectors, are available to each custom role. For more information, see Manage custom roles on Enterprise plans.

• /code-review --fix now applies review findings to your working tree after the review, surfacing reuse, simplification, and efficiency suggestions; /simplify now invokes /code-review --fix
• Skills and slash commands can now set disallowed-tools in frontmatter to remove tools from the model while the skill is active
• Added /reload-skills command to re-scan skill directories without restarting the session
• SessionStart hooks can now return reloadSkills: true to re-scan skill directories, making skills installed by the hook available in the same session
• SessionStart hooks can now set the session title via hookSpecificOutput.sessionTitle on startup and resume
• Added a MessageDisplay hook event that lets hooks transform or hide assistant message text as it is displayed
• Added pluginSuggestionMarketplaces managed setting: admins can allowlist org marketplaces whose plugins may be suggested via context-aware tips
• claude plugin marketplace remove now accepts --scope user|project|local for symmetry with marketplace add, install, and uninstall
• Claude Code now switches to your configured --fallback-model for the rest of the session when the primary model is not found, instead of failing every request
• Auto mode no longer requires opt-in consent
• Vim mode: / in NORMAL mode now opens reverse history search (like Ctrl+R), matching bash/zsh vi-mode …

• /usage now shows a per-category breakdown of what's driving your limits usage — skills, subagents, plugins, and per-MCP-server cost
• /diff detail view can now be scrolled with the keyboard (arrows, j/k, PgUp/PgDn, Space, Home/End)
• Markdown output now renders GFM task list checkboxes (- [ ] todo / - [x] done) instead of plain bullets
• Enterprise: added the allowAllClaudeAiMcps managed setting to load claude.ai cloud MCP connectors alongside managed-mcp.json
• Fixed a PowerShell permission bypass: built-in cd functions (cd.., cd\, cd~, X:) changed the working directory undetected, letting a later command read outside the workspace
• Fixed the sandbox write allowlist in git worktrees covering the entire main repository root instead of only the shared .git directory (with hooks/ and config denied)
• Fixed PowerShell prefix/wildcard allow rules (e.g. PowerShell(dotnet.exe build *)) not pre-approving native executables and scripts
• Fixed a permission-analysis gap where the parser trusted stale variable-tracking values for PWD/OLDPWD/DIRSTACK across cd/pushd/popd
• Fixed find in the Bash tool exhausting the macOS system file/vnode table and crashing the host on large directory trees
• Fixed the managed-settings approval dialog leaving the terminal frozen after accepting at startup …

• Pinned background sessions (Ctrl+T in claude agents) now stay alive when idle, are restarted in place to apply Claude Code updates, and are shed under memory pressure only after non-pinned sessions
• Renamed /simplify to /code-review. It now reports correctness bugs at a chosen effort level (e.g., /code-review high); pass --comment to post findings as inline GitHub PR comments. The old cleanup-and-fix behavior has been removed
• Improved auto-updater: retries transient network failures, reports specific error categories and OS error codes on failure, and shows the current version when an update fails
• Improved diff rendering performance for large file edits
• Prompt history no longer records consecutive duplicate entries — recalling a prompt with arrow-up and submitting it again won't add another copy
• Fixed enterprise login restrictions (forceLoginOrgUUID and forceLoginMethod managed-settings) not being enforced against third-party-provider and API-key sessions
• Fixed & in ! command output displaying as &, which broke copy-pasting URLs from commands like gcloud auth login on headless machines
• Fixed unknown slash commands silently doing nothing in headless/SDK mode — they now show an error message
• Fixed /help rendering a broken tab header and showing only one command per page on small terminals when not in fullscreen mode …

• Added claude agents --json to list live Claude sessions as JSON for scripting (tmux-resurrect, status bars, session pickers)
• Added agent_id and parent_agent_id attributes to claude_code.tool OTEL spans, and fixed trace parenting so background subagent spans nest under the dispatching Agent tool span
• Status line JSON input now includes GitHub repo and PR information when detected
• /plugin Discover and Browse screens now show a plugin's commands, agents, skills, hooks, and MCP/LSP servers before installation
• claude agents terminal tab title now shows the awaiting-input count so an alt-tabbed window tells you when an agent needs attention
• Slash command and @-mention suggestion list now supports mouse hover and click in fullscreen mode
• Stop and SubagentStop hook input now includes background_tasks and session_crons fields
• Fixed a permission-prompt bypass where bare variable assignments to non-allowlisted environment variables in Bash commands were auto-approved
• Fixed MCP prompt slash commands showing raw server validation errors when a required argument is omitted — the error now names the missing argument and shows expected usage
• Fixed the spinner and elapsed-time display freezing until a keypress after the terminal was resized or refocused
• Fixed the cross-project resume hint failing in default Windows PowerShell 5.1 — Windows now uses ; as the command separator
• Fixed voice push-to-talk not working in the agent view's reply pane …

• Added /resume support for background sessions — sessions started via claude --bg or agent view now appear alongside interactive ones, marked with bg
• Added elapsed duration to background subagent completion notifications (e.g. "Agent completed · 3h 2m 5s")
• The /plugin browse and discover panes now show when a plugin was last updated
• /model now changes the model for the current session only; press d in the model picker to set a default for new sessions
• Renamed "extra usage" to "usage credits" across CLI copy; /extra-usage is now /usage-credits (old name still works)
• Fixed startup hanging up to 75s when api.anthropic.com is unreachable (captive portal, firewall, VPN issues) — side-channel API calls now time out after 15s
• Fixed garbled terminal output after a missed window-resize event (e.g. dragging a VS Code split-pane divider) — now self-heals on the next frame instead of requiring Ctrl+L
• Fixed progressive terminal display corruption (stale/garbled glyphs) that could appear in very long sessions and only cleared on terminal resize or restart
• Reduced terminal rendering glitches in VS Code by reducing spinner animation color count
• Fixed macOS background sessions crashing with "exit 1 before init" when the project lives under a Full Disk Access-protected folder (regression in 2.1.143)
• Fixed an unrecoverable conversation when reading a file whose image extension doesn't match its contents (e.g. HTML saved as .png) — now falls back to text …

• MCP tunnels is now available as a research preview, so you can connect to MCP servers in your private network.
• Self-hosted sandboxes are now available for Claude Managed Agents, as an alternative to running tool execution in Anthropic's infrastructure. See Self-hosted sandboxes.
• With Claude Managed Agents, you can now update the agent's MCP server and tool configurations associated with an active session.
• With Claude Managed Agents, large outputs from agent_toolset and MCP tools exceeding 100K characters (about 25K tokens) are now automatically spilled to a file in the sandbox. The model receives a truncated preview with the file path and can read the full content from there.

• Added plugin dependency enforcement: claude plugin disable now refuses when another enabled plugin depends on the target (with a copy-pasteable disable-chain hint), and claude plugin enable force-enables transitive dependencies
• Added projected context cost (per-turn and per-invocation token estimates) to the /plugin marketplace browse pane
• Added worktree.bgIsolation: "none" setting to let background sessions edit the working copy directly without EnterWorktree, for repos where worktrees are impractical
• PowerShell tool now passes -ExecutionPolicy Bypass. Opt out with CLAUDE_CODE_POWERSHELL_RESPECT_EXECUTION_POLICY=1
• Background sessions now preserve the model and effort level you set after waking from idle
• Shift+Tab in attached agent sessions now includes auto mode in the cycle
• Fixed a corrupt .credentials.json with a non-array scopes value hanging the CLI on startup or silently aborting OAuth token refresh
• Fixed right-click paste in claude agents on Windows Terminal and WSL
• Fixed stop hooks that block repeatedly looping forever — the turn now ends with a warning after 8 consecutive blocks (override via CLAUDE_CODE_STOP_HOOK_BLOCK_CAP)
• Fixed Esc/Ctrl+C not cancelling a pending /loop wakeup while Claude is idle between iterations
• Fixed /goal evaluator firing while background shells or delegated subagents are still running …

• Added new claude agents flags: --add-dir, --settings, --mcp-config, --plugin-dir, --permission-mode, --model, --effort, and --dangerously-skip-permissions to configure dispatched background sessions
• Fast mode now uses Opus 4.7 by default (previously Opus 4.6). Set CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE=1 to pin fast mode to Opus 4.6
• Plugins with a root-level SKILL.md and no skills/ subdirectory are now surfaced as a skill
• The /plugin details pane and claude plugin details now show LSP servers a plugin provides
• /web-setup warns before replacing an existing GitHub App connection
• Fixed MCP_TOOL_TIMEOUT not raising the per-request fetch timeout for remote HTTP and SSE MCP servers, which capped tool calls at 60 seconds regardless of the configured value
• Fixed background sessions not recognizing pre-existing git worktrees, blocking Edit while EnterWorktree refused to create a duplicate
• Fixed background sessions disappearing and daemon reconnect failing after macOS sleep/wake — the daemon now detects clock jumps instead of treating them as elapsed idle time
• Fixed daemon not exiting cleanly after the binary is upgraded (e.g. brew upgrade), causing dispatched agents to crash-loop on the deleted path
• Fixed background agents crash-looping when the Claude-in-Chrome extension is connected without a shared tab …

• Added terminalSequence field to hook JSON output so hooks can emit desktop notifications, window titles, and bells without a controlling terminal
• Added CLAUDE_CODE_PLUGIN_PREFER_HTTPS to clone GitHub plugin sources over HTTPS instead of SSH, for environments without a GitHub SSH key
• Added ANTHROPIC_WORKSPACE_ID environment variable for workload identity federation — scopes the minted token to a specific workspace when the federation rule covers more than one
• Added claude agents --cwd <path> to scope the session list to a directory
• /feedback can now include recent sessions (last 24 hours or 7 days) for issues spanning more than the current session
• Rewind menu: added "Summarize up to here" to compress earlier context while keeping recent turns intact
• Auto mode permission dialog now explains when a permissions.ask rule caused the prompt
• Restored the "view diff in your IDE" option on file-edit permission prompts when an IDE is connected
• Background agents launched via /bg or ←← now preserve the current permission mode instead of reverting to default
• claude agents: agents that finish work but leave a background shell running now move to Completed instead of staying under Working
• Improved spinner feedback during long thinking periods — the spinner now warms to amber after 10 seconds to signal Claude is still working …

• Improved Agent tool subagent_type matching to accept case- and separator-insensitive values (e.g. "Code Reviewer" resolves to code-reviewer)
• Updated agent color palette
• Fixed /goal silently hanging when disableAllHooks or allowManagedHooksOnly is set — now shows a clear message instead of an indicator that never resolves
• Fixed a regression in settings hot-reload where symlinked settings files caused misattributed change events and spurious ConfigChange hooks
• Fixed claude --bg failing with "connection dropped mid-request" when the background service was about to idle-exit
• Fixed background service startup failing on machines with enterprise endpoint security by allowing more time
• Fixed remote managed settings not retrying on 401 — now retries once with a force-refreshed token
• Fixed managed extraKnownMarketplaces auto-update policy not being persisted to known_marketplaces.json
• Fixed /loop scheduling redundant wakeups to poll for background tasks that already notify on completion
• Fixed a recurring event-loop stall on Windows when a missing executable (e.g. gh) triggered synchronous where.exe re-spawns on every check
• Fixed Read tool calls failing validation when offset is passed as a whitespace-padded or +-prefixed string
• Fixed native terminal cursor not staying at the input caret when the terminal loses focus …