Claude Code v2.1.63 / Changelog

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20 entries

Changesopen

/batch Command #

What

New slash command that researches and plans a large-scale change, then executes it in parallel across 5–30 isolated git worktree agents that each open a PR.

Usage

/batch migrate from react to vue
/batch replace all uses of lodash with native equivalents
/batch add type annotations to all JavaScript files

Details

Requires a git repository (spawns agents in isolated worktrees)
Each agent independently implements its portion and opens a PR
User-invocable only (disableModelInvocation: true) — the model cannot invoke this on its own
Operates in two phases: first plans in plan mode, then spawns parallel workers after approval

Evidence

Slash command registration (search for name: "batch", "Research and plan a large-scale change")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

/simplify Command #

What

New slash command that reviews changed code for reuse, quality, and efficiency, then fixes any issues found.

Usage

/simplify

Details

Runs a 3-agent parallel review process: Code Reuse Review, Quality Review, and Efficiency Review
Examines all changed files (via git diff)
User-invocable only

Evidence

Slash command registration (search for name: "simplify", "Review changed code for reuse, quality, and efficiency")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

v2.1.203 /code-review Tip Description Updated

HTTP Hooks (Now Functional)#

What

HTTP hooks, previously stubbed with "HTTP hooks are not yet supported," are now fully implemented and operational.

Usage

{
  "hooks": {
    "PostToolUse": [{
      "matcher": "Write",
      "hooks": [{
        "type": "http",
        "url": "https://hooks.example.com/on-write",
        "headers": { "Authorization": "Bearer $MY_TOKEN" },
        "allowedEnvVars": ["MY_TOKEN"]
      }]
    }]
  }
}

Details

Sends POST requests with hook input as JSON body
Supports environment variable interpolation in headers via $VAR_NAME or ${VAR_NAME} syntax
SSRF protection: private/link-local addresses are blocked; loopback (127.0.0.1, ::1) is allowed for local development
New managed setting allowedHttpHookUrls for organization-level URL allowlisting with wildcard support (e.g., "https://hooks.example.com/*")
New managed setting httpHookAllowedEnvVars restricts which environment variables hooks can interpolate, intersecting with per-hook allowedEnvVars
Responses must be valid JSON

Evidence

HTTP hook execution code (search for "Hooks: HTTP hook POST to", "ERR_HTTP_HOOK_BLOCKED_ADDRESS", "allowedHttpHookUrls")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

MCP Elicitation Hooks #

What

Two new hook events that let hooks intercept MCP server elicitation requests (when an MCP server asks the user for input).

Details

Elicitation hook fires when an MCP server requests user input. Hook can accept, decline, cancel, or provide content to auto-respond.
ElicitationResult hook fires after the user responds to an elicitation. Hook can override the response action or content.
Supports both form-based and URL-based elicitation modes
If a hook declines, the elicitation is blocked with "Elicitation denied by hook"

Evidence

Hook event definitions (search for "Elicitation" and "ElicitationResult" near hook_event_name)

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Task Tool Renamed to Agent #

What

The Task tool has been renamed to Agent to better reflect its purpose. Task is kept as a backward-compatible alias.

Details

Tool name changed from "Task" to "Agent"
Description changed from "Launch a new task" to "Launch a new agent"
"Task" remains as an alias — existing CLAUDE.md files and permissions referencing "Task" will continue to work
Hook event descriptions updated from "Task tool call" to "Agent tool call"

Evidence

Tool definition (search for var tq = "Agent", aliases: containing "Task")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Git Sparse-Checkout for Marketplace Plugins #

What

New --sparse CLI option and sparsePaths config field for marketplace plugin installation, enabling cone-mode sparse-checkout for monorepo plugin sources.

Usage

claude plugin marketplace add my-marketplace --sparse .claude-plugin plugins

Details

Uses git sparse-checkout in cone mode to clone only specified directories
Useful for monorepos where the marketplace lives in a subdirectory
Combines --filter=blob:none for blobless clones with sparse-checkout for minimal disk usage
If sparsePaths is removed from config but the repo is already sparse, triggers a re-clone for full checkout

Evidence

CLI option definition (search for "--sparse <paths...>", "sparse-checkout", "sparsePaths")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

v2.1.69 git-subdir Plugin Source

Copy Full Response Setting #

What

New copyFullResponse boolean config option that makes /copy always copy the full response, skipping the block-picker dialog.

Usage

Enable via /config → "Always copy full response (skip /copy picker)"
Or toggle from the /copy picker itself: "Skip this picker in the future (revert via /config)"

Details

Default: false (existing block-picker behavior preserved)
When enabled, /copy immediately copies the entire last response
Reversible via /config at any time

Evidence

Config definition (search for "copyFullResponse", "Always copy full response")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

--permission-mode CLI Flag #

What

New top-level CLI flag for controlling permission handling in sessions.

Usage

claude --permission-mode acceptEdits
claude remote-control --permission-mode bypassPermissions

Details

Applies both as a general CLI option and specifically in claude remote-control
Available modes correspond to existing permission modes (e.g., acceptEdits, bypassPermissions)
Used when spawning sub-sessions and for remote control configuration

Evidence

CLI argument definition (search for "--permission-mode")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Marketplace Seed Directory Support #

What

New CLAUDE_CODE_PLUGIN_SEED_DIR environment variable for pre-populating marketplace plugins in managed/enterprise environments.

Details

Reads known_marketplaces.json from the seed directory
Syncs seed marketplaces into the user's configuration with autoUpdate: false
Supports seed-managed plugin caches and external plugin caching
Seed-managed marketplaces are marked read-only and cannot be overwritten by user operations

Evidence

Seed directory function (search for "CLAUDE_CODE_PLUGIN_SEED_DIR", "marketplace(s) from seed dir")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

claude.ai MCP Servers Enabled by Default #

The claude.ai MCP server integration has changed from opt-in to enabled by default (still GrowthBook-gated for rollout). Users who previously had to set ENABLE_CLAUDEAI_MCP_SERVERS=true no longer need to. To opt out, set ENABLE_CLAUDEAI_MCP_SERVERS=false.

Evidence

Changed message from "require ENABLE_CLAUDEAI_MCP_SERVERS=true" (v2.1.62) to "enabled by default (GrowthBook-gated). To opt out, set ENABLE_CLAUDEAI_MCP_SERVERS=false" (v2.1.63)

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

/model Command Shows Current Model #

The /model command description is now dynamic, displaying the currently active model: "Set the AI model for Claude Code (currently Claude Sonnet 4.6)" instead of the previous static "Set the AI model for Claude Code".

Evidence

Changed from static description: to get description() getter (search for "Set the AI model for Claude Code (currently")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Improved Escape Key UX #

The Escape key behavior has been refined with clearer feedback:

Status line now shows "ctrl+c to interrupt · Esc again to clear" during response generation
A "keep holding…" animation appears when holding Escape
Replaces the previous simpler "Esc to clear again" text

Evidence

New UI strings (search for "ctrl+c to interrupt · Esc again to clear", "keep holding")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Stricter SSH Host Key Checking #

Git clone operations for marketplace plugins now use StrictHostKeyChecking=yes instead of the previous StrictHostKeyChecking=accept-new. This means new host keys are no longer automatically trusted — the user must explicitly add them first. Improved error messages now provide specific remediation steps:

For changed host keys: shows ssh-keygen -R <host> command
For unknown hosts: shows ssh -T git@<host> command
Detects REMOTE HOST IDENTIFICATION HAS CHANGED and Host key verification failed scenarios

Evidence

SSH config change (search for "StrictHostKeyChecking=yes", "SSH host key has changed")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Enhanced Shell Security Checks #

New Zsh-specific and general shell security checks for the Bash tool:

Zsh process substitution =() — detected and flagged
Zsh glob qualifiers with command execution (+ — detected and flagged
Zsh try/always constructs } always { — detected and flagged
Dangerous Zsh builtins (zmodload, zpty, ztcp, zsocket, zf_rm, etc.) — blocked
fc -e command detection — prevents arbitrary command execution via editor
Backslash-escaped operators — detects \;, \|, \&, \<, \> outside quotes that can hide command structure
Comment quote desync — detects quote characters inside # comments that can confuse quote tracking
Tilde expansion variants (~user, ~+, ~-) — require manual approval
Compound cd + git commands — flagged to prevent bare repository attacks

Evidence

Security check functions (search for "Zsh process substitution", "backslash-escaped operators", "comment quote desync", "fc -e")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Config File Write Protection #

A new safety mechanism prevents concurrent config writes from wiping authentication data in ~/.claude.json. Before writing, the system re-reads the file and refuses to proceed if the disk version is missing oauthAccount or hasCompletedOnboarding data that exists in the in-memory cache. This addresses a race condition reported in GitHub issue #3117.

Evidence

Config lock function (search for "saveConfigWithLock", "re-read config is missing auth that cache has")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

WSL Voice Mode Guard #

Voice mode now detects WSL (Windows Subsystem for Linux) and provides a clear error message explaining that audio devices are unavailable, suggesting users run Claude Code in native Windows instead.

Evidence

WSL detection guard (search for "Voice mode is not supported in WSL")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

Fast Mode Cooldown State #

Fast mode now has a three-state model: "on", "off", and "cooldown" (after a rate limit). Network errors show a temporary unavailability message rather than fully disabling fast mode. The fast_mode_state field is now included in API response schemas.

Evidence

Fast mode state function (search for "Fast mode is temporarily unavailable due to a network error")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

SubagentStart / SubagentStop Hook Event Descriptions #

The SubagentStart and SubagentStop hook event descriptions have been updated from "Task tool call" to "Agent tool call" to match the Task→Agent rename. The events themselves are unchanged.

Evidence

Hook event descriptions (search for "subagent (Agent tool call)")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

4 entries

Bug Fixesopen

#

Fixed race condition where concurrent config writes could wipe authentication data from ~/.claude.json (search for "See GH #3117")
Improved OAuth callback handling with better error message when the redirect URL is missing the authorization code (search for "Invalid callback URL: missing authorization code")
Fixed "Prompt cancelled by user" error propagation when prompts are cancelled during hook flows (search for "Prompt cancelled by user")
Improved orphaned version cleanup with better error handling for stat failures (search for "Failed to stat orphaned marker")
MCP server .mcp.json writes now use atomic datasync + rename pattern with proper file permission preservation, replacing the previous simpler write approach

Tool Result Summarization [Gradual Rollout]#

What

A feature that instructs the model to preserve important information from tool results in its response text, since original tool results may be cleared later (for context window management).

Status

Feature-flagged via tengu_summarize_tool_results (default false)

Details

When enabled, appends a system instruction: "When working with tool results, write down any important information you might need later in your response, as the original tool result may be cleared later."
Prepares for a future where tool results are more aggressively pruned from context

Evidence

Gated by tengu_summarize_tool_results flag (search for "tengu_summarize_tool_results")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Asciicast Terminal Recording [Internal]#

What

Infrastructure for recording terminal sessions in asciicast v2 format (.cast files).

Status

Internal infrastructure — no user-facing command to enable or control recording.

Details

Monkey-patches process.stdout.write to capture all terminal output with timestamps
Recordings stored under ~/.claude/projects/<project>/ as .cast files
Supports flushing and renaming recordings for session management
File permissions set to owner read/write only (mode 384)

Evidence

Recording infrastructure (search for "[asciicast] Recording to", "[asciicast] Renamed recording")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

v2.1.235 Terminal recordings can be kept in the storage backend instead of loose files

Custom Subagent Definitions [In Development]#

What

Schema support for defining custom subagent types that can be invoked via the Agent tool.

Status

Schema definitions exist but no user-facing documentation or invocation path found.

Details

New schema field: "Definition for a custom subagent that can be invoked via the Agent tool"
Includes fields for agent type identifier, description, model alias, and tool availability
Suggests future ability to define custom agent types in configuration

Evidence

Schema descriptions (search for "Definition for a custom subagent", "Agent type identifier")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

1 entry

Notesopen

#

Task → Agent migration: If you have CLAUDE.md files, hooks, or permissions referencing the Task tool by name, they will continue to work — Task is retained as an alias. However, new documentation and tool output will use Agent.
HTTP hook security: Organizations deploying HTTP hooks should review the new allowedHttpHookUrls and httpHookAllowedEnvVars managed settings to restrict which URLs hooks can call and which environment variables can be interpolated.
SSH host key change: The switch to StrictHostKeyChecking=yes means marketplace plugin installations via SSH may fail if the host key isn't already in known_hosts. Run ssh -T git@<host> once manually to add it, or use HTTPS URLs for public repos.
/todos removed: The /todos slash command has been removed. The TodoWrite tool for in-session task tracking remains available.

Claude Code v2.1.63

Changesopen

/batch Command #

/simplify Command #

Related

HTTP Hooks (Now Functional)#

MCP Elicitation Hooks #

Task Tool Renamed to Agent #

Git Sparse-Checkout for Marketplace Plugins #

Related

Copy Full Response Setting #

--permission-mode CLI Flag #

Marketplace Seed Directory Support #

claude.ai MCP Servers Enabled by Default #

/model Command Shows Current Model #

Improved Escape Key UX #

Stricter SSH Host Key Checking #

Enhanced Shell Security Checks #

Config File Write Protection #

WSL Voice Mode Guard #

Related

Fast Mode Cooldown State #

SubagentStart / SubagentStop Hook Event Descriptions #

Bug Fixesopen

#

Tool Result Summarization [Gradual Rollout]#

Asciicast Terminal Recording [Internal]#

Related

Custom Subagent Definitions [In Development]#

Notesopen

#

Anthropic’s official release notes