# Claude Code v2.1.20 > Claude Code v2.1.20, released 27 Jan 2026 (2026-01-27). 20 entries read out of the shipped bundle. Unofficial, and not affiliated with Anthropic. Web version: https://changelogs.core-directive.com/v/2.1.20 Version 2.1.20 introduces a comprehensive keybindings customization system via a new `/keybindings` skill, adds several new CLI debugging flags (`--debug-file`, `--hard-fail`, `--who-owns`), significantly enhances sandbox security with Unix socket ownership verification, and refactors the teammate messaging system with a new `SendMessageTool`. The release also removes the git attribution system and improves UI notifications throughout. ## Changes ### Keybindings Customization Skill **What** New `/keybindings` skill enables full customization of keyboard shortcuts via `~/.claude/keybindings.json` configuration file. **Usage** `/keybindings` **Details** - Create custom keybindings organized by context (Global, Chat, Autocomplete, etc.) - Support for chord bindings (multi-keystroke shortcuts like `ctrl+k ctrl+s`) - Validation integrated into `/doctor` command with detailed error/warning messages - Unbind default shortcuts by setting them to `null` - Schema validation with JSON Schema support for editor autocomplete - Documentation at https://code.claude.com/docs/en/keybindings **Evidence** Skill registration at line 748555 (`name: "keybindings-help"`, contains `"Use when the user wants to customize keyboard shortcuts"`) ### Debug Logging to File **What** New `--debug-file` CLI flag writes debug logs to a specific file path. **Usage** `claude --debug-file /path/to/debug.log claude --debug-file=/path/to/debug.log` **Details** - Implicitly enables debug mode when specified - Useful for persistent debugging and troubleshooting **Evidence** Argument parser at line 2836 (`if (K.startsWith("--debug-file="))`) and help text at line 577087 (`"--debug-file "`) ### Hard Fail Mode **What** New `--hard-fail` CLI flag causes Claude Code to exit immediately on certain errors rather than attempting recovery. **Usage** `claude --hard-fail` **Details** - Useful for CI/CD pipelines and automated testing - Ensures failures are detected rather than silently handled **Evidence** Detection at line 5582 (`return process.argv.includes("--hard-fail")`) ### Package Manager Ownership Detection **What** New `--who-owns` integration for Alpine Linux (apk) package manager to verify file ownership. **Usage** Internal feature - automatically used when verifying Claude Code installation on Alpine Linux. **Details** - Detects apk-managed installations with logging: "Detected apk installation: ..." - Also detects deb, rpm, and pacman installations - Enables better package manager integration and update guidance **Evidence** APK query at line 419998 (`OP1("apk", ["info", "--who-owns", K]`) and detection logs at lines 420004, 420011, 420018, 420025 ### SendMessageTool for Teammate Communication **What** New `SendMessageTool` replaces previous teammate messaging implementation with clearer protocol separation. **Usage** Internal tool used by agents in swarm mode. **Details** - Handles message, broadcast, request, and response types - Protocol subtypes for shutdown and plan approval workflows - Better error messages for missing parameters - Improved in-process teammate abort handling **Evidence** Tool definition at line 448126 (`SendMessageTool: () => tT2`) with logging prefix `[SendMessageTool]` at lines 448249, 448275, 448284 ### Compact Conversation Keybinding **What** New `ctrl+k ctrl+k` chord keybinding to trigger `/compact` command. **Usage** `ctrl+k ctrl+k` **Details** - Quick access to conversation compaction - Uses the new chord keybinding system - Replaces removed `ctrl+k ctrl+c` for `/commit` **Evidence** Keybinding definition at line 486662 (`"ctrl+k ctrl+k": "command:compact"`) ### "Newspapering" Feature **What** New feature or mode referenced in codebase (details unclear from minified code). **Usage** Internal implementation detail. **Evidence** String literal at line 388067 (`"Newspapering"`) ### Enhanced Sandbox Security **What** Significantly improved Unix domain socket security with ownership verification and stale socket cleanup. **Details** - Socket directory ownership check: warns if directory owned by different user - Stale socket cleanup: removes sockets for non-running PIDs - Better seccomp filter path discovery for global `@anthropic-ai/sandbox-runtime` installations - Added `.npm-global` to seccomp binary search paths - Improved error messages with actionable installation instructions - Warning when seccomp binaries unavailable: "[Sandbox Linux] Seccomp binaries not available - unix socket blocking disabled. Install @anthropic-ai/sandbox-runtime globally for full protection." **Evidence** Socket ownership check at line 523583 (`"Socket directory not owned by current user"`), stale socket cleanup messages, seccomp search paths at line 95936 (`".npm-global"`), warning at line 96398 ### Browser MCP Accessibility Tree Improvements **What** MCP browser tool's accessibility tree output limit is now configurable. **Details** - Default limit remains 50,000 characters - New parameter allows setting custom limits for clients that can handle larger outputs - More flexible description: "Output is limited to 50000 characters by default" (was: "Output is limited to 50000 characters") - New parameter: "Maximum characters for output (default: 50000). Set to a higher value if your client can handle large outputs." **Evidence** Description change at line 522359 and parameter at line 522387 ### Updated Conversation Compaction Notification **What** Compaction notification now shows "✻ Conversation compacted" with visual symbol instead of plain text. **Details** - Old: `Conversation compacted · {keybinding} for history` - New: `✻ Conversation compacted ({keybinding} for history)` - More visually distinct in transcript **Evidence** Notification text at line 410281 (`"✻ Conversation compacted ("`) ### Improved Permission Dialog Text **What** Refined safety check messaging for workspace trust. **Details** - Slightly more concise wording in safety prompt - Old: "Quick safety check: ... If not, take a moment to review what's in this folder first." - New: "Quick safety check: ... If not, take a moment to review what" - Message continues with context about Claude Code's file access capabilities **Evidence** Safety message at line 570322 ### Guest Pass Notification Enhancement **What** Clearer guest pass sharing notification in UI. **Details** - More prominent formatting: "You have free guest passes to share · /passes" - Encourages user engagement with referral system **Evidence** Notification at line 562731 ### Enhanced Task and Agent Status Logging **What** More detailed logging for task claiming and agent operations. **Details** - New logs: `[inProcessRunner] Claimed task #N: {subject}` - Task failure logging: `[inProcessRunner] Failed to claim task #N` - Task list check errors: `[inProcessRunner] Error checking task list:` - New logs for task assignment and completion **Evidence** Logs at lines 422622, 522622, 522628 with prefix `[inProcessRunner]` ### Layout Engine Identification **What** Explicit layout engine logging for debugging rendering issues. **Details** - Logs: "Layout engine: yoga" and "[render] initLayout starting/complete" - Helps diagnose UI rendering problems **Evidence** Engine log at line 174577, render logs at lines 182436-182438 ### Message Structure Repair **What** Automatic repair of malformed tool result pairings in conversation history. **Details** - Detects and repairs missing `tool_result` blocks - Logs: `ensureToolResultPairing: repaired missing tool_result blocks (X -> Y messages)` - Prevents conversation corruption from improperly paired tool uses **Evidence** Repair logging at line 469512 ### Team Workflow Enhancements **What** Improved teammate communication and protocol handling. **Details** - Operation descriptions now mention "discoverTeams to list available teams to join" - Better error messages for missing parameters in teammate operations - Clearer separation between message types (message, broadcast, request, response) **Evidence** Operation description updates in SendMessageTool schema, error messages for missing `recipient`, `request_id`, etc. ### Git Attribution System **What** Removed automatic git commit trailer attribution system. **Details** - Removed all "Attribution hook:" logging - Removed `Claude-Generated-By:` git trailers - Removed `Claude-Escapes:`, `Claude-Permission-Prompts:`, `Claude-Session:`, `Claude-Steers:` trailers - No longer tracks file contributions or calculates Claude percentage - Simplifies git workflow and removes potentially confusing commit metadata **Evidence** All `Attribution:` and `Attribution hook:` log strings removed from codebase (verified absent in v2.1.20) ### Removed `/commit` Keybinding **What** Removed `ctrl+k ctrl+k` keybinding for `/commit` command. **Details** - Previous binding: `ctrl+k ctrl+c` → `/commit` - Now unbound by default - Users can re-add via custom keybindings if desired **Evidence** Binding `"ctrl+k ctrl+c": "command:commit"` existed in v2.1.19 line 483280, not present in v2.1.20 ### Removed Permission UI Elements **What** Simplified permission request UI removed some verbose text and interactive elements. **Details** - Removed: "Do you trust the files in this folder?" - Removed: "(shift+↑/↓ to select)" navigation hints - Removed: Several verbose permission dialog messages - Streamlined to clearer, more concise safety checks **Evidence** Strings like "Do you trust the files in this folder?", "shift+↑/↓ to select" removed from v2.1.20 ### PR Status Footer [Gradual Rollout] **What** GitHub pull request status displayed in footer area. **Status** Feature-flagged behind `tengu_pr_status_cli` **Details** - Settings option: "Show PR status footer" (enabled by default when flag is on) - Infrastructure exists in settings menu at line 480230 - Will display PR status information in CLI footer when enabled **Evidence** Feature flag check at line 480226 (`i4("tengu_pr_status_cli", !1)`) with settings UI at line 480230 (`label: "Show PR status footer"`)