← Claude Code changelog

Claude Code 2.1.277

This release features AGENTS.md support as an alternative for project instructions, alongside new gateway proxy options for advanced configurations. Numerous stability improvements address issues like sessions hanging or crashing, unexpected logouts, and incorrect tool behavior with Grep, Glob, Write, and Edit. Performance enhancements encompass faster headless session startup and improved prompt handling, while VS Code users benefit from copy response buttons, background task management, and session cost/token usage details. Plugin management, update reliability, and authentication issues have also seen resolutions for a more robust experience.

Added

  • Added AGENTS.md support: in a project with no CLAUDE.md, Claude Code reads AGENTS.md instead; change it under "Project instructions" in `/config` (not yet on Bedrock, Vertex or Foundry)
  • Added `CLAUDE_GATEWAY_PROXY_IS_EGRESS_BOUNDARY=1` for Claude apps gateways whose only egress is a forward proxy: every outbound request hands the proxy the hostname instead of resolving it locally
  • Added an optional `headers:` map on Claude apps gateway upstreams, to send static headers to a proxy you run in front of a provider
  • Added a line saying a background task's update is waiting when it finishes while a panel such as `/tasks` is open
  • Added a Sign out row to the panel menu, with `/logout` in the typed command menu
  • Added background shells and other running tasks to the agent map, each with a Stop, and a typed `/tasks` that opens it
  • Added a Copy response button on responses and a typed `/copy`
  • Added a one-time notice when inactive sessions are archived automatically, and an "Unarchive all" action on the Archived sessions group
  • Added the session's cost and token usage to the Account & usage dialog and the session manager where plan limits do not apply (Vertex, Bedrock, Foundry, API key)

Improved

  • Improved session start-up for SDK and headless (`-p`) use: the first turn no longer waits on the per-directory CLAUDE.md lookup
  • Improved the Claude apps gateway's loopback error messages to name `CLAUDE_GATEWAY_ALLOW_LOOPBACK`
  • Improved `/plugin` Installed: an MCP server listed apart from its plugin now shows which plugin it belongs to
  • Improved `claude plugin install` on an already-installed plugin: it now says when the marketplace offers a newer version and names the `claude plugin update` command
  • Improved the startup notice overflow line under the logo: it now reads "N more notices hidden" instead of "+N more · /status"
  • Improved prompt handling: invisible Unicode formatting and tag characters in a prompt are removed and the cleaned prompt is shown for review before it is sent
  • Improved `/ultrareview` when there's nothing to review: messages say which case you're in, offer a command that reviews your latest commit, and a new repository's first commit is reviewed in full
  • Improved artifact link handling so Claude reads claude.ai artifact links with the Artifact tool instead of WebFetch when that tool is available
  • Improved the dangerous-rm permission prompt to name the flagged rm command and suggest a `${VAR:?}` guard, so headless runs can recover
  • Improved the Artifact tool's permission prompts: shorter sentences, pages and artifacts named by title or file name, and links listed after the text

Changed

  • Changed Fable to always appear in `/model` on the Anthropic API; it is greyed out only when your organization's settings disable it
  • Changed the Bash sandbox instructions on Bedrock, Vertex and Foundry to the first-party wording, which frames the sandbox as the boundary of what the task was given
  • Changed `/ultrareview` in non-interactive sessions to refuse when the repository has no base branch or shared history
  • Changed subagent results to reach the main agent under a header marking them as subagent output, with the result indented, so text in a subagent's result cannot pass as the session's own instructions
  • Changed workflow scripts' computed `agent()` prompts on Bedrock, Vertex and Foundry to reach the subagent framed as script-authored text, so the safety classifier does not read them as the user
  • [Claude Code on the web] Added Personal and Organization sections to the environment picker on Team and Enterprise plans, and admins can now share a personal environment with the organization
  • [Claude Code on the web] Changed organization environments to open as a read-only summary from the Code tab on Team and Enterprise plans, with editing under Admin settings → Cloud environments
  • [Claude Code on the web] Changed the admin Claude Code setting labeled "Web" to "Cloud sessions" and removed the redundant read-only Mobile row beneath it
  • [Claude Tag] Changed the Pylon credential preset in Claude Tag access bundles so admins can point it at Pylon's EU host

Fixed

  • Fixed `claude -p` and Agent SDK sessions that could hang with no result after an internal error; they now report the error and exit with code 1
  • Fixed conversations failing every request with "text content blocks must be non-empty" when an earlier assistant turn held an empty text block beside other content, including after `--resume`
  • Fixed being unexpectedly logged out when an older Claude Code build (for example an IDE extension's bundled CLI) runs on the same machine as the current one
  • Fixed interactive start-up hanging or showing an error for `ANTHROPIC_API_KEY` users when `~/.claude.json` holds a malformed `customApiKeyResponses` value
  • Fixed update checks erroring every 30 minutes, and `claude update` hanging when a minimum or maximum version is set, if a proxy returns an invalid version; a malformed `minimumVersion` is now ignored
  • Fixed `claude update` on winget- or apk-managed installs reporting "up to date" when the version lookup failed
  • Fixed `claude plugin install` sometimes failing and breaking the installed copy when reinstalling a plugin version that a session or another program was using; an unchanged copy is now left alone
  • Fixed Grep and Glob reporting no matches when the search could not start because the system was out of processes, memory or file handles; they now return an error saying so
  • Fixed the Write tool silently ending the turn as a declined permission when the target path is an existing directory; it now reports a clear error
  • Fixed the Edit tool treating an escaped backslash followed by `uXXXX` text as a `\uXXXX` escape, which could make an edit of a non-ASCII character rewrite an escaped backslash sequence instead
  • Fixed the Edit tool reporting "Invalid regular expression: regular expression too large" instead of "String not found in file" when a very large edit containing non-ASCII text did not match the file
  • Fixed a turn ending early with "Path contains null bytes" when a tool call's file path contained `\u0000` written as an escape sequence; escaped control characters now stay as literal text
  • Fixed background sessions (`claude --bg`) exiting when a plugin's LSP server exited or closed its stdin
  • Fixed a crash ("Type error") when opening `/mcp` or `/plugin manage` with a malformed `claudeAiMcpEverConnected` value in `~/.claude.json`
  • Fixed a crash at launch when `~/.claude.json` holds a malformed `theme` value
  • Fixed a crash ("unrecoverable interface error") when the prompt held text containing terminal color codes, for example a prompt recalled from history or text loaded from the external editor
  • Fixed a crash when resuming a session whose saved history holds an assistant message stored as a plain string
  • Fixed sessions on slow or heavily loaded machines sometimes exiting with "Claude Code exited after an unrecoverable interface error" when the first spinner appeared
  • Fixed a rare case where the screen could stop updating for the rest of the session after an internal rendering error
  • Fixed a rare case on Windows where a turn could stop with an error such as "Out of memory" right after Claude replied, so that reply's tool calls never ran
  • Fixed sessions continued after `/clear` (restart, `--continue`, `--resume`) missing part of their first message when a SessionStart hook printed output, causing a full prompt-cache miss
  • Fixed messages from other agents (such as a subagent's SendMessage) that arrived mid-turn showing up below the "Ran N shell commands" row instead of where they arrived
  • Fixed the "copied" notice not appearing after drag-selecting text in the fullscreen `/resume` picker and other panels that cover the prompt area
  • Fixed `$TMPDIR` expanding empty in Bash commands that run outside the sandbox while sandboxing is enabled
  • Fixed WebFetch and WebSearch in Cowork cloud sessions not telling Claude why a request was refused, such as a used-up fetch budget or an admin policy
  • Fixed the Claude apps gateway's telemetry relay ignoring a collector hostname or domain listed in `NO_PROXY` when a proxy is set
  • Fixed one malformed `strictKnownMarketplaces` or `blockedMarketplaces` entry silently disabling the whole enterprise marketplace policy
  • Fixed failed auto-updates leaving large staged downloads behind in `~/.cache/claude/staging`
  • Fixed `/plugin` not stripping terminal control characters from messages on the Installed tab, such as the error of a failed plugin update
  • Fixed `/plugin` → Installed and `/skills` crashing when a skill or legacy command is named like a built-in Object property such as `constructor` or `toString`
  • Fixed `/plugin` closing with no message when every install in a multi-select failed
  • Fixed uninstalled plugins reappearing as "failed to load" rows in `/plugin` Installed, and Remove not clearing such a row
  • Fixed plugins from the official marketplace being recorded without their commit in `installed_plugins.json`, and `installed_plugins.json` keeping the old commit after updating a pinned-commit plugin
  • Fixed plugin reload previews keeping every previewed copy of a plugin archive unpacked until exit, and overwriting the cached `--plugin-url` archive a reload falls back to when its download fails
  • Fixed Remote Control session bookkeeping failing when `~/.claude.json` holds a malformed placeholder record
  • Fixed the error after a revoked claude.ai login blaming an expired Anthropic profile; it now leads with `/login`
  • Fixed typed or pasted text occasionally coming out scrambled in the `claude agents` dispatch input during key repeat or very fast input
  • Fixed a crash ("unrecoverable interface error") when resuming a session whose saved transcript contains a stop hook summary without a well-formed hook list
  • Fixed Enter on a selected agent panel row doing nothing when `keybindings.json` rebinds Enter in the Chat context, for example to `chat:queueSubmit`
  • Fixed PDF page reads on Windows failing when the working folder's path is long (about 120 characters or more)
  • Fixed a headless resume (`claude -p --resume`, the SDK, a VS Code extension window reload) starting the session's cost and usage totals at zero; headless sessions now save their totals at exit
  • Fixed project skills from the main repository not loading in `--worktree` sessions when `.claude/skills` is untracked
  • Fixed a `sandbox.excludedCommands` glob exempting an entire compound Bash command from the sandbox when only one part matched; every part must now match
  • Fixed resumed subagents and teammates re-rendering the MCP tool definitions they had loaded, which broke prompt caching for that agent
  • Fixed rate-limited artifact publishes telling Claude to stop retrying; Claude is now told nothing was published and when to send the same publish again
  • Fixed attachments recorded earlier in a conversation being re-rendered after a resume or relaunch, which dropped extended thinking and missed the prompt cache
  • Fixed Console sign-in showing only "Request failed with status code 400" when the server refuses to create an API key; it now shows the server's message
  • Fixed messages typed while Claude is still working sometimes being ignored by the model
  • Fixed the "General config" menu row showing `/config` usage text instead of opening settings, and made typed `/mcp`, `/hooks`, `/memory`, `/rewind` and similar commands open their dialogs
  • Fixed the effort slider's level not persisting into later sessions on a model that already had a level saved with `/effort`
  • Fixed Auto missing from the mode picker for conversations opened in an already-used panel when the saved model setting is a differently-cased alias such as "Sonnet"
  • Fixed `/fast` not saving fast mode as the default, so it was lost when the extension relaunched Claude Code
  • [Claude Code on the web] Fixed a cloud environment saved with Custom network access and no domains silently reverting to Trusted; the dialog now asks for at least one domain
  • [Claude Tag] Fixed routines created in a Slack channel on an Enterprise Grid org-wide install failing to read other public channels in their workspace when they ran
  • [Claude Tag] Fixed the "Learn more" links on credential presets in Claude Tag access bundles to open each vendor's credential-setup page instead of a generic API reference
  • [Claude Tag] Fixed Google Cloud credential forms in Claude Tag access bundles: a refused key file now says why, the website and scopes stay locked, and a rejected rotation keeps the pasted key
  • [Claude Tag] Fixed the network events log in Claude Tag admin settings showing no response status for requests through connections that use AWS signing, client certificates or a custom CA

Removed

  • Removed the background Haiku auto-title request from `claude -p` runs launched outside an SDK or IDE
  • Removed the deprecated TaskOutput tool; Claude reads a background task's output file with Read instead, and the `taskOutputMaxChars` setting and `TASK_MAX_OUTPUT_LENGTH` no longer have any effect