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anthropic Claude Code Releases · · 2.1.277

Anthropic Claude Code v2.1.277 Updates with AGENTS.md Support and Bug Fixes

sdkaideprecationengineerenergy
feature patch

This patch release for Anthropic Claude Code, version 2.1.277, introduces support for AGENTS.md as an alternative to CLAUDE.md for project instructions, alongside several enhancements for Claude apps gateways. Gateway improvements include options for egress proxy handling and sending static headers to upstream proxies. The update also delivers a significant number of bug fixes addressing issues like hung sessions, conversation failures, unexpected logouts, and problems with plugin management and tool execution. These changes improve stability, reliability, and configuration flexibility for developers using the Claude Code CLI, SDK, and related applications.

  • →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
  • →Fixed claude update on winget- or apk-managed installs reporting "up to date" when the version lookup failed
  • →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
Features (4) ›

  • 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
Enhancements (15) ›
  • 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 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

Fixes (48) ›

  • 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
Read the original announcement →

https://github.com/anthropics/claude-code/releases/tag/v2.1.277

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