v2.1.212 Claude Code Release Notes

Jul 17, 2026

Claude's Analysisby Sonnet 4.6

New session-wide caps curb runaway WebSearch and subagent loops, /fork now launches background sessions, and a broad hang-fix pass spans CLI, SDK, hooks, and MCP.

Changes

Total Changes (vs Average)

4.1×

Version Type

Patch

Release Focus

Bug Fixes

Day Since Prior Release

Release # This Month

#15 of 15

Bug Fix Ratio

60%

Post-Release Edits

—

Change Category

Ecosystem Impact

This is the month's 15th release, just 1 day after v2.1.211. MCP (8/10), Windows (7/10), and Terminals (6/10) have appeared in most recent releases — a sustained cross-platform stability push, not a one-off patch.

Key Themes

9Runaway-loop safeguards & workflow changes|8Hang & session-reliability fixes|8SDK & observability fixes|7Windows & terminal UX polish

May Help If You've Noticed

Claude Code hung or left orphaned processes after you interrupted a running command

Added3 changes

•Added claude auto-mode reset to restore the default auto-mode configuration, with a confirmation prompt (pass --yes to skip)
•Added a session-wide limit on WebSearch tool calls (default 200, tunable via CLAUDE_CODE_MAX_WEB_SEARCHES_PER_SESSION) to stop runaway search loops
•Added a per-session cap on subagent spawns (default 200, override with CLAUDE_CODE_MAX_SUBAGENTS_PER_SESSION) to stop runaway delegation loops; /clear resets the budget

Improved4 changes

•Improved web search and web fetch reliability by retrying 529 errors and rate-limited requests with bounded backoff
•Improved prompt caching: the mid-conversation system block now works behind LLM gateways and custom base URLs (Bedrock, Vertex, 1P)
•Improved background agent attach: cold-attaching now instantly shows the formatted transcript while the session boots, instead of a blank wait
•Reduced token usage in inter-agent messaging: SendMessage bodies are no longer duplicated into replayed history and tool results

Fixed29 changes

•Fixed plan mode auto-running file-modifying Bash commands (e.g. touch, rm) without a permission prompt or SDK canUseTool callback
•Fixed worktree creation following a repository-committed symlink at .claude/worktrees, which could create files outside the repository
•Fixed a continue:false hook's halt being dropped when the tool fails or completes mid-stream, and hook infrastructure errors being misreported as user rejections
•Fixed SIGTERM during a running Bash tool orphaning the command's process tree in print/SDK mode; the CLI now aborts the turn, kills the tree, and exits 143
•Fixed /background and claude --bg failing with "EUNKNOWN: unknown error, uv_spawn" on Windows when Group Policy blocks PowerShell 5.1; the daemon now prefers PowerShell 7
•Fixed shell mode (!) not executing commands containing file paths while the path autocomplete popup was open
•Fixed auto-mode denial notifications rendering broken characters when a long denial reason was truncated mid-emoji
•Fixed Ctrl+J not inserting a newline in the agent view dispatch input on terminals with extended key reporting, and surfaced the newline shortcut in the ? help overlay
•Fixed /ultrareview rejecting PR references like #123, PR 123, and pasted PR URLs; error hints now name the command you actually typed
•Fixed /ultrareview <branch> not fetching the branch from origin when it exists remotely; it now suggests the closest branch name on typos
•Fixed /ultrareview skipping the billing confirmation in a new conversation after /clear
•Fixed /ultrareview's "not a git repository" error on Claude Desktop now suggesting the project's repository folder instead of terminal commands
•Fixed hosted (host-managed) sessions failing at startup when repository settings configured mTLS certs, extra CA bundles, or OAuth scopes; these transport settings are now ignored with a warning
•Fixed a spurious "File has not been read yet" error when editing a file that had been read with offset/limit before resuming a session
•Fixed ExitWorktree failing with "no active EnterWorktree session" after resuming a session with --continue/--resume in print/SDK mode
•Fixed the workflow agent grid staying empty for Remote Control clients that join a session mid-run
•Fixed streaming-mode control requests being marked complete before their handler finished, which could lose the request on session restart
•Fixed background sessions created with /fork losing their live-parent protection after a state write failure
•Fixed reopening a stopped background session from the agent view failing silently — it now resumes the session, or shows why it can't and lets you force a restart
•Fixed agent teams: a stopping teammate could send the leader duplicate idle notifications when team initialization re-ran within a session
•Fixed the plan-approval dialog footer splitting "ctrl+g to edit in <editor>" apart when the file path is long
•Fixed the welcome banner keeping its old panel widths after a combined width+height terminal resize in fullscreen mode
•Fixed diff previews losing their line numbers and +/- markers in narrow layouts
•Fixed @-mentions attaching nothing after a partial file read, plugin uninstall targeting the wrong marketplace, and false "Command timed out" on exit code 143
•Fixed OpenTelemetry HTTP exports being rejected with 411/400 by Azure Monitor and other endpoints that don't accept chunked transfer encoding
•Fixed OTLP event log records missing trace_id/span_id when TRACEPARENT is set in SDK/headless mode
•Fixed conversations with many images incorrectly failing with "Request too large" errors, and improved the error message to explain the actual cause
•Fixed web search and web fetch returning "API Error" text as search results or page content when the API was overloaded
•Corrected an earlier release note (2.1.200): tmux through the 3.6 series lacks synchronized output; newer tmux with support is detected automatically

Changed8 changes

•Changed /fork to name the copy after your prompt when the session has no title, so the row is recognizable in the agent view
•Changed bare /btw to reopen the side-question panel on your most recent exchange so you can browse earlier answers
•Changed the ← footer hint to pulse N done for a moment when a background agent finishes while nothing needs your input
•Changed Enterprise forceLoginMethod to be enforced for VS Code extension, SDK, setup-token, and install-github-app logins, not just the terminal
•Changed session transcripts to record the reasoning effort level on each assistant message
•Changed headless/SDK sessions to apply a set_model control request mid-turn; the next model round-trip uses the new model instead of waiting for the next turn
•Changed agent view / claude agents --json: sessions waiting on a sandbox, MCP-input, or managed-settings prompt now show as "Needs input" instead of "Working"
•Updated the auth status panel title from "Cloud authentication" to "Authentication"

Removed1 change

•Deprecated the Task tool's mode parameter (now ignored); subagents inherit the parent session's permission mode by default

Other3 changes

•/fork now copies your conversation into a new background session (its own row in claude agents) while you keep working; the in-session subagent it used to launch is now /subtask
•MCP tool calls running longer than 2 minutes now move to the background automatically so the session stays usable; configure the threshold or disable with CLAUDE_CODE_MCP_AUTO_BACKGROUND_MS
•Typing /resume in the agent view now opens a picker of past sessions — including sessions deleted from the list — and resumes your pick as a background session

Added3 changes

•Added claude auto-mode reset to restore the default auto-mode configuration, with a confirmation prompt (pass --yes to skip)

•Added a session-wide limit on WebSearch tool calls (default 200, tunable via CLAUDE_CODE_MAX_WEB_SEARCHES_PER_SESSION) to stop runaway search loops

•Added a per-session cap on subagent spawns (default 200, override with CLAUDE_CODE_MAX_SUBAGENTS_PER_SESSION) to stop runaway delegation loops; /clear resets the budget

Improved4 changes

•Improved web search and web fetch reliability by retrying 529 errors and rate-limited requests with bounded backoff

•Improved prompt caching: the mid-conversation system block now works behind LLM gateways and custom base URLs (Bedrock, Vertex, 1P)

•Improved background agent attach: cold-attaching now instantly shows the formatted transcript while the session boots, instead of a blank wait

•Reduced token usage in inter-agent messaging: SendMessage bodies are no longer duplicated into replayed history and tool results

Fixed29 changes

•Fixed plan mode auto-running file-modifying Bash commands (e.g. touch, rm) without a permission prompt or SDK canUseTool callback

•Fixed worktree creation following a repository-committed symlink at .claude/worktrees, which could create files outside the repository

•Fixed a continue:false hook's halt being dropped when the tool fails or completes mid-stream, and hook infrastructure errors being misreported as user rejections

•Fixed SIGTERM during a running Bash tool orphaning the command's process tree in print/SDK mode; the CLI now aborts the turn, kills the tree, and exits 143

•Fixed /background and claude --bg failing with "EUNKNOWN: unknown error, uv_spawn" on Windows when Group Policy blocks PowerShell 5.1; the daemon now prefers PowerShell 7

•Fixed shell mode (!) not executing commands containing file paths while the path autocomplete popup was open

•Fixed auto-mode denial notifications rendering broken characters when a long denial reason was truncated mid-emoji

•Fixed Ctrl+J not inserting a newline in the agent view dispatch input on terminals with extended key reporting, and surfaced the newline shortcut in the ? help overlay

•Fixed /ultrareview rejecting PR references like #123, PR 123, and pasted PR URLs; error hints now name the command you actually typed

•Fixed /ultrareview <branch> not fetching the branch from origin when it exists remotely; it now suggests the closest branch name on typos

•Fixed /ultrareview skipping the billing confirmation in a new conversation after /clear

•Fixed /ultrareview's "not a git repository" error on Claude Desktop now suggesting the project's repository folder instead of terminal commands

•Fixed hosted (host-managed) sessions failing at startup when repository settings configured mTLS certs, extra CA bundles, or OAuth scopes; these transport settings are now ignored with a warning

•Fixed a spurious "File has not been read yet" error when editing a file that had been read with offset/limit before resuming a session

•Fixed ExitWorktree failing with "no active EnterWorktree session" after resuming a session with --continue/--resume in print/SDK mode

•Fixed the workflow agent grid staying empty for Remote Control clients that join a session mid-run

•Fixed streaming-mode control requests being marked complete before their handler finished, which could lose the request on session restart

•Fixed background sessions created with /fork losing their live-parent protection after a state write failure

•Fixed reopening a stopped background session from the agent view failing silently — it now resumes the session, or shows why it can't and lets you force a restart

•Fixed agent teams: a stopping teammate could send the leader duplicate idle notifications when team initialization re-ran within a session

•Fixed the plan-approval dialog footer splitting "ctrl+g to edit in <editor>" apart when the file path is long

•Fixed the welcome banner keeping its old panel widths after a combined width+height terminal resize in fullscreen mode

•Fixed diff previews losing their line numbers and +/- markers in narrow layouts

•Fixed @-mentions attaching nothing after a partial file read, plugin uninstall targeting the wrong marketplace, and false "Command timed out" on exit code 143

•Fixed OpenTelemetry HTTP exports being rejected with 411/400 by Azure Monitor and other endpoints that don't accept chunked transfer encoding

•Fixed OTLP event log records missing trace_id/span_id when TRACEPARENT is set in SDK/headless mode

•Fixed conversations with many images incorrectly failing with "Request too large" errors, and improved the error message to explain the actual cause

•Fixed web search and web fetch returning "API Error" text as search results or page content when the API was overloaded

•Corrected an earlier release note (2.1.200): tmux through the 3.6 series lacks synchronized output; newer tmux with support is detected automatically

Changed8 changes

•Changed /fork to name the copy after your prompt when the session has no title, so the row is recognizable in the agent view

•Changed bare /btw to reopen the side-question panel on your most recent exchange so you can browse earlier answers

•Changed the ← footer hint to pulse N done for a moment when a background agent finishes while nothing needs your input

•Changed Enterprise forceLoginMethod to be enforced for VS Code extension, SDK, setup-token, and install-github-app logins, not just the terminal

•Changed session transcripts to record the reasoning effort level on each assistant message

•Changed headless/SDK sessions to apply a set_model control request mid-turn; the next model round-trip uses the new model instead of waiting for the next turn

•Changed agent view / claude agents --json: sessions waiting on a sandbox, MCP-input, or managed-settings prompt now show as "Needs input" instead of "Working"

•Updated the auth status panel title from "Cloud authentication" to "Authentication"

Other3 changes

•/fork now copies your conversation into a new background session (its own row in claude agents) while you keep working; the in-session subagent it used to launch is now /subtask

•MCP tool calls running longer than 2 minutes now move to the background automatically so the session stays usable; configure the threshold or disable with CLAUDE_CODE_MCP_AUTO_BACKGROUND_MS

•Typing /resume in the agent view now opens a picker of past sessions — including sessions deleted from the list — and resumes your pick as a background session

v2.1.212 Claude Code Release Notes

Changes in Claude Code v2.1.212

Added3 changes

Improved4 changes

Fixed29 changes

Changed8 changes

Removed1 change

Other3 changes

v2.1.212 Claude Code Release Notes

Changes in Claude Code v2.1.212

Added3 changes

Improved4 changes

Fixed29 changes

Changed8 changes

Removed1 change

Other3 changes