v2.1.154 Claude Code Release Notes

May 28, 2026

Claude's Analysisby Sonnet 4.6

Opus 4.8 launches with Fast mode at 2x cost for 2.5x speed; /workflows orchestrates hundreds of background agents; lean system prompt now default; 20 background-session fixes.

Changes

Total Changes (vs Average)

4.1×

Version Type

Patch

Release Focus

Mixed

Day Since Prior Release

Release # This Month

#23 of 27

Bug Fix Ratio

45%

Post-Release Edits

—

Change Category

Ecosystem Impact

Plugins/Skills, MCP, and Terminals each appear in 8 of the last 10 releases — sustained, parallel investment in Claude's extensibility layer. This release also reunites Bedrock, Vertex, and Foundry with agents-view and streaming-tool-execution parity.

Key Themes

May Help If You've Noticed

Pinned background agents keep restarting every few minutes after updating Claude

Added1 change

•Added Claude Opus 4.8 support and 4.7 → 4.8 migration guidance to the /claude-api skill

Improved1 change

•Improved the auto-mode classifier's detection of data exfiltration, particularly bulk transfers of repository contents

Fixed20 changes

•Fixed rm -rf $HOME not being blocked as a dangerous path when HOME has a trailing slash
•Fixed $TMPDIR resolving to different directories in sandboxed vs unsandboxed Bash commands within the same session
•Fixed unreadable highlighted-row text in claude agents when the Claude Code theme doesn't match the terminal background
•Fixed background-agent completion notifications triggering premature "out of context" behavior on some 1M-context models
•Fixed background-session classifier losing the user's goal when a scheduled /command fires
•Fixed pinned background sessions respawning every minute after a Claude Code update, causing repeated agent-start notifications and process churn at idle
•Fixed background sessions stuck at "blocked", "running", or "working" not retiring after the idle grace period
•Fixed subagents in background sessions bypassing the worktree-isolation guard and writing to the shared checkout
•Fixed orphaned claude --bg-pty-host processes spinning at 100% CPU after the daemon exits on macOS
•Fixed number key shortcuts not working for options shown below the divider in option dialogs
•Fixed worktree.baseRef: "head" resolving to the main checkout's HEAD instead of the current worktree's HEAD when spawning subagents or calling EnterWorktree from inside a linked worktree
•Fixed a stray leading space on wrapped lines when the previous line ended exactly at the terminal width
•Fixed intermittent terminal rendering corruption in VS Code by capping the number of distinct colors the thinking spinner produces
•Fixed plan file names including [Image #N] / [Pasted text #N] placeholders when a plan-mode prompt starts with pasted images or text
•Fixed a single invalid allowedMcpServers/deniedMcpServers entry in managed settings discarding all managed-settings policy; the bad entry is now dropped with a claude doctor warning
•Fixed API 400 errors on models that don't support the effort parameter when CLAUDE_CODE_ALWAYS_ENABLE_EFFORT is set
•Fixed the task panel below the prompt showing a stray unselectable "main" row when only a workflow is running
•Fixed /mcp tools list and tool detail rendering when MCP servers have long or multi-line tool names or long descriptions
•Fixed the /model picker not showing fast mode pricing on the Default option for API (pay-as-you-go) users when fast mode is on
•Fixed auto mode incorrectly blocking actions with "could not evaluate this action" when the safety classifier ran out of output tokens while reasoning

Changed1 change

•Renamed the /effort slider labels from "Speed"/"Intelligence" to "Faster"/"Smarter" for clarity

Removed4 changes

•Deprecated CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE (will be removed on 06/01). To use fast mode on Opus 4.6, switch with /model claude-opus-4-6[1m] and then /fast on
•Fixed a phantom expand/click affordance on colored tool output: short ANSI-colored lines that fit on screen no longer show a "ctrl+o to expand" hint
•Removed the stale "& for background" hint from the shortcuts help panel
•[VSCode] Auto mode no longer requires the bypass-permissions setting to appear in the mode picker, and a dismissable notice on the new-session screen explains auto mode the first time it's active

Other17 changes

•Opus 4.8 is here! Now defaults to high effort · /effort xhigh for your hardest tasks
•Introducing dynamic workflows: ask Claude to create a workflow and it orchestrates work across tens to hundreds of agents in the background, so you can take on larger, more complex tasks. Run /workflows to view your runs
•Fast mode on Opus 4.8 is now available at a fraction of its previous cost: 2x the standard rate for 2.5x the speed
•The lean system prompt is now the default for all models except Haiku, Sonnet, and Opus 4.7 and earlier
•Claude now reserves the multiple-choice question prompt for decisions it genuinely cannot make itself, instead of asking when it already has enough context to proceed
•/simplify now runs a cleanup-only review (reuse, simplification, efficiency, altitude) and applies the fixes, instead of running the full /code-review --fix bug-hunting review
•claude agents: type ! <command> to run a shell command as a background session you can attach to and detach from. Also available as claude --bg --exec '<command>'
•claude agents: /logout now signs you out instead of being sent to a background session
•←← to open the agents view now works on Bedrock, Vertex, Foundry, and with telemetry disabled
•Claude in Chrome: pick which connected browser to use via /chrome → "Select browser…", or in-chat when a browser action runs with multiple connected
•Plugins can now declare defaultEnabled: false in plugin.json or a marketplace entry; enable them with /plugin or claude plugin enable. Dependencies of enabled plugins are still enabled automatically
•The /plugin Discover tab now pins plugins whose relevance signals match the current directory with a "suggested for this directory" annotation
•Streaming tool execution is now always enabled, including when telemetry is disabled or on Bedrock/Vertex/Foundry (previously behind a feature flag)
•Stdio MCP server subprocesses now receive CLAUDE_CODE_SESSION_ID and CLAUDECODE=1 in their environment
•claude mcp list/get now show unapproved .mcp.json servers as ⏸ Pending approval instead of auto-approving and connecting when output is piped
•/remote-control autocomplete now shows "Disconnect Remote Control" when Remote Control is already active
•Windows: Fixed update failures caused by claude.exe being in use showing a generic error instead of telling you to close other sessions and retry

Fixed20 changes

•Fixed rm -rf $HOME not being blocked as a dangerous path when HOME has a trailing slash

•Fixed $TMPDIR resolving to different directories in sandboxed vs unsandboxed Bash commands within the same session

•Fixed unreadable highlighted-row text in claude agents when the Claude Code theme doesn't match the terminal background

•Fixed background-agent completion notifications triggering premature "out of context" behavior on some 1M-context models

•Fixed background-session classifier losing the user's goal when a scheduled /command fires

•Fixed pinned background sessions respawning every minute after a Claude Code update, causing repeated agent-start notifications and process churn at idle

•Fixed background sessions stuck at "blocked", "running", or "working" not retiring after the idle grace period

•Fixed subagents in background sessions bypassing the worktree-isolation guard and writing to the shared checkout

•Fixed orphaned claude --bg-pty-host processes spinning at 100% CPU after the daemon exits on macOS

•Fixed number key shortcuts not working for options shown below the divider in option dialogs

•Fixed worktree.baseRef: "head" resolving to the main checkout's HEAD instead of the current worktree's HEAD when spawning subagents or calling EnterWorktree from inside a linked worktree

•Fixed a stray leading space on wrapped lines when the previous line ended exactly at the terminal width

•Fixed intermittent terminal rendering corruption in VS Code by capping the number of distinct colors the thinking spinner produces

•Fixed plan file names including [Image #N] / [Pasted text #N] placeholders when a plan-mode prompt starts with pasted images or text

•Fixed a single invalid allowedMcpServers/deniedMcpServers entry in managed settings discarding all managed-settings policy; the bad entry is now dropped with a claude doctor warning

•Fixed API 400 errors on models that don't support the effort parameter when CLAUDE_CODE_ALWAYS_ENABLE_EFFORT is set

•Fixed the task panel below the prompt showing a stray unselectable "main" row when only a workflow is running

•Fixed /mcp tools list and tool detail rendering when MCP servers have long or multi-line tool names or long descriptions

•Fixed the /model picker not showing fast mode pricing on the Default option for API (pay-as-you-go) users when fast mode is on

•Fixed auto mode incorrectly blocking actions with "could not evaluate this action" when the safety classifier ran out of output tokens while reasoning

Removed4 changes

•Deprecated CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE (will be removed on 06/01). To use fast mode on Opus 4.6, switch with /model claude-opus-4-6[1m] and then /fast on

•Fixed a phantom expand/click affordance on colored tool output: short ANSI-colored lines that fit on screen no longer show a "ctrl+o to expand" hint

•Removed the stale "& for background" hint from the shortcuts help panel

•[VSCode] Auto mode no longer requires the bypass-permissions setting to appear in the mode picker, and a dismissable notice on the new-session screen explains auto mode the first time it's active

Other17 changes

•Opus 4.8 is here! Now defaults to high effort · /effort xhigh for your hardest tasks

•Introducing dynamic workflows: ask Claude to create a workflow and it orchestrates work across tens to hundreds of agents in the background, so you can take on larger, more complex tasks. Run /workflows to view your runs

•Fast mode on Opus 4.8 is now available at a fraction of its previous cost: 2x the standard rate for 2.5x the speed

•The lean system prompt is now the default for all models except Haiku, Sonnet, and Opus 4.7 and earlier

•Claude now reserves the multiple-choice question prompt for decisions it genuinely cannot make itself, instead of asking when it already has enough context to proceed

•/simplify now runs a cleanup-only review (reuse, simplification, efficiency, altitude) and applies the fixes, instead of running the full /code-review --fix bug-hunting review

•claude agents: type ! <command> to run a shell command as a background session you can attach to and detach from. Also available as claude --bg --exec '<command>'

•claude agents: /logout now signs you out instead of being sent to a background session

•←← to open the agents view now works on Bedrock, Vertex, Foundry, and with telemetry disabled

•Claude in Chrome: pick which connected browser to use via /chrome → "Select browser…", or in-chat when a browser action runs with multiple connected

•Plugins can now declare defaultEnabled: false in plugin.json or a marketplace entry; enable them with /plugin or claude plugin enable. Dependencies of enabled plugins are still enabled automatically

•The /plugin Discover tab now pins plugins whose relevance signals match the current directory with a "suggested for this directory" annotation

•Streaming tool execution is now always enabled, including when telemetry is disabled or on Bedrock/Vertex/Foundry (previously behind a feature flag)

•Stdio MCP server subprocesses now receive CLAUDE_CODE_SESSION_ID and CLAUDECODE=1 in their environment

•claude mcp list/get now show unapproved .mcp.json servers as ⏸ Pending approval instead of auto-approving and connecting when output is piped

•/remote-control autocomplete now shows "Disconnect Remote Control" when Remote Control is already active

•Windows: Fixed update failures caused by claude.exe being in use showing a generic error instead of telling you to close other sessions and retry

v2.1.154 Claude Code Release Notes

Changes in Claude Code v2.1.154

Added1 change

Improved1 change

Fixed20 changes

Changed1 change

Removed4 changes

Other17 changes

v2.1.154 Claude Code Release Notes

Changes in Claude Code v2.1.154

Added1 change

Improved1 change

Fixed20 changes

Changed1 change

Removed4 changes

Other17 changes