Claude Code v2.1.154: Opus 4.8, Dynamic Workflows, and Major Fixes

Anthropic released Claude Code v2.1.154, adding Claude Opus 4.8 and dynamic workflows. The model defaults to high effort; use /effort xhigh for the hardest tasks. Fast mode is available at 2x the standard rate for 2.5x speed — a significant cost reduction.

Dynamic Workflows

The headline feature: you can now ask Claude to create a workflow, and it orchestrates work across tens to hundreds of background agents for larger, more complex tasks. Use /workflows to view running workflows.

Agent & Shell Enhancements

In claude agents, prefix a shell command with ! to run it as a background session you can attach/detach from. The equivalent CLI flag is claude --bg --exec '<command>'. Also, /logout now actually signs you out (not sent to a background session). The agents view (double left arrow) now works on Bedrock, Vertex, Foundry, and with telemetry disabled.

Plugin Changes

Plugins can now declare defaultEnabled: false in plugin.json or a marketplace entry. Enable them with /plugin or claude plugin enable; dependencies remain auto-enabled. The Discover tab pins plugins matching your current directory with a “suggested for this directory” annotation.

Other Notable Improvements

• Lean system prompt is now default for all models except Haiku, Sonnet, and Opus 4.7 and earlier.
• Multiple-choice prompts are reserved for decisions Claude genuinely cannot make.
• /simplify now runs a cleanup-only review (reuse, simplification, efficiency, altitude) and applies fixes — no longer runs full bug-hunting /code-review --fix.
• Streaming tool execution is always enabled, including on Bedrock/Vertex/Foundry and with telemetry disabled.
• Stdio MCP server subprocesses receive CLAUDE_CODE_SESSION_ID and CLAUDECODE=1 environment variables.
• /chrome lets you pick which connected browser to use when multiple are connected.

Bug Fixes

• Fixed rm -rf $HOME not being blocked when HOME has a trailing slash.
• Fixed $TMPDIR resolving inconsistently between sandboxed and unsandboxed Bash commands.
• Fixed pinned background sessions respawning every minute after a Claude Code update, causing notification churn.
• Fixed subagents in background sessions bypassing worktree-isolation guard and writing to shared checkout.
• Fixed orphaned claude --bg-pty-host processes spinning at 100% CPU on macOS.
• Fixed worktree.baseRef: "head" resolving to main checkout’s HEAD instead of current worktree’s HEAD.
• Fixed intermittent terminal rendering corruption in VS Code (capped spinner colors).
• Many others, including background session state management, keyboard shortcuts, and classifier detection of data exfiltration.