[Release] anthropics/claude-code v2.1.154: v2.1.154

Claude Code v2.1.154 introduces Opus 4.8 with dynamic workflows for orchestrating multi-agent tasks, fast mode at reduced costs, and a lean system prompt as default. Key improvements include enhanced safety controls, better plugin management with directory-aware suggestions, and numerous bug fixes for background sessions, terminal rendering, and MCP server handling. The release also deprecates legacy environment variables and improves the user experience across multiple platforms including Bedrock, Vertex, and Chrome integration.

Key Points

• •Opus 4.8 now defaults to high-effort mode (/effort xhigh) for complex tasks with 2.5x speed at 2x standard rate in fast mode
• •Dynamic workflows enable Claude to orchestrate work across tens to hundreds of agents automatically; view runs with /workflows command
• •Lean system prompt is now default for all models except Haiku, Sonnet, and Opus 4.7 and earlier
• •/simplify command now performs cleanup-only review (reuse, simplification, efficiency, altitude) instead of full bug-hunting review
• •Background sessions with shell commands: use ! <command> syntax or claude --bg --exec '<command>' for detachable background work
• •Plugin system improvements: declare defaultEnabled: false in plugin.json, directory-aware suggestions with 'suggested for this directory' annotation
• •Streaming tool execution now always enabled across all platforms including Bedrock, Vertex, Foundry, and telemetry-disabled modes
• •Enhanced safety: improved auto-mode classifier for data exfiltration detection, fixed dangerous path blocking for HOME with trailing slash
• •MCP server improvements: unapproved servers show as 'Pending approval', stdio subprocesses receive CLAUDE_CODE_SESSION_ID and CLAUDECODE=1 environment variables
• •Multiple bug fixes for background sessions, terminal rendering, worktree isolation, and cross-platform compatibility (Windows, macOS, VS Code)

Workflow Diagram

Concepts