Claude Code 2.1.212 adds /fork, subagent caps, MCP auto-background

Expands /fork to copy conversation into a background session and renames in-session subagent to /subtask. Adds configurable session limits (default 200) on WebSearch calls and subagent spawns, and auto-moves MCP tool calls >2 min to background; fixes plan mode auto-running file-modifying commands without permission prompt.