claude-code

By default a headless Claude Code run emits only tool_use and tool_result blocks from its subagents, so the delegated reasoning is invisible. Pass --forward-subagent-text (Claude Code 2.1.211+) to get subagent text and thinking in the stream-json output, and demultiplex it by parent_tool_use_id.

Version 2.1.219 raises the default subagent spawn depth from 1 to 3, adds a workflowSizeGuideline settings key, and ships a fail-closed sandbox network allowlist.

Claude Code, Cursor, and the GitHub Copilot coding agent all ship host allowlists for outbound traffic, and all three default to something looser than you want. The exact settings keys, a policy you can copy, and the four surfaces the allowlist does not cover.

The legacy HTTP+SSE transport used two endpoints and a sticky connection. Streamable HTTP uses one. Here is the step-by-step migration for the TypeScript and Python SDKs, the client configs you have to repoint, and the proxy buffering gotcha that makes the new endpoint look broken.

Version 2.1.218 moves /code-review off your main conversation into a background subagent, and fork-context skills now background by default. Here is what changed and how to opt out.

Version 2.1.213 caps concurrent subagents and stops nested spawns by default, building on the per-session limits from 2.1.212. Here are the new defaults and env vars.

Claude Code compacts, then a single oversized file read or tool result immediately refills the window and it compacts again. Drop the item with /clear, read files in slices, and force big output to disk.

An MCP server on Node 16 warns EBADENGINE at install, then dies with 'fetch is not defined' on the first tool call. Upgrade to Node 18+ (20+ for the 2.x SDK) or polyfill the web globals.

Claude Code logs every MCP server stderr line at [ERROR] and marks working servers as failed. If your tools still run, it is cosmetic. Here is how to confirm it and quiet the noise.

Validate the MCP config file when several servers disappear after an edit. Check JSON syntax, client-specific schemas, scope and encoding without assuming every client fails alike.