Frontmatter

Definition

A short block of settings at the very top of a file such as SKILL.md or a subagent file, written in YAML between two lines of three dashes, that tells Claude Code things like the file's name and when to use it.

More from Claude Code

• --plugin-dir

  A Claude Code launch option that loads a plugin straight from a folder on your computer for one session, so you can try it while you're still building it.

• @-mention (File Reference)

  Typing @ followed by a file's name in a Claude Code prompt to point Claude at that exact file, so it doesn't have to search for it.

• Agentic Loop

  The repeating cycle Claude Code works in: look around the project, take one step such as editing a file or running a command, check what happened, and decide the next step until the task is done.

• Checkpoint (/rewind)

  A restore point Claude Code saves before each edit Claude makes, so you can run /rewind (or press Esc twice) to go back to an earlier moment. It only tracks Claude's own file edits, so it doesn't replace Git.

• CLAUDE_PLUGIN_ROOT

  A placeholder, written `${CLAUDE_PLUGIN_ROOT}`, that Claude Code swaps for the folder a plugin is installed in, so the plugin's file paths work on everyone's computer. That folder changes with each update, so anything the plugin needs to keep goes in `${CLAUDE_PLUGIN_DATA}` instead.

• CLAUDE.md

  A notes file in your project that Claude Code reads at the start of every session, holding the rules and commands you'd otherwise repeat in every prompt (/init writes a starter version).