Claude Code glossary

Instructions file Claude Code reads every turn. Three levels: user (~/.claude/CLAUDE.md, personal), project (./CLAUDE.md, shared via git), directory (path-specific).

.gitignore-syntax file that excludes paths from Claude Code's reads. Controls reading, not writing. For blocking writes, use hooks.

Path-specific rules with YAML glob frontmatter that apply across an entire codebase — unlike directory-level CLAUDE.md which is location-bound.

Mode where Claude proposes a plan before executing destructive changes. Use for multi-file migrations, architecture decisions, or anything you want to inspect first.

User-triggered prompt template in .claude/commands/. File name becomes /name. For repeatable workflows like /pr-review, /release.

Folder with SKILL.md describing when to trigger and what to do. The 'description' frontmatter field is Claude's routing signal. May include supporting files.

Skill option that runs the skill in an isolated subagent context, keeping verbose output out of the main conversation window. Preserves parent context.

External script fired on lifecycle events (PreToolUse, PostToolUse, Stop). Exit 0 allows; exit 2 blocks and surfaces stderr to Claude as feedback. Deterministic gate.

CLI flag: claude -p 'prompt' runs a single non-interactive turn and exits. Mandatory for CI/CD pipelines — without it the job hangs waiting for input.

Programmatic API to drive Claude Code sessions from your own code. For building higher-level tools, dashboards, or batch automations on top.