Overview

Claude Code is Anthropic’s AI coding assistant delivered as a CLI tool. It operates within a project-scoped configuration directory (.claude/) that the team checks into version control. The central design philosophy is that the .claude/ directory is team infrastructure — treated like code, reviewed like code, and shared on clone.

.claude/ as team infrastructure

The .claude/ directory contains three key artefacts:

The practical effect is that team conventions, quality gates, and AI interaction patterns are codified and version-controlled alongside the application code itself, rather than living in individual heads or onboarding documents.

Plan mode

Claude Code has a dedicated plan mode in which it produces a full specification from a brief without generating any implementation code. This is used as the Planner role in the Planner-Generator-Evaluator pattern.

Community skill ecosystem

A large community of practitioners shares reusable Claude Code skills as open-source markdown files. Skills are plain text, version-controllable, and composable. The two dominant community skill frameworks are GSD (for large, iterative projects) and Superpowers (for small-to-medium, well-defined work). Beyond these, skills exist for session context management, multi-agent orchestration, security auditing, credential handling, and self-improvement of the skills themselves.

See Claude Code skills for the full taxonomy, design patterns, and key community frameworks. See Session context persistence for the /close pattern and memory management. See Self-improving agents for the meta-skill pattern.

Background injection

Background injection is a Claude Code harness capability: when a background command launched by the agent exits, Claude Code automatically re-invokes the agent with the command’s output injected into context — at zero additional token cost until the wake event fires.

This enables zero-token waiting patterns such as the Multi-agent communication channel wait primitive: the agent launches a filesystem-event watcher as a background command, which blocks (kqueue on macOS, inotify on Linux) until a peer message arrives, then exits — waking the agent exactly once with the message in context.

As of 2026, Claude Code is the only major AI coding harness with this capability. Codex and OpenCode have open PRs to add it.

Resources