Claude Code — Repository Skill

Project Overview

Claude Code is Anthropic's CLI tool for interacting with Claude from the terminal. It supports file editing, shell commands, git workflows, code review, multi-agent coordination, IDE integration (VS Code, JetBrains), and Model Context Protocol (MCP).

Codebase: ~1,900 files, 512,000+ lines of TypeScript under src/.

Tech Stack

Architecture

Directory Map (src/)

Key Files

Entry Points & Initialization Sequence

1. src/main.tsx — Commander CLI parser, startup profiling
2. src/entrypoints/init.ts — Config, telemetry, OAuth, MDM
3. src/entrypoints/cli.tsx — CLI session orchestration
4. src/entrypoints/mcp.ts — MCP server mode
5. src/entrypoints/sdk/ — Agent SDK (programmatic API)
6. src/replLauncher.tsx — REPL session launcher

Startup performs parallel initialization: MDM policy reads, Keychain prefetch, feature flag checks, then core init.

Patterns & Conventions

Tool Definition

Each tool lives in src/tools/{ToolName}/ and uses buildTool:

export const MyTool = buildTool({
  name: 'MyTool',
  aliases: ['my_tool'],
  description: 'What this tool does',
  inputSchema: z.object({
    param: z.string(),
  }),
  async call(args, context, canUseTool, parentMessage, onProgress) {
    // Execute and return { data: result, newMessages?: [...] }
  },
  async checkPermissions(input, context) { /* Permission checks */ },
  isConcurrencySafe(input) { /* Can run in parallel? */ },
  isReadOnly(input) { /* Non-destructive? */ },
  prompt(options) { /* System prompt injection */ },
  renderToolUseMessage(input, options) { /* UI for invocation */ },
  renderToolResultMessage(content, progressMessages, options) { /* UI for result */ },
})

Directory structure per tool: {ToolName}.ts or .tsx (main), UI.tsx (rendering), prompt.ts (system prompt), plus utility files.

Command Definition

Commands live in src/commands/ and follow three types:

• PromptCommand — Sends a formatted prompt with injected tools (most commands)
• LocalCommand — Runs in-process, returns text
• LocalJSXCommand — Runs in-process, returns React JSX

const command = {
  type: 'prompt',
  name: 'my-command',
  description: 'What this command does',
  progressMessage: 'working...',
  allowedTools: ['Bash(git *)', 'FileRead(*)'],
  source: 'builtin',
  async getPromptForCommand(args, context) {
    return [{ type: 'text', text: '...' }]
  },
} satisfies Command

Commands are registered in src/commands.ts and invoked via /command-name in the REPL.

Component Structure

• Functional React components with Ink primitives (Box, Text, useInput())
• Styled with Chalk for terminal colors
• React Compiler for optimized re-renders
• Design system primitives in src/components/design-system/

State Management

• AppState via React context + custom store (src/state/AppStateStore.ts)
• Mutable state object passed to tool contexts
• Selector functions for derived state
• Change observers in src/state/onChangeAppState.ts

Permission System

• Modes: default (prompt per operation), plan (show plan, ask once), bypassPermissions (auto-approve), auto (ML classifier)
• Rules: Wildcard patterns — Bash(git *), FileEdit(/src/*)
• Tools implement checkPermissions() returning { granted: boolean, reason?, prompt? }

Feature Flags & Build

Bun's bun:bundle feature flags enable dead-code elimination at build time:

import { feature } from 'bun:bundle'
if (feature('PROACTIVE')) { /* proactive agent tools */ }

Notable flags: PROACTIVE, KAIROS, BRIDGE_MODE, VOICE_MODE, COORDINATOR_MODE, DAEMON, WORKFLOW_SCRIPTS.

Some features are also gated via process.env.USER_TYPE === 'ant'.

Naming Conventions

Import Practices

• ES modules with .js extensions (Bun convention)
• Lazy imports for circular dependency breaking: const getModule = () => require('./heavy.js')
• Conditional imports via feature flags or process.env
• biome-ignore markers for manual import ordering where needed

Services

Configuration

Settings locations:

• Global: ~/.claude/config.json, ~/.claude/settings.json
• Project: .claude/config.json, .claude/settings.json
• System: macOS Keychain + MDM, Windows Registry + MDM
• Managed: Remote sync for Enterprise users

Guidelines

1. Read relevant source files before making changes — understand existing patterns first.
2. Follow the tool/command/component patterns above when adding new ones.
3. Keep edits minimal and focused — avoid unnecessary refactoring.
4. Use Zod for all input validation at system boundaries.
5. Gate experimental features behind bun:bundle feature flags or env checks.
6. Respect the permission system — tools that modify state must implement checkPermissions().
7. Use lazy imports when adding dependencies that could create circular references.
8. Update this file as project conventions evolve.