name

claude-code-dev

description

How to develop, modify, and extend the Claude Code codebase following its established programming style, patterns, and conventions. Use this skill whenever working on the claude-code source — adding tools, commands, utils, components, types, hooks, services, or fixing bugs. Also use when the user asks about claude-code architecture, coding standards, file organization, or wants to understand how the codebase works. This skill ensures all contributions match the existing codebase style exactly.

Claude Code Development Style Guide

This skill captures the programming style, patterns, and conventions used in the Claude Code codebase (@anthropic-ai/claude-code). Each topic below links to a dedicated deep-dive document with comprehensive examples and rules extracted from the actual source.

Summary

Claude Code is an ESM TypeScript Node.js CLI application using Ink (React for terminals) for its UI, esbuild for transpilation, and Bun internally for feature flags and dead code elimination. Key stack: TypeScript, Zod v4, lodash-es, React/Ink, esbuild.

Detailed Guides (Resource Files)

Each topic below is covered in depth in its own resource file within this skill's directory. Read the relevant file before working on that area of the codebase.

#	Topic	File	Summary
01	Project Overview	`01-project-overview.md`	Tech stack, build system, runtime environment, key dependencies
02	Directory Structure	`02-directory-structure.md`	Full `src/` layout, file organization patterns, where things go
03	Import Conventions	`03-import-conventions.md`	`.js` extensions, `import type`, lodash cherry-picks, feature flags, cycle breaking
04	Naming Conventions	`04-naming-conventions.md`	camelCase/PascalCase/UPPER_SNAKE rules, file naming, safety names
05	TypeScript Patterns	`05-typescript-patterns.md`	Branded types, discriminated unions, `as const`, `satisfies`, Zod schemas, generics
06	Commenting Style	`06-commenting-style.md`	JSDoc, why-not-what philosophy, PR references, section headers, lint suppression
07	Error Handling	`07-error-handling.md`	Custom error classes, utility functions, graceful degradation, catch conventions
08	Function Patterns	`08-function-patterns.md`	`buildTool()` factory, memoize, async generators, guard clauses, fire-and-forget
09	Tool Architecture	`09-tool-architecture.md`	Tool directory structure, `buildTool()` API, schemas, permissions, UI rendering
10	Command Architecture	`10-command-architecture.md`	Command types, index.ts pattern, lazy loading, registration
11	State Management	`11-state-management.md`	Module-level state, getter/setter, AppState threading, cleanup registry
12	Testing Conventions	`12-testing-conventions.md`	Reset helpers, NODE_ENV guards, test-only exports, deterministic sorting
13	Formatting Rules	`13-formatting-rules.md`	No semicolons, single quotes, trailing commas, indentation, expression style
14	Quick References	`14-quick-references.md`	Step-by-step checklists for adding tools, commands, utils, and types

Claude Code Development Style Guide

Summary

Detailed Guides (Resource Files)

Each topic below is covered in depth in its own resource file within this skill's directory. Read the relevant file before working on that area of the codebase.

Topic

File

Summary

Project Overview

01-project-overview.md

Tech stack, build system, runtime environment, key dependencies

Directory Structure

02-directory-structure.md

Full src/ layout, file organization patterns, where things go

Import Conventions

03-import-conventions.md

.js extensions, import type, lodash cherry-picks, feature flags, cycle breaking

Naming Conventions

04-naming-conventions.md

camelCase/PascalCase/UPPER_SNAKE rules, file naming, safety names

TypeScript Patterns

05-typescript-patterns.md

Branded types, discriminated unions, as const, satisfies, Zod schemas, generics

Commenting Style

06-commenting-style.md

JSDoc, why-not-what philosophy, PR references, section headers, lint suppression

Error Handling

07-error-handling.md

Custom error classes, utility functions, graceful degradation, catch conventions

Function Patterns

08-function-patterns.md

buildTool() factory, memoize, async generators, guard clauses, fire-and-forget

Tool Architecture

09-tool-architecture.md

Tool directory structure, buildTool() API, schemas, permissions, UI rendering

Command Architecture

10-command-architecture.md

Command types, index.ts pattern, lazy loading, registration

State Management

11-state-management.md

Module-level state, getter/setter, AppState threading, cleanup registry

Testing Conventions

12-testing-conventions.md

Reset helpers, NODE_ENV guards, test-only exports, deterministic sorting

Formatting Rules

13-formatting-rules.md

No semicolons, single quotes, trailing commas, indentation, expression style

Quick References

14-quick-references.md

Step-by-step checklists for adding tools, commands, utils, and types