eisland-dev-refactor-module-split

name	eisland-dev-refactor-module-split
author	JNTMTMTM
description	Refactor a monolithic React component file into a standardized module structure with components/, hooks/, utils/, and config/ subdirectories. Use this skill whenever the user asks to "split", "refactor", "拆分", "拆解", or "restructure" a component file into subdirectories, or when they mention organizing code into utils/hooks/config/components folders.

Refactor Module Split

Split a monolithic React component file into a clean module structure with four subdirectories: components/, hooks/, utils/, and config/.

When to use

• A single .tsx file has grown large and contains multiple concerns (utility functions, hooks, sub-components, constants)
• The user explicitly asks to split/refactor a component into subdirectories
• The file is a React component that mixes UI rendering, state management, utility logic, and configuration

Process

Step 1: Analyze the source file

Read the target file in full. Categorize every piece of code into one of four buckets:

Bucket	Criteria	Target directory
Pure functions	No React hooks, no side effects, deterministic input→output	utils/
React hooks	Uses useState, useEffect, useMemo, useCallback, or custom hooks	hooks/
Sub-components	Returns JSX, used within the main component	components/
Constants	const values, config keys, i18n keys/defaults, type-only definitions used across modules	config/

Also check if the file's sibling directories already exist (e.g., components/ or hooks/ may already have files from prior refactoring). Don't duplicate existing extractions.

Step 2: Create the extracted files

For each extracted piece, create a new file in the appropriate directory. Every file must include:

1. License header — copy the exact GPL-3.0 block from the source file
2. File-level JSDoc — @file, @description, @author tags
3. Function/type JSDoc — @param, @returns for all exported functions
4. Correct imports — relative paths back to shared types or store slices

Naming conventions:

• utils/ — camelCase function name as filename (e.g., findCurrentIndex.ts, formatDatetime.ts)
• hooks/ — camelCase with use prefix (e.g., useBeijingClock.ts, useLyricsSettings.ts)
• components/ — PascalCase component name (e.g., KaraokeSyllableLine.tsx, AnnouncementHeader.tsx)
• config/ — camelCase descriptive name (e.g., lyricsConstants.ts, announcementDefaults.ts)

Step 3: Rewrite the source file

Replace the extracted code in the original file with imports from the new modules. The source file should become a thin composition layer that:

• Imports from ./hooks/, ./components/, ./utils/, ./config/
• Calls hooks at the top level
• Renders sub-components in JSX
• Contains no extracted logic

Step 4: Verify

Run these checks in order — all must pass before committing:

# 1. TypeScript compilation
npx tsc --noEmit --pretty

# 2. Comment standards compliance (file headers, JSDoc)
npm run comment:check

# 3. i18n completeness (all t() keys exist in both zh-CN and en-US)
npm run i18n:check

# 4. Unit tests
npm run test

If any check fails, fix the issue before proceeding. Common failures:

• comment:check — missing license header, missing @file/@description/@author, missing JSDoc on exported functions
• i18n:check — a t('key') call references a key not present in both locale files
• test — a refactored import path broke a test, or an extracted function changed behavior

Step 5: Commit

Use a conventional commit message:

refactor(<module-name>): extract utils, hooks, components, config from <OriginalFile>

- utils/<name>.ts: <what it does>
- components/<Name>.tsx: <what it does>
- hooks/<name>.ts: <what it does>
- config/<name>.ts: <what it contains>
- <OriginalFile>.ts: simplified from <N> to <M> lines

Directory structure example

feature/
├── FeatureContent.tsx          (thin composition layer)
├── components/
│   └── FeatureHeader.tsx       (sub-component)
├── hooks/
│   ├── useFeatureData.ts       (data fetching hook)
│   └── useFeatureSettings.ts   (settings listener hook)
├── utils/
│   └── formatValue.ts          (pure utility function)
└── config/
    └── featureConstants.ts     (i18n keys, store keys, defaults)

Acceptance criteria

Every extracted file MUST satisfy ALL of the following before the refactoring is considered complete.

Comment standards (references/COMMENT_STANDARDS.md)

#	Criterion	Check
C1	Every .ts/.tsx file starts with the GPL-3.0 license block (project name, URL, copyright, author, GPL notice)	npm run comment:check
C2	Every .ts/.tsx file has a file-level JSDoc with @file, @description, @author	npm run comment:check
C3	Every exported function/class/method has JSDoc with @param and @returns	npm run comment:check
C4	@author is set to 鸡哥 (project default)	Visual check
C5	Comments are in Chinese, explain "why" not "what"	Visual check
C6	No comments on simple getters/setters, self-explanatory assignments, or template code	Visual check

Frontend standards (references/FRONTEND_STANDARDS.md)

#	Criterion	Check
F1	Use const for constants, let for reassignable vars, never var	npm run test (lint)
F2	One variable per declaration	Visual check
F3	No any type — use explicit types or unknown	npx tsc --noEmit
F4	Interface over type for object shapes; type only for unions/tuples	Visual check
F5	ES6 modules (import/export), no require()	Visual check
F6	Import order: builtins → external → internal (absolute) → parent relative → sibling relative	Visual check
F7	No file extension in import paths	Visual check
F8	Single quotes for JS/TS strings, double quotes for JSX attribute values	Visual check
F9	2-space indentation	Visual check
F10	Semicolons at end of statements	Visual check
F11	Unix line endings (\n)	Visual check
F12	Variables/functions: camelCase; Classes/interfaces/types/enums: PascalCase; Constants: UPPER_SNAKE_CASE	Visual check
F13	React components defined as named function declarations, not anonymous arrow functions	Visual check
F14	No unused React import (JSX transform handles it)	npx tsc --noEmit
F15	Hooks called only at top level, never in conditions/loops	Visual check

i18n completeness

#	Criterion	Check
I1	Every t('key') in extracted files has a matching entry in both zh-CN.json and en-US.json	npm run i18n:check
I2	No hardcoded Chinese or English strings in UI code — all wrapped in t()	npm run i18n:check

Behavioral preservation

#	Criterion	Check
B1	TypeScript compiles with zero errors	npx tsc --noEmit
B2	All existing tests pass	npm run test
B3	No logic changes — the refactored code produces identical behavior	npm run test
B4	Every useEffect extracted to a hook preserves the same dependency array	Visual check against original

Important rules

• All four directories must exist. If a directory has no files, create a .gitkeep placeholder. The user expects the full structure.
• Extract ALL hooks. Every useEffect, useState, useMemo, useCallback block in the original file must end up in a hook file. The main component should have zero useEffect calls after refactoring (unless the effect is trivially tied to a single prop and extracting it would overcomplicate the code — justify with a comment).
• Extract ALL pure functions. If a function has no React hooks and no side effects, it belongs in utils/. Don't leave pure functions in the component.
• Match existing style. Use the same comment density, naming patterns, and import ordering as the rest of the project.
• Preserve behavior exactly. This is a pure structural refactor — no logic changes, no new features, no "improvements" to adjacent code.
• Relative imports from subdirectories. A file in hooks/ that needs a store type uses ../../../../store/types, not an alias.
• i18n keys stay in components. The t() calls remain in the JSX; only the default values and key constants move to config/.
• Run all four verification commands before committing. Do not skip any check. If a check fails, fix it before committing.