Code Deduplication

作者 alinaqi72a456e6ccf0無授權條款707 個星標收錄於 2026年10月8日更新於 2026年10月8日儲存庫2 週前更新

Prevent semantic code duplication with capability index and check-before-write

僅含說明Software Development
AI 產生的概覽

透過維護能力索引並在撰寫新程式碼前檢查現有函式，防止語意層面的程式碼重複。

功能
此技能定義了一套避免重複程式碼的工作流程，透過維護 CODE_INDEX.md 檔案，依能力而非檔案位置記錄現有函式、鉤子和元件。它規定了先檢查後撰寫的步驟、檔案標頭和函式文件格式，以及用於找出重疊實作的定期稽核清單。它也說明了針對大型程式庫的選用向量資料庫索引方案。
適用情境
在建立新的工具函式或共用程式碼之前使用，或在新增可能已存在於程式庫中的功能時使用。它也用於定期稽核工具函式、API 呼叫、驗證、錯誤處理、元件和鉤子中的語意重疊。
執行需求
不隨附指令碼，僅為說明性指示。它需要專案程式庫；若採用選用的向量搜尋設定，還需要 Python 以及 ChromaDB 或 LanceDB。

Code Deduplication Skill

Purpose: Prevent semantic duplication and code bloat. Maintain a capability index so Claude always knows what exists before writing something new.

Core Philosophy

┌─────────────────────────────────────────────────────────────────┐│  CHECK BEFORE YOU WRITE                                         ││  ─────────────────────────────────────────────────────────────  ││  AI doesn't copy/paste - it reimplements.                       ││  The problem isn't duplicate code, it's duplicate PURPOSE.      ││                                                                 ││  Before writing ANY new function:                               ││  1. Check CODE_INDEX.md for existing capabilities               ││  2. Search codebase for similar functionality                   ││  3. Extend existing code if possible                            ││  4. Only create new if nothing suitable exists                  │├─────────────────────────────────────────────────────────────────┤│  AFTER WRITING: Update the index immediately.                   ││  PERIODICALLY: Run /audit-duplicates to catch overlap.          │└─────────────────────────────────────────────────────────────────┘

Code Index Structure

Maintain CODE_INDEX.md in project root, organized by capability not file location:

markdown
# Code Index
*Last updated: [timestamp]**Run `/update-code-index` to regenerate*
## Quick Reference
| Category | Count | Location ||----------|-------|----------|| Date/Time | 5 functions | src/utils/dates.ts || Validation | 8 functions | src/utils/validate.ts || API Clients | 12 functions | src/api/*.ts || Auth | 6 functions | src/auth/*.ts |
---
## Date/Time Operations
| Function | Location | Does What | Params ||----------|----------|-----------|--------|| `formatDate()` | utils/dates.ts:15 | Formats Date → "Jan 15, 2024" | `(date: Date, format?: string)` || `formatRelative()` | utils/dates.ts:32 | Formats Date → "2 days ago" | `(date: Date)` || `parseDate()` | utils/dates.ts:48 | Parses string → Date | `(str: string, format?: string)` || `isExpired()` | auth/tokens.ts:22 | Checks if timestamp past now | `(timestamp: number)` || `addDays()` | utils/dates.ts:61 | Adds days to date | `(date: Date, days: number)` |
---
## Validation
| Function | Location | Does What | Params ||----------|----------|-----------|--------|| `isEmail()` | utils/validate.ts:10 | Validates email format | `(email: string)` || `isPhone()` | utils/validate.ts:25 | Validates phone with country | `(phone: string, country?: string)` || `isURL()` | utils/validate.ts:42 | Validates URL format | `(url: string)` || `isUUID()` | utils/validate.ts:55 | Validates UUID v4 | `(id: string)` || `sanitizeHTML()` | utils/sanitize.ts:12 | Strips XSS from input | `(html: string)` || `sanitizeSQL()` | utils/sanitize.ts:28 | Escapes SQL special chars | `(input: string)` |
---
## String Operations
| Function | Location | Does What | Params ||----------|----------|-----------|--------|| `slugify()` | utils/strings.ts:8 | Converts to URL slug | `(str: string)` || `truncate()` | utils/strings.ts:20 | Truncates with ellipsis | `(str: string, len: number)` || `capitalize()` | utils/strings.ts:32 | Capitalizes first letter | `(str: string)` || `pluralize()` | utils/strings.ts:40 | Adds s/es correctly | `(word: string, count: number)` |
---
## API Clients
| Function | Location | Does What | Returns ||----------|----------|-----------|---------|| `fetchUser()` | api/users.ts:15 | GET /users/:id | `Promise<User>` || `fetchUsers()` | api/users.ts:28 | GET /users with pagination | `Promise<User[]>` || `createUser()` | api/users.ts:45 | POST /users | `Promise<User>` || `updateUser()` | api/users.ts:62 | PATCH /users/:id | `Promise<User>` || `deleteUser()` | api/users.ts:78 | DELETE /users/:id | `Promise<void>` |
---
## Error Handling
| Function/Class | Location | Does What ||----------------|----------|-----------|| `AppError` | utils/errors.ts:5 | Base error class with code || `ValidationError` | utils/errors.ts:20 | Input validation failures || `NotFoundError` | utils/errors.ts:32 | Resource not found || `handleAsync()` | utils/errors.ts:45 | Wraps async route handlers || `errorMiddleware()` | middleware/error.ts:10 | Express error handler |
---
## Hooks (React)
| Hook | Location | Does What ||------|----------|-----------|| `useAuth()` | hooks/useAuth.ts | Auth state + login/logout || `useUser()` | hooks/useUser.ts | Current user data || `useDebounce()` | hooks/useDebounce.ts | Debounces value changes || `useLocalStorage()` | hooks/useLocalStorage.ts | Persisted state || `useFetch()` | hooks/useFetch.ts | Data fetching with loading/error |
---
## Components (React)
| Component | Location | Does What ||-----------|----------|-----------|| `Button` | components/Button.tsx | Styled button with variants || `Input` | components/Input.tsx | Form input with validation || `Modal` | components/Modal.tsx | Dialog overlay || `Toast` | components/Toast.tsx | Notification popup || `Spinner` | components/Spinner.tsx | Loading indicator |

File Header Format

Every file should have a summary header:

TypeScript/JavaScript

typescript
/** * @file User authentication utilities * @description Handles login, logout, session management, and token refresh. * * Key exports: * - login(email, password) - Authenticates user, returns tokens * - logout() - Clears session and tokens * - refreshToken() - Gets new access token * - validateSession() - Checks if session is valid * * @see src/api/auth.ts for API endpoints * @see src/hooks/useAuth.ts for React hook */
import { ... } from '...';

Python

python
"""User authentication utilities.
Handles login, logout, session management, and token refresh.
Key exports:    - login(email, password) - Authenticates user, returns tokens    - logout() - Clears session and tokens    - refresh_token() - Gets new access token    - validate_session() - Checks if session is valid
See Also:    - src/api/auth.py for API endpoints    - src/services/user.py for user operations"""
from typing import ...

Function Documentation

Every function needs a one-line summary:

TypeScript

typescript
/** * Formats a date into a human-readable relative string. * Examples: "2 minutes ago", "yesterday", "3 months ago" */export function formatRelative(date: Date): string {  // ...}
/** * Validates email format and checks for disposable domains. * Returns true for valid non-disposable emails. */export function isValidEmail(email: string): boolean {  // ...}

Python

python
def format_relative(date: datetime) -> str:    """Formats a date into a human-readable relative string.
    Examples: "2 minutes ago", "yesterday", "3 months ago"    """    ...
def is_valid_email(email: str) -> bool:    """Validates email format and checks for disposable domains.
    Returns True for valid non-disposable emails.    """    ...

Check Before Write Process

Before Creating ANY New Function

┌─────────────────────────────────────────────────────────────────┐│  BEFORE WRITING NEW CODE                                        ││  ─────────────────────────────────────────────────────────────  ││                                                                 ││  1. DESCRIBE what you need in plain English                     ││     "I need to format a date as relative time"                  ││                                                                 ││  2. CHECK CODE_INDEX.md                                         ││     Search for: date, time, format, relative                    ││     → Found: formatRelative() in utils/dates.ts                 ││                                                                 ││  3. EVALUATE if existing code works                             ││     - Does it do what I need? → Use it                          ││     - Close but not quite? → Extend it                          ││     - Nothing suitable? → Create new, update index              ││                                                                 ││  4. If extending, check for breaking changes                    ││     - Add optional params, don't change existing behavior       ││     - Update tests for new functionality                        │└─────────────────────────────────────────────────────────────────┘

Decision Tree

Need new functionality        │        ▼Check CODE_INDEX.md for similar        │        ├─► Found exact match ──────► USE IT        │        ├─► Found similar ──────────► Can it be extended?        │                                   │        │                    ┌──────────────┴──────────────┐        │                    ▼                             ▼        │               Yes: Extend                   No: Create new        │               (add params)                  (update index)        │        └─► Nothing found ──────────► Create new (update index)

Common Duplication Patterns

Pattern 1: Utility Function Reimplementation

❌ Bad: Creating validateEmail() when isEmail() exists

typescript
// DON'T: This already exists as isEmail()function validateEmail(email: string): boolean {  return /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(email);}

✅ Good: Check index first, use existing

typescript
import { isEmail } from '@/utils/validate';
if (isEmail(userInput)) { ... }

Pattern 2: Slightly Different Versions

❌ Bad: Multiple date formatters with slight variations

typescript
// In file Afunction formatDate(d: Date) { return d.toLocaleDateString(); }
// In file Bfunction displayDate(d: Date) { return d.toLocaleDateString('en-US'); }
// In file Cfunction showDate(d: Date) { return d.toLocaleDateString('en-US', { month: 'short' }); }

✅ Good: One function with options

typescript
// utils/dates.tsfunction formatDate(d: Date, options?: { locale?: string; format?: 'short' | 'long' }) {  const locale = options?.locale ?? 'en-US';  const formatOpts = options?.format === 'short'    ? { month: 'short', day: 'numeric' }    : { month: 'long', day: 'numeric', year: 'numeric' };  return d.toLocaleDateString(locale, formatOpts);}

Pattern 3: Inline Logic That Should Be Extracted

❌ Bad: Same validation logic scattered across files

typescript
// In signup.tsif (!email || !email.includes('@') || email.length < 5) { ... }
// In profile.tsif (!email || !email.includes('@') || email.length < 5) { ... }
// In invite.tsif (!email || !email.includes('@') || email.length < 5) { ... }

✅ Good: Extract once, import everywhere

typescript
// utils/validate.tsexport const isEmail = (email: string) =>  email && email.includes('@') && email.length >= 5;
// Everywhere elseimport { isEmail } from '@/utils/validate';if (!isEmail(email)) { ... }

Periodic Audit

Run /audit-duplicates periodically to catch semantic overlap:

Audit Checklist

  • Utility functions: Any functions doing similar things?
  • API calls: Multiple ways to fetch same data?
  • Validation: Scattered inline validation logic?
  • Error handling: Inconsistent error patterns?
  • Components: Similar UI components that could merge?
  • Hooks: Custom hooks with overlapping logic?

Audit Output Format

markdown
## Duplicate Audit - [DATE]
### 🔴 High Priority (Merge These)
1. **Date formatting** - 3 similar functions found   - `formatDate()` in utils/dates.ts   - `displayDate()` in components/Header.tsx   - `showDate()` in pages/Profile.tsx   - **Action:** Consolidate into utils/dates.ts
2. **Email validation** - Inline logic in 5 files   - signup.ts:42   - profile.ts:28   - invite.ts:15   - settings.ts:67   - admin.ts:33   - **Action:** Extract to utils/validate.ts
### 🟡 Medium Priority (Consider Merging)
1. **User fetching** - 2 different patterns   - `fetchUser()` in api/users.ts   - `getUser()` in services/user.ts   - **Action:** Decide on one pattern
### 🟢 Low Priority (Monitor)
1. **Button components** - 3 variants exist   - May be intentional for different use cases   - **Action:** Document the differences

Vector DB Integration (Optional)

For large codebases (100+ files), add vector search:

Setup with ChromaDB

python
# scripts/index_codebase.pyimport chromadbfrom chromadb.utils import embedding_functions
# Initializeclient = chromadb.PersistentClient(path="./.chroma")ef = embedding_functions.DefaultEmbeddingFunction()collection = client.get_or_create_collection("code_index", embedding_function=ef)
# Index a functioncollection.add(    documents=["Formats a date into human-readable relative string like '2 days ago'"],    metadatas=[{"function": "formatRelative", "file": "utils/dates.ts", "line": 32}],    ids=["formatRelative"])
# Search before writingresults = collection.query(    query_texts=["format date as relative time"],    n_results=5)# Returns: formatRelative in utils/dates.ts - 0.92 similarity

Setup with LanceDB (Lighter)

python
# scripts/index_codebase.pyimport lancedb
db = lancedb.connect("./.lancedb")
# Create tabledata = [    {"function": "formatRelative", "file": "utils/dates.ts", "description": "Formats date as relative time"},    {"function": "isEmail", "file": "utils/validate.ts", "description": "Validates email format"},]table = db.create_table("code_index", data)
# Searchresults = table.search("validate email address").limit(5).to_list()

When to Use Vector DB

Codebase SizeRecommendation
< 50 filesMarkdown index only
50-200 filesMarkdown + periodic audit
200+ filesAdd vector DB
500+ filesVector DB essential

Claude Instructions

At Session Start

  1. Read CODE_INDEX.md if it exists
  2. Note the categories and key functions available
  3. Keep this context for the session

Before Writing New Code

  1. Pause and check: "Does something like this exist?"
  2. Search CODE_INDEX.md for similar capabilities
  3. If unsure, search the codebase: grep -r "functionName\|similar_term" src/
  4. Only create new if confirmed nothing suitable exists

After Writing New Code

  1. Immediately update CODE_INDEX.md
  2. Add file header if new file
  3. Add function docstring
  4. Commit index update with code

When User Says "Add X functionality"

Before implementing, let me check if we already have something similar...
[Checks CODE_INDEX.md]
Found: `existingFunction()` in utils/file.ts does something similar.Options:1. Use existing function as-is2. Extend it with new capability3. Create new (if truly different use case)
Which approach would you prefer?

Quick Reference

Update Index Command

bash
/update-code-index

Audit Command

bash
/audit-duplicates

File Header Template

typescript
/** * @file [Short description] * @description [What this file does] * * Key exports: * - function1() - [what it does] * - function2() - [what it does] */

Function Template

typescript
/** * [One line description of what it does] */export function name(params): ReturnType {

Index Entry Template

markdown
| `functionName()` | path/file.ts:line | Does what in plain English | `(params)` |

來源與署名

來源：alinaqi/maggy位於skills/code-deduplication提交72a456e

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