越界 / 不理想

重新造了一个早已存在的轮子

Rebuilt something that already existed

智能体没去找已有的函数、组件或服务，而是又写了一个，从此要同步维护两份。

适用于: Claude Code · Cursor · Codex · Copilot agent

症状

新出现一个 `formatCurrency`、`useDebounce` 或 `apiClient`，和代码库里已在用的那个并存，行为还略有不同。

为什么会这样

写新代码比找旧代码快，而智能体的上下文很少包含整个仓库。Kaplira 的第一步就是“检查智能体是否找到了现有实现”，并指出再写一份实现会扩大任务范围却没解决根因。久而久之，这就是 developertoolkit.ai 说的“侵蚀”。

示例

示意。

text

existing: src/lib/money.ts       export function formatCurrency(cents, locale)
new:      src/cart/utils.ts      export const fmtPrice = (n) => "$" + n.toFixed(2)

复制即用的修复

按你用的智能体挑选文件。规则片段用英文写，放进任何仓库都能用。

规则

Claude Code：加入 CLAUDE.md

CLAUDE.md

## Reuse before you write
- Before writing a helper, hook, component or client, search the repo for an existing one
  (`rg -n "format.*currency|useDebounce|apiClient" src`) and report what you found.
- Use the existing implementation. If it doesn't fit, say why, and extend it rather than writing a parallel one.
- Keep a short "Where things live" section in this file for common utilities.

规则

Codex、Copilot 编码智能体等：加入 AGENTS.md

AGENTS.md

## Reuse before you write
- Before writing a helper, hook, component or client, search the repo for an existing one
  (`rg -n "format.*currency|useDebounce|apiClient" src`) and report what you found.
- Use the existing implementation. If it doesn't fit, say why, and extend it rather than writing a parallel one.
- Keep a short "Where things live" section in this file for common utilities.

Cursor 规则

Cursor：项目规则

.cursor/rules/duplicate-implementation.mdc

---
description: "AgentFails: Rebuilt something that already existed"
alwaysApply: true
---

## Reuse before you write
- Before writing a helper, hook, component or client, search the repo for an existing one
  (`rg -n "format.*currency|useDebounce|apiClient" src`) and report what you found.
- Use the existing implementation. If it doesn't fit, say why, and extend it rather than writing a parallel one.
- Keep a short "Where things live" section in this file for common utilities.

模板

CLAUDE.md / AGENTS.md 中的“东西放在哪”段落

CLAUDE.md

## Where things live (use these, don't recreate them)
- Money/currency formatting: src/lib/money.ts
- HTTP client (auth, retries): src/lib/api.ts
- Date helpers: src/lib/dates.ts
- Shared UI components: src/components/ui/

来源与致谢

在 GitHub 上改进这条遇到了、但修复没用？告诉我们