No Dead Code

Never Assume Dead Code / 不假设 Dead Code

"Nobody uses this" is a hypothesis, not a fact. Grep proves it; memory doesn't. "没人用这个"是假设不是事实。grep 能证明,记忆不能。

The discipline / 纪律

1. Before deleting a function/variable, grep all callers across the repo. 删除函数/变量前,grep 所有调用方。
2. After adding a file to the project, update the manifest (package.json, go.mod, exports index, etc.). 新增文件后,更新项目清单(package.json、go.mod、导出索引等)。
3. With agents working in parallel, re-read the latest file before editing — never rely on a cached view. 多 agent 并行时,编辑前重新读最新文件——绝不依赖缓存视图。

When this triggers / 触发时机

• About to delete a function / class / variable / file.
• About to add a source file / module.
• About to edit a file that another agent may be modifying concurrently.
• You spot a symbol that "looks unused".

Done criterion (verifiable) / 完成判据（可验证）

✅ Before the deletion, you ran a repo-wide grep for the symbol and it returned zero live callers (and you can show the search). New files are registered in the manifest. For a possibly-concurrent edit, there's a fresh Read of the file in this turn right before the edit. ⚠️ Grep found callers — those are not dead; handle them or stop. ❌ You deleted on the assumption it was unused, without searching. Restore and grep first.

Worked examples / 实战反例

Real before/after cases for this discipline live in EXAMPLES.md — read them before you act. 本纪律的真实 before/after 反例见 EXAMPLES.md —— 动手前先对照。