# Lwgui Git Diff Skill

> ***

- Skill: `jasonma0012/lwgui-git-diff-skill` (Agent Skill)
- Install (CLI): `npx skillmds@latest add jasonma0012/lwgui-git-diff-skill`
- Raw SKILL.md: https://api.skillmd.com/api/skills/jasonma0012/lwgui-git-diff-skill/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: jasonma0012 (https://skillmd.com/u/jasonma0012)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/jasonma0012/lwgui-git-diff-skill

---

***

name: git-diff-skill
description: Git diff and patch generation guide, focusing on encoding pitfalls and correct practices when using git diff redirection in the Trae (PowerShell) environment
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# Git Diff & Patch Generation

参考文档：<https://git-scm.com/docs/git-diff>

## `git diff A..B` 语法

`git diff A..B` = `git diff A B`，显示把 **A** 变成 **B** 需要做哪些修改。

<br />

```
git diff A..B -- path/         → 仅限指定目录
git diff A..B --stat -- path/  → 仅统计
```

## 生成 Patch 文件

```
git diff A..B -- path/ > output.patch
```

## ⚠️ PowerShell `>` 重定向编码问题

Trae 的终端环境是 PowerShell。PowerShell 的 `>` 是 `Out-File` 的别名，在接收原生命令（如 `git`）的输出时，会使用 `$OutputEncoding`（默认 **US-ASCII**，代码页 20127）进行编码转换。

`git diff` 输出为 **UTF-8 no BOM**，当输出中包含非 ASCII 字符（如中文注释）时：

1. PowerShell 试图按 ASCII 解码，无法表示的字节被丢弃或替换
2. 导致文件内容损坏、行结构破坏
3. 最终文件可能仅剩数十字节，完全不可用

**对比实测：**

| 方式                                 | 结果                |
| ---------------------------------- | ----------------- |
| `git diff ... > file` (PowerShell) | 14 字节，内容几乎为空      |
| `git diff ... > file` (Git Bash)   | 56.8 KB，1603 行，正确 |
| `bash -c "git diff ... > file"`    | 正确                |

**解决方案：必须通过 Git Bash 执行重定向。** Git 安装路径通常为 `C:\Program Files\Git\bin\bash.exe`。

```powershell
& "C:\Program Files\Git\bin\bash.exe" -c "cd 'e:/path/to/repo' && git diff A..B -- path/ > output.patch"
```

**不需要重定向时（如** **`--stat`）可在 PowerShell 直接执行：**

```
git diff A..B --stat -- path/
```

**不推荐的做法：**

- `Set-Content -Encoding UTF8` 可指定编码，但在 Trae 中可能被误判为高风险命令触发手动确认
- 修改 `$OutputEncoding` 为 UTF-8 会全局生效，影响其他脚本