feat: libra add reset subcommand.

[yyjeqhc]

Part of #1239
实现libra reset子命令的基本功能。

hard reset

root@MSI:~/724/2# libra init

# 第一次提交：1.txt，分支 1
echo "content 1" > 1.txt
libra add 1.txt
libra commit -m "commit 1: add 1.txt"
libra branch 1

# 第二次提交：2.txt，分支 2
echo "content 2" > 2.txt
libra add 2.txt
libra commit -m "commit 2: add 2.txt"
libra branch 2

# 第三次提交：3.txt，分支 3
echo "content 3" > 3.txt
libra add 3.txt
libra commit -m "commit 3: add 3.txt"
libra branch 3

# 第四次提交：4.txt，分支 4
echo "content 4" > 4.txt
libra add 4.txt
libra commit -m "commit 4: add 4.txt"
libra branch 4

echo "eee">>3.txt
echo "eee">>4.txt
echo "eee">>5.txt
libra add 3.txt
Initializing empty Libra repository in ./.libra
root@MSI:~/724/2# libra status
On branch master
Changes to be committed:
  use "libra restore --staged <file>..." to unstage
        modified: 3.txt
Changes not staged for commit:
  use "libra add <file>..." to update what will be committed
  use "libra restore <file>..." to discard changes in working directory
        modified: 4.txt
Untracked files:
  use "libra add <file>..." to include in what will be committed
        5.txt
root@MSI:~/724/2# libra reset --hard 1
HEAD is now at 5ae57f8
root@MSI:~/724/2# ls
1.txt  5.txt

mixed reset

#创建仓库的操作同上

root@MSI:~/724/2# libra reset 1
HEAD is now at 594ebc7
root@MSI:~/724/2# ls
1.txt  2.txt  3.txt  4.txt  5.txt
root@MSI:~/724/2# cat 3.txt
content 3
eee
root@MSI:~/724/2# cat 4.txt
content 4
eee
root@MSI:~/724/2# cat 5.txt
eee
root@MSI:~/724/2# libra status
On branch master
Untracked files:
  use "libra add <file>..." to include in what will be committed
        3.txt
        4.txt
        5.txt
        2.txt

soft reset

#创建仓库的操作同上
root@MSI:~/724/2# libra reset --soft 1
HEAD is now at 2f229d7
root@MSI:~/724/2# libra status
On branch master
Changes to be committed:
  use "libra restore --staged <file>..." to unstage
        new file: 2.txt
        new file: 3.txt
        new file: 4.txt
Changes not staged for commit:
  use "libra add <file>..." to update what will be committed
  use "libra restore <file>..." to discard changes in working directory
        modified: 4.txt
Untracked files:
  use "libra add <file>..." to include in what will be committed
        5.txt
#经检查，文件内容正常

综上，3种reset以后工作区/暂存区文件列表和文件内容，表现和git一致。

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Name	Status	Preview	Comments	Updated (UTC)
mega	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jul 25, 2025 2:01pm

[Copilot]

Pull Request Overview

This PR implements the libra reset subcommand, adding the ability to reset the current HEAD to a specified state with three different modes (soft, mixed, hard). This is part of issue #1239 and provides Git-compatible reset functionality.

• Implements three reset modes: soft (HEAD only), mixed (HEAD + index), and hard (HEAD + index + working directory)
• Adds comprehensive test coverage for all reset modes and edge cases
• Integrates reset command into the CLI interface with proper argument parsing

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
libra/src/command/reset.rs	Core implementation of reset functionality with all three modes
libra/tests/command/reset_test.rs	Comprehensive test suite covering soft, mixed, hard reset scenarios
libra/src/command/mod.rs	Module declaration for reset command
libra/src/cli.rs	CLI integration and command parsing for reset
libra/tests/command/mod.rs	Test module declaration

[Copilot]

The load method call doesn't handle potential errors. This could panic if the blob object doesn't exist or is corrupted. Use load_object function instead which returns a Result that can be properly handled.

Suggested change

	let blob = mercury::internal::object::blob::Blob::load(&item.id);
	let blob = load_object(&item.id)
	.map_err(|e| format!("failed to load blob: {e}"))?;

[Copilot]

The function name changes_to_be_staged() suggests it returns staged changes, but it's being used to check for unstaged changes. This appears to be a semantic mismatch that could lead to incorrect test behavior.

Suggested change

	let unstaged = changes_to_be_staged();
	let unstaged = unstaged_changes();

[Copilot]

Same issue as above - changes_to_be_staged() function name suggests staged changes but is being used to verify unstaged changes after hard reset.

Suggested change

	let unstaged = changes_to_be_staged();
	let unstaged = unstaged_changes();

[Copilot]

Consistent with previous issues - the function name and usage don't align semantically, which could lead to test failures or incorrect assertions.

Suggested change

	let unstaged = changes_to_be_staged();
	let unstaged = unstaged_changes();

[genedna]

@yyjeqhc ， 请在 https://github.com/web3infra-foundation/mega/tree/main/aria/contents/docs/libra/command 这里参照其它命令，添加 reset 的文档