feat: libra add revert subcommand.

[yyjeqhc]

Part of #1239
实现libra revert子命令的基本功能

#!/bin/bash

# --- 环境准备 ---
# 清理旧环境
rm -rf .libra *.txt

# 初始化仓库
libra init
echo "✅ 仓库已初始化"

# 创建一系列提交
echo "content a" > a.txt
libra add a.txt
libra commit -m "commit 1: add a.txt"

echo "content b" > b.txt
libra add b.txt
libra commit -m "commit 2: add b.txt"

echo "content c" > c.txt
libra add c.txt
libra commit -m "commit 3: add c.txt"

echo "d.txt will be untracked" > d_untracked.txt

echo "✅ 准备工作完成，当前状态如下："
libra log

root@MSI:~/724/2# libra revert HEAD~
[fb62b48] Revert commit bd0032e
root@MSI:~/724/2# ls
a.txt  c.txt  d_untracked.txt
root@MSI:~/724/2# libra log
commit fb62b481596df7236b63de6d4061dfef81616304 (HEAD -> master)
Author: mega <admin@mega.org>
Date: 2025-07-26 10:52:05 UTC +0800

Revert ""

This reverts commit bd0032ead734fec9835156f1f2d4f4558fd1a812.

commit bd43015230c3dd1c76222940ea35633bc16e0786
Author: mega <admin@mega.org>
Date: 2025-07-26 10:51:58 UTC +0800

commit 3: add c.txt

commit bd0032ead734fec9835156f1f2d4f4558fd1a812
Author: mega <admin@mega.org>
Date: 2025-07-26 10:51:58 UTC +0800

commit 2: add b.txt

commit 7715d01d9610950b2824460151968ea9f7128763
Author: mega <admin@mega.org>
Date: 2025-07-26 10:51:58 UTC +0800

commit 1: add a.txt

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Name	Status	Preview	Comments	Updated (UTC)
mega	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jul 27, 2025 4:32am

[Copilot]

Pull Request Overview

This PR implements the libra revert subcommand to create new commits that undo changes from existing commits, following standard Git revert behavior. It provides a safe way to undo changes without altering project history.

Key changes include:

• Core revert implementation with support for regular commits and root commits
• --no-commit flag to stage changes without committing
• Comprehensive test coverage for various revert scenarios

Reviewed Changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
libra/src/command/revert.rs	Main implementation of revert functionality with commit resolution, tree manipulation, and conflict detection
libra/src/command/mod.rs	Module registration and typo fix in save_object parameter name
libra/src/cli.rs	CLI integration for the new revert command
libra/tests/command/revert_test.rs	Comprehensive test suite covering basic revert, no-commit flag, root commits, and error cases
libra/tests/command/mod.rs	Test module registration
aria/contents/docs/libra/command/revert/index.mdx	Documentation for the revert command usage and examples

Comments suppressed due to low confidence (1)

libra/tests/command/revert_test.rs:302

• The error test doesn't verify that the operation actually fails or check the error message. It should assert that the revert operation returns an error and verify the working directory remains unchanged.

    // Test reverting non-existent commit should fail gracefully

[Copilot]

The conflict detection logic is flawed. This condition will trigger false conflicts when the current file state legitimately differs from the reverted commit due to other changes. The check should compare if the current state conflicts with applying the revert, not just if it differs from the original commit.

Suggested change

	if current_files.get(path) != Some(&reverted_hash) && current_files.contains_key(path) {
	return Err(format!(
	"conflict: file '{}' was modified in a later commit",
	path.display()
	));
	if let Some(current_hash) = current_files.get(path) {
	if let Some(parent_hash) = parent_hash {
	// Check if applying the revert would overwrite legitimate changes
	if current_hash != parent_hash {
	return Err(format!(
	"conflict: file '{}' was modified in a later commit",
	path.display()
	));
	}
	} else {
	// File was newly added in the reverted commit, check if it still exists
	return Err(format!(
	"conflict: file '{}' was added in a later commit",
	path.display()
	));
	}

[Copilot]

Using only file_name() will cause issues with files in subdirectories as they will lose their directory structure. Files like 'dir/file.txt' will be stored as just 'file.txt' at the root level.

Suggested change

	name: path_buf.file_name().unwrap().to_str().unwrap().to_string(),
	name: path_buf.to_str().unwrap().to_string(), // Use full relative path

[Copilot]

Loading blob objects just to get their size is inefficient. The size information should be available from the index entry or object metadata without loading the entire blob content.