litvc 1.3.0

Lit - The agentic-first distributed version control system. A complete Git replacement designed for AI agents first and humans second.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130

use crate::core::{find_repo_root, read_ref, update_head, write_ref, Object, ObjectHash, Tree};
use crate::response::CheckoutResponse;
use crate::storage::{Index, ObjectStore};
use std::fs;
use std::path::Path;

pub fn execute(
    target: String,
    create_new: bool,
) -> Result<CheckoutResponse, crate::errors::LitError> {
    let repo_root = find_repo_root()?;

    if create_new {
        use crate::core::read_head;
        let head_hash = read_head(&repo_root)?;
        write_ref(&repo_root, &format!("heads/{}", target), &head_hash)?;
        update_head(&repo_root, &target)?;
        checkout_commit(&repo_root, &ObjectHash::from_hex(head_hash))?;
        Ok(CheckoutResponse {
            target,
            is_new_branch: true,
            is_detached: false,
        })
    } else if let Ok(commit_hash) = read_ref(&repo_root, &format!("heads/{}", target)) {
        update_head(&repo_root, &target)?;
        checkout_commit(&repo_root, &ObjectHash::from_hex(commit_hash))?;
        Ok(CheckoutResponse {
            target,
            is_new_branch: false,
            is_detached: false,
        })
    } else {
        let hash = ObjectHash::from_hex(target.clone());
        checkout_commit(&repo_root, &hash)?;
        use crate::core::set_head_detached;
        set_head_detached(&repo_root, &target)?;
        Ok(CheckoutResponse {
            target,
            is_new_branch: false,
            is_detached: true,
        })
    }
}

fn checkout_commit(
    repo_root: &Path,
    commit_hash: &ObjectHash,
) -> Result<(), crate::errors::LitError> {
    let store = ObjectStore::new(repo_root);

    // Read commit
    let commit = match store.read(commit_hash)? {
        Object::Commit(c) => c,
        _ => return Err("Not a commit".into()),
    };

    // Read tree
    let tree = match store.read(&commit.tree)? {
        Object::Tree(t) => t,
        _ => return Err("Not a tree".into()),
    };

    // Update the working directory and the index in one walk.
    //
    // These were two walks, and only this one recursed. The index was rebuilt
    // from the root tree's entries alone, keyed by entry name, so a
    // subdirectory was recorded as though it were a file — `src` with the
    // subtree's hash — and the blobs beneath it got no entry at all. `status`
    // then called `fs::read` on a directory and failed outright, so any
    // repository with a subdirectory was broken by a checkout. Populating the
    // index from the same recursion that writes the files keeps the two in
    // step by construction.
    let mut index = Index::new();
    checkout_tree(repo_root, &tree, &store, "", &mut index)?;
    index.save(repo_root)?;

    Ok(())
}

/// Write a tree to the working directory, recording each blob in `index`
/// under its full path.
fn checkout_tree(
    repo_root: &Path,
    tree: &Tree,
    store: &ObjectStore,
    prefix: &str,
    index: &mut Index,
) -> Result<(), crate::errors::LitError> {
    for entry in &tree.entries {
        let path = if prefix.is_empty() {
            entry.name.clone()
        } else {
            format!("{}/{}", prefix, entry.name)
        };

        let full_path = repo_root.join(&path);

        match entry.object_type.as_str() {
            "blob" => {
                // Write file
                let blob = match store.read(&entry.hash)? {
                    Object::Blob(b) => b,
                    _ => return Err("Expected blob".into()),
                };

                if let Some(parent) = full_path.parent() {
                    fs::create_dir_all(parent)
                        .map_err(|e| format!("Failed to create directory: {}", e))?;
                }

                fs::write(&full_path, &blob.content)
                    .map_err(|e| format!("Failed to write file: {}", e))?;

                index.add(path, entry.hash.to_string(), entry.mode.clone());
            }
            "tree" => {
                // Recursively checkout subtree
                let subtree = match store.read(&entry.hash)? {
                    Object::Tree(t) => t,
                    _ => return Err("Expected tree".into()),
                };

                checkout_tree(repo_root, &subtree, store, &path, index)?;
            }
            _ => {}
        }
    }

    Ok(())
}