Function parse_diff_files

atomic-cli/src/commands/git/parallel.rs:3885–4004

Parse files from a git diff. For each changed file we capture: - The operation type (Added / Modified / Deleted / Renamed / Copied) - The new file content (for adds/modifies) - The old file content (for modifies/deletes) - The exact diff lines that git computed, so Phase 2 can build BranchOps directly from git's diff rather than re-diffing.

(
    git_repo: &GitRepository,
    diff: &Diff,
    tree: &Tree,
    parent_tree: Option<&Tree>,
    capture_diff_lines: bool,
)

///   - The exact diff lines that git computed, so Phase 2 can build
///     BranchOps directly from git's diff rather than re-diffing.
fn parse_diff_files(
    git_repo: &GitRepository,
    diff: &Diff,
    tree: &Tree,
    parent_tree: Option<&Tree>,
    capture_diff_lines: bool,
) -> CliResult<Vec<ParsedFile>> {
    use std::collections::HashMap;

    // ── Step 1: collect per-file diff lines via diff.foreach ────────────
    //
    // git2::Diff::foreach gives us each DiffLine with its origin (`+`/`-`/` `),
    // raw bytes, and old/new line numbers — exactly what `git diff` outputs.
    // We key by file path so we can attach them to the ParsedFile below.

    // Map from file path → accumulated diff lines for that file.
    let mut lines_by_path: HashMap<String, Vec<GitDiffLine>> = HashMap::new();

    if capture_diff_lines {
        let _ = diff.foreach(
            &mut |_delta, _progress| true, // file_cb  (no-op)
            None,                          // binary_cb
            None,                          // hunk_cb
            Some(&mut |delta, _hunk, line| {
                let origin = line.origin();
                // We only keep `+`, `-`, and context (` `) lines.
                if origin != '+' && origin != '-' && origin != ' ' {
                    return true;
                }
                let path = delta
                    .new_file()
                    .path()
                    .or_else(|| delta.old_file().path())
                    .map(|p| p.to_string_lossy().to_string())
                    .unwrap_or_default();

                lines_by_path.entry(path).or_default().push(GitDiffLine {
                    origin,
                    content: line.content().to_vec(),
                    old_lineno: line.old_lineno(),
                    new_lineno: line.new_lineno(),
                });
                true
            }),
        );
    }

    // ── Step 2: build ParsedFile entries from the delta list ─────────────

    let mut files = Vec::new();

    for delta in diff.deltas() {
        let new_file = delta.new_file();
        let old_file = delta.old_file();

        // Skip submodules silently (warnings printed during Phase 2)
        if new_file.mode() == git2::FileMode::Commit || old_file.mode() == git2::FileMode::Commit {
            continue;