Function list_dir_blobs_at

crates/flowtrace-cli/src/git.rs:284–298

For every leaf file under `dir_rel` in the tree at `sha`, return `(filename, blob bytes)`. Reads are batched against a single repo open; intended for "render this run's reply stream as of commit X". Returns `Ok(vec![])` if the directory doesn't exist at that commit.

(
    root: &Path,
    sha: &str,
    dir_rel: &str,
)

/// intended for "render this run's reply stream as of commit X". Returns
/// `Ok(vec![])` if the directory doesn't exist at that commit.
pub fn list_dir_blobs_at(
    root: &Path,
    sha: &str,
    dir_rel: &str,
) -> Result<Vec<(String, Vec<u8>)>> {
    with_subtree_at(root, sha, dir_rel, vec![], |repo, dir_tree| {
        let mut out = Vec::with_capacity(dir_tree.len());
        for e in dir_tree.iter() {
            let Some(name) = e.name() else { continue };
            let blob = repo.find_blob(e.id())?;
            out.push((name.to_string(), blob.content().to_vec()));
        }
        Ok(out)
    })
}

/// Walk the tree at `runs/<run_id>/` at `sha` and return per-step committed
/// files as `{step_id: [<file>, ...]}`. Files at `<step>/sub/x.png` flatten