Function read_prepared_commit 

pub fn read_prepared_commit(
    context: &GitContext,
    shadow: &Path,
) -> Result<PreparedCommit, GitFailure>

What: Reads the prepared commit from the shadow HEAD: its object, its tree and whether it is signed. Why: The header block ends at the first empty line; a signature header in it marks the commit signed.

In TS you’d write (pseudocode):

await readPreparedCommit({ gitPath, shadowPath });