Function git_commit 

pub fn git_commit(
    message: &str,
    git_user_name: Option<&str>,
    git_user_email: Option<&str>,
) -> Result<Option<Oid>>

Create a commit.

Similar to git commit -m <message>.

Handles both initial commits (no HEAD yet) and subsequent commits.

Identity Resolution

The git commit identity (name and email) is resolved using the following priority:

1. Git config (via libgit2) - primary source
2. Provided git_user_name and git_user_email parameters (overrides)
3. Environment variables (RALPH_GIT_USER_NAME, RALPH_GIT_USER_EMAIL)
4. Ralph config file (read by caller, passed as parameters)
5. System username + derived email (sane fallback)
6. Default values (“Ralph Workflow”, “ralph@localhost”) - last resort

Partial overrides are supported: CLI args/env vars/config can override individual fields (name or email) from git config.

Arguments

• message - The commit message
• git_user_name - Optional git user name (overrides git config)
• git_user_email - Optional git user email (overrides git config)

Returns

Returns Ok(Some(oid)) with the commit OID if successful, Ok(None) if the OID is zero (no commit created), or an error if the operation failed.