Function record_decision 

pub fn record_decision(
    common_dir: Option<&Path>,
    command: &str,
    outcome: Outcome,
    reason: &str,
    detail: &str,
    branch: Option<&str>,
)

What: Records one decision: a debug line always (when verbose), and one appended line when the common Git directory is known. Why: The command’s result never depends on the record: a file that cannot be written is only a debug line.

In TS you’d write (pseudocode):

recordDecision(commonDir, 'merge', 'declined', 'upstream-equals-tip', detail, branch)