Function progress_comment 

pub fn progress_comment(
    cliban_key: &str,
    status: &str,
    plan_body: Option<&str>,
    activity: &[ActivityLogEntry],
) -> String

The comment push posts on the Linear issue: where the plan stands and what happened since the last sync.

Additive by construction — a comment can never destroy anything a human wrote, which is why it is on by default while the description rewrite is opt-in.