I am implementing the Raft protocol in Rust, reading the specification given by the original author.
The description of HandleAppendEntriesRequest says that followers, upon an AppendEntries message sometimes reply with an AppendEntriesResponse with success=false/true, but they are cases where there is no response at all, e.g., when a new entry is appended to the log (line 382) or when there is a conflict (line 374). This will require a second message (like a heartbeat) from the Leader to achieve a reply from the follower confirming that the entry was inserted successfully. I understand from the Raft Visualization that followers always reply if they are not stopped and don't wait for second messages.
Am I understanding incorrectly the TLA+ specification or replying to all AppendEntries requests is just a performance decision?