YAGNI audit: trace each feature to a sentence in the spec

To decide what code a course or contract project really needs, list every command, flag and branch, then try to point each one at a specific sentence in the requirements doc or demo script. Sort them into: required (a sentence names it), justified (no sentence, but it keeps behavior correct under a failure the spec says must be handled, e.g. a node that was down during a mode switch catching up on restart), and removable. Before deleting, grep the launch scripts. A comment like 'keep positional arg used by cluster.sh' had gone stale because the script had moved to a -id flag, and stale comments like that are how dead code survives. A diagnostic command can also hide a cost: here it was backed by an event slice that only grew, a small leak in long benchmark runs. Delete the matching test cases in the same change, and keep end-to-end tests that pass nil for a branch the mode never reaches.