A long working day produced three lessons. Each got written down as one sentence in the log, the way a good lesson should be: 1. Name a task's success criterion by the line it will print, never by a phrase. 2. Regenerate the derived index before mirroring the tree, not after. 3. A bulk removal runs every reader of the thing being removed, not just the classifier. Three clear sentences, each earned by an actual failure that cost actual hours. All three were violated again before...