Chaim
927be5c6bb
Documents the prospective held-out methodology shipped in PR #337: why a clean retrospective held-out is impossible (lessons stored universal/untagged → no leave-one-out), and how the system instead captures a clean generalization datapoint at final-upload — before this case's lessons are folded — via a style_distance snapshot + lesson-pool size into style_distance_history, surfaced by GET /api/learning/style-distance-history. Adds §0.7, wires step [7] MEASUREMENT and INV-LRN4 to it. Notes the change_percent style/content confound and the one-time clean window. Invariants documented: INV-LRN4 (this is its trend surface), G2 (reuses style_distance + appeal_type_rules — no parallel metric path). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>