EDA-Viz Block (RFM35 Pattern)

# EDA-Viz Block (RFM35 Pattern) Refresh target: turn a messy transactions table into an RFM-style EDA with three charts and three stated insights. Follow `Submission_assignments/playbooks/EDA.md`. ## 1. Clean first, plot second Parse dates, coerce numerics, dedupe on the order key, and quarantine (never silently drop) rows with missing customer ids. Reshape with merge/pivot/melt: one row per customer with Recency/Frequency/Monetary columns. ## 2. The three charts 1. Distribution of Monetary per customer (log-scale if skewed) — where is the mass? 2. Recency vs Frequency scatter — do recent buyers buy more often? 3. Monthly revenue trend with annotation of the largest drop — what changed? ## 3. Insight discipline Each chart gets one falsifiable sentence: direction, magnitude, and the segment it applies to. "Revenue fell" is not an insight; "Top-decile customers drove 62% of the March dip after promo end" is. Dataset: `homepage_ab_test.csv` for the drill; ecommerce transactions for the mini. ## Recap Clean (parse/coerce/dedupe/quarantine), reshape to one-row-per-customer RFM, plot distribution + recency-frequency + trend, and write one falsifiable sentence per chart.