A 150-line pure-Python TSP heuristic that beats Nearest Neighbor by +10–13.8% on real-world data — including 10,000 US cities in under 17 minutes. Two versions in one repo: Cook's Ruler Classic – real Earth miles (Haversine) **Cook's Ruler Euclidean Monster** – flat-space domination (+21.5% in 0.3 seconds) No training. No compilation. No e