Last active 1 month ago
Second half of a Claude Code session (~145 KB). Architectural discussion of evolving a 1:1 resource→line-item billing engine to handle product trees, time-varying topology, dynamic and grandfathered modifiers, usage-driven rate decisions (Burstable Internet), and derived charges. Covers the Charge model, four-stage rating pipeline, rate-context cascade, derived-charge protocol, time-slicing strategies, idempotent re-rating, a complete Burstable worked example, build-vs-buy analysis vs Lago/Metronome/AWS, AWS-style flat-rating-with-attribution as the production pattern, and a one-month tactical plan to ship the new product into the existing engine.