[thelastbackspace]

• The CPU-cost finding matches its hottest functions (≥10% of CPU) against known library costs: Mongoose, TypeORM, Sequelize, Prisma, Express's per-response ETag, class-transformer/validator, large JSON, password hashing, logging, GC. From the NestJS + TypeORM run: 26% Express res.send, ~40% TypeORM query building.
• README: -H, --probe, the CPU-cost and failed-response findings, mysql.
• Test: the Prometheus histogram test flaked about 1 in 6 full runs (a no-op call measured over 5 ms on a busy machine); bucket margins widened.