Observation identity is key plus revision; reject conflicting redelivery while preserving legitimate revisions, and sort integer keys numerically

Observation identity is key plus revision; reject conflicting redelivery while preserving legitimate revisions, and sort integer keys numerically. The complete application includes native models, services, repository projections, a working preview and visible acceptance cases. Preserve the other documented invariants and run bash test/run.sh.

Work with the stack you want to practice. Your workspace and timer start after you choose.