[eximius]

The system we're building now meets most of these but not necessarily in the way described.

First, we're building a runtime configuration system on top of AWS AppConfig. YAML/proto validation that pushes to AppConfig via gitops and bazel. Configurations are namespaced so the unique names is solved. It's all open in git.

Feature flags are special cases of runtime configuration.

We are distinguishing backend feature flags from experimentation/variants for users. We don't have (or want) cohorting by user IDs or roles. We have a separate system for that and it does it well.

The last two points - distinguishing between experimentation/feature variants and feature flags as runtime configuration are somewhat axiomatic differences. Folks might disagree but ultimately we have that separate system that solves that case. They're complimentary and share a lot of properties but ultimately it solves a lot of angst if you don't force both to be the same tool.