stacks-feature-flags

# Scoped feature flags This package manages user-targeted runtime values. Framework bundle enablement through the named `feature()` export from `@stacksjs/config` is a different surface; read stacks-features. ## Define, scope, and evaluate Import Feature or createFeatureFlags from @stacksjs/feature-flags. Definitions can be fixed values or resolvers. Feature.for(scope) returns a scoped facade with async value/values/all, active/inactive, activate/deactivate/forget and when/unless. Await evaluations and writes; they are not synchronous booleans. percentage(percent) and variants(weights) deterministically bucket a flag name and scope key. Keep scope identities stable to preserve cohort assignment. The manager supports explicit missing-flag behavior and evaluation listeners. Changing a definition is not the same as forgetting already-persisted values. ## Drivers and boundaries The global Feature facade resolves configured memory or database storage lazily. Memory state is process-local. The SQL driver supports the dialects checked by configuredDriver, and failures raise FeatureFlagStoreError rather than silently switching a production experiment to memory. Inspect the actual config and store schema before rollout. Persisted value types are validated by the package. Do not send private cohort inputs to the browser or use a feature flag as the only authorization check. Test stable scope keys, variant assignment, missing definitions, persistence, concurrent evaluation and explicit value overrides. Source: core/feature-flags/src/{index,manager,scope,strategies,schema,value}.ts and drivers/. Retained evidence: manager, global, scope, strategies and both driver test suites.