feature_flag_kit 0.1.0

A platform-agnostic feature flag and staged-rollout evaluation engine with deterministic MurmurHash3 bucketing, instant kill-switches, targeting rules, and explainable evaluation results. Zero runtime [...]

Changelog

0.1.0 - 2026-07-10

Initial release.

• Package scaffold: strict analysis options, CI, MIT license, architecture docs.
• Vendored MurmurHash3 x86 32-bit (web-safe 16-bit limb arithmetic), verified against published reference vectors.
• getRolloutBucket(userId, featureKey): deterministic 0-99 bucketing via murmur3("userId:featureKey") % 100, with pinned permanence-guard regression vectors.
• Config models (RemoteConfig, FeatureConfig, TargetingRules, UserContext, EvaluationResult) with strict, atomic JSON validation: schema violations throw ConfigValidationException with the offending JSON path and are never partially applied. Round-trip toJson support for Last-Known-Good caching.
• evaluateFlag: pure, synchronous evaluation walking the strict hierarchy kill-switch > targeting (numeric per-component minAppVersion, case-insensitive allowedCountries, AND semantics, safe-default exclusion on missing attributes) > percentage rollout (0/100 short-circuit) > fallback, every decision explained via EvaluationResult.
• ConfigSessionController with selective freeze: boots on compiled-in defaults, hydrates from the Last-Known-Good cache, persists fresh fetches for the next launch while freezing non-emergency changes mid-session, and applies kill-switch activations live (monotonic within a session) with change notifications. Abstract ConfigFetcher/ConfigStore interfaces keep the package free of network and storage dependencies.