2.19.0

Minor changes

• fef3076 Report flags that local evaluation could not resolve on PostHog.FeatureFlags.evaluate_flags/2 snapshots. The new unresolved_flags field of PostHog.FeatureFlags.Evaluations maps each such flag key to a reason: :experience_continuity, :unsupported_definition, :unresolved_dependency or :missing_context. When flag definitions load, log one warning for each flag that local evaluation can never resolve (experience continuity, a static cohort, an unknown operator, a malformed value, a regex that only the server can evaluate, or a missing or circular flag dependency), and log it again only when the definition of that flag changes.

  Behaviour changes (these apply to every flag function, including check/3 and get_feature_flag_result/4, not only to evaluate_flags/2):

  • A condition no longer stops at a filter that only the server can evaluate, such as a static cohort. If another filter in the condition does not match, the condition does not match, and a later condition can resolve the flag locally. Before, such a flag fell back to a remote request, or stayed unresolved with only_evaluate_locally: true.
  • An unexpected error in a filter that follows a filter local evaluation can't check now makes only that condition inconclusive, and a later condition can still resolve the flag. Before, the flag fell back to a remote request, or stayed unresolved with only_evaluate_locally: true.
  • A condition that depends on a flag that only the server can evaluate, such as a flag with a static cohort, now makes the flag fall back to a remote request, or stay unresolved with only_evaluate_locally: true. Before, a later condition could resolve the flag locally to a different value than the server returns. A condition that depends on a flag with experience continuity enabled is still only inconclusive: a later condition can still resolve the flag, and only when none does, the flag falls back to a remote request, or stays unresolved with only_evaluate_locally: true.
  • $feature_flag_called events from snapshot reads report local_evaluation_inconclusive instead of flag_missing for flags in unresolved_flags. — Thanks @gustavohstrassburger for your first contribution 🎉!