The groups-cache opt-out is a developer debugging knob, not a user-facing config. Gating the env-var lookup behind cfg!(debug_assertions) makes release builds ignore the variable; the optimiser removes the lookup entirely, so the variable name doesn't appear in release binary strings output. Doc-comments updated to reflect the new behaviour. Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>