Gate application code behind an existing Harness FME feature flag. Detect the app's language, framework and any existing flag wrapper first; ask only what that can't resolve (target app, subject identity, gating point, treatment/config/fallback names, extension needs). Prefer an existing wrapper; otherwise propose a thin, customer-extensible facade or hook — never a new framework or second SDK client — approved before editing. Map named treatments to branches with a safe, non-boolean-coerced fallback, then add tests at the wrapper and call-site boundary. New flags delegate to create-feature-flag with the one environment actually selected; missing targeting delegates to update-flag-targeting under fresh approval. Not for flag creation alone, metrics (choose-metric, create-metric, instrument-metric), or first-time onboarding (feature-flag-onboarding). Trigger phrases: gate this code behind a flag, add flag check, wire up getTreatment, add SDK evaluation call.