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A discount code can now apply to a subset of policies on a product (e.g. "Patron and Pro but not Creator") instead of being limited to exactly one policy or the entire product. - Migration 0018 adds `applies_to_policy_ids_json` (nullable JSON array of policy ids). Legacy `applies_to_policy_id` stays as the singular fallback when the JSON column is empty/NULL. - `DiscountCode::allowed_policy_ids()` helper unifies multi + singular into one Vec. Purchase + preview scope checks consult it. - `find_applicable_featured_discount` now narrows multi-policy candidates in Rust (small candidate set; index-friendly SQL would require json_each, deferred). - Admin API: `POST /v1/admin/discount-codes` accepts `policy_slugs` (array) alongside the existing `policy_slug` (singular). Multi wins when both are present. PATCH does not allow scope edits — same rule as the singular field (disable + recreate to re-scope). - UI: pill multi-select replaces the policy dropdown on the create form. Edit modal's scope label renders the comma-separated list. UI + schema both back-compat: existing codes keep working unchanged. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>