refactor: remove redundant PrizeClaimed storage flag, use paid_at as sole guard

Author: Shadow-MMN

contracts/events/src/event_ops.rs

@@ -737,11 +737,6 @@ pub fn claim_prize(
 
     recipient.require_auth();
 
-    // Prevent double-claim for this (event, recipient, position).
-    if storage::is_prize_claimed(env, event_id, &recipient, position) {
-        return Err(Error::PrizeAlreadyClaimed);
-    }
-
     // Look up the anchor index stored at selection time (O(1) instead of
     // a linear scan). Returns NoSubmissions if no winner matches or the
     // prize has already been claimed (canonical guard: paid_at).
@@ -768,9 +763,6 @@ pub fn claim_prize(
     escrow::release(env, &event.token, &recipient, amount);
     event.remaining_escrow = event.remaining_escrow.saturating_sub(amount);
 
-    // Mark prize claimed (prevents replay for this recipient + position).
-    storage::mark_prize_claimed(env, event_id, &recipient, position);
-
     // Update the anchor row in-place with the paid timestamp instead of
     // appending a duplicate row. This keeps winner_count == selected count.
     storage::set_winner_at(

contracts/events/src/storage.rs

@@ -648,27 +648,6 @@ pub fn set_crowdfunding_milestones_claimed(env: &Env, id: u64, count: u32) {
     touch_event_persistent(env, &key);
 }
 
-// ============================================================
-// PRIZE CLAIMS (persistent; per-(event, recipient, position))
-//
-// Tracks which winners have claimed their prize in the pull-model flow for
-// Single-release events (bounties, hackathons). Written by claim_prize.
-// ============================================================
-pub fn is_prize_claimed(env: &Env, id: u64, recipient: &Address, position: u32) -> bool {
-    let key = DataKey::PrizeClaimed(id, recipient.clone(), position);
-    let claimed: Option<bool> = env.storage().persistent().get(&key);
-    if claimed.is_some() {
-        touch_event_persistent(env, &key);
-    }
-    claimed.unwrap_or(false)
-}
-
-pub fn mark_prize_claimed(env: &Env, id: u64, recipient: &Address, position: u32) {
-    let key = DataKey::PrizeClaimed(id, recipient.clone(), position);
-    env.storage().persistent().set(&key, &true);
-    touch_event_persistent(env, &key);
-}
-
 // ============================================================
 // CANCELLATION STATE (persistent; present only while Cancelling)
 // ============================================================

contracts/events/src/types.rs

@@ -197,9 +197,6 @@ pub enum DataKey {
     // Appended in 1.2.0 to preserve existing key discriminants.
     NonOwnerContributionTotal(u64),
 
-    // Added last so earlier variant discriminants remain stable on upgrade.
-    PrizeClaimed(u64, Address, u32),
-
     // Winner anchor index for O(1) claim_prize lookup (added 2026-07).
     WinnerIndex(u64, Address, u32),