diff --git a/services/activity-service/internal/service/luckygift/service_test.go b/services/activity-service/internal/service/luckygift/service_test.go
index 7bd3d98e..e7f16607 100644
--- a/services/activity-service/internal/service/luckygift/service_test.go
+++ b/services/activity-service/internal/service/luckygift/service_test.go
@@ -10,7 +10,9 @@ import (
 	walletv1 "hyapp.local/api/proto/wallet/v1"
 	"hyapp/pkg/appcode"
 	"hyapp/pkg/tencentim"
+	broadcastdomain "hyapp/services/activity-service/internal/domain/broadcast"
 	domain "hyapp/services/activity-service/internal/domain/luckygift"
+	broadcastservice "hyapp/services/activity-service/internal/service/broadcast"
 )
 
 func TestGetConfigReturnsPoolDefault(t *testing.T) {
@@ -54,6 +56,7 @@ func TestProcessPendingDrawOutboxCreditsWalletAndPublishesRoomIM(t *testing.T) {
 		"user_id":                42,
 		"sender_user_id":         42,
 		"target_user_id":         99,
+		"visible_region_id":      210,
 		"room_id":                "room-1",
 		"gift_id":                "rose",
 		"gift_count":             1,
@@ -73,7 +76,8 @@ func TestProcessPendingDrawOutboxCreditsWalletAndPublishesRoomIM(t *testing.T) {
 	}
 	wallet := &fakeLuckyGiftWallet{}
 	publisher := &fakeLuckyGiftPublisher{}
-	service := New(repository, WithWallet(wallet), WithRoomPublisher(publisher))
+	broadcaster := &fakeLuckyGiftRegionBroadcaster{}
+	service := New(repository, WithWallet(wallet), WithRoomPublisher(publisher), WithRegionBroadcaster(broadcaster))
 	service.SetClock(func() time.Time { return time.UnixMilli(1760000001000).UTC() })
 
 	processed, err := service.ProcessPendingDrawOutbox(context.Background(), WorkerOptions{WorkerID: "worker-1"})
@@ -89,6 +93,16 @@ func TestProcessPendingDrawOutboxCreditsWalletAndPublishesRoomIM(t *testing.T) {
 	if publisher.last.GroupID != "room-1" || publisher.last.Desc != "lucky_gift_drawn" || publisher.last.EventID != "lucky_gift_drawn:lucky_draw_test" {
 		t.Fatalf("room im message mismatch: %+v", publisher.last)
 	}
+	if broadcaster.last.EventID != "lucky_gift_big_win:lucky_draw_test" || broadcaster.last.BroadcastType != broadcastdomain.TypeLuckyGiftBigWin || broadcaster.last.RegionID != 210 {
+		t.Fatalf("region lucky broadcast mismatch: %+v", broadcaster.last)
+	}
+	var broadcastPayload map[string]any
+	if err := json.Unmarshal([]byte(broadcaster.last.PayloadJSON), &broadcastPayload); err != nil {
+		t.Fatalf("decode region broadcast payload failed: %v", err)
+	}
+	if broadcastPayload["event_type"] != "lucky_gift_drawn" || broadcastPayload["broadcast_type"] != broadcastdomain.TypeLuckyGiftBigWin || broadcastPayload["room_id"] != "room-1" {
+		t.Fatalf("region broadcast payload mismatch: %+v", broadcastPayload)
+	}
 	if repository.grantedDrawID != "lucky_draw_test" || repository.deliveredOutboxID != "lucky_lucky_draw_test" {
 		t.Fatalf("repository settlement mismatch: granted=%s delivered=%s", repository.grantedDrawID, repository.deliveredOutboxID)
 	}
@@ -176,3 +190,12 @@ func (p *fakeLuckyGiftPublisher) PublishGroupCustomMessage(_ context.Context, me
 	p.last = message
 	return nil
 }
+
+type fakeLuckyGiftRegionBroadcaster struct {
+	last broadcastservice.PublishInput
+}
+
+func (b *fakeLuckyGiftRegionBroadcaster) PublishRegionBroadcast(_ context.Context, input broadcastservice.PublishInput) (broadcastdomain.PublishResult, error) {
+	b.last = input
+	return broadcastdomain.PublishResult{EventID: input.EventID, Status: broadcastdomain.StatusPending, Created: true}, nil
+}
diff --git a/services/activity-service/internal/storage/mysql/lucky_gift_repository.go b/services/activity-service/internal/storage/mysql/lucky_gift_repository.go
index 4292d6c4..b0958db6 100644
--- a/services/activity-service/internal/storage/mysql/lucky_gift_repository.go
+++ b/services/activity-service/internal/storage/mysql/lucky_gift_repository.go
@@ -1326,10 +1326,9 @@ func (r *Repository) updateLuckyRiskCounters(ctx context.Context, tx *sql.Tx, ap
 
 func (r *Repository) selectLuckyCandidate(config domain.Config, pool string, stageFeedback bool, globalWindow, giftWindow luckyRTPWindow, platformPool, roomPool, giftPool, atmosphere luckyPool, activityRemaining int64, counters map[string]luckyCounter, minFutureMax int64) (luckyCandidate, map[string]bool, error) {
 	minRequired := maxInt64(globalWindow.minRequired(minFutureMax), giftWindow.minRequired(minFutureMax))
-	rtpMaxAllowed := minInt64(globalWindow.remainingPayout(), giftWindow.remainingPayout())
 	poolCapacity := luckyWeightedPoolCapacity(platformPool, roomPool, giftPool, config)
 	riskCapacity := luckyRiskCapacity(config, counters)
-	baseMaxAllowed := minInt64(rtpMaxAllowed, minInt64(poolCapacity, riskCapacity))
+	baseMaxAllowed := minInt64(poolCapacity, riskCapacity)
 	limited := map[string]bool{}
 
 	baseCandidates := make([]luckyCandidate, 0, len(config.Tiers))
diff --git a/services/activity-service/internal/storage/mysql/lucky_gift_repository_test.go b/services/activity-service/internal/storage/mysql/lucky_gift_repository_test.go
index ad106ca0..c4f4228d 100644
--- a/services/activity-service/internal/storage/mysql/lucky_gift_repository_test.go
+++ b/services/activity-service/internal/storage/mysql/lucky_gift_repository_test.go
@@ -100,6 +100,26 @@ func TestLuckyAutoWeightedBaseCandidatesDoesNotDiluteDeficitAcrossLargeWindow(t
 	}
 }
 
+func TestLuckyAutoWeightedBaseCandidatesInterpolatesSingleDrawBelowOneX(t *testing.T) {
+	candidates := []luckyCandidate{
+		{TierID: "none", BaseReward: 0},
+		{TierID: "rebate_1x", BaseReward: 100},
+	}
+	window := luckyRTPWindow{ControlDraws: 100_000, TargetPayoutCoins: 95}
+
+	weighted := luckyAutoWeightedBaseCandidates(candidates, 0, window, window)
+
+	if len(weighted) != 2 {
+		t.Fatalf("expected 0x and 1x interpolation candidates, got %#v", weighted)
+	}
+	if weighted[0].TierID != "none" || weighted[0].Weight != 50_000 {
+		t.Fatalf("expected 0x to keep 5%% probability, got %#v", weighted[0])
+	}
+	if weighted[1].TierID != "rebate_1x" || weighted[1].Weight != 950_000 {
+		t.Fatalf("expected 1x to carry 95%% probability, got %#v", weighted[1])
+	}
+}
+
 func TestSelectLuckyCandidateDoesNotInjectNoneTier(t *testing.T) {
 	config := domain.Config{
 		GiftID:                domain.DefaultPoolID,
diff --git a/services/room-service/internal/room/service/lucky_gift_test.go b/services/room-service/internal/room/service/lucky_gift_test.go
index 34b4a6b6..f3feff88 100644
--- a/services/room-service/internal/room/service/lucky_gift_test.go
+++ b/services/room-service/internal/room/service/lucky_gift_test.go
@@ -104,7 +104,11 @@ func TestSendGiftReturnsLuckyGiftDrawResult(t *testing.T) {
 		t.Fatalf("expected one lucky draw, got %d", len(luckyGift.draws))
 	}
 	drawMeta := luckyGift.draws[0].GetLuckyGift()
-	if drawMeta.GetCommandId() != "cmd-lucky" || drawMeta.GetCoinSpent() != 100 || drawMeta.GetDeviceId() != "device-session-1" || drawMeta.GetAnchorId() != "101" {
+	if drawMeta.GetCommandId() != "cmd-lucky" ||
+		drawMeta.GetCoinSpent() != 100 ||
+		drawMeta.GetDeviceId() != "device-session-1" ||
+		drawMeta.GetAnchorId() != "101" ||
+		drawMeta.GetVisibleRegionId() != 9001 {
 		t.Fatalf("lucky draw meta mismatch: %+v", drawMeta)
 	}
 }