修复(#4): 抽奖发奖修正 — 保底奖不参与随机 + 无订阅时按套餐自动新建订阅

- weighted_picker: Pick 排除 is_fallback 保底奖，避免真实奖被"谢谢参与"挤占
- vpn_duration handler: 无活跃订阅且奖品配置 subscribe_id 时，按该套餐在抽奖
  事务内新建订阅并发放时长；未配置则沿用旧的安全跳过
- 补充单测：picker 排除保底奖、vpn_duration 自动新建订阅、draw 端到端链路

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/logic/lottery/draw/service_test.go

@@ -13,7 +13,9 @@ import (
 	"time"
 
 	"github.com/DATA-DOG/go-sqlmock"
+	handler "github.com/perfect-panel/server/internal/logic/lottery/handler"
 	"github.com/perfect-panel/server/internal/model/lottery"
+	usermodel "github.com/perfect-panel/server/internal/model/user"
 	"github.com/perfect-panel/server/pkg/xerr"
 	"gorm.io/driver/mysql"
 	"gorm.io/gorm"
@@ -915,3 +917,165 @@ func (m claimDataIsValidJSON) Match(v driver.Value) bool {
 	}
 	return true
 }
+
+// ---- E2E: real VPNDurationHandler wired into the draw flow -----------------
+
+// fakeE2ELedger 让真实 VPNDurationHandler 的幂等账本 Reserve 永远返回“新建行”，
+// 从而走真实发放分支（而非幂等命中）。
+type fakeE2ELedger struct{}
+
+func (fakeE2ELedger) Reserve(_ context.Context, _ *gorm.DB, entry lottery.GrantLedger) (*lottery.GrantLedger, bool, error) {
+	return &lottery.GrantLedger{Id: 77, ExternalRef: entry.ExternalRef}, false, nil
+}
+
+// fakeNoSubUserModel 嵌入 usermodel.Model（其余方法不会被调用），仅覆盖
+// FindActiveSubscribe 返回“无活跃订阅”，模拟问题2 的复现前提。
+type fakeNoSubUserModel struct {
+	usermodel.Model
+}
+
+func (fakeNoSubUserModel) FindActiveSubscribe(context.Context, int64) (*usermodel.Subscribe, error) {
+	return nil, gorm.ErrRecordNotFound
+}
+
+// TestDraw_E2E_VPNDurationAutoCreatesSubscription 串起完整链路（问题2 的端到端回归）：
+// 抽中 vpn_duration → 真实 handler 派发 → 用户无活跃订阅 + 奖品配了 subscribe_id →
+// 同一抽奖事务内加载套餐、新建订阅、发放时长、回写账本，最终整体 COMMIT。
+func TestDraw_E2E_VPNDurationAutoCreatesSubscription(t *testing.T) {
+	db, mock, cleanup := newTestDB(t)
+	defer cleanup()
+
+	expectRunningActivity(mock, 100)
+	expectPrizePool(mock, 100,
+		lottery.Prize{
+			Id: 30, ActivityId: 100, Slot: 5, Type: lottery.PrizeTypeVPNDuration,
+			Name:   "5 天",
+			Config: `{"duration_days":5,"subscribe_id":7}`,
+			Weight: 100,
+		},
+	)
+
+	realHandler := handler.NewVPNDurationHandler(handler.VPNDurationDeps{
+		UserModel:            fakeNoSubUserModel{},
+		Ledger:               fakeE2ELedger{},
+		DB:                   db,
+		ResolveEffectiveUser: func(_ context.Context, uid int64) (int64, error) { return uid, nil },
+	})
+
+	mock.ExpectBegin()
+	expectExistingDrawEmpty(mock)
+	// unlimited stock → no lottery_prize UPDATE
+	mock.ExpectExec("INSERT INTO `lottery_draw`").
+		WillReturnResult(sqlmock.NewResult(1234, 1))
+	mock.ExpectExec("INSERT INTO `lottery_prize_snapshot`").
+		WillReturnResult(sqlmock.NewResult(1, 1))
+	mock.ExpectExec("INSERT INTO `lottery_eligibility_snapshot`").
+		WillReturnResult(sqlmock.NewResult(1, 1))
+	// handler.Dispatch: findActiveSubscribe 的 DB 回退查询 → 无行
+	mock.ExpectQuery("FROM `user_subscribe`").
+		WillReturnError(gorm.ErrRecordNotFound)
+	// 加载 subscribe 套餐计划
+	mock.ExpectQuery("FROM `subscribe`").
+		WillReturnRows(sqlmock.NewRows([]string{"id", "traffic", "node_group_id"}).
+			AddRow(int64(7), int64(2048), int64(3)))
+	// 新建 user_subscribe
+	mock.ExpectExec("INSERT INTO `user_subscribe`").
+		WillReturnResult(sqlmock.NewResult(900, 1))
+	// 回写账本 payload
+	mock.ExpectExec("UPDATE `lottery_grant_ledger`").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+	// finalize draw.dispatch_state
+	mock.ExpectExec("UPDATE `lottery_draw`").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectCommit()
+
+	svc := NewService(Deps{
+		DB:             db,
+		Enabled:        true,
+		Chance:         &fakeChance{consumeRemaining: 1},
+		Evaluator:      &fakeEvaluator{passed: true},
+		Picker:         &fakePicker{idx: 0},
+		Registry:       &stubRegistry{handlers: map[string]lottery.PrizeHandler{lottery.PrizeTypeVPNDuration: realHandler}},
+		ContextBuilder: fakeContextBuilder{},
+	})
+	res, err := svc.Draw(context.Background(), Request{UserId: 42, ActivityId: 100, ClientNonce: "e2e-1"})
+	if err != nil {
+		t.Fatalf("Draw: %v", err)
+	}
+	if !res.IsWin {
+		t.Fatalf("expected IsWin=true for vpn_duration")
+	}
+	if !res.Claim.AutoClaimed {
+		t.Fatalf("expected AutoClaimed=true, got %+v", res.Claim)
+	}
+	if res.Message != "已新建订阅并加 5 天" {
+		t.Fatalf("expected auto-create message, got %q", res.Message)
+	}
+	if res.Prize == nil || res.Prize.Type != lottery.PrizeTypeVPNDuration {
+		t.Fatalf("expected vpn_duration prize summary, got %+v", res.Prize)
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Fatalf("unmet expectations: %v", err)
+	}
+}
+
+// TestDraw_E2E_VPNDurationNoPlanSkipsGrant 覆盖对照组：同样无活跃订阅，但奖品未配
+// subscribe_id → 真实 handler 走“跳过发放”，不产生任何订阅相关写操作，抽奖照常提交。
+func TestDraw_E2E_VPNDurationNoPlanSkipsGrant(t *testing.T) {
+	db, mock, cleanup := newTestDB(t)
+	defer cleanup()
+
+	expectRunningActivity(mock, 100)
+	expectPrizePool(mock, 100,
+		lottery.Prize{
+			Id: 31, ActivityId: 100, Slot: 5, Type: lottery.PrizeTypeVPNDuration,
+			Name:   "5 天",
+			Config: `{"duration_days":5}`,
+			Weight: 100,
+		},
+	)
+
+	realHandler := handler.NewVPNDurationHandler(handler.VPNDurationDeps{
+		UserModel:            fakeNoSubUserModel{},
+		Ledger:               fakeE2ELedger{},
+		DB:                   db,
+		ResolveEffectiveUser: func(_ context.Context, uid int64) (int64, error) { return uid, nil },
+	})
+
+	mock.ExpectBegin()
+	expectExistingDrawEmpty(mock)
+	mock.ExpectExec("INSERT INTO `lottery_draw`").
+		WillReturnResult(sqlmock.NewResult(1235, 1))
+	mock.ExpectExec("INSERT INTO `lottery_prize_snapshot`").
+		WillReturnResult(sqlmock.NewResult(1, 1))
+	mock.ExpectExec("INSERT INTO `lottery_eligibility_snapshot`").
+		WillReturnResult(sqlmock.NewResult(1, 1))
+	// findActiveSubscribe fallback → none; then skip (no subscribe/insert)
+	mock.ExpectQuery("FROM `user_subscribe`").
+		WillReturnError(gorm.ErrRecordNotFound)
+	mock.ExpectExec("UPDATE `lottery_grant_ledger`").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectExec("UPDATE `lottery_draw`").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectCommit()
+
+	svc := NewService(Deps{
+		DB:             db,
+		Enabled:        true,
+		Chance:         &fakeChance{consumeRemaining: 1},
+		Evaluator:      &fakeEvaluator{passed: true},
+		Picker:         &fakePicker{idx: 0},
+		Registry:       &stubRegistry{handlers: map[string]lottery.PrizeHandler{lottery.PrizeTypeVPNDuration: realHandler}},
+		ContextBuilder: fakeContextBuilder{},
+	})
+	res, err := svc.Draw(context.Background(), Request{UserId: 42, ActivityId: 100, ClientNonce: "e2e-2"})
+	if err != nil {
+		t.Fatalf("Draw: %v", err)
+	}
+	if !strings.Contains(res.Message, "跳过") {
+		t.Fatalf("expected skip message, got %q", res.Message)
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Fatalf("unmet expectations: %v", err)
+	}
+}

internal/logic/lottery/handler/vpn_duration.go

@@ -16,8 +16,11 @@ import (
 	"fmt"
 	"time"
 
+	"github.com/google/uuid"
 	"github.com/perfect-panel/server/internal/model/lottery"
+	subscribemodel "github.com/perfect-panel/server/internal/model/subscribe"
 	usermodel "github.com/perfect-panel/server/internal/model/user"
+	"github.com/perfect-panel/server/pkg/uuidx"
 	"gorm.io/gorm"
 )
 
@@ -88,6 +91,9 @@ func (*VPNDurationHandler) ClaimSchema() json.RawMessage { return nil }
 // vpnDurationConfig 是奖品 Config JSON 的解码目标。
 type vpnDurationConfig struct {
 	DurationDays int `json:"duration_days"`
+	// SubscribeId 指定“无活跃订阅时新建订阅”所用的套餐计划 ID。
+	// 0 表示不新建：延续历史行为（无活跃订阅则记录 skipped 不发放）。
+	SubscribeId int64 `json:"subscribe_id"`
 }
 
 // vpnDurationPayload 落库到 lottery_grant_ledger.payload，用于幂等重放时返回同一
@@ -151,7 +157,25 @@ func (h *VPNDurationHandler) Dispatch(ctx context.Context, tx *gorm.DB, req lott
 	// 未存在 → 真实发放。查用户的活跃订阅。
 	activeSub, findErr := h.findActiveSubscribe(ctx, effectiveUserID)
 	if errors.Is(findErr, gorm.ErrRecordNotFound) {
-		// 与 grantGiftDays 一致：无活跃订阅时记录 skipped 但不失败。
+		// 无活跃订阅：
+		//  - 若奖品配置了 subscribe_id，则按该套餐新建一条订阅并发放时长；
+		//  - 否则延续旧行为：记录 skipped 但不失败（避免抽奖事务因无处发放而回滚）。
+		if cfg.SubscribeId > 0 {
+			newSub, createErr := h.createSubscription(ctx, tx, effectiveUserID, req.DrawId, cfg)
+			if createErr != nil {
+				return lottery.DispatchResult{}, fmt.Errorf("auto-create subscribe for user %d: %w", effectiveUserID, createErr)
+			}
+			payload := vpnDurationPayload{
+				EffectiveUserID: effectiveUserID,
+				SubscribeID:     newSub.Id,
+				Days:            cfg.DurationDays,
+				Message:         fmt.Sprintf("已新建订阅并加 %d 天", cfg.DurationDays),
+			}
+			if err := h.writeBackPayload(ctx, tx, row.Id, payload); err != nil {
+				return lottery.DispatchResult{}, err
+			}
+			return lottery.DispatchResult{State: lottery.DispatchStateAutoClaimed, Message: payload.Message}, nil
+		}
 		payload := vpnDurationPayload{
 			EffectiveUserID: effectiveUserID,
 			Days:            cfg.DurationDays,
@@ -225,6 +249,41 @@ func (h *VPNDurationHandler) findActiveSubscribe(ctx context.Context, userID int
 	return &fallback, nil
 }
 
+// createSubscription 在无活跃订阅时，按奖品配置的 subscribe_id 套餐为用户新建一条
+// 订阅，时长为 cfg.DurationDays 天。套餐属性（流量、节点组）继承自计划，token/uuid
+// 现场生成。整个操作在 caller 的事务内完成，随抽奖事务一起提交/回滚。
+func (h *VPNDurationHandler) createSubscription(ctx context.Context, tx *gorm.DB, userID, drawID int64, cfg vpnDurationConfig) (*usermodel.Subscribe, error) {
+	if tx == nil {
+		return nil, errors.New("createSubscription requires a transaction")
+	}
+	var plan subscribemodel.Subscribe
+	if err := tx.WithContext(ctx).Where("id = ?", cfg.SubscribeId).First(&plan).Error; err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			return nil, fmt.Errorf("subscribe plan %d not found", cfg.SubscribeId)
+		}
+		return nil, err
+	}
+	now := time.Now()
+	// token 需全局唯一：用 lottery draw 维度做种子，避免与订单 token 冲突。
+	tokenSeed := fmt.Sprintf("lottery:%d:%d:%d", cfg.SubscribeId, userID, drawID)
+	newSub := &usermodel.Subscribe{
+		UserId:      userID,
+		OrderId:     0,
+		SubscribeId: plan.Id,
+		NodeGroupId: plan.NodeGroupId,
+		StartTime:   now,
+		ExpireTime:  now.Add(time.Duration(cfg.DurationDays) * 24 * time.Hour),
+		Traffic:     plan.Traffic,
+		Token:       uuidx.SubscribeToken(tokenSeed),
+		UUID:        uuid.New().String(),
+		Status:      1,
+	}
+	if err := tx.WithContext(ctx).Create(newSub).Error; err != nil {
+		return nil, err
+	}
+	return newSub, nil
+}
+
 func (h *VPNDurationHandler) writeBackPayload(ctx context.Context, tx *gorm.DB, ledgerID int64, payload vpnDurationPayload) error {
 	raw, err := json.Marshal(payload)
 	if err != nil {

internal/logic/lottery/handler/vpn_duration_test.go

@@ -343,3 +343,144 @@ func TestVPNDuration_BadConfigRejected(t *testing.T) {
 	}
 	_ = json.Unmarshal
 }
+
+// TestVPNDuration_NoActiveSubscribeCreatesSubscription 覆盖“无活跃订阅 + 奖品配置了
+// subscribe_id”时按该套餐新建订阅并发放时长的路径（问题2 的修复）。
+func TestVPNDuration_NoActiveSubscribeCreatesSubscription(t *testing.T) {
+	db, mock, cleanup := newHandlerTestDB(t)
+	defer cleanup()
+
+	ledger := &fakeLedger{
+		reserveFn: func(_ context.Context, _ *gorm.DB, entry lottery.GrantLedger) (*lottery.GrantLedger, bool, error) {
+			return &lottery.GrantLedger{Id: 5, ExternalRef: entry.ExternalRef}, false, nil
+		},
+	}
+	fake := &fakeUserModel{
+		findActive: func(context.Context, int64) (*usermodel.Subscribe, error) {
+			return nil, gorm.ErrRecordNotFound
+		},
+		updateSubscribe: func(context.Context, *usermodel.Subscribe, ...*gorm.DB) error {
+			t.Fatal("must NOT UpdateSubscribe when creating a new subscription")
+			return nil
+		},
+	}
+
+	// 1) findActiveSubscribe 的 DB 回退查询 → 无行
+	mock.ExpectQuery("FROM `user_subscribe`").
+		WillReturnError(gorm.ErrRecordNotFound)
+	// 2) 加载 subscribe 套餐计划
+	mock.ExpectQuery("FROM `subscribe`").
+		WillReturnRows(sqlmock.NewRows([]string{"id", "traffic", "node_group_id"}).
+			AddRow(int64(7), int64(1024), int64(3)))
+	// 3) 新建 user_subscribe
+	mock.ExpectExec("INSERT INTO `user_subscribe`").
+		WillReturnResult(sqlmock.NewResult(555, 1))
+	// 4) 回写 ledger payload
+	mock.ExpectExec("UPDATE `lottery_grant_ledger`").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	h := NewVPNDurationHandler(VPNDurationDeps{
+		Ledger: ledger, UserModel: fake, DB: db, ResolveEffectiveUser: identityResolver,
+	})
+	res, err := h.Dispatch(context.Background(), db, lottery.DispatchRequest{
+		UserId:         42,
+		ActivityId:     100,
+		DrawId:         200,
+		Prize:          lottery.Prize{Config: `{"duration_days":5,"subscribe_id":7}`},
+		IdempotencyKey: "lottery:100:200",
+	})
+	if err != nil {
+		t.Fatalf("Dispatch: %v", err)
+	}
+	if res.State != lottery.DispatchStateAutoClaimed {
+		t.Fatalf("expected auto_claimed, got %q", res.State)
+	}
+	if res.Message != "已新建订阅并加 5 天" {
+		t.Fatalf("unexpected message: %q", res.Message)
+	}
+}
+
+// TestVPNDuration_NoActiveSubscribeNoPlanStillSkips 确认未配置 subscribe_id 时，
+// 仍沿用旧的“跳过发放”行为（不新建订阅），保持向后兼容。
+func TestVPNDuration_NoActiveSubscribeNoPlanStillSkips(t *testing.T) {
+	db, mock, cleanup := newHandlerTestDB(t)
+	defer cleanup()
+
+	ledger := &fakeLedger{
+		reserveFn: func(_ context.Context, _ *gorm.DB, entry lottery.GrantLedger) (*lottery.GrantLedger, bool, error) {
+			return &lottery.GrantLedger{Id: 5, ExternalRef: entry.ExternalRef}, false, nil
+		},
+	}
+	fake := &fakeUserModel{
+		findActive: func(context.Context, int64) (*usermodel.Subscribe, error) {
+			return nil, gorm.ErrRecordNotFound
+		},
+		updateSubscribe: func(context.Context, *usermodel.Subscribe, ...*gorm.DB) error {
+			t.Fatal("must NOT touch subscription when no plan configured")
+			return nil
+		},
+	}
+
+	mock.ExpectQuery("FROM `user_subscribe`").
+		WillReturnError(gorm.ErrRecordNotFound)
+	mock.ExpectExec("UPDATE `lottery_grant_ledger`").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	h := NewVPNDurationHandler(VPNDurationDeps{
+		Ledger: ledger, UserModel: fake, DB: db, ResolveEffectiveUser: identityResolver,
+	})
+	res, err := h.Dispatch(context.Background(), db, lottery.DispatchRequest{
+		UserId:         42,
+		ActivityId:     100,
+		DrawId:         200,
+		Prize:          lottery.Prize{Config: `{"duration_days":5}`},
+		IdempotencyKey: "lottery:100:200",
+	})
+	if err != nil {
+		t.Fatalf("Dispatch: %v", err)
+	}
+	if !strings.Contains(res.Message, "跳过") {
+		t.Fatalf("expected skip message, got %q", res.Message)
+	}
+}
+
+// TestVPNDuration_NoActiveSubscribePlanNotFound 确认配置的 subscribe_id 不存在时，
+// Dispatch 返回错误（让抽奖事务回滚），而不是静默成功。
+func TestVPNDuration_NoActiveSubscribePlanNotFound(t *testing.T) {
+	db, mock, cleanup := newHandlerTestDB(t)
+	defer cleanup()
+
+	ledger := &fakeLedger{
+		reserveFn: func(_ context.Context, _ *gorm.DB, entry lottery.GrantLedger) (*lottery.GrantLedger, bool, error) {
+			return &lottery.GrantLedger{Id: 5, ExternalRef: entry.ExternalRef}, false, nil
+		},
+	}
+	fake := &fakeUserModel{
+		findActive: func(context.Context, int64) (*usermodel.Subscribe, error) {
+			return nil, gorm.ErrRecordNotFound
+		},
+		updateSubscribe: func(context.Context, *usermodel.Subscribe, ...*gorm.DB) error { return nil },
+	}
+
+	mock.ExpectQuery("FROM `user_subscribe`").
+		WillReturnError(gorm.ErrRecordNotFound)
+	mock.ExpectQuery("FROM `subscribe`").
+		WillReturnError(gorm.ErrRecordNotFound)
+
+	h := NewVPNDurationHandler(VPNDurationDeps{
+		Ledger: ledger, UserModel: fake, DB: db, ResolveEffectiveUser: identityResolver,
+	})
+	_, err := h.Dispatch(context.Background(), db, lottery.DispatchRequest{
+		UserId:         42,
+		ActivityId:     100,
+		DrawId:         200,
+		Prize:          lottery.Prize{Config: `{"duration_days":5,"subscribe_id":999}`},
+		IdempotencyKey: "lottery:100:200",
+	})
+	if err == nil {
+		t.Fatalf("expected error when configured plan is missing")
+	}
+	if !strings.Contains(err.Error(), "not found") {
+		t.Fatalf("expected 'not found' error, got %v", err)
+	}
+}

internal/model/lottery/weighted_picker.go

@@ -23,8 +23,12 @@ func NewWeightedPicker(seed int64) WeightedPicker {
 	}
 }
 
-// Pick 从 candidates 中返回一个索引。权重为 0 的奖品不参与随机；累计权重
-// 为 0（如所有奖品 weight 都是 0）返回 ErrEmptyPool。
+// Pick 从 candidates 中返回一个索引。以下奖品不参与随机：
+//   - 权重 <= 0
+//   - is_fallback=true 的保底奖（只在限量奖售罄时兜底发放，绝不能被随机抽中，
+//     否则真实奖品会被“谢谢参与”类保底项挤占）
+//
+// 累计权重为 0（无任何可抽奖品）返回 ErrEmptyPool。
 //
 // 算法：累计权重线性扫描一次，取 [0, total) 随机数落到哪个区间。稳定、
 // 不需要预分配，并对小池（<20 项）足够快。
@@ -32,9 +36,12 @@ func (p *weightedPicker) Pick(candidates []Prize) (int, error) {
 	if len(candidates) == 0 {
 		return 0, ErrEmptyPool
 	}
+	// eligible 判定：非保底 && 权重为正，才计入随机池。
+	eligible := func(c Prize) bool { return !c.IsFallback && c.Weight > 0 }
+
 	var total int64
 	for _, c := range candidates {
-		if c.Weight > 0 {
+		if eligible(c) {
 			total += int64(c.Weight)
 		}
 	}
@@ -48,7 +55,7 @@ func (p *weightedPicker) Pick(candidates []Prize) (int, error) {
 
 	var cum int64
 	for i, c := range candidates {
-		if c.Weight <= 0 {
+		if !eligible(c) {
 			continue
 		}
 		cum += int64(c.Weight)
@@ -56,9 +63,9 @@ func (p *weightedPicker) Pick(candidates []Prize) (int, error) {
 			return i, nil
 		}
 	}
-	// 走到这里说明浮点/累加异常，回退到最后一个非 0 权重项。
+	// 走到这里说明浮点/累加异常，回退到最后一个参与随机的项。
 	for i := len(candidates) - 1; i >= 0; i-- {
-		if candidates[i].Weight > 0 {
+		if eligible(candidates[i]) {
 			return i, nil
 		}
 	}

internal/model/lottery/weighted_picker_test.go

@@ -58,6 +58,34 @@ func TestWeightedPicker_DistributionCloseToWeights(t *testing.T) {
 	}
 }
 
+func TestWeightedPicker_ExcludesFallback(t *testing.T) {
+	p := NewWeightedPicker(3)
+	pool := []Prize{
+		{Id: 1, Weight: 100, IsFallback: true},         // 保底奖：即便权重很高也绝不被随机抽中
+		{Id: 2, Weight: 5, Type: PrizeTypeVPNDuration}, // 唯一可抽真实奖品
+	}
+	for i := 0; i < 300; i++ {
+		idx, err := p.Pick(pool)
+		if err != nil {
+			t.Fatalf("Pick err: %v", err)
+		}
+		if idx != 1 {
+			t.Fatalf("fallback prize must never be picked; expected idx 1, got %d", idx)
+		}
+	}
+}
+
+func TestWeightedPicker_AllFallbackYieldsEmptyPool(t *testing.T) {
+	p := NewWeightedPicker(9)
+	pool := []Prize{
+		{Id: 1, Weight: 10, IsFallback: true},
+		{Id: 2, Weight: 20, IsFallback: true},
+	}
+	if _, err := p.Pick(pool); err != ErrEmptyPool {
+		t.Fatalf("expected ErrEmptyPool when only fallback prizes exist, got %v", err)
+	}
+}
+
 func TestWeightedPicker_DeterministicWithFixedSeed(t *testing.T) {
 	pool := []Prize{
 		{Id: 1, Weight: 1},