diff --git a/config/config.go b/config/config.go
index 0079b29..85f6f96 100644
--- a/config/config.go
+++ b/config/config.go
@@ -14,6 +14,7 @@ type Config struct {
 	AlipaySandbox AlipaySandboxConfig `mapstructure:"alipay_sandbox"`
 	Wechat        WechatConfig        `mapstructure:"wechat"`
 	QuerySync     QuerySyncConfig     `mapstructure:"query_sync"`
+	Reconcile     ReconcileConfig     `mapstructure:"reconcile"`
 	// Biz 通用：任意业务系统（jiu / dudu / …）在 config 的 biz.<name> 下声明即可接入，无需改代码。
 	Biz map[string]BizSystemConfig `mapstructure:"biz"`
 	// Accounts 多账户配置注册表（v2）：凭证不写死配置，只存 env 前缀，真值运行时从环境变量取。
@@ -98,6 +99,23 @@ type QuerySyncConfig struct {
 	MaxAgeMin   int  `mapstructure:"max_age_min"`  // 只查创建时间在该分钟数内的待支付单
 }
 
+// ReconcileConfig v2 后台守护/对账周期任务开关与间隔。
+type ReconcileConfig struct {
+	Enabled            bool `mapstructure:"enabled"`
+	OrderTTLMin        int  `mapstructure:"order_ttl_min"`         // pending 订单存活 TTL(分钟),超则关闭
+	ExpireEverySec     int  `mapstructure:"expire_every_sec"`      // 过期清理间隔
+	SyncEverySec       int  `mapstructure:"sync_every_sec"`        // 查单对账间隔
+	UsageEverySec      int  `mapstructure:"usage_every_sec"`       // 用量快照刷新间隔
+	SpotCheckEverySec  int  `mapstructure:"spot_check_every_sec"`  // 已付抽查间隔
+	SpotCheckWindowMin int  `mapstructure:"spot_check_window_min"` // 抽查回溯窗(分钟)
+	OrphanEverySec     int  `mapstructure:"orphan_every_sec"`      // crypto 孤儿扫描间隔(Task 6)
+	OrphanWindowMin    int  `mapstructure:"orphan_window_min"`     // 孤儿扫描回溯窗(Task 6)
+	// —— 以下两项为 P4 T3 opus review 追加义务(退款修复扫描 + 卡滞退款告警),
+	// 本期归到本任务(对账主体)一起装配,brief 原表未列。
+	RefundApplyEverySec int `mapstructure:"refund_apply_every_sec"` // 退款修复扫描 + 卡滞告警 共用间隔
+	RefundStuckWarnMin  int `mapstructure:"refund_stuck_warn_min"`  // 退款卡滞 processing/manual_pending 告警阈值(分钟)
+}
+
 var C Config
 
 func Load() {
@@ -130,6 +148,17 @@ func Load() {
 	viper.SetDefault("query_sync.enabled", true)
 	viper.SetDefault("query_sync.interval_sec", 30)
 	viper.SetDefault("query_sync.max_age_min", 30)
+	viper.SetDefault("reconcile.enabled", true)
+	viper.SetDefault("reconcile.order_ttl_min", 60)
+	viper.SetDefault("reconcile.expire_every_sec", 300)
+	viper.SetDefault("reconcile.sync_every_sec", 30)
+	viper.SetDefault("reconcile.usage_every_sec", 60)
+	viper.SetDefault("reconcile.spot_check_every_sec", 300)
+	viper.SetDefault("reconcile.spot_check_window_min", 180)
+	viper.SetDefault("reconcile.orphan_every_sec", 300)
+	viper.SetDefault("reconcile.orphan_window_min", 180)
+	viper.SetDefault("reconcile.refund_apply_every_sec", 300)
+	viper.SetDefault("reconcile.refund_stuck_warn_min", 30)
 
 	if err := viper.ReadInConfig(); err != nil {
 		log.Println("[config] 未找到 config.yaml，使用默认值 + 环境变量")
diff --git a/internal/provider/crypto/crypto.go b/internal/provider/crypto/crypto.go
index 33b7520..0576132 100644
--- a/internal/provider/crypto/crypto.go
+++ b/internal/provider/crypto/crypto.go
@@ -73,6 +73,10 @@ func WithHTTPClient(c *http.Client) Option             { return func(p *Provider
 func WithReservationLoader(l ReservationLoader) Option { return func(p *Provider) { p.loader = l } }
 func WithNow(f func() time.Time) Option                { return func(p *Provider) { p.now = f } }
 
+// SetReservationLoader 构造后注入冷启动预留源(装配期 main 在 BuildRegistry 之后调用:
+// loader 依赖 OrderStore,而注册表构造不便传 store)。非并发安全,仅启动期单线程调用。
+func (p *Provider) SetReservationLoader(l ReservationLoader) { p.loader = l }
+
 func New(accts *accounts.Registry, opts ...Option) *Provider {
 	p := &Provider{
 		accts:    accts,
diff --git a/internal/reconcile/refund_apply.go b/internal/reconcile/refund_apply.go
new file mode 100644
index 0000000..fbfb561
--- /dev/null
+++ b/internal/reconcile/refund_apply.go
@@ -0,0 +1,119 @@
+package reconcile
+
+import (
+	"context"
+	"log"
+	"time"
+
+	"github.com/wangjia/pay/internal/model"
+	"github.com/wangjia/pay/internal/store"
+)
+
+// RefundApplyTask 是「RefundApply 修复扫描」:P4 T3 opus review 追加的义务(P4 退款
+// 代码本体在主 checkout,未落到本 worktree;此处只对本 worktree 已有的
+// store.RefundStore/OrderStore 接口(P4 T2,在 base 里)建自愈扫描,设计为能在合并
+// P4 后继续工作)。
+//
+// 动机:退款成功的崩溃窗口 —— RefundStore.MarkRefundStatus 把某笔退款翻成
+// succeeded 后,调用方在再调 OrderStore.ApplyRefundToOrder 前进程崩溃/网络抖动,
+// 订单状态卡在 paid(或旧的 partially_refunded),与「已实际退款成功」的事实脱节。
+// 本任务周期重算每个候选订单的 succeeded 退款之和,按既有 ApplyRefundToOrder 的
+// 条件 UPDATE 语义重新 apply 一次 —— 状态已一致时 UPDATE 影响 0 行,天然幂等。
+//
+// 候选订单 = distinct(有 succeeded 退款的订单) ∪ (当前处于 refunding/partially_refunded
+// 态的订单):前者直接命中"退款成功但订单未跟上"的崩溃窗口;后者兜住"已在退款流程
+// 中、但后续又有退款 succeeded 未被重算"的情形。
+func RefundApplyTask(orders *store.OrderStore, refunds *store.RefundStore, limit int) func(ctx context.Context) error {
+	return func(ctx context.Context) error {
+		succeededNos, err := refunds.ListDistinctOutTradeNosByStatus(model.RefundSucceeded, limit)
+		if err != nil {
+			return err
+		}
+		refundingOrders, err := orders.ListOrdersByStatus(
+			[]model.OrderStatusV2{model.OrderRefundingV2, model.OrderPartRefundedV2}, limit)
+		if err != nil {
+			return err
+		}
+
+		seen := make(map[string]bool, len(succeededNos)+len(refundingOrders))
+		candidates := make([]string, 0, len(succeededNos)+len(refundingOrders))
+		for _, no := range succeededNos {
+			if !seen[no] {
+				seen[no] = true
+				candidates = append(candidates, no)
+			}
+		}
+		for i := range refundingOrders {
+			no := refundingOrders[i].OutTradeNo
+			if !seen[no] {
+				seen[no] = true
+				candidates = append(candidates, no)
+			}
+		}
+
+		for _, no := range candidates {
+			if err := reapplyRefundState(orders, refunds, no); err != nil {
+				log.Printf("[reconcile] 退款修复扫描 out_trade_no=%s: %v", no, err)
+			}
+		}
+		return nil
+	}
+}
+
+// reapplyRefundState 对单个订单重算 succeeded 退款之和并按需重新 apply 状态转移。
+// 只有目标态与当前态不同才真正调用 ApplyRefundToOrder(避免每轮扫描都打"翻转"日志噪声);
+// 没有 succeeded 退款(sum==0)的订单跳过 —— 它不属于本扫描要修的窗口。
+func reapplyRefundState(orders *store.OrderStore, refunds *store.RefundStore, outTradeNo string) error {
+	succ, err := refunds.RefundSum(outTradeNo, model.RefundSucceeded)
+	if err != nil {
+		return err
+	}
+	if succ <= 0 {
+		return nil
+	}
+	o, err := orders.GetOrder(outTradeNo)
+	if err != nil {
+		return err
+	}
+
+	fully := succ >= o.AmountMinor
+	next := model.OrderPartRefundedV2
+	if fully {
+		next = model.OrderRefundedV2
+	}
+	if o.Status == next {
+		return nil // 已一致,无需自愈
+	}
+
+	flipped, err := orders.ApplyRefundToOrder(outTradeNo, fully)
+	if err != nil {
+		return err
+	}
+	if flipped {
+		log.Printf("[reconcile][退款自愈] out_trade_no=%s 本地曾卡于 %s,succeeded 退款 %d/%d → 重新 apply 为 %s",
+			outTradeNo, o.Status, succ, o.AmountMinor, next)
+	}
+	return nil
+}
+
+// RefundStuckAlertTask 是「卡滞 processing/manual_pending 退款告警」义务:同 sweep
+// 家族的姊妹任务,只读观测 —— 只打 WARN,绝不改状态(状态机翻转是
+// RefundApplyTask/业务方的事)。渠道退款查询 API 面(主动向渠道问退款进度)留待后续;
+// 这里先用「本地卡滞时长」兜底可见性。
+func RefundStuckAlertTask(refunds *store.RefundStore, threshold time.Duration, now func() time.Time) func(ctx context.Context) error {
+	return func(ctx context.Context) error {
+		cutoff := now().Add(-threshold)
+		stuck, err := refunds.ListStuckRefunds(
+			[]model.RefundStatus{model.RefundProcessing, model.RefundManualPending}, cutoff, 200)
+		if err != nil {
+			return err
+		}
+		for i := range stuck {
+			r := &stuck[i]
+			log.Printf("[reconcile][WARN][退款卡滞] refund_id=%s out_trade_no=%s status=%s 已卡滞 %s(阈值 %s)——"+
+				"仅观测告警不改状态;渠道退款查询 API 面留待后续",
+				r.RefundID, r.OutTradeNo, r.Status, now().Sub(r.UpdatedAt).Round(time.Minute), threshold)
+		}
+		return nil
+	}
+}
diff --git a/internal/reconcile/refund_apply_test.go b/internal/reconcile/refund_apply_test.go
new file mode 100644
index 0000000..8a3c752
--- /dev/null
+++ b/internal/reconcile/refund_apply_test.go
@@ -0,0 +1,189 @@
+package reconcile_test
+
+import (
+	"bytes"
+	"context"
+	"log"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/wangjia/pay/internal/model"
+	"github.com/wangjia/pay/internal/reconcile"
+	"github.com/wangjia/pay/internal/store"
+)
+
+// TestRefundApplyTaskSelfHealsStuckPaidOrder 钉住 P4 T3 review 的崩溃窗口:
+// MarkRefundStatus 把退款翻成 succeeded 后、调用方在调 ApplyRefundToOrder 前崩溃,
+// 订单卡在 paid。RefundApplyTask 应重算 succeeded 之和并重新 apply,自愈成
+// refunded(全额)。
+func TestRefundApplyTaskSelfHealsStuckPaidOrder(t *testing.T) {
+	db := model.OpenTestDB(t)
+	orders := store.NewOrderStore(db)
+	refunds := store.NewRefundStore(db)
+
+	if err := orders.CreateOrder(&model.OrderV2{OutTradeNo: "STUCK-1", AmountMinor: 10000, Currency: "CNY", Status: model.OrderPaidV2}); err != nil {
+		t.Fatal(err)
+	}
+	if err := refunds.CreateRefund(&model.Refund{RefundID: "rf-stuck-1", OutTradeNo: "STUCK-1", AttemptProviderRef: "STUCK-1",
+		AmountMinor: 10000, Currency: "CNY", Status: model.RefundSucceeded, InitiatedBy: "business"}); err != nil {
+		t.Fatal(err)
+	}
+
+	task := reconcile.RefundApplyTask(orders, refunds, 200)
+	if err := task(context.Background()); err != nil {
+		t.Fatalf("task: %v", err)
+	}
+
+	o, err := orders.GetOrder("STUCK-1")
+	if err != nil || o.Status != model.OrderRefundedV2 {
+		t.Fatalf("应自愈为 refunded, got %+v, err=%v", o, err)
+	}
+}
+
+// TestRefundApplyTaskPartialStaysPartial 部分退款(succeeded 之和 < 订单金额)应自愈为
+// partially_refunded,而非误判 fully。
+func TestRefundApplyTaskPartialStaysPartial(t *testing.T) {
+	db := model.OpenTestDB(t)
+	orders := store.NewOrderStore(db)
+	refunds := store.NewRefundStore(db)
+
+	if err := orders.CreateOrder(&model.OrderV2{OutTradeNo: "STUCK-2", AmountMinor: 10000, Currency: "CNY", Status: model.OrderPaidV2}); err != nil {
+		t.Fatal(err)
+	}
+	if err := refunds.CreateRefund(&model.Refund{RefundID: "rf-stuck-2", OutTradeNo: "STUCK-2", AttemptProviderRef: "STUCK-2",
+		AmountMinor: 4000, Currency: "CNY", Status: model.RefundSucceeded, InitiatedBy: "business"}); err != nil {
+		t.Fatal(err)
+	}
+
+	task := reconcile.RefundApplyTask(orders, refunds, 200)
+	if err := task(context.Background()); err != nil {
+		t.Fatalf("task: %v", err)
+	}
+	o, err := orders.GetOrder("STUCK-2")
+	if err != nil || o.Status != model.OrderPartRefundedV2 {
+		t.Fatalf("应自愈为 partially_refunded, got %+v, err=%v", o, err)
+	}
+}
+
+// TestRefundApplyTaskIdempotentNoOpOnRerun 幂等:自愈一次后重跑不应报错、不应再次
+// "翻转"(状态已一致,ApplyRefundToOrder 不应被重复触发出错误的副作用)。
+func TestRefundApplyTaskIdempotentNoOpOnRerun(t *testing.T) {
+	db := model.OpenTestDB(t)
+	orders := store.NewOrderStore(db)
+	refunds := store.NewRefundStore(db)
+
+	if err := orders.CreateOrder(&model.OrderV2{OutTradeNo: "STUCK-3", AmountMinor: 5000, Currency: "CNY", Status: model.OrderPaidV2}); err != nil {
+		t.Fatal(err)
+	}
+	if err := refunds.CreateRefund(&model.Refund{RefundID: "rf-stuck-3", OutTradeNo: "STUCK-3", AttemptProviderRef: "STUCK-3",
+		AmountMinor: 5000, Currency: "CNY", Status: model.RefundSucceeded, InitiatedBy: "business"}); err != nil {
+		t.Fatal(err)
+	}
+
+	task := reconcile.RefundApplyTask(orders, refunds, 200)
+	for i := 0; i < 3; i++ {
+		if err := task(context.Background()); err != nil {
+			t.Fatalf("run %d: %v", i, err)
+		}
+	}
+	o, err := orders.GetOrder("STUCK-3")
+	if err != nil || o.Status != model.OrderRefundedV2 {
+		t.Fatalf("重跑后仍应 refunded, got %+v, err=%v", o, err)
+	}
+}
+
+// TestRefundApplyTaskConsistentOrderUntouched 已一致(无 succeeded 退款,或订单已是
+// 该退款对应的终态)的订单不应被误触发。
+func TestRefundApplyTaskConsistentOrderUntouched(t *testing.T) {
+	db := model.OpenTestDB(t)
+	orders := store.NewOrderStore(db)
+	refunds := store.NewRefundStore(db)
+
+	if err := orders.CreateOrder(&model.OrderV2{OutTradeNo: "OK-1", AmountMinor: 1000, Currency: "CNY", Status: model.OrderPaidV2}); err != nil {
+		t.Fatal(err)
+	}
+	// 有一笔 processing(未 succeeded)退款,不该触发自愈。
+	if err := refunds.CreateRefund(&model.Refund{RefundID: "rf-ok-1", OutTradeNo: "OK-1", AttemptProviderRef: "OK-1",
+		AmountMinor: 500, Currency: "CNY", Status: model.RefundProcessing, InitiatedBy: "business"}); err != nil {
+		t.Fatal(err)
+	}
+
+	task := reconcile.RefundApplyTask(orders, refunds, 200)
+	if err := task(context.Background()); err != nil {
+		t.Fatalf("task: %v", err)
+	}
+	o, err := orders.GetOrder("OK-1")
+	if err != nil || o.Status != model.OrderPaidV2 {
+		t.Fatalf("无 succeeded 退款不应被翻转, got %+v, err=%v", o, err)
+	}
+}
+
+// TestRefundStuckAlertTaskLogsWarnWithoutChangingState 卡滞 processing/manual_pending
+// 超阈值只应打 WARN 日志,不改任何状态(观测型)。
+func TestRefundStuckAlertTaskLogsWarnWithoutChangingState(t *testing.T) {
+	db := model.OpenTestDB(t)
+	refunds := store.NewRefundStore(db)
+	now := time.Date(2026, 7, 10, 12, 0, 0, 0, time.UTC)
+
+	if err := refunds.CreateRefund(&model.Refund{RefundID: "rf-stall-1", OutTradeNo: "STALL-1",
+		AmountMinor: 100, Currency: "CNY", Status: model.RefundProcessing}); err != nil {
+		t.Fatal(err)
+	}
+	if err := db.Model(&model.Refund{}).Where("refund_id = ?", "rf-stall-1").
+		Update("updated_at", now.Add(-45*time.Minute)).Error; err != nil {
+		t.Fatal(err)
+	}
+
+	var buf bytes.Buffer
+	orig := log.Writer()
+	log.SetOutput(&buf)
+	defer log.SetOutput(orig)
+
+	task := reconcile.RefundStuckAlertTask(refunds, 30*time.Minute, func() time.Time { return now })
+	if err := task(context.Background()); err != nil {
+		t.Fatalf("task: %v", err)
+	}
+
+	if !strings.Contains(buf.String(), "rf-stall-1") || !strings.Contains(buf.String(), "WARN") {
+		t.Fatalf("应打 WARN 日志含 refund_id, got: %s", buf.String())
+	}
+
+	r, err := refunds.GetRefund("rf-stall-1")
+	if err != nil || r.Status != model.RefundProcessing {
+		t.Fatalf("告警不应改状态, got %+v, err=%v", r, err)
+	}
+}
+
+// TestRefundStuckAlertTaskSkipsFreshAndTerminal 未超阈值 / 已终态的退款不应被告警。
+func TestRefundStuckAlertTaskSkipsFreshAndTerminal(t *testing.T) {
+	db := model.OpenTestDB(t)
+	refunds := store.NewRefundStore(db)
+	now := time.Date(2026, 7, 10, 12, 0, 0, 0, time.UTC)
+
+	if err := refunds.CreateRefund(&model.Refund{RefundID: "rf-fresh", OutTradeNo: "FRESH-1",
+		AmountMinor: 100, Currency: "CNY", Status: model.RefundProcessing}); err != nil {
+		t.Fatal(err)
+	}
+	if err := refunds.CreateRefund(&model.Refund{RefundID: "rf-done", OutTradeNo: "DONE-1",
+		AmountMinor: 100, Currency: "CNY", Status: model.RefundSucceeded}); err != nil {
+		t.Fatal(err)
+	}
+	if err := db.Model(&model.Refund{}).Where("refund_id = ?", "rf-done").
+		Update("updated_at", now.Add(-2*time.Hour)).Error; err != nil {
+		t.Fatal(err)
+	}
+
+	var buf bytes.Buffer
+	orig := log.Writer()
+	log.SetOutput(&buf)
+	defer log.SetOutput(orig)
+
+	task := reconcile.RefundStuckAlertTask(refunds, 30*time.Minute, func() time.Time { return now })
+	if err := task(context.Background()); err != nil {
+		t.Fatalf("task: %v", err)
+	}
+	if strings.Contains(buf.String(), "rf-fresh") || strings.Contains(buf.String(), "rf-done") {
+		t.Fatalf("未超阈值/已终态不应告警, got: %s", buf.String())
+	}
+}
diff --git a/internal/reconcile/sync.go b/internal/reconcile/sync.go
new file mode 100644
index 0000000..749b2a4
--- /dev/null
+++ b/internal/reconcile/sync.go
@@ -0,0 +1,59 @@
+package reconcile
+
+import (
+	"context"
+	"log"
+	"time"
+
+	"github.com/wangjia/pay/internal/gateway"
+	"github.com/wangjia/pay/internal/provider"
+	"github.com/wangjia/pay/internal/store"
+)
+
+// SyncPendingTask 调度 P2 gateway.SyncPendingAttempts:逐 pending attempt 查单收敛(防掉单)。
+// 其内部已对 not_found/amount_mismatch/failed 打日志(settle-sync,764ed55),此处不重复。
+func SyncPendingTask(gw *gateway.Gateway, limit int) func(ctx context.Context) error {
+	return func(ctx context.Context) error {
+		n, err := gw.SyncPendingAttempts(ctx, limit)
+		if err != nil {
+			return err
+		}
+		if n > 0 {
+			log.Printf("[reconcile] 查单对账收敛 %d 笔待支付 → paid", n)
+		}
+		return nil
+	}
+}
+
+// PaidSpotCheckTask 已付订单抽查:对近 window 内已付 attempt 反查渠道,金额/币种漂移即告警
+// (如渠道侧已退款/拒付而本地仍 paid)。只发现不改状态——状态机翻转属 P4。
+// crypto 之类 query-only 渠道:paid 后再查若命中同额即一致;查不到(链上历史滚出窗口)不报错跳过。
+func PaidSpotCheckTask(orders *store.OrderStore, providers *provider.Registry, window time.Duration, now func() time.Time) func(ctx context.Context) error {
+	return func(ctx context.Context) error {
+		atts, err := orders.ListRecentlyPaidAttempts(now().Add(-window), 100)
+		if err != nil {
+			return err
+		}
+		for i := range atts {
+			a := &atts[i]
+			prov, err := providers.Get(a.Channel)
+			if err != nil {
+				continue
+			}
+			created := a.CreatedAt
+			ev, err := prov.Query(ctx, provider.QueryRequest{
+				ProviderRef: a.ProviderRef, OutTradeNo: a.OutTradeNo, AccountID: a.AccountID,
+				AmountMinor: a.AmountMinor, Currency: a.Currency, CreatedAt: created, ExpiresAt: a.ExpiresAt,
+			})
+			if err != nil || ev == nil {
+				continue // 查不到/瞬时错:抽查尽力而为,不阻断
+			}
+			// 本地 paid,渠道却报非成功,或金额/币种对不上 → 对账差异,必须可见。
+			if ev.Status != provider.PaidSucceeded || ev.PaidCurrency != a.Currency || ev.PaidAmountMinor < a.AmountMinor {
+				log.Printf("[reconcile][对账差异] attempt=%s channel=%s 本地 paid 但渠道 status=%s amount=%d/%s(本地 %d/%s)",
+					a.ProviderRef, a.Channel, ev.Status, ev.PaidAmountMinor, ev.PaidCurrency, a.AmountMinor, a.Currency)
+			}
+		}
+		return nil
+	}
+}
diff --git a/internal/reconcile/sync_test.go b/internal/reconcile/sync_test.go
new file mode 100644
index 0000000..475aca6
--- /dev/null
+++ b/internal/reconcile/sync_test.go
@@ -0,0 +1,72 @@
+package reconcile_test
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/wangjia/pay/config"
+	"github.com/wangjia/pay/internal/accounts"
+	"github.com/wangjia/pay/internal/gateway"
+	"github.com/wangjia/pay/internal/model"
+	"github.com/wangjia/pay/internal/provider"
+	"github.com/wangjia/pay/internal/provider/fake"
+	"github.com/wangjia/pay/internal/reconcile"
+	"github.com/wangjia/pay/internal/store"
+)
+
+type stubResolver struct{}
+
+func (stubResolver) Resolve(sku, currency string) (int64, string, string, error) {
+	return 29990000, "Pro", "pro_year", nil
+}
+
+type nopEnq struct{}
+
+// Enqueue 签名依当前仓库 gateway.WebhookEnqueuer(4 个 string + map;brief 草稿只写 3 个 —
+// P4 T2 之后加了 refundID 参数,此处适配现状,见 task-5-report.md 记录的漂移)。
+func (nopEnq) Enqueue(_, _, _, _ string, _ map[string]any) error { return nil }
+
+func TestSyncPendingTaskSettlesViaQuery(t *testing.T) {
+	db := model.OpenTestDB(t)
+	orders := store.NewOrderStore(db)
+	preg := provider.NewRegistry()
+	fp := fake.New()
+	preg.Register(fp)
+	areg := accounts.New([]config.AccountConfig{{AccountID: "fake-a1", Channel: "fake", Region: "global", Enabled: true}})
+	gw := gateway.New(orders, preg, accounts.NewRouter(areg, nil, nil), stubResolver{}, nopEnq{}, "global")
+
+	res, _ := gw.CreateOrder(context.Background(), gateway.CreateOrderInput{SKU: "pro_year", Method: "fake", BizSystem: "pangolin", BizRef: "u-1"})
+	atts, _ := orders.ListAttemptsByStatus(model.AttemptPending, 10)
+	fp.SetQueryResult(atts[0].ProviderRef, provider.PaidEvent{
+		ProviderRef: atts[0].ProviderRef, Status: provider.PaidSucceeded, PaidAmountMinor: 29990000, PaidCurrency: "USDT"})
+
+	task := reconcile.SyncPendingTask(gw, 50)
+	if err := task(context.Background()); err != nil {
+		t.Fatalf("task: %v", err)
+	}
+	o, _ := orders.GetOrder(res.OrderNo)
+	if o.Status != model.OrderPaidV2 {
+		t.Fatalf("查单对账后应 paid, got %v", o.Status)
+	}
+	_ = time.Second
+}
+
+func TestPaidSpotCheckTaskRunsCleanOnConsistent(t *testing.T) {
+	db := model.OpenTestDB(t)
+	orders := store.NewOrderStore(db)
+	preg := provider.NewRegistry()
+	fp := fake.New()
+	preg.Register(fp)
+	now := time.Date(2026, 7, 10, 12, 0, 0, 0, time.UTC)
+	paid := now.Add(-10 * time.Minute)
+	_ = orders.CreateAttempt(&model.Attempt{OutTradeNo: "O1", Channel: "fake", ProviderRef: "R-O1",
+		AmountMinor: 100, Currency: "USDT", Status: model.AttemptPaid, PaidAt: &paid})
+	// 渠道侧查单仍报 succeeded 同额 → 一致,无告警。
+	fp.SetQueryResult("R-O1", provider.PaidEvent{ProviderRef: "R-O1", Status: provider.PaidSucceeded, PaidAmountMinor: 100, PaidCurrency: "USDT"})
+
+	task := reconcile.PaidSpotCheckTask(orders, preg, time.Hour, func() time.Time { return now })
+	if err := task(context.Background()); err != nil {
+		t.Fatalf("spotcheck: %v", err) // 只求不报错、不 panic;漂移检测走日志
+	}
+}
diff --git a/internal/store/order_query.go b/internal/store/order_query.go
index 53884d0..1f07bae 100644
--- a/internal/store/order_query.go
+++ b/internal/store/order_query.go
@@ -147,3 +147,30 @@ func (s *OrderStore) SumPaidAttemptMinorByAccountSince(since time.Time) (map[str
 	}
 	return out, nil
 }
+
+// ListRecentlyPaidAttempts 列近期(paid_at>=since)已付 attempt,供对账抽查反查渠道核对。
+func (s *OrderStore) ListRecentlyPaidAttempts(since time.Time, limit int) ([]model.Attempt, error) {
+	if limit <= 0 || limit > 500 {
+		limit = 100
+	}
+	var out []model.Attempt
+	if err := s.db.Where("status = ? AND paid_at >= ?", model.AttemptPaid, since).
+		Order("id DESC").Limit(limit).Find(&out).Error; err != nil {
+		return nil, fmt.Errorf("store.ListRecentlyPaidAttempts: %w", err)
+	}
+	return out, nil
+}
+
+// ListOrdersByStatus 按状态集合列订单,供退款修复扫描(Task 5 P4 义务)定位「当前处于
+// 退款相关态」的候选订单,与 RefundStore.ListDistinctOutTradeNosByStatus(succeeded)取并集。
+func (s *OrderStore) ListOrdersByStatus(statuses []model.OrderStatusV2, limit int) ([]model.OrderV2, error) {
+	if limit <= 0 || limit > 500 {
+		limit = 200
+	}
+	var out []model.OrderV2
+	if err := s.db.Where("status IN ?", statuses).
+		Order("id ASC").Limit(limit).Find(&out).Error; err != nil {
+		return nil, fmt.Errorf("store.ListOrdersByStatus: %w", err)
+	}
+	return out, nil
+}
diff --git a/internal/store/order_query_test.go b/internal/store/order_query_test.go
index 820714d..968aa50 100644
--- a/internal/store/order_query_test.go
+++ b/internal/store/order_query_test.go
@@ -123,3 +123,56 @@ func TestSumPaidAttemptMinorByAccountSince(t *testing.T) {
 		t.Fatalf("聚合 = %+v, want acct-1=15000 acct-2=7000", got)
 	}
 }
+
+func TestListRecentlyPaidAttempts(t *testing.T) {
+	db := model.OpenTestDB(t)
+	s := store.NewOrderStore(db)
+	now := time.Date(2026, 7, 10, 12, 0, 0, 0, time.UTC)
+	mk := func(no string, st model.AttemptStatus, paidAgo time.Duration) {
+		paid := now.Add(-paidAgo)
+		_ = s.CreateAttempt(&model.Attempt{OutTradeNo: no, Channel: "fake", ProviderRef: "R-" + no,
+			AmountMinor: 100, Currency: "USDT", Status: st, PaidAt: &paid})
+	}
+	mk("RECENT", model.AttemptPaid, 10*time.Minute) // 近期已付 → 命中
+	mk("OLD", model.AttemptPaid, 5*time.Hour)       // 太旧 → 不命中
+	mk("PEND", model.AttemptPending, 1*time.Minute) // 未付 → 不命中
+
+	got, err := s.ListRecentlyPaidAttempts(now.Add(-time.Hour), 50)
+	if err != nil {
+		t.Fatalf("list: %v", err)
+	}
+	if len(got) != 1 || got[0].OutTradeNo != "RECENT" {
+		t.Fatalf("只应含 RECENT, got %+v", got)
+	}
+}
+
+// TestListOrdersByStatus 供 P6+P4 义务的「退款修复扫描」定位候选订单:按状态集合
+// 列订单(如 refunding/partially_refunded),与 refund 表的 succeeded 记录取并集
+// 作为重算候选。
+func TestListOrdersByStatus(t *testing.T) {
+	db := model.OpenTestDB(t)
+	s := store.NewOrderStore(db)
+	mk := func(no string, st model.OrderStatusV2) {
+		_ = s.CreateOrder(&model.OrderV2{OutTradeNo: no, AmountMinor: 100, Currency: "CNY", Status: st})
+	}
+	mk("O-PAID", model.OrderPaidV2)
+	mk("O-REFUNDING", model.OrderRefundingV2)
+	mk("O-PART", model.OrderPartRefundedV2)
+	mk("O-DONE", model.OrderRefundedV2)
+	mk("O-PENDING", model.OrderPendingV2)
+
+	got, err := s.ListOrdersByStatus([]model.OrderStatusV2{model.OrderRefundingV2, model.OrderPartRefundedV2}, 50)
+	if err != nil {
+		t.Fatalf("list: %v", err)
+	}
+	if len(got) != 2 {
+		t.Fatalf("应命中 2 张(REFUNDING/PART), got %d: %+v", len(got), got)
+	}
+	seen := map[string]bool{}
+	for _, o := range got {
+		seen[o.OutTradeNo] = true
+	}
+	if !seen["O-REFUNDING"] || !seen["O-PART"] {
+		t.Fatalf("命中集合不对: %+v", got)
+	}
+}
diff --git a/internal/store/refund.go b/internal/store/refund.go
index 4f93df4..49370be 100644
--- a/internal/store/refund.go
+++ b/internal/store/refund.go
@@ -128,6 +128,38 @@ func (s *RefundStore) MarkRefundStatus(refundID string, from, to model.RefundSta
 	return res.RowsAffected > 0, nil
 }
 
+// ListDistinctOutTradeNosByStatus 列有某状态退款的 distinct out_trade_no,供退款修复
+// 扫描(RefundApplyTask)定位「有 succeeded 退款」的候选订单——self-heal「退款成功但
+// 订单卡 paid」的崩溃窗口(P4 T3 review 义务,见 task-5-brief 外的两条追加义务)。
+func (s *RefundStore) ListDistinctOutTradeNosByStatus(status model.RefundStatus, limit int) ([]string, error) {
+	if limit <= 0 || limit > 500 {
+		limit = 200
+	}
+	var out []string
+	if err := s.db.Model(&model.Refund{}).Where("status = ?", status).
+		Group("out_trade_no").Order("out_trade_no ASC").Limit(limit).
+		Pluck("out_trade_no", &out).Error; err != nil {
+		return nil, fmt.Errorf("store.ListDistinctOutTradeNosByStatus: %w", err)
+	}
+	return out, nil
+}
+
+// ListStuckRefunds 列 status 落在给定集合、且 updated_at 早于 before 的退款行,供
+// 「卡滞 processing/manual_pending 退款告警」只读观测扫描用(不改状态)。updated_at
+// 用作「进入当前状态」的近似时刻——本表除 MarkRefundStatus/CreateRefundGuarded 外
+// 不写,近似成立。
+func (s *RefundStore) ListStuckRefunds(statuses []model.RefundStatus, before time.Time, limit int) ([]model.Refund, error) {
+	if limit <= 0 || limit > 500 {
+		limit = 200
+	}
+	var out []model.Refund
+	if err := s.db.Where("status IN ? AND updated_at < ?", statuses, before).
+		Order("updated_at ASC").Limit(limit).Find(&out).Error; err != nil {
+		return nil, fmt.Errorf("store.ListStuckRefunds: %w", err)
+	}
+	return out, nil
+}
+
 // ListManualPending lists refunds awaiting manual (crypto) settlement.
 func (s *RefundStore) ListManualPending(limit int) ([]model.Refund, error) {
 	if limit <= 0 || limit > 200 {
diff --git a/internal/store/refund_test.go b/internal/store/refund_test.go
index 906f925..7370a5e 100644
--- a/internal/store/refund_test.go
+++ b/internal/store/refund_test.go
@@ -100,6 +100,68 @@ func TestApplyRefundToOrderFully(t *testing.T) {
 	}
 }
 
+// TestListDistinctOutTradeNosByStatus 供退款修复扫描定位「有 succeeded 退款」的候选
+// 订单(自愈依据):同订单多笔 succeeded 退款只应出现一次(distinct)。
+func TestListDistinctOutTradeNosByStatus(t *testing.T) {
+	db := model.OpenTestDB(t)
+	rs := NewRefundStore(db)
+	_ = rs.CreateRefund(&model.Refund{RefundID: "s1", OutTradeNo: "PAY-S1", AmountMinor: 100, Currency: "CNY", Status: model.RefundSucceeded})
+	_ = rs.CreateRefund(&model.Refund{RefundID: "s2", OutTradeNo: "PAY-S1", AmountMinor: 200, Currency: "CNY", Status: model.RefundSucceeded}) // 同单第二笔
+	_ = rs.CreateRefund(&model.Refund{RefundID: "s3", OutTradeNo: "PAY-S2", AmountMinor: 100, Currency: "CNY", Status: model.RefundSucceeded})
+	_ = rs.CreateRefund(&model.Refund{RefundID: "p1", OutTradeNo: "PAY-S3", AmountMinor: 100, Currency: "CNY", Status: model.RefundProcessing}) // 非 succeeded,不应命中
+
+	got, err := rs.ListDistinctOutTradeNosByStatus(model.RefundSucceeded, 50)
+	if err != nil {
+		t.Fatalf("list: %v", err)
+	}
+	if len(got) != 2 {
+		t.Fatalf("应 distinct 出 2 个 out_trade_no, got %d: %+v", len(got), got)
+	}
+	seen := map[string]bool{}
+	for _, no := range got {
+		seen[no] = true
+	}
+	if !seen["PAY-S1"] || !seen["PAY-S2"] {
+		t.Fatalf("命中集合不对: %+v", got)
+	}
+}
+
+// TestListStuckRefunds 供「卡滞 processing/manual_pending 退款告警」:只挑 updated_at
+// 早于阈值的 processing/manual_pending 行,requested/succeeded/failed 不命中。
+func TestListStuckRefunds(t *testing.T) {
+	db := model.OpenTestDB(t)
+	rs := NewRefundStore(db)
+	now := time.Date(2026, 7, 10, 12, 0, 0, 0, time.UTC)
+	mk := func(id, no string, st model.RefundStatus, updatedAgo time.Duration) {
+		if err := rs.CreateRefund(&model.Refund{RefundID: id, OutTradeNo: no, AmountMinor: 100, Currency: "CNY", Status: st}); err != nil {
+			t.Fatal(err)
+		}
+		if err := db.Model(&model.Refund{}).Where("refund_id = ?", id).
+			Update("updated_at", now.Add(-updatedAgo)).Error; err != nil {
+			t.Fatal(err)
+		}
+	}
+	mk("stuck-proc", "PAY-T1", model.RefundProcessing, 45*time.Minute)   // 超阈值 → 命中
+	mk("fresh-proc", "PAY-T2", model.RefundProcessing, 5*time.Minute)    // 未超 → 不命中
+	mk("stuck-manual", "PAY-T3", model.RefundManualPending, 2*time.Hour) // 超阈值 → 命中
+	mk("done", "PAY-T4", model.RefundSucceeded, 2*time.Hour)             // 已终态 → 不命中
+
+	got, err := rs.ListStuckRefunds([]model.RefundStatus{model.RefundProcessing, model.RefundManualPending}, now.Add(-30*time.Minute), 50)
+	if err != nil {
+		t.Fatalf("list: %v", err)
+	}
+	if len(got) != 2 {
+		t.Fatalf("应命中 2 笔卡滞, got %d: %+v", len(got), got)
+	}
+	seen := map[string]bool{}
+	for _, r := range got {
+		seen[r.RefundID] = true
+	}
+	if !seen["stuck-proc"] || !seen["stuck-manual"] {
+		t.Fatalf("命中集合不对: %+v", got)
+	}
+}
+
 func TestListManualPending(t *testing.T) {
 	db := model.OpenTestDB(t)
 	rs := NewRefundStore(db)
diff --git a/main.go b/main.go
index 17813e7..2cd8cdc 100644
--- a/main.go
+++ b/main.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"errors"
 	"log"
 	"strings"
@@ -17,6 +18,7 @@ import (
 	"github.com/wangjia/pay/internal/gateway"
 	"github.com/wangjia/pay/internal/model"
 	"github.com/wangjia/pay/internal/providerbuild"
+	"github.com/wangjia/pay/internal/reconcile"
 	"github.com/wangjia/pay/internal/router"
 	"github.com/wangjia/pay/internal/store"
 	"github.com/wangjia/pay/internal/webhook"
@@ -53,11 +55,39 @@ func main() {
 	acctReg := accounts.New(config.C.Accounts)
 	pReg := providerbuild.BuildRegistry(acctReg) // 配置驱动:有 enabled 账户才注册对应渠道(P3)
 	// P5 多账户路由:按 config.routing.<channel> 选策略(缺省 round_robin)。
-	// limit_aware 用量数据源 P6 对账就绪前用空源(NopUsage,退化为 round_robin)。
-	acctPicker := accounts.NewRouter(acctReg, config.C.Routing, accounts.NopUsage{})
+	// limit_aware 用量数据源:P6 对账 Runner 周期 Refresh 的真实用量源(替 NopUsage)。
+	usage := reconcile.NewUsageSource(orderStore, time.Now)
+	acctPicker := accounts.NewRouter(acctReg, config.C.Routing, usage)
 	gw := gateway.New(orderStore, pReg, acctPicker, productResolver, notifier, "cn")
 	router.SetupV2(r, gw)
 
+	// P6 后台守护 / 对账:订单过期清理 + 用量刷新 + 查单对账收敛 + 已付抽查 +
+	// 退款修复扫描/卡滞告警(P4 T3 review 追加义务,归到本任务一起装配)。
+	// crypto 预留冷启动 Warm + 孤儿扫描留给 Task 6 追加(AddCryptoJobs)。
+	if config.C.Reconcile.Enabled {
+		rc := config.C.Reconcile
+		refundStore := store.NewRefundStore(db)
+		runner := reconcile.NewRunner()
+		runner.Add("order-expire", time.Duration(rc.ExpireEverySec)*time.Second,
+			reconcile.OrderExpirerTask(orderStore, time.Duration(rc.OrderTTLMin)*time.Minute, time.Now))
+		runner.Add("usage-refresh", time.Duration(rc.UsageEverySec)*time.Second,
+			reconcile.RefreshUsageTask(usage))
+		runner.Add("sync-pending", time.Duration(rc.SyncEverySec)*time.Second,
+			reconcile.SyncPendingTask(gw, 100))
+		runner.Add("paid-spotcheck", time.Duration(rc.SpotCheckEverySec)*time.Second,
+			reconcile.PaidSpotCheckTask(orderStore, pReg, time.Duration(rc.SpotCheckWindowMin)*time.Minute, time.Now))
+		runner.Add("refund-apply-sweep", time.Duration(rc.RefundApplyEverySec)*time.Second,
+			reconcile.RefundApplyTask(orderStore, refundStore, 200))
+		runner.Add("refund-stuck-alert", time.Duration(rc.RefundApplyEverySec)*time.Second,
+			reconcile.RefundStuckAlertTask(refundStore, time.Duration(rc.RefundStuckWarnMin)*time.Minute, time.Now))
+		// crypto 孤儿扫描(Task 6)在此追加:reconcile.AddCryptoJobs(runner, pReg, acctReg, orderStore, rc)
+
+		ctx := context.Background()
+		runner.RunOnce(ctx) // 启动预热:先跑一遍(usage 快照/过期清理/退款自愈立即生效)
+		runner.Start(ctx)
+		log.Printf("[reconcile] 后台守护已启动(过期清理/用量刷新/查单对账/已付抽查/退款修复扫描/退款卡滞告警)")
+	}
+
 	if config.C.QuerySync.Enabled {
 		orderSvc.StartQuerySync(
 			time.Duration(config.C.QuerySync.IntervalSec)*time.Second,