diff --git a/docs/membership/redeem_integration_2026-02-28.md b/docs/membership/redeem_integration_2026-02-28.md
new file mode 100644
index 0000000..9b86b6e
--- /dev/null
+++ b/docs/membership/redeem_integration_2026-02-28.md
@@ -0,0 +1,37 @@
+# 兑换码开通会员集成验证（2026-02-28）
+
+对应 issue：`#8 [P0][T5] 兑换码开通会员 API 集成测试`
+
+## 覆盖场景
+
+1. 成功兑换
+- 用例：`TestRedeemCodeServiceRedeemSuccessAndRepeat`
+- 结果：通过
+- 校验点：创建会员成功、`used_uses` 递增、结果字段可用。
+
+2. 重复兑换
+- 用例：`TestRedeemCodeServiceRedeemSuccessAndRepeat`
+- 结果：通过
+- 校验点：第二次兑换返回 `ErrRedeemCodeUsedUp`。
+
+3. 过期码
+- 用例：`TestRedeemCodeServiceRedeemExpiredCode`
+- 结果：通过
+- 校验点：返回 `ErrRedeemCodeExpired`。
+
+4. 非法码
+- 用例：`TestRedeemCodeServiceRedeemInvalidCode`
+- 结果：通过
+- 校验点：返回 `ErrRedeemCodeInvalid`。
+
+5. 会员状态更新及时可见
+- 用例：`TestRedeemCodeServiceRedeemExtendsActiveMembership`
+- 结果：通过
+- 校验点：已激活会员再次兑换后 `extended=true`，且 `ends_at` 向后延长。
+
+## 执行命令
+
+```bash
+go test ./internal/membership/service -run TestRedeemCodeServiceRedeem -v
+go test ./...
+```
diff --git a/go.mod b/go.mod
index d8960dc..9586edc 100755
--- a/go.mod
+++ b/go.mod
@@ -32,6 +32,7 @@ require (
 	github.com/klauspost/cpuid/v2 v2.3.0 // indirect
 	github.com/leodido/go-urn v1.4.0 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/mattn/go-sqlite3 v1.14.22 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421 // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
@@ -49,4 +50,5 @@ require (
 	golang.org/x/text v0.27.0 // indirect
 	golang.org/x/tools v0.34.0 // indirect
 	google.golang.org/protobuf v1.36.9 // indirect
+	gorm.io/driver/sqlite v1.6.0 // indirect
 )
diff --git a/go.sum b/go.sum
index 0cce27b..9f8d4b9 100644
--- a/go.sum
+++ b/go.sum
@@ -57,6 +57,8 @@ github.com/leodido/go-urn v1.4.0 h1:WT9HwE9SGECu3lg4d/dIA+jxlljEa1/ffXKmRjqdmIQ=
 github.com/leodido/go-urn v1.4.0/go.mod h1:bvxc+MVxLKB4z00jd1z+Dvzr47oO32F/QSNjSBOlFxI=
 github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
 github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/mattn/go-sqlite3 v1.14.22 h1:2gZY6PC6kBnID23Tichd1K+Z0oS6nE/XwU+Vz/5o4kU=
+github.com/mattn/go-sqlite3 v1.14.22/go.mod h1:Uh1q+B4BYcTPb+yiD3kU8Ct7aC0hY9fxUwlHK0RXw+Y=
 github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421 h1:ZqeYNhU3OHLH3mGKHDcjJRFFRrJa6eAM5H+CtDdOsPc=
 github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
 github.com/modern-go/reflect2 v1.0.2 h1:xBagoLtFs94CBntxluKeaWgTMpvLxC4ur3nMaC9Gz0M=
@@ -111,5 +113,7 @@ gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gorm.io/driver/mysql v1.6.0 h1:eNbLmNTpPpTOVZi8MMxCi2aaIm0ZpInbORNXDwyLGvg=
 gorm.io/driver/mysql v1.6.0/go.mod h1:D/oCC2GWK3M/dqoLxnOlaNKmXz8WNTfcS9y5ovaSqKo=
+gorm.io/driver/sqlite v1.6.0 h1:WHRRrIiulaPiPFmDcod6prc4l2VGVWHz80KspNsxSfQ=
+gorm.io/driver/sqlite v1.6.0/go.mod h1:AO9V1qIQddBESngQUKWL9yoH93HIeA1X6V633rBwyT8=
 gorm.io/gorm v1.31.1 h1:7CA8FTFz/gRfgqgpeKIBcervUn3xSyPUmr6B2WXJ7kg=
 gorm.io/gorm v1.31.1/go.mod h1:XyQVbO2k6YkOis7C2437jSit3SsDK72s7n7rsSHd+Gs=
diff --git a/internal/membership/service/redeem_code_service_integration_test.go b/internal/membership/service/redeem_code_service_integration_test.go
new file mode 100644
index 0000000..bcecdc4
--- /dev/null
+++ b/internal/membership/service/redeem_code_service_integration_test.go
@@ -0,0 +1,154 @@
+package service
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+
+	membershipmodel "wx_service/internal/membership/model"
+	usermodel "wx_service/internal/model"
+
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+	"gorm.io/gorm/logger"
+)
+
+func setupRedeemTestDB(t *testing.T) *gorm.DB {
+	t.Helper()
+
+	db, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{
+		Logger: logger.Default.LogMode(logger.Silent),
+	})
+	if err != nil {
+		t.Fatalf("open sqlite: %v", err)
+	}
+
+	if err := db.AutoMigrate(
+		&membershipmodel.MembershipRedeemCode{},
+		&membershipmodel.MembershipRedemption{},
+		&usermodel.UserMembership{},
+	); err != nil {
+		t.Fatalf("auto migrate: %v", err)
+	}
+
+	return db
+}
+
+func seedRedeemCode(t *testing.T, db *gorm.DB, plainCode string, durationDays int, expiresAt *time.Time, maxUses int, status string) membershipmodel.MembershipRedeemCode {
+	t.Helper()
+
+	code := normalizeCode(plainCode)
+	record := membershipmodel.MembershipRedeemCode{
+		CodeHash:     hashCode(code),
+		CodeSuffix:   suffixOf(code, 6),
+		Plan:         "month",
+		DurationDays: durationDays,
+		ExpiresAt:    expiresAt,
+		MaxUses:      maxUses,
+		UsedUses:     0,
+		Status:       status,
+	}
+	if err := db.Create(&record).Error; err != nil {
+		t.Fatalf("seed redeem code: %v", err)
+	}
+	return record
+}
+
+func TestRedeemCodeServiceRedeemSuccessAndRepeat(t *testing.T) {
+	t.Parallel()
+
+	db := setupRedeemTestDB(t)
+	svc := NewRedeemCodeService(db, "")
+	user := &usermodel.User{ID: 1, MiniProgramID: 10}
+
+	code := "TEST-CODE-001"
+	seedRedeemCode(t, db, code, 30, nil, 1, "active")
+
+	res, err := svc.Redeem(context.Background(), user, code, "127.0.0.1", "ut")
+	if err != nil {
+		t.Fatalf("redeem success: %v", err)
+	}
+	if res == nil || res.Extended {
+		t.Fatalf("first redeem should create membership and extended=false")
+	}
+
+	var membership usermodel.UserMembership
+	if err := db.Where("mini_program_id = ? AND user_id = ?", user.MiniProgramID, user.ID).First(&membership).Error; err != nil {
+		t.Fatalf("query membership: %v", err)
+	}
+	if membership.Status != "active" {
+		t.Fatalf("membership status=%s, want=active", membership.Status)
+	}
+
+	var storedCode membershipmodel.MembershipRedeemCode
+	if err := db.Where("code_hash = ?", hashCode(normalizeCode(code))).First(&storedCode).Error; err != nil {
+		t.Fatalf("query redeem code: %v", err)
+	}
+	if storedCode.UsedUses != 1 {
+		t.Fatalf("used_uses=%d, want=1", storedCode.UsedUses)
+	}
+
+	_, err = svc.Redeem(context.Background(), user, code, "127.0.0.1", "ut")
+	if !errors.Is(err, ErrRedeemCodeUsedUp) {
+		t.Fatalf("repeat redeem err=%v, want ErrRedeemCodeUsedUp", err)
+	}
+}
+
+func TestRedeemCodeServiceRedeemExpiredCode(t *testing.T) {
+	t.Parallel()
+
+	db := setupRedeemTestDB(t)
+	svc := NewRedeemCodeService(db, "")
+	user := &usermodel.User{ID: 2, MiniProgramID: 10}
+
+	expired := time.Now().Add(-1 * time.Hour)
+	code := "TEST-CODE-EXPIRED"
+	seedRedeemCode(t, db, code, 30, &expired, 1, "active")
+
+	_, err := svc.Redeem(context.Background(), user, code, "127.0.0.1", "ut")
+	if !errors.Is(err, ErrRedeemCodeExpired) {
+		t.Fatalf("redeem expired err=%v, want ErrRedeemCodeExpired", err)
+	}
+}
+
+func TestRedeemCodeServiceRedeemInvalidCode(t *testing.T) {
+	t.Parallel()
+
+	db := setupRedeemTestDB(t)
+	svc := NewRedeemCodeService(db, "")
+	user := &usermodel.User{ID: 3, MiniProgramID: 10}
+
+	_, err := svc.Redeem(context.Background(), user, "NOT-FOUND-CODE", "127.0.0.1", "ut")
+	if !errors.Is(err, ErrRedeemCodeInvalid) {
+		t.Fatalf("redeem invalid err=%v, want ErrRedeemCodeInvalid", err)
+	}
+}
+
+func TestRedeemCodeServiceRedeemExtendsActiveMembership(t *testing.T) {
+	t.Parallel()
+
+	db := setupRedeemTestDB(t)
+	svc := NewRedeemCodeService(db, "")
+	user := &usermodel.User{ID: 4, MiniProgramID: 10}
+
+	firstCode := "TEST-CODE-A"
+	secondCode := "TEST-CODE-B"
+	seedRedeemCode(t, db, firstCode, 10, nil, 1, "active")
+	seedRedeemCode(t, db, secondCode, 15, nil, 1, "active")
+
+	firstRes, err := svc.Redeem(context.Background(), user, firstCode, "127.0.0.1", "ut")
+	if err != nil {
+		t.Fatalf("first redeem: %v", err)
+	}
+	secondRes, err := svc.Redeem(context.Background(), user, secondCode, "127.0.0.1", "ut")
+	if err != nil {
+		t.Fatalf("second redeem: %v", err)
+	}
+	if secondRes == nil || !secondRes.Extended {
+		t.Fatalf("second redeem should extend existing membership")
+	}
+	if !secondRes.EndsAt.After(firstRes.EndsAt) {
+		t.Fatalf("second ends_at=%s should be after first ends_at=%s", secondRes.EndsAt, firstRes.EndsAt)
+	}
+}