diff --git a/internal/expiry/expiry.go b/internal/expiry/expiry.go
new file mode 100644
index 0000000..57b9c19
--- /dev/null
+++ b/internal/expiry/expiry.go
@@ -0,0 +1,133 @@
+package expiry
+
+import (
+	"time"
+
+	"github.com/gin-gonic/gin"
+	"github.com/redis/go-redis/v9"
+	"gorm.io/gorm"
+
+	expiryhandler "wx_service/internal/expiry/handler"
+	expirymodel "wx_service/internal/expiry/model"
+	expiryrepo "wx_service/internal/expiry/repository"
+	expiryservice "wx_service/internal/expiry/service"
+)
+
+const (
+	CategoryFood     = expirymodel.CategoryFood
+	CategoryMedicine = expirymodel.CategoryMedicine
+	CategoryCosmetic = expirymodel.CategoryCosmetic
+	CategoryOther    = expirymodel.CategoryOther
+
+	StatusNormal    = expirymodel.StatusNormal
+	StatusExpiring  = expirymodel.StatusExpiring
+	StatusExpired   = expirymodel.StatusExpired
+	StatusUsed      = expirymodel.StatusUsed
+	StatusDiscarded = expirymodel.StatusDiscarded
+)
+
+var defaultRemindDays = expirymodel.DefaultRemindDays
+
+type ExpiryItem = expirymodel.ExpiryItem
+type ExpiryUserSettings = expirymodel.ExpiryUserSettings
+
+type Repository = expiryrepo.Repository
+type Service = expiryservice.Service
+type Handler = expiryhandler.Handler
+type SummaryCache = expiryservice.SummaryCache
+
+type CreateItemRequest = expiryservice.CreateItemRequest
+type UpdateItemRequest = expiryservice.UpdateItemRequest
+type ItemFilters = expiryservice.ItemFilters
+type ItemView = expiryservice.ItemView
+type ItemListResponse = expiryservice.ItemListResponse
+type SummaryResponse = expiryservice.SummaryResponse
+type SettingsResponse = expiryservice.SettingsResponse
+
+var (
+	ErrExpiryItemNotFound = expiryrepo.ErrExpiryItemNotFound
+
+	ErrExpiryNameInvalid           = expiryservice.ErrExpiryNameInvalid
+	ErrExpiryCategoryInvalid       = expiryservice.ErrExpiryCategoryInvalid
+	ErrExpiryMiniProgramRequired   = expiryservice.ErrExpiryMiniProgramRequired
+	ErrExpiryQuantityInvalid       = expiryservice.ErrExpiryQuantityInvalid
+	ErrExpiryLocationTooLong       = expiryservice.ErrExpiryLocationTooLong
+	ErrExpiryRemarkTooLong         = expiryservice.ErrExpiryRemarkTooLong
+	ErrExpiryDateRequired          = expiryservice.ErrExpiryDateRequired
+	ErrExpiryShelfLifeDaysInvalid  = expiryservice.ErrExpiryShelfLifeDaysInvalid
+	ErrExpiryFilterStatusInvalid   = expiryservice.ErrExpiryFilterStatusInvalid
+	ErrExpiryFilterCategoryInvalid = expiryservice.ErrExpiryFilterCategoryInvalid
+	ErrExpiryFilterSortInvalid     = expiryservice.ErrExpiryFilterSortInvalid
+	ErrExpiryStatusInvalid         = expiryservice.ErrExpiryStatusInvalid
+	ErrExpiryRemindDaysInvalid     = expiryservice.ErrExpiryRemindDaysInvalid
+)
+
+func NewRepository(db *gorm.DB) *Repository {
+	return expiryrepo.NewRepository(db)
+}
+
+func NewService(repo *Repository) *Service {
+	return expiryservice.NewService(repo)
+}
+
+func NewHandler(service *Service) *Handler {
+	return expiryhandler.NewHandler(service)
+}
+
+func NewSummaryCache(rc *redis.Client, keyPrefix string, ttl time.Duration) *SummaryCache {
+	return expiryservice.NewSummaryCache(rc, keyPrefix, ttl)
+}
+
+func dateOnly(t time.Time) time.Time {
+	return expirymodel.DateOnly(t)
+}
+
+func normalizeFilters(filters ItemFilters) ItemFilters {
+	return expiryservice.NormalizeFilters(filters)
+}
+
+func validateFilters(filters ItemFilters) error {
+	return expiryservice.ValidateFilters(filters)
+}
+
+func validateBaseFields(name, category string, quantity int, location, remark string) error {
+	return expiryservice.ValidateBaseFields(name, category, quantity, location, remark)
+}
+
+func applyExpiryDate(item *ExpiryItem, expiryDate *time.Time, shelfLifeDays *int) error {
+	return expiryservice.ApplyExpiryDate(item, expiryDate, shelfLifeDays)
+}
+
+func isValidCategory(category string) bool {
+	return expiryservice.IsValidCategory(category)
+}
+
+func validateRemindDays(days []int) ([]int, error) {
+	return expiryservice.ValidateRemindDays(days)
+}
+
+func toItemView(item ExpiryItem) ItemView {
+	return expiryservice.ToItemView(item)
+}
+
+func writeExpirySuccess(c *gin.Context, message string, data interface{}) {
+	resp := gin.H{
+		"code":    0,
+		"message": message,
+	}
+	if data != nil {
+		resp["data"] = data
+	}
+	c.JSON(200, resp)
+}
+
+func writeExpiryError(c *gin.Context, code int, message string) {
+	c.JSON(code, gin.H{
+		"code":    code,
+		"message": message,
+	})
+}
+
+func writeExpiryServerError(c *gin.Context) {
+	writeExpiryError(c, 500, "服务器错误")
+}
diff --git a/internal/expiry/handler.go b/internal/expiry/handler/handler.go
similarity index 81%
rename from internal/expiry/handler.go
rename to internal/expiry/handler/handler.go
index 1702b20..3e93641 100644
--- a/internal/expiry/handler.go
+++ b/internal/expiry/handler/handler.go
@@ -1,4 +1,4 @@
-package expiry
+package handler
 
 import (
 	"errors"
@@ -10,15 +10,17 @@ import (
 
 	"github.com/gin-gonic/gin"
 
+	expiryrepo "wx_service/internal/expiry/repository"
+	expiryservice "wx_service/internal/expiry/service"
 	"wx_service/internal/middleware"
 )
 
 // Handler 负责 HTTP 层处理。
 type Handler struct {
-	service *Service
+	service *expiryservice.Service
 }
 
-func NewHandler(service *Service) *Handler {
+func NewHandler(service *expiryservice.Service) *Handler {
 	return &Handler{service: service}
 }
 
@@ -72,7 +74,7 @@ func (h *Handler) GetItems(c *gin.Context) {
 
 	page := parseIntWithDefault(c.Query("page"), 1)
 	pageSize := parseIntWithDefault(c.Query("page_size"), 20)
-	filters := ItemFilters{
+	filters := expiryservice.ItemFilters{
 		Status:   strings.TrimSpace(c.DefaultQuery("status", "all")),
 		Category: strings.TrimSpace(c.DefaultQuery("category", "all")),
 		Sort:     strings.TrimSpace(c.DefaultQuery("sort", "expiry_date")),
@@ -119,7 +121,7 @@ func (h *Handler) CreateItem(c *gin.Context) {
 		return
 	}
 
-	writeExpirySuccess(c, "添加成功", toItemView(*item))
+	writeExpirySuccess(c, "添加成功", expiryservice.ToItemView(*item))
 }
 
 // UpdateItem 更新物品。
@@ -144,7 +146,7 @@ func (h *Handler) UpdateItem(c *gin.Context) {
 
 	item, err := h.service.UpdateItem(id, user.ID, serviceReq)
 	if err != nil {
-		if errors.Is(err, ErrExpiryItemNotFound) {
+		if errors.Is(err, expiryrepo.ErrExpiryItemNotFound) {
 			writeExpiryError(c, http.StatusNotFound, "物品不存在")
 			return
 		}
@@ -156,7 +158,7 @@ func (h *Handler) UpdateItem(c *gin.Context) {
 		return
 	}
 
-	writeExpirySuccess(c, "更新成功", toItemView(*item))
+	writeExpirySuccess(c, "更新成功", expiryservice.ToItemView(*item))
 }
 
 // DeleteItem 删除物品。
@@ -169,7 +171,7 @@ func (h *Handler) DeleteItem(c *gin.Context) {
 
 	err := h.service.DeleteItem(id, user.ID)
 	if err != nil {
-		if errors.Is(err, ErrExpiryItemNotFound) {
+		if errors.Is(err, expiryrepo.ErrExpiryItemNotFound) {
 			writeExpiryError(c, http.StatusNotFound, "物品不存在")
 			return
 		}
@@ -195,7 +197,7 @@ func (h *Handler) UpdateStatus(c *gin.Context) {
 	}
 
 	if err := h.service.UpdateItemStatus(id, user.ID, strings.TrimSpace(req.Status)); err != nil {
-		if errors.Is(err, ErrExpiryItemNotFound) {
+		if errors.Is(err, expiryrepo.ErrExpiryItemNotFound) {
 			writeExpiryError(c, http.StatusNotFound, "物品不存在")
 			return
 		}
@@ -256,15 +258,15 @@ func (h *Handler) UpdateSettings(c *gin.Context) {
 	writeExpirySuccess(c, "更新成功", resp)
 }
 
-func (h *Handler) toCreateItemRequest(miniProgramID uint, req createOrUpdateItemRequest) (CreateItemRequest, error) {
+func (h *Handler) toCreateItemRequest(miniProgramID uint, req createOrUpdateItemRequest) (expiryservice.CreateItemRequest, error) {
 	productionDate, err := parseDateString(req.ProductionDate)
 	if err != nil {
-		return CreateItemRequest{}, errors.New("production_date 格式错误，应为 YYYY-MM-DD")
+		return expiryservice.CreateItemRequest{}, errors.New("production_date 格式错误，应为 YYYY-MM-DD")
 	}
 
 	expiryDate, err := parseDateString(req.ExpiryDate)
 	if err != nil {
-		return CreateItemRequest{}, errors.New("expiry_date 格式错误，应为 YYYY-MM-DD")
+		return expiryservice.CreateItemRequest{}, errors.New("expiry_date 格式错误，应为 YYYY-MM-DD")
 	}
 
 	quantity := 1
@@ -272,7 +274,7 @@ func (h *Handler) toCreateItemRequest(miniProgramID uint, req createOrUpdateItem
 		quantity = *req.Quantity
 	}
 
-	return CreateItemRequest{
+	return expiryservice.CreateItemRequest{
 		MiniProgramID:  miniProgramID,
 		Name:           req.Name,
 		Category:       req.Category,
@@ -318,19 +320,19 @@ func parseItemID(c *gin.Context) (uint, bool) {
 }
 
 func isExpiryBadRequestError(err error) bool {
-	return errors.Is(err, ErrExpiryNameInvalid) ||
-		errors.Is(err, ErrExpiryCategoryInvalid) ||
-		errors.Is(err, ErrExpiryMiniProgramRequired) ||
-		errors.Is(err, ErrExpiryQuantityInvalid) ||
-		errors.Is(err, ErrExpiryLocationTooLong) ||
-		errors.Is(err, ErrExpiryRemarkTooLong) ||
-		errors.Is(err, ErrExpiryDateRequired) ||
-		errors.Is(err, ErrExpiryShelfLifeDaysInvalid) ||
-		errors.Is(err, ErrExpiryFilterStatusInvalid) ||
-		errors.Is(err, ErrExpiryFilterCategoryInvalid) ||
-		errors.Is(err, ErrExpiryFilterSortInvalid) ||
-		errors.Is(err, ErrExpiryStatusInvalid) ||
-		errors.Is(err, ErrExpiryRemindDaysInvalid)
+	return errors.Is(err, expiryservice.ErrExpiryNameInvalid) ||
+		errors.Is(err, expiryservice.ErrExpiryCategoryInvalid) ||
+		errors.Is(err, expiryservice.ErrExpiryMiniProgramRequired) ||
+		errors.Is(err, expiryservice.ErrExpiryQuantityInvalid) ||
+		errors.Is(err, expiryservice.ErrExpiryLocationTooLong) ||
+		errors.Is(err, expiryservice.ErrExpiryRemarkTooLong) ||
+		errors.Is(err, expiryservice.ErrExpiryDateRequired) ||
+		errors.Is(err, expiryservice.ErrExpiryShelfLifeDaysInvalid) ||
+		errors.Is(err, expiryservice.ErrExpiryFilterStatusInvalid) ||
+		errors.Is(err, expiryservice.ErrExpiryFilterCategoryInvalid) ||
+		errors.Is(err, expiryservice.ErrExpiryFilterSortInvalid) ||
+		errors.Is(err, expiryservice.ErrExpiryStatusInvalid) ||
+		errors.Is(err, expiryservice.ErrExpiryRemindDaysInvalid)
 }
 
 func writeExpirySuccess(c *gin.Context, message string, data interface{}) {
diff --git a/internal/expiry/model.go b/internal/expiry/model/model.go
similarity index 95%
rename from internal/expiry/model.go
rename to internal/expiry/model/model.go
index 02429d2..83794fd 100644
--- a/internal/expiry/model.go
+++ b/internal/expiry/model/model.go
@@ -1,4 +1,4 @@
-package expiry
+package model
 
 import (
 	"time"
@@ -23,7 +23,7 @@ const (
 	StatusDiscarded = "discarded"
 )
 
-var defaultRemindDays = []int{7, 3, 1}
+var DefaultRemindDays = []int{7, 3, 1}
 
 // ExpiryItem 表示保质期物品数据模型。
 type ExpiryItem struct {
@@ -50,8 +50,8 @@ func (ExpiryItem) TableName() string {
 
 // CalculateDaysLeft 计算当前日期与过期日期之间的天数差。
 func (item *ExpiryItem) CalculateDaysLeft() int {
-	now := dateOnly(time.Now())
-	expiry := dateOnly(item.ExpiryDate)
+	now := DateOnly(time.Now())
+	expiry := DateOnly(item.ExpiryDate)
 	return int(expiry.Sub(now).Hours() / 24)
 }
 
@@ -85,7 +85,7 @@ func (ExpiryUserSettings) TableName() string {
 	return "expiry_user_settings"
 }
 
-func dateOnly(t time.Time) time.Time {
+func DateOnly(t time.Time) time.Time {
 	year, month, day := t.In(time.Local).Date()
 	return time.Date(year, month, day, 0, 0, 0, 0, time.Local)
 }
diff --git a/internal/expiry/repository.go b/internal/expiry/repository/repository.go
similarity index 75%
rename from internal/expiry/repository.go
rename to internal/expiry/repository/repository.go
index 3e02ffc..e9ff7ed 100644
--- a/internal/expiry/repository.go
+++ b/internal/expiry/repository/repository.go
@@ -1,10 +1,12 @@
-package expiry
+package repository
 
 import (
 	"errors"
 	"fmt"
 	"time"
 
+	expirymodel "wx_service/internal/expiry/model"
+
 	"gorm.io/gorm"
 )
 
@@ -22,7 +24,7 @@ func NewRepository(db *gorm.DB) *Repository {
 }
 
 // Create 创建物品。
-func (r *Repository) Create(item *ExpiryItem) error {
+func (r *Repository) Create(item *expirymodel.ExpiryItem) error {
 	if err := r.db.Create(item).Error; err != nil {
 		return fmt.Errorf("create expiry item: %w", err)
 	}
@@ -30,7 +32,7 @@ func (r *Repository) Create(item *ExpiryItem) error {
 }
 
 // Update 更新物品。
-func (r *Repository) Update(item *ExpiryItem) error {
+func (r *Repository) Update(item *expirymodel.ExpiryItem) error {
 	updates := map[string]interface{}{
 		"mini_program_id": item.MiniProgramID,
 		"name":            item.Name,
@@ -44,7 +46,7 @@ func (r *Repository) Update(item *ExpiryItem) error {
 		"status":          item.Status,
 	}
 
-	tx := r.db.Model(&ExpiryItem{}).
+	tx := r.db.Model(&expirymodel.ExpiryItem{}).
 		Where("id = ? AND user_id = ?", item.ID, item.UserID).
 		Updates(updates)
 	if tx.Error != nil {
@@ -58,7 +60,7 @@ func (r *Repository) Update(item *ExpiryItem) error {
 
 // Delete 软删除物品。
 func (r *Repository) Delete(id, userID uint) error {
-	tx := r.db.Where("id = ? AND user_id = ?", id, userID).Delete(&ExpiryItem{})
+	tx := r.db.Where("id = ? AND user_id = ?", id, userID).Delete(&expirymodel.ExpiryItem{})
 	if tx.Error != nil {
 		return fmt.Errorf("delete expiry item: %w", tx.Error)
 	}
@@ -69,8 +71,8 @@ func (r *Repository) Delete(id, userID uint) error {
 }
 
 // FindByID 根据 ID 查询单个物品。
-func (r *Repository) FindByID(id, userID uint) (*ExpiryItem, error) {
-	var item ExpiryItem
+func (r *Repository) FindByID(id, userID uint) (*expirymodel.ExpiryItem, error) {
+	var item expirymodel.ExpiryItem
 	err := r.db.Where("id = ? AND user_id = ?", id, userID).First(&item).Error
 	if err != nil {
 		if errors.Is(err, gorm.ErrRecordNotFound) {
@@ -86,7 +88,7 @@ func (r *Repository) FindByUser(
 	userID uint,
 	filters map[string]interface{},
 	page, pageSize int,
-) ([]ExpiryItem, int64, error) {
+) ([]expirymodel.ExpiryItem, int64, error) {
 	if page <= 0 {
 		page = 1
 	}
@@ -97,22 +99,22 @@ func (r *Repository) FindByUser(
 		pageSize = 100
 	}
 
-	query := r.db.Model(&ExpiryItem{}).Where("user_id = ?", userID)
-	now := dateOnly(time.Now())
+	query := r.db.Model(&expirymodel.ExpiryItem{}).Where("user_id = ?", userID)
+	now := expirymodel.DateOnly(time.Now())
 	sevenDaysLater := now.AddDate(0, 0, 7)
 
 	if status, ok := filters["status"].(string); ok && status != "" && status != "all" {
 		switch status {
-		case StatusExpiring:
-			query = query.Where("status NOT IN ?", []string{StatusUsed, StatusDiscarded}).
+		case expirymodel.StatusExpiring:
+			query = query.Where("status NOT IN ?", []string{expirymodel.StatusUsed, expirymodel.StatusDiscarded}).
 				Where("expiry_date BETWEEN ? AND ?", now, sevenDaysLater)
-		case StatusExpired:
-			query = query.Where("status NOT IN ?", []string{StatusUsed, StatusDiscarded}).
+		case expirymodel.StatusExpired:
+			query = query.Where("status NOT IN ?", []string{expirymodel.StatusUsed, expirymodel.StatusDiscarded}).
 				Where("expiry_date < ?", now)
-		case StatusNormal:
-			query = query.Where("status NOT IN ?", []string{StatusUsed, StatusDiscarded}).
+		case expirymodel.StatusNormal:
+			query = query.Where("status NOT IN ?", []string{expirymodel.StatusUsed, expirymodel.StatusDiscarded}).
 				Where("expiry_date > ?", sevenDaysLater)
-		case StatusUsed, StatusDiscarded:
+		case expirymodel.StatusUsed, expirymodel.StatusDiscarded:
 			query = query.Where("status = ?", status)
 		}
 	}
@@ -137,7 +139,7 @@ func (r *Repository) FindByUser(
 		return nil, 0, fmt.Errorf("count expiry items: %w", err)
 	}
 
-	var items []ExpiryItem
+	var items []expirymodel.ExpiryItem
 	offset := (page - 1) * pageSize
 	if err := query.Offset(offset).Limit(pageSize).Find(&items).Error; err != nil {
 		return nil, 0, fmt.Errorf("list expiry items: %w", err)
@@ -148,11 +150,11 @@ func (r *Repository) FindByUser(
 
 // GetSummary 获取首页汇总统计数据。
 func (r *Repository) GetSummary(userID uint) (map[string]int, error) {
-	now := dateOnly(time.Now())
+	now := expirymodel.DateOnly(time.Now())
 	sevenDaysLater := now.AddDate(0, 0, 7)
 
 	base := func() *gorm.DB {
-		return r.db.Model(&ExpiryItem{}).Where("user_id = ?", userID)
+		return r.db.Model(&expirymodel.ExpiryItem{}).Where("user_id = ?", userID)
 	}
 
 	count := func(tx *gorm.DB) (int64, error) {
@@ -163,35 +165,35 @@ func (r *Repository) GetSummary(userID uint) (map[string]int, error) {
 		return v, nil
 	}
 
-	totalItems, err := count(base().Where("status NOT IN ?", []string{StatusUsed, StatusDiscarded}))
+	totalItems, err := count(base().Where("status NOT IN ?", []string{expirymodel.StatusUsed, expirymodel.StatusDiscarded}))
 	if err != nil {
 		return nil, fmt.Errorf("count total items: %w", err)
 	}
 
-	expiringSoon, err := count(base().Where("status NOT IN ?", []string{StatusUsed, StatusDiscarded}).
+	expiringSoon, err := count(base().Where("status NOT IN ?", []string{expirymodel.StatusUsed, expirymodel.StatusDiscarded}).
 		Where("expiry_date BETWEEN ? AND ?", now, sevenDaysLater))
 	if err != nil {
 		return nil, fmt.Errorf("count expiring items: %w", err)
 	}
 
-	expired, err := count(base().Where("status NOT IN ?", []string{StatusUsed, StatusDiscarded}).
+	expired, err := count(base().Where("status NOT IN ?", []string{expirymodel.StatusUsed, expirymodel.StatusDiscarded}).
 		Where("expiry_date < ?", now))
 	if err != nil {
 		return nil, fmt.Errorf("count expired items: %w", err)
 	}
 
-	normal, err := count(base().Where("status NOT IN ?", []string{StatusUsed, StatusDiscarded}).
+	normal, err := count(base().Where("status NOT IN ?", []string{expirymodel.StatusUsed, expirymodel.StatusDiscarded}).
 		Where("expiry_date > ?", sevenDaysLater))
 	if err != nil {
 		return nil, fmt.Errorf("count normal items: %w", err)
 	}
 
-	used, err := count(base().Where("status = ?", StatusUsed))
+	used, err := count(base().Where("status = ?", expirymodel.StatusUsed))
 	if err != nil {
 		return nil, fmt.Errorf("count used items: %w", err)
 	}
 
-	discarded, err := count(base().Where("status = ?", StatusDiscarded))
+	discarded, err := count(base().Where("status = ?", expirymodel.StatusDiscarded))
 	if err != nil {
 		return nil, fmt.Errorf("count discarded items: %w", err)
 	}
@@ -208,7 +210,7 @@ func (r *Repository) GetSummary(userID uint) (map[string]int, error) {
 
 // UpdateStatus 更新物品状态（used/discarded）。
 func (r *Repository) UpdateStatus(id, userID uint, status string) error {
-	tx := r.db.Model(&ExpiryItem{}).
+	tx := r.db.Model(&expirymodel.ExpiryItem{}).
 		Where("id = ? AND user_id = ?", id, userID).
 		Update("status", status)
 	if tx.Error != nil {
@@ -221,8 +223,8 @@ func (r *Repository) UpdateStatus(id, userID uint, status string) error {
 }
 
 // GetSettings 查询用户提醒设置。
-func (r *Repository) GetSettings(userID uint) (*ExpiryUserSettings, error) {
-	var settings ExpiryUserSettings
+func (r *Repository) GetSettings(userID uint) (*expirymodel.ExpiryUserSettings, error) {
+	var settings expirymodel.ExpiryUserSettings
 	err := r.db.Where("user_id = ?", userID).First(&settings).Error
 	if err != nil {
 		if errors.Is(err, gorm.ErrRecordNotFound) {
@@ -234,14 +236,14 @@ func (r *Repository) GetSettings(userID uint) (*ExpiryUserSettings, error) {
 }
 
 // UpdateSettings 更新用户提醒设置（不存在则创建）。
-func (r *Repository) UpdateSettings(userID uint, remindDays []int) (*ExpiryUserSettings, error) {
+func (r *Repository) UpdateSettings(userID uint, remindDays []int) (*expirymodel.ExpiryUserSettings, error) {
 	settings, err := r.GetSettings(userID)
 	if err != nil {
 		return nil, err
 	}
 
 	if settings == nil {
-		settings = &ExpiryUserSettings{
+		settings = &expirymodel.ExpiryUserSettings{
 			UserID:     userID,
 			RemindDays: copyIntSlice(remindDays),
 		}
diff --git a/internal/expiry/cache.go b/internal/expiry/service/cache.go
similarity index 99%
rename from internal/expiry/cache.go
rename to internal/expiry/service/cache.go
index 5d119b0..4e2532f 100644
--- a/internal/expiry/cache.go
+++ b/internal/expiry/service/cache.go
@@ -1,4 +1,4 @@
-package expiry
+package service
 
 import (
 	"context"
diff --git a/internal/expiry/service.go b/internal/expiry/service/service.go
similarity index 83%
rename from internal/expiry/service.go
rename to internal/expiry/service/service.go
index 645e6d4..3346f7b 100644
--- a/internal/expiry/service.go
+++ b/internal/expiry/service/service.go
@@ -1,10 +1,13 @@
-package expiry
+package service
 
 import (
 	"context"
 	"errors"
 	"strings"
 	"time"
+
+	expirymodel "wx_service/internal/expiry/model"
+	expiryrepo "wx_service/internal/expiry/repository"
 )
 
 var (
@@ -25,7 +28,7 @@ var (
 
 // Service 封装保质期模块业务逻辑。
 type Service struct {
-	repo         *Repository
+	repo         *expiryrepo.Repository
 	summaryCache *SummaryCache
 }
 
@@ -94,7 +97,7 @@ type SettingsResponse struct {
 	RemindDays []int `json:"remind_days"`
 }
 
-func NewService(repo *Repository) *Service {
+func NewService(repo *expiryrepo.Repository) *Service {
 	return &Service{repo: repo}
 }
 
@@ -104,7 +107,7 @@ func (s *Service) BindSummaryCache(cache *SummaryCache) {
 }
 
 // CreateItem 创建物品，并处理过期日期自动计算。
-func (s *Service) CreateItem(userID uint, req CreateItemRequest) (*ExpiryItem, error) {
+func (s *Service) CreateItem(userID uint, req CreateItemRequest) (*expirymodel.ExpiryItem, error) {
 	if req.MiniProgramID == 0 {
 		return nil, ErrExpiryMiniProgramRequired
 	}
@@ -115,7 +118,7 @@ func (s *Service) CreateItem(userID uint, req CreateItemRequest) (*ExpiryItem, e
 		return nil, ErrExpiryShelfLifeDaysInvalid
 	}
 
-	item := &ExpiryItem{
+	item := &expirymodel.ExpiryItem{
 		UserID:        userID,
 		MiniProgramID: req.MiniProgramID,
 		Name:          strings.TrimSpace(req.Name),
@@ -123,7 +126,7 @@ func (s *Service) CreateItem(userID uint, req CreateItemRequest) (*ExpiryItem, e
 		Quantity:      req.Quantity,
 		Location:      strings.TrimSpace(req.Location),
 		Remark:        strings.TrimSpace(req.Remark),
-		Status:        StatusNormal,
+		Status:        expirymodel.StatusNormal,
 	}
 
 	if item.Quantity == 0 {
@@ -131,7 +134,7 @@ func (s *Service) CreateItem(userID uint, req CreateItemRequest) (*ExpiryItem, e
 	}
 
 	if req.ProductionDate != nil {
-		pd := dateOnly(*req.ProductionDate)
+		pd := expirymodel.DateOnly(*req.ProductionDate)
 		item.ProductionDate = &pd
 	}
 
@@ -149,7 +152,7 @@ func (s *Service) CreateItem(userID uint, req CreateItemRequest) (*ExpiryItem, e
 }
 
 // UpdateItem 更新物品。
-func (s *Service) UpdateItem(id, userID uint, req UpdateItemRequest) (*ExpiryItem, error) {
+func (s *Service) UpdateItem(id, userID uint, req UpdateItemRequest) (*expirymodel.ExpiryItem, error) {
 	item, err := s.repo.FindByID(id, userID)
 	if err != nil {
 		return nil, err
@@ -178,7 +181,7 @@ func (s *Service) UpdateItem(id, userID uint, req UpdateItemRequest) (*ExpiryIte
 		item.Quantity = 1
 	}
 	if req.ProductionDate != nil {
-		pd := dateOnly(*req.ProductionDate)
+		pd := expirymodel.DateOnly(*req.ProductionDate)
 		item.ProductionDate = &pd
 	}
 
@@ -187,8 +190,8 @@ func (s *Service) UpdateItem(id, userID uint, req UpdateItemRequest) (*ExpiryIte
 	}
 
 	// 已标记为 used/discarded 的物品保留状态，其余回归可计算状态。
-	if item.Status != StatusUsed && item.Status != StatusDiscarded {
-		item.Status = StatusNormal
+	if item.Status != expirymodel.StatusUsed && item.Status != expirymodel.StatusDiscarded {
+		item.Status = expirymodel.StatusNormal
 	}
 
 	if err := s.repo.Update(item); err != nil {
@@ -210,7 +213,7 @@ func (s *Service) DeleteItem(id, userID uint) error {
 }
 
 // GetItem 获取单个物品。
-func (s *Service) GetItem(id, userID uint) (*ExpiryItem, error) {
+func (s *Service) GetItem(id, userID uint) (*expirymodel.ExpiryItem, error) {
 	item, err := s.repo.FindByID(id, userID)
 	if err != nil {
 		return nil, err
@@ -237,7 +240,7 @@ func (s *Service) GetItems(userID uint, filters ItemFilters) (*ItemListResponse,
 
 	result := make([]ItemView, 0, len(items))
 	for _, item := range items {
-		result = append(result, toItemView(item))
+		result = append(result, ToItemView(item))
 	}
 
 	return &ItemListResponse{
@@ -275,7 +278,7 @@ func (s *Service) GetSummary(userID uint) (*SummaryResponse, error) {
 // UpdateItemStatus 标记物品状态。
 func (s *Service) UpdateItemStatus(id, userID uint, status string) error {
 	status = strings.TrimSpace(status)
-	if status != StatusUsed && status != StatusDiscarded {
+	if status != expirymodel.StatusUsed && status != expirymodel.StatusDiscarded {
 		return ErrExpiryStatusInvalid
 	}
 	if err := s.repo.UpdateStatus(id, userID, status); err != nil {
@@ -294,7 +297,7 @@ func (s *Service) GetSettings(userID uint) (*SettingsResponse, error) {
 
 	if settings == nil || len(settings.RemindDays) == 0 {
 		return &SettingsResponse{
-			RemindDays: copyIntSlice(defaultRemindDays),
+			RemindDays: copyIntSlice(expirymodel.DefaultRemindDays),
 		}, nil
 	}
 
@@ -344,16 +347,16 @@ func validateBaseFields(name, category string, quantity int, location, remark st
 	return nil
 }
 
-func applyExpiryDate(item *ExpiryItem, expiryDate *time.Time, shelfLifeDays *int) error {
+func applyExpiryDate(item *expirymodel.ExpiryItem, expiryDate *time.Time, shelfLifeDays *int) error {
 	// 若提供生产日期 + 保质期，优先自动计算过期日期。
 	if item.ProductionDate != nil && shelfLifeDays != nil {
 		item.ShelfLifeDays = shelfLifeDays
-		item.ExpiryDate = dateOnly(item.ProductionDate.AddDate(0, 0, *shelfLifeDays))
+		item.ExpiryDate = expirymodel.DateOnly(item.ProductionDate.AddDate(0, 0, *shelfLifeDays))
 		return nil
 	}
 
 	if expiryDate != nil {
-		item.ExpiryDate = dateOnly(*expiryDate)
+		item.ExpiryDate = expirymodel.DateOnly(*expiryDate)
 		item.ShelfLifeDays = shelfLifeDays
 		return nil
 	}
@@ -385,13 +388,13 @@ func normalizeFilters(filters ItemFilters) ItemFilters {
 
 func validateFilters(filters ItemFilters) error {
 	switch filters.Status {
-	case "all", StatusExpiring, StatusExpired, StatusNormal, StatusUsed, StatusDiscarded:
+	case "all", expirymodel.StatusExpiring, expirymodel.StatusExpired, expirymodel.StatusNormal, expirymodel.StatusUsed, expirymodel.StatusDiscarded:
 	default:
 		return ErrExpiryFilterStatusInvalid
 	}
 
 	switch filters.Category {
-	case "all", CategoryFood, CategoryMedicine, CategoryCosmetic, CategoryOther:
+	case "all", expirymodel.CategoryFood, expirymodel.CategoryMedicine, expirymodel.CategoryCosmetic, expirymodel.CategoryOther:
 	default:
 		return ErrExpiryFilterCategoryInvalid
 	}
@@ -407,14 +410,14 @@ func validateFilters(filters ItemFilters) error {
 
 func isValidCategory(category string) bool {
 	switch category {
-	case CategoryFood, CategoryMedicine, CategoryCosmetic, CategoryOther:
+	case expirymodel.CategoryFood, expirymodel.CategoryMedicine, expirymodel.CategoryCosmetic, expirymodel.CategoryOther:
 		return true
 	default:
 		return false
 	}
 }
 
-func toItemView(item ExpiryItem) ItemView {
+func ToItemView(item expirymodel.ExpiryItem) ItemView {
 	calculatedStatus := item.CalculateStatus()
 	return ItemView{
 		ID:             item.ID,
@@ -482,3 +485,36 @@ func (s *Service) invalidateSummaryCache(userID uint) {
 	}
 	_ = s.summaryCache.Delete(context.Background(), userID)
 }
+
+func copyIntSlice(values []int) []int {
+	if len(values) == 0 {
+		return nil
+	}
+	copied := make([]int, len(values))
+	copy(copied, values)
+	return copied
+}
+
+func NormalizeFilters(filters ItemFilters) ItemFilters {
+	return normalizeFilters(filters)
+}
+
+func ValidateFilters(filters ItemFilters) error {
+	return validateFilters(filters)
+}
+
+func ValidateBaseFields(name, category string, quantity int, location, remark string) error {
+	return validateBaseFields(name, category, quantity, location, remark)
+}
+
+func ApplyExpiryDate(item *expirymodel.ExpiryItem, expiryDate *time.Time, shelfLifeDays *int) error {
+	return applyExpiryDate(item, expiryDate, shelfLifeDays)
+}
+
+func IsValidCategory(category string) bool {
+	return isValidCategory(category)
+}
+
+func ValidateRemindDays(days []int) ([]int, error) {
+	return validateRemindDays(days)
+}