修复合同到期时间与终止恢复规则

- 合同动作中文化并将到期时间设为必填\n- 隐藏修订记录无业务意义的删除时间\n- 禁止已终止合同直接启用，统一三端状态规则\n- 补充回归测试、模拟数据回填和中文文档

backend/api/internal/logic/platform/gasorder/gasorder.go

@@ -144,11 +144,11 @@ func CreateGasorderContract(ctx *gin.Context) {
 		DefaultDeliveryFee  int64      `json:"default_delivery_fee"`
 		SignedAt            time.Time  `json:"signed_at" binding:"required"`
 		EffectiveAt         time.Time  `json:"effective_at" binding:"required"`
-		ExpiredAt           *time.Time `json:"expired_at"`
+		ExpiredAt           *time.Time `json:"expired_at" binding:"required"`
 	}
 	if err := ctx.ShouldBindJSON(&request); err != nil || request.DefaultDeliveryFee < 0 ||
 		request.SignedAt.IsZero() || request.EffectiveAt.IsZero() ||
-		(request.ExpiredAt != nil && !request.ExpiredAt.After(request.EffectiveAt)) {
+		request.ExpiredAt == nil || !request.ExpiredAt.After(request.EffectiveAt) {
 		infra.Response.Error(ctx, errcode.ErrInvalidArgument)
 		return
 	}
@@ -213,10 +213,10 @@ func UpdateGasorderContract(ctx *gin.Context) {
 		DefaultDeliveryFee int64      `json:"default_delivery_fee"`
 		SignedAt           time.Time  `json:"signed_at" binding:"required"`
 		EffectiveAt        time.Time  `json:"effective_at" binding:"required"`
-		ExpiredAt          *time.Time `json:"expired_at"`
+		ExpiredAt          *time.Time `json:"expired_at" binding:"required"`
 	}
 	if err := ctx.ShouldBindJSON(&request); err != nil || request.DefaultDeliveryFee < 0 ||
-		(request.ExpiredAt != nil && !request.ExpiredAt.After(request.EffectiveAt)) {
+		request.ExpiredAt == nil || !request.ExpiredAt.After(request.EffectiveAt) {
 		infra.Response.Error(ctx, errcode.ErrInvalidArgument)
 		return
 	}
@@ -307,11 +307,11 @@ func TerminateGasorderContract(ctx *gin.Context) {
 func RenewGasorderContract(ctx *gin.Context) {
 	var request struct {
 		EffectiveAt time.Time  `json:"effective_at" binding:"required"`
-		ExpiredAt   *time.Time `json:"expired_at"`
+		ExpiredAt   *time.Time `json:"expired_at" binding:"required"`
 		Reason      string     `json:"reason" binding:"required"`
 	}
 	if err := ctx.ShouldBindJSON(&request); err != nil ||
-		(request.ExpiredAt != nil && !request.ExpiredAt.After(request.EffectiveAt)) {
+		request.ExpiredAt == nil || !request.ExpiredAt.After(request.EffectiveAt) {
 		infra.Response.Error(ctx, errcode.ErrInvalidArgument)
 		return
 	}
@@ -351,7 +351,7 @@ func changeGasorderContract(ctx *gin.Context, action string, target int) {
 		if err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).Where("identity = ?", ctx.Param("identity")).First(&contract).Error; err != nil {
 			return err
 		}
-		if action == "activate" && contract.ContractStatus != common.StatusDraft && contract.ContractStatus != common.StatusTerminated {
+		if action == "activate" && !contractCanActivate(contract.ContractStatus) {
 			return errContractCannotActivate
 		}
 		if action == "terminate" && contract.ContractStatus != common.StatusActive {
@@ -395,6 +395,11 @@ func changeGasorderContract(ctx *gin.Context, action string, target int) {
 	infra.Response.Success(ctx, gin.H{"updated": true, "contract_status": target})
 }
 
+// contractCanActivate 限制启用动作仅用于首次启用草稿合同，终止合同必须通过续签恢复。
+func contractCanActivate(status int) bool {
+	return status == common.StatusDraft
+}
+
 // isContractChangeBusinessError 仅允许预定义业务原因透传，避免泄露数据库内部错误。
 func isContractChangeBusinessError(err error) bool {
 	return errors.Is(err, errContractCannotActivate) ||

backend/api/internal/logic/platform/gasorder/gasorder_test.go

@@ -106,6 +106,18 @@ func TestContractRevisionKeepsSingleContractHistory(t *testing.T) {
 	}
 }
 
+// TestTerminatedContractCannotActivate 验证终止合同不能绕过续签流程直接恢复生效。
+func TestTerminatedContractCannotActivate(t *testing.T) {
+	if !contractCanActivate(common.StatusDraft) {
+		t.Fatal("草稿合同应允许首次启用")
+	}
+	for _, status := range []int{common.StatusActive, common.StatusExpired, common.StatusTerminated} {
+		if contractCanActivate(status) {
+			t.Fatalf("合同状态 %d 不应允许直接启用", status)
+		}
+	}
+}
+
 func TestContractDeliveryRequiresDirectGasOwnership(t *testing.T) {
 	if !contractDeliveryMatchesGas(10, 10) {
 		t.Fatal("合同气站的直属配送点被错误拒绝")

backend/api/internal/seed/mock.go

@@ -544,6 +544,8 @@ func MockData(database *gorm.DB) error {
 // seedAdditionalCoreScenarios 补齐十组可独立检索的核心主数据。
 // 每组记录都使用本组父表的数据库 ID 建立关联，避免仅有展示字段而无真实关系。
 func seedAdditionalCoreScenarios(database *gorm.DB, passwordHash string, now time.Time) error {
+	// 联调合同统一设置一年有效期，保证合同详情具有明确到期时间。
+	nextYear := now.AddDate(1, 0, 0)
 	for scenario := 2; scenario <= 10; scenario++ {
 		sequence := 1000 + scenario*100
 		suffix := fmt.Sprintf("%03d", scenario)
@@ -635,11 +637,17 @@ func seedAdditionalCoreScenarios(database *gorm.DB, passwordHash string, now tim
 			ContractNo: "MOCK-CONTRACT-" + suffix, UserAccountID: user.ID, GasBasicID: gas.ID,
 			DeliveryBasicID: delivery.ID, Title: fmt.Sprintf("示例供气合同 %d", scenario),
 			Terms: "仅用于开发联调。", DefaultDeliveryFee: 500,
-			SignedAt: now, EffectiveAt: now,
+			SignedAt: now, EffectiveAt: now, ExpiredAt: &nextYear,
 		}
 		if err := put(database, &contract); err != nil {
 			return err
 		}
+		// 仅回填本函数生成的联调合同，修复旧种子执行后已存在的空到期时间。
+		if err := database.Model(&models.GasorderContract{}).
+			Where("identity = ? AND contract_no = ? AND expired_at IS NULL", contract.Identity, contract.ContractNo).
+			Update("expired_at", nextYear).Error; err != nil {
+			return fmt.Errorf("backfill mock contract expiry: %w", err)
+		}
 
 		contractProduct := models.GasorderContractProduct{
 			Entity: entity(sequence+11, common.StatusEnable), GasorderContractID: contract.ID,