feat: add AI model CRUD functions (7 models)

- Provider/Model/ApiKey: standard CRUD + special lookups
- Conversation: user-scoped pagination
- ChatMessage: conversation-ordered retrieval
- UsageRecord: insert + user-scoped pagination
- UserQuota: freeze/settle/unfreeze atomic operations

backend/model/ai_api_key_model.go

@@ -0,0 +1,87 @@
+package model
+
+import (
+	"context"
+	"errors"
+
+	"gorm.io/gorm"
+)
+
+// AIApiKeyInsert 插入AI API密钥
+func AIApiKeyInsert(ctx context.Context, db *gorm.DB, apiKey *AIApiKey) (int64, error) {
+	result := db.WithContext(ctx).Create(apiKey)
+	if result.Error != nil {
+		return 0, result.Error
+	}
+	return apiKey.Id, nil
+}
+
+// AIApiKeyFindOne 根据ID查询AI API密钥
+func AIApiKeyFindOne(ctx context.Context, db *gorm.DB, id int64) (*AIApiKey, error) {
+	var apiKey AIApiKey
+	result := db.WithContext(ctx).First(&apiKey, id)
+	if result.Error != nil {
+		if errors.Is(result.Error, gorm.ErrRecordNotFound) {
+			return nil, ErrNotFound
+		}
+		return nil, result.Error
+	}
+	return &apiKey, nil
+}
+
+// AIApiKeyFindList 查询AI API密钥列表（分页）
+func AIApiKeyFindList(ctx context.Context, db *gorm.DB, page, pageSize int64) ([]AIApiKey, int64, error) {
+	var apiKeys []AIApiKey
+	var total int64
+
+	query := db.WithContext(ctx).Model(&AIApiKey{})
+
+	if err := query.Count(&total).Error; err != nil {
+		return nil, 0, err
+	}
+
+	offset := (page - 1) * pageSize
+	if offset < 0 {
+		offset = 0
+	}
+	err := query.Order("created_at DESC").Offset(int(offset)).Limit(int(pageSize)).Find(&apiKeys).Error
+	if err != nil {
+		return nil, 0, err
+	}
+
+	return apiKeys, total, nil
+}
+
+// AIApiKeyUpdate 更新AI API密钥
+func AIApiKeyUpdate(ctx context.Context, db *gorm.DB, apiKey *AIApiKey) error {
+	result := db.WithContext(ctx).Save(apiKey)
+	return result.Error
+}
+
+// AIApiKeyDelete 删除AI API密钥
+func AIApiKeyDelete(ctx context.Context, db *gorm.DB, id int64) error {
+	result := db.WithContext(ctx).Delete(&AIApiKey{}, id)
+	return result.Error
+}
+
+// AIApiKeyFindByProviderAndUser 根据供应商ID和用户ID查询API密钥
+func AIApiKeyFindByProviderAndUser(ctx context.Context, db *gorm.DB, providerId, userId int64) ([]AIApiKey, error) {
+	var apiKeys []AIApiKey
+	err := db.WithContext(ctx).Where("provider_id = ? AND user_id = ?", providerId, userId).
+		Order("created_at DESC").Find(&apiKeys).Error
+	if err != nil {
+		return nil, err
+	}
+	return apiKeys, nil
+}
+
+// AIApiKeyFindSystemKeys 查询系统级API密钥（userId=0为系统密钥）
+func AIApiKeyFindSystemKeys(ctx context.Context, db *gorm.DB, providerId int64) ([]AIApiKey, error) {
+	var apiKeys []AIApiKey
+	err := db.WithContext(ctx).Where("provider_id = ? AND user_id = 0", providerId).
+		Order("created_at DESC").Find(&apiKeys).Error
+	if err != nil {
+		return nil, err
+	}
+	return apiKeys, nil
+}

backend/model/ai_chat_message_model.go

@@ -0,0 +1,27 @@
+package model
+
+import (
+	"context"
+
+	"gorm.io/gorm"
+)
+
+// AIChatMessageInsert 插入AI聊天消息
+func AIChatMessageInsert(ctx context.Context, db *gorm.DB, message *AIChatMessage) (int64, error) {
+	result := db.WithContext(ctx).Create(message)
+	if result.Error != nil {
+		return 0, result.Error
+	}
+	return message.Id, nil
+}
+
+// AIChatMessageFindByConversation 根据对话ID查询所有消息（按创建时间升序，不分页）
+func AIChatMessageFindByConversation(ctx context.Context, db *gorm.DB, conversationId int64) ([]AIChatMessage, error) {
+	var messages []AIChatMessage
+	err := db.WithContext(ctx).Where("conversation_id = ?", conversationId).
+		Order("created_at ASC").Find(&messages).Error
+	if err != nil {
+		return nil, err
+	}
+	return messages, nil
+}

backend/model/ai_conversation_model.go

@@ -0,0 +1,65 @@
+package model
+
+import (
+	"context"
+	"errors"
+
+	"gorm.io/gorm"
+)
+
+// AIConversationInsert 插入AI对话
+func AIConversationInsert(ctx context.Context, db *gorm.DB, conversation *AIConversation) (int64, error) {
+	result := db.WithContext(ctx).Create(conversation)
+	if result.Error != nil {
+		return 0, result.Error
+	}
+	return conversation.Id, nil
+}
+
+// AIConversationFindOne 根据ID查询AI对话
+func AIConversationFindOne(ctx context.Context, db *gorm.DB, id int64) (*AIConversation, error) {
+	var conversation AIConversation
+	result := db.WithContext(ctx).First(&conversation, id)
+	if result.Error != nil {
+		if errors.Is(result.Error, gorm.ErrRecordNotFound) {
+			return nil, ErrNotFound
+		}
+		return nil, result.Error
+	}
+	return &conversation, nil
+}
+
+// AIConversationUpdate 更新AI对话
+func AIConversationUpdate(ctx context.Context, db *gorm.DB, conversation *AIConversation) error {
+	result := db.WithContext(ctx).Save(conversation)
+	return result.Error
+}
+
+// AIConversationDelete 删除AI对话
+func AIConversationDelete(ctx context.Context, db *gorm.DB, id int64) error {
+	result := db.WithContext(ctx).Delete(&AIConversation{}, id)
+	return result.Error
+}
+
+// AIConversationFindByUser 根据用户ID查询对话列表（分页，按更新时间倒序）
+func AIConversationFindByUser(ctx context.Context, db *gorm.DB, userId int64, page, pageSize int64) ([]AIConversation, int64, error) {
+	var conversations []AIConversation
+	var total int64
+
+	query := db.WithContext(ctx).Model(&AIConversation{}).Where("user_id = ?", userId)
+
+	if err := query.Count(&total).Error; err != nil {
+		return nil, 0, err
+	}
+
+	offset := (page - 1) * pageSize
+	if offset < 0 {
+		offset = 0
+	}
+	err := query.Order("updated_at DESC").Offset(int(offset)).Limit(int(pageSize)).Find(&conversations).Error
+	if err != nil {
+		return nil, 0, err
+	}
+
+	return conversations, total, nil
+}

backend/model/ai_model_model.go

@@ -0,0 +1,98 @@
+package model
+
+import (
+	"context"
+	"errors"
+
+	"gorm.io/gorm"
+)
+
+// AIModelInsert 插入AI模型
+func AIModelInsert(ctx context.Context, db *gorm.DB, aiModel *AIModel) (int64, error) {
+	result := db.WithContext(ctx).Create(aiModel)
+	if result.Error != nil {
+		return 0, result.Error
+	}
+	return aiModel.Id, nil
+}
+
+// AIModelFindOne 根据ID查询AI模型
+func AIModelFindOne(ctx context.Context, db *gorm.DB, id int64) (*AIModel, error) {
+	var aiModel AIModel
+	result := db.WithContext(ctx).First(&aiModel, id)
+	if result.Error != nil {
+		if errors.Is(result.Error, gorm.ErrRecordNotFound) {
+			return nil, ErrNotFound
+		}
+		return nil, result.Error
+	}
+	return &aiModel, nil
+}
+
+// AIModelFindList 查询AI模型列表（分页）
+func AIModelFindList(ctx context.Context, db *gorm.DB, page, pageSize int64) ([]AIModel, int64, error) {
+	var models []AIModel
+	var total int64
+
+	query := db.WithContext(ctx).Model(&AIModel{})
+
+	if err := query.Count(&total).Error; err != nil {
+		return nil, 0, err
+	}
+
+	offset := (page - 1) * pageSize
+	if offset < 0 {
+		offset = 0
+	}
+	err := query.Order("sort_order ASC, id ASC").Offset(int(offset)).Limit(int(pageSize)).Find(&models).Error
+	if err != nil {
+		return nil, 0, err
+	}
+
+	return models, total, nil
+}
+
+// AIModelUpdate 更新AI模型
+func AIModelUpdate(ctx context.Context, db *gorm.DB, aiModel *AIModel) error {
+	result := db.WithContext(ctx).Save(aiModel)
+	return result.Error
+}
+
+// AIModelDelete 删除AI模型
+func AIModelDelete(ctx context.Context, db *gorm.DB, id int64) error {
+	result := db.WithContext(ctx).Delete(&AIModel{}, id)
+	return result.Error
+}
+
+// AIModelFindByModelId 根据模型标识查询AI模型
+func AIModelFindByModelId(ctx context.Context, db *gorm.DB, modelId string) (*AIModel, error) {
+	var aiModel AIModel
+	result := db.WithContext(ctx).Where("model_id = ?", modelId).First(&aiModel)
+	if result.Error != nil {
+		if errors.Is(result.Error, gorm.ErrRecordNotFound) {
+			return nil, ErrNotFound
+		}
+		return nil, result.Error
+	}
+	return &aiModel, nil
+}
+
+// AIModelFindByProvider 根据供应商ID查询AI模型列表
+func AIModelFindByProvider(ctx context.Context, db *gorm.DB, providerId int64) ([]AIModel, error) {
+	var models []AIModel
+	err := db.WithContext(ctx).Where("provider_id = ?", providerId).Order("sort_order ASC, id ASC").Find(&models).Error
+	if err != nil {
+		return nil, err
+	}
+	return models, nil
+}
+
+// AIModelFindAllActive 查询所有启用的AI模型
+func AIModelFindAllActive(ctx context.Context, db *gorm.DB) ([]AIModel, error) {
+	var models []AIModel
+	err := db.WithContext(ctx).Where("is_active = ?", true).Order("sort_order ASC, id ASC").Find(&models).Error
+	if err != nil {
+		return nil, err
+	}
+	return models, nil
+}

backend/model/ai_provider_model.go

@@ -0,0 +1,88 @@
+package model
+
+import (
+	"context"
+	"errors"
+
+	"gorm.io/gorm"
+)
+
+// AIProviderInsert 插入AI供应商
+func AIProviderInsert(ctx context.Context, db *gorm.DB, provider *AIProvider) (int64, error) {
+	result := db.WithContext(ctx).Create(provider)
+	if result.Error != nil {
+		return 0, result.Error
+	}
+	return provider.Id, nil
+}
+
+// AIProviderFindOne 根据ID查询AI供应商
+func AIProviderFindOne(ctx context.Context, db *gorm.DB, id int64) (*AIProvider, error) {
+	var provider AIProvider
+	result := db.WithContext(ctx).First(&provider, id)
+	if result.Error != nil {
+		if errors.Is(result.Error, gorm.ErrRecordNotFound) {
+			return nil, ErrNotFound
+		}
+		return nil, result.Error
+	}
+	return &provider, nil
+}
+
+// AIProviderFindList 查询AI供应商列表（分页）
+func AIProviderFindList(ctx context.Context, db *gorm.DB, page, pageSize int64) ([]AIProvider, int64, error) {
+	var providers []AIProvider
+	var total int64
+
+	query := db.WithContext(ctx).Model(&AIProvider{})
+
+	if err := query.Count(&total).Error; err != nil {
+		return nil, 0, err
+	}
+
+	offset := (page - 1) * pageSize
+	if offset < 0 {
+		offset = 0
+	}
+	err := query.Order("sort_order ASC, id ASC").Offset(int(offset)).Limit(int(pageSize)).Find(&providers).Error
+	if err != nil {
+		return nil, 0, err
+	}
+
+	return providers, total, nil
+}
+
+// AIProviderUpdate 更新AI供应商
+func AIProviderUpdate(ctx context.Context, db *gorm.DB, provider *AIProvider) error {
+	result := db.WithContext(ctx).Save(provider)
+	return result.Error
+}
+
+// AIProviderDelete 删除AI供应商
+func AIProviderDelete(ctx context.Context, db *gorm.DB, id int64) error {
+	result := db.WithContext(ctx).Delete(&AIProvider{}, id)
+	return result.Error
+}
+
+// AIProviderFindByName 根据名称查询AI供应商
+func AIProviderFindByName(ctx context.Context, db *gorm.DB, name string) (*AIProvider, error) {
+	var provider AIProvider
+	result := db.WithContext(ctx).Where("name = ?", name).First(&provider)
+	if result.Error != nil {
+		if errors.Is(result.Error, gorm.ErrRecordNotFound) {
+			return nil, ErrNotFound
+		}
+		return nil, result.Error
+	}
+	return &provider, nil
+}
+
+// AIProviderFindAllActive 查询所有启用的AI供应商
+func AIProviderFindAllActive(ctx context.Context, db *gorm.DB) ([]AIProvider, error) {
+	var providers []AIProvider
+	err := db.WithContext(ctx).Where("is_active = ?", true).Order("sort_order ASC, id ASC").Find(&providers).Error
+	if err != nil {
+		return nil, err
+	}
+	return providers, nil
+}

backend/model/ai_usage_record_model.go

@@ -0,0 +1,39 @@
+package model
+
+import (
+	"context"
+
+	"gorm.io/gorm"
+)
+
+// AIUsageRecordInsert 插入AI使用记录
+func AIUsageRecordInsert(ctx context.Context, db *gorm.DB, record *AIUsageRecord) (int64, error) {
+	result := db.WithContext(ctx).Create(record)
+	if result.Error != nil {
+		return 0, result.Error
+	}
+	return record.Id, nil
+}
+
+// AIUsageRecordFindByUser 根据用户ID查询使用记录（分页，按创建时间倒序）
+func AIUsageRecordFindByUser(ctx context.Context, db *gorm.DB, userId int64, page, pageSize int64) ([]AIUsageRecord, int64, error) {
+	var records []AIUsageRecord
+	var total int64
+
+	query := db.WithContext(ctx).Model(&AIUsageRecord{}).Where("user_id = ?", userId)
+
+	if err := query.Count(&total).Error; err != nil {
+		return nil, 0, err
+	}
+
+	offset := (page - 1) * pageSize
+	if offset < 0 {
+		offset = 0
+	}
+	err := query.Order("created_at DESC").Offset(int(offset)).Limit(int(pageSize)).Find(&records).Error
+	if err != nil {
+		return nil, 0, err
+	}
+
+	return records, total, nil
+}

backend/model/ai_user_quota_model.go

@@ -0,0 +1,91 @@
+package model
+
+import (
+	"context"
+	"errors"
+
+	"gorm.io/gorm"
+)
+
+// AIUserQuotaFindByUser 根据用户ID查询额度
+func AIUserQuotaFindByUser(ctx context.Context, db *gorm.DB, userId int64) (*AIUserQuota, error) {
+	var quota AIUserQuota
+	result := db.WithContext(ctx).Where("user_id = ?", userId).First(&quota)
+	if result.Error != nil {
+		if errors.Is(result.Error, gorm.ErrRecordNotFound) {
+			return nil, ErrNotFound
+		}
+		return nil, result.Error
+	}
+	return &quota, nil
+}
+
+// AIUserQuotaEnsure 查找或创建用户额度记录
+func AIUserQuotaEnsure(ctx context.Context, db *gorm.DB, userId int64) (*AIUserQuota, error) {
+	var quota AIUserQuota
+	result := db.WithContext(ctx).Where("user_id = ?", userId).First(&quota)
+	if result.Error != nil {
+		if errors.Is(result.Error, gorm.ErrRecordNotFound) {
+			quota = AIUserQuota{UserId: userId}
+			if err := db.WithContext(ctx).Create(&quota).Error; err != nil {
+				return nil, err
+			}
+			return &quota, nil
+		}
+		return nil, result.Error
+	}
+	return &quota, nil
+}
+
+// AIUserQuotaFreeze 冻结额度（原子操作：balance -= amount, frozen_amount += amount）
+func AIUserQuotaFreeze(ctx context.Context, db *gorm.DB, userId int64, amount float64) error {
+	result := db.WithContext(ctx).Model(&AIUserQuota{}).
+		Where("user_id = ? AND balance >= ?", userId, amount).
+		Updates(map[string]interface{}{
+			"balance":       gorm.Expr("balance - ?", amount),
+			"frozen_amount": gorm.Expr("frozen_amount + ?", amount),
+		})
+	if result.Error != nil {
+		return result.Error
+	}
+	if result.RowsAffected == 0 {
+		return errors.New("insufficient balance")
+	}
+	return nil
+}
+
+// AIUserQuotaSettle 结算额度（原子操作：frozen_amount -= frozenAmount, total_consumed += actualCost, balance += refund）
+func AIUserQuotaSettle(ctx context.Context, db *gorm.DB, userId int64, frozenAmount, actualCost float64) error {
+	refund := frozenAmount - actualCost
+	result := db.WithContext(ctx).Model(&AIUserQuota{}).
+		Where("user_id = ?", userId).
+		Updates(map[string]interface{}{
+			"frozen_amount":  gorm.Expr("frozen_amount - ?", frozenAmount),
+			"total_consumed": gorm.Expr("total_consumed + ?", actualCost),
+			"balance":        gorm.Expr("balance + ?", refund),
+		})
+	if result.Error != nil {
+		return result.Error
+	}
+	if result.RowsAffected == 0 {
+		return ErrNotFound
+	}
+	return nil
+}
+
+// AIUserQuotaUnfreeze 解冻额度（原子操作：frozen_amount -= amount, balance += amount）
+func AIUserQuotaUnfreeze(ctx context.Context, db *gorm.DB, userId int64, amount float64) error {
+	result := db.WithContext(ctx).Model(&AIUserQuota{}).
+		Where("user_id = ?", userId).
+		Updates(map[string]interface{}{
+			"frozen_amount": gorm.Expr("frozen_amount - ?", amount),
+			"balance":       gorm.Expr("balance + ?", amount),
+		})
+	if result.Error != nil {
+		return result.Error
+	}
+	if result.RowsAffected == 0 {
+		return ErrNotFound
+	}
+	return nil
+}