feat(channel): 缓存扁平化 + 网关映射集成 + 计费模式统一 + 模型限制

- 缓存按 (groupID, platform, model) 三维 key 扁平化，避免跨平台同名模型冲突
- buildCache 批量查询 group platform，按平台过滤展开定价和映射
- model_mapping 改为嵌套格式 {platform: {src: dst}}
- channel_model_pricing 新增 platform 列
- 前端按平台维度重构：每个平台独立配置分组/映射/定价
- 迁移 086: platform 列 + model_mapping 嵌套格式迁移

backend/internal/repository/channel_repo.go

@@ -406,8 +406,9 @@ func (r *channelRepository) GetGroupsInOtherChannels(ctx context.Context, channe
 	return conflicting, nil
 }
 
-// marshalModelMapping 将 model mapping 序列化为 JSON 字节，nil/空 map 返回 '{}'
-func marshalModelMapping(m map[string]string) ([]byte, error) {
+// marshalModelMapping 将 model mapping 序列化为嵌套 JSON 字节
+// 格式：{"platform": {"src": "dst"}, ...}
+func marshalModelMapping(m map[string]map[string]string) ([]byte, error) {
 	if len(m) == 0 {
 		return []byte("{}"), nil
 	}
@@ -418,14 +419,43 @@ func marshalModelMapping(m map[string]string) ([]byte, error) {
 	return data, nil
 }
 
-// unmarshalModelMapping 将 JSON 字节反序列化为 model mapping
-func unmarshalModelMapping(data []byte) map[string]string {
+// unmarshalModelMapping 将 JSON 字节反序列化为嵌套 model mapping
+func unmarshalModelMapping(data []byte) map[string]map[string]string {
 	if len(data) == 0 {
 		return nil
 	}
-	var m map[string]string
+	var m map[string]map[string]string
 	if err := json.Unmarshal(data, &m); err != nil {
 		return nil
 	}
 	return m
 }
+
+// GetGroupPlatforms 批量查询分组 ID 对应的平台
+func (r *channelRepository) GetGroupPlatforms(ctx context.Context, groupIDs []int64) (map[int64]string, error) {
+	if len(groupIDs) == 0 {
+		return make(map[int64]string), nil
+	}
+	rows, err := r.db.QueryContext(ctx,
+		`SELECT id, platform FROM groups WHERE id = ANY($1)`,
+		pq.Array(groupIDs),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("get group platforms: %w", err)
+	}
+	defer rows.Close()
+
+	result := make(map[int64]string, len(groupIDs))
+	for rows.Next() {
+		var id int64
+		var platform string
+		if err := rows.Scan(&id, &platform); err != nil {
+			return nil, fmt.Errorf("scan group platform: %w", err)
+		}
+		result[id] = platform
+	}
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("iterate group platforms: %w", err)
+	}
+	return result, nil
+}

backend/internal/repository/channel_repo_pricing.go

@@ -15,7 +15,7 @@ import (
 
 func (r *channelRepository) ListModelPricing(ctx context.Context, channelID int64) ([]service.ChannelModelPricing, error) {
 	rows, err := r.db.QueryContext(ctx,
-		`SELECT id, channel_id, models, billing_mode, input_price, output_price, cache_write_price, cache_read_price, image_output_price, per_request_price, created_at, updated_at
+		`SELECT id, channel_id, platform, models, billing_mode, input_price, output_price, cache_write_price, cache_read_price, image_output_price, per_request_price, created_at, updated_at
 		 FROM channel_model_pricing WHERE channel_id = $1 ORDER BY id`, channelID,
 	)
 	if err != nil {
@@ -56,10 +56,10 @@ func (r *channelRepository) UpdateModelPricing(ctx context.Context, pricing *ser
 	}
 	result, err := r.db.ExecContext(ctx,
 		`UPDATE channel_model_pricing
-		 SET models = $1, billing_mode = $2, input_price = $3, output_price = $4, cache_write_price = $5, cache_read_price = $6, image_output_price = $7, per_request_price = $8, updated_at = NOW()
-		 WHERE id = $9`,
+		 SET models = $1, billing_mode = $2, input_price = $3, output_price = $4, cache_write_price = $5, cache_read_price = $6, image_output_price = $7, per_request_price = $8, platform = $9, updated_at = NOW()
+		 WHERE id = $10`,
 		modelsJSON, billingMode, pricing.InputPrice, pricing.OutputPrice, pricing.CacheWritePrice, pricing.CacheReadPrice,
-		pricing.ImageOutputPrice, pricing.PerRequestPrice, pricing.ID,
+		pricing.ImageOutputPrice, pricing.PerRequestPrice, pricing.Platform, pricing.ID,
 	)
 	if err != nil {
 		return fmt.Errorf("update model pricing: %w", err)
@@ -90,7 +90,7 @@ func (r *channelRepository) ReplaceModelPricing(ctx context.Context, channelID i
 // batchLoadModelPricing 批量加载多个渠道的模型定价（含区间）
 func (r *channelRepository) batchLoadModelPricing(ctx context.Context, channelIDs []int64) (map[int64][]service.ChannelModelPricing, error) {
 	rows, err := r.db.QueryContext(ctx,
-		`SELECT id, channel_id, models, billing_mode, input_price, output_price, cache_write_price, cache_read_price, image_output_price, per_request_price, created_at, updated_at
+		`SELECT id, channel_id, platform, models, billing_mode, input_price, output_price, cache_write_price, cache_read_price, image_output_price, per_request_price, created_at, updated_at
 		 FROM channel_model_pricing WHERE channel_id = ANY($1) ORDER BY channel_id, id`,
 		pq.Array(channelIDs),
 	)
@@ -169,7 +169,7 @@ func scanModelPricingRows(rows *sql.Rows) ([]service.ChannelModelPricing, []int6
 		var p service.ChannelModelPricing
 		var modelsJSON []byte
 		if err := rows.Scan(
-			&p.ID, &p.ChannelID, &modelsJSON, &p.BillingMode,
+			&p.ID, &p.ChannelID, &p.Platform, &modelsJSON, &p.BillingMode,
 			&p.InputPrice, &p.OutputPrice, &p.CacheWritePrice, &p.CacheReadPrice,
 			&p.ImageOutputPrice, &p.PerRequestPrice, &p.CreatedAt, &p.UpdatedAt,
 		); err != nil {
@@ -223,10 +223,14 @@ func createModelPricingExec(ctx context.Context, exec dbExec, pricing *service.C
 	if billingMode == "" {
 		billingMode = service.BillingModeToken
 	}
+	platform := pricing.Platform
+	if platform == "" {
+		platform = "anthropic"
+	}
 	err = exec.QueryRowContext(ctx,
-		`INSERT INTO channel_model_pricing (channel_id, models, billing_mode, input_price, output_price, cache_write_price, cache_read_price, image_output_price, per_request_price)
-		 VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9) RETURNING id, created_at, updated_at`,
-		pricing.ChannelID, modelsJSON, billingMode,
+		`INSERT INTO channel_model_pricing (channel_id, platform, models, billing_mode, input_price, output_price, cache_write_price, cache_read_price, image_output_price, per_request_price)
+		 VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10) RETURNING id, created_at, updated_at`,
+		pricing.ChannelID, platform, modelsJSON, billingMode,
 		pricing.InputPrice, pricing.OutputPrice, pricing.CacheWritePrice, pricing.CacheReadPrice,
 		pricing.ImageOutputPrice, pricing.PerRequestPrice,
 	).Scan(&pricing.ID, &pricing.CreatedAt, &pricing.UpdatedAt)