feat(channel): 渠道管理全链路集成 — 模型映射、定价、限制、用量统计

- 渠道模型映射：支持精确匹配和通配符映射，按平台隔离
- 渠道模型定价：支持 token/按次/图片三种计费模式，区间分层定价
- 模型限制：渠道可限制仅允许定价列表中的模型
- 计费模型来源：支持 requested/upstream 两种计费模型选择
- 用量统计：usage_logs 新增 channel_id/model_mapping_chain/billing_tier/billing_mode 字段
- Dashboard 支持 model_source 维度（requested/upstream/mapping）查看模型统计
- 全部 gateway handler 统一接入 ResolveChannelMappingAndRestrict
- 修复测试：同步 SoraGenerationRepository 接口、SQL INSERT 参数、scan 字段

backend/internal/repository/channel_repo_pricing.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"database/sql"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"strings"
 
@@ -274,7 +275,8 @@ func replaceModelPricingTx(ctx context.Context, exec dbExec, channelID int64, pr
 
 // isUniqueViolation 检查 pq 唯一约束违反错误
 func isUniqueViolation(err error) bool {
-	if pqErr, ok := err.(*pq.Error); ok {
+	var pqErr *pq.Error
+	if errors.As(err, &pqErr) && pqErr != nil {
 		return pqErr.Code == "23505"
 	}
 	return false

backend/internal/repository/channel_repo_test.go

@@ -0,0 +1,227 @@
+//go:build unit
+
+package repository
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"testing"
+
+	"github.com/lib/pq"
+	"github.com/stretchr/testify/require"
+)
+
+// --- marshalModelMapping ---
+
+func TestMarshalModelMapping(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    map[string]map[string]string
+		wantJSON string // expected JSON output (exact match)
+	}{
+		{
+			name:     "empty map",
+			input:    map[string]map[string]string{},
+			wantJSON: "{}",
+		},
+		{
+			name:     "nil map",
+			input:    nil,
+			wantJSON: "{}",
+		},
+		{
+			name: "populated map",
+			input: map[string]map[string]string{
+				"openai": {"gpt-4": "gpt-4-turbo"},
+			},
+		},
+		{
+			name: "nested values",
+			input: map[string]map[string]string{
+				"openai":    {"*": "gpt-5.4"},
+				"anthropic": {"claude-old": "claude-new"},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result, err := marshalModelMapping(tt.input)
+			require.NoError(t, err)
+
+			if tt.wantJSON != "" {
+				require.Equal(t, []byte(tt.wantJSON), result)
+			} else {
+				// round-trip: unmarshal and compare with input
+				var parsed map[string]map[string]string
+				require.NoError(t, json.Unmarshal(result, &parsed))
+				require.Equal(t, tt.input, parsed)
+			}
+		})
+	}
+}
+
+// --- unmarshalModelMapping ---
+
+func TestUnmarshalModelMapping(t *testing.T) {
+	tests := []struct {
+		name    string
+		input   []byte
+		wantNil bool
+		want    map[string]map[string]string
+	}{
+		{
+			name:    "nil data",
+			input:   nil,
+			wantNil: true,
+		},
+		{
+			name:    "empty data",
+			input:   []byte{},
+			wantNil: true,
+		},
+		{
+			name:    "invalid JSON",
+			input:   []byte("not-json"),
+			wantNil: true,
+		},
+		{
+			name:    "type error - number",
+			input:   []byte("42"),
+			wantNil: true,
+		},
+		{
+			name:    "type error - array",
+			input:   []byte("[1,2,3]"),
+			wantNil: true,
+		},
+		{
+			name: "valid JSON",
+			input: []byte(`{"openai":{"gpt-4":"gpt-4-turbo"},"anthropic":{"old":"new"}}`),
+			want: map[string]map[string]string{
+				"openai":    {"gpt-4": "gpt-4-turbo"},
+				"anthropic": {"old": "new"},
+			},
+		},
+		{
+			name:  "empty object",
+			input: []byte("{}"),
+			want:  map[string]map[string]string{},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := unmarshalModelMapping(tt.input)
+			if tt.wantNil {
+				require.Nil(t, result)
+			} else {
+				require.NotNil(t, result)
+				require.Equal(t, tt.want, result)
+			}
+		})
+	}
+}
+
+// --- escapeLike ---
+
+func TestEscapeLike(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  string
+	}{
+		{
+			name:  "no special chars",
+			input: "hello",
+			want:  "hello",
+		},
+		{
+			name:  "backslash",
+			input: `a\b`,
+			want:  `a\\b`,
+		},
+		{
+			name:  "percent",
+			input: "50%",
+			want:  `50\%`,
+		},
+		{
+			name:  "underscore",
+			input: "a_b",
+			want:  `a\_b`,
+		},
+		{
+			name:  "all special chars",
+			input: `a\b%c_d`,
+			want:  `a\\b\%c\_d`,
+		},
+		{
+			name:  "empty string",
+			input: "",
+			want:  "",
+		},
+		{
+			name:  "consecutive special chars",
+			input: "%_%",
+			want:  `\%\_\%`,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			require.Equal(t, tt.want, escapeLike(tt.input))
+		})
+	}
+}
+
+// --- isUniqueViolation ---
+
+func TestIsUniqueViolation(t *testing.T) {
+	tests := []struct {
+		name string
+		err  error
+		want bool
+	}{
+		{
+			name: "unique violation code 23505",
+			err:  &pq.Error{Code: "23505"},
+			want: true,
+		},
+		{
+			name: "different pq error code",
+			err:  &pq.Error{Code: "23503"},
+			want: false,
+		},
+		{
+			name: "non-pq error",
+			err:  errors.New("some generic error"),
+			want: false,
+		},
+		{
+			name: "typed nil pq.Error",
+			err: func() error {
+				var pqErr *pq.Error
+				return pqErr
+			}(),
+			want: false,
+		},
+		{
+			name: "bare nil",
+			err:  nil,
+			want: false,
+		},
+		{
+			name: "wrapped pq error with 23505",
+			err:  fmt.Errorf("wrapped: %w", &pq.Error{Code: "23505"}),
+			want: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			require.Equal(t, tt.want, isUniqueViolation(tt.err))
+		})
+	}
+}

backend/internal/repository/usage_log_repo.go

@@ -3144,6 +3144,30 @@ func (r *usageLogRepository) GetUserBreakdownStats(ctx context.Context, startTim
 		query += fmt.Sprintf(" AND %s = $%d", col, len(args)+1)
 		args = append(args, dim.Endpoint)
 	}
+	if dim.UserID > 0 {
+		query += fmt.Sprintf(" AND ul.user_id = $%d", len(args)+1)
+		args = append(args, dim.UserID)
+	}
+	if dim.APIKeyID > 0 {
+		query += fmt.Sprintf(" AND ul.api_key_id = $%d", len(args)+1)
+		args = append(args, dim.APIKeyID)
+	}
+	if dim.AccountID > 0 {
+		query += fmt.Sprintf(" AND ul.account_id = $%d", len(args)+1)
+		args = append(args, dim.AccountID)
+	}
+	if dim.RequestType != nil {
+		query += fmt.Sprintf(" AND ul.request_type = $%d", len(args)+1)
+		args = append(args, *dim.RequestType)
+	}
+	if dim.Stream != nil {
+		query += fmt.Sprintf(" AND ul.stream = $%d", len(args)+1)
+		args = append(args, *dim.Stream)
+	}
+	if dim.BillingType != nil {
+		query += fmt.Sprintf(" AND ul.billing_type = $%d", len(args)+1)
+		args = append(args, *dim.BillingType)
+	}
 
 	query += " GROUP BY ul.user_id, u.email ORDER BY actual_cost DESC"
 	if limit > 0 {

backend/internal/repository/usage_log_repo_request_type_test.go

@@ -80,6 +80,10 @@ func TestUsageLogRepositoryCreateSyncRequestTypeAndLegacyFields(t *testing.T) {
 			sqlmock.AnyArg(), // inbound_endpoint
 			sqlmock.AnyArg(), // upstream_endpoint
 			log.CacheTTLOverridden,
+			sqlmock.AnyArg(), // channel_id
+			sqlmock.AnyArg(), // model_mapping_chain
+			sqlmock.AnyArg(), // billing_tier
+			sqlmock.AnyArg(), // billing_mode
 			createdAt,
 		).
 		WillReturnRows(sqlmock.NewRows([]string{"id", "created_at"}).AddRow(int64(99), createdAt))
@@ -153,6 +157,10 @@ func TestUsageLogRepositoryCreate_PersistsServiceTier(t *testing.T) {
 			sqlmock.AnyArg(),
 			sqlmock.AnyArg(),
 			log.CacheTTLOverridden,
+			sqlmock.AnyArg(), // channel_id
+			sqlmock.AnyArg(), // model_mapping_chain
+			sqlmock.AnyArg(), // billing_tier
+			sqlmock.AnyArg(), // billing_mode
 			createdAt,
 		).
 		WillReturnRows(sqlmock.NewRows([]string{"id", "created_at"}).AddRow(int64(100), createdAt))
@@ -463,6 +471,10 @@ func TestScanUsageLogRequestTypeAndLegacyFallback(t *testing.T) {
 			sql.NullString{},
 			sql.NullString{},
 			false,
+			sql.NullInt64{},  // channel_id
+			sql.NullString{}, // model_mapping_chain
+			sql.NullString{}, // billing_tier
+			sql.NullString{}, // billing_mode
 			now,
 		}})
 		require.NoError(t, err)
@@ -506,6 +518,10 @@ func TestScanUsageLogRequestTypeAndLegacyFallback(t *testing.T) {
 			sql.NullString{},
 			sql.NullString{},
 			false,
+			sql.NullInt64{},  // channel_id
+			sql.NullString{}, // model_mapping_chain
+			sql.NullString{}, // billing_tier
+			sql.NullString{}, // billing_mode
 			now,
 		}})
 		require.NoError(t, err)
@@ -549,6 +565,10 @@ func TestScanUsageLogRequestTypeAndLegacyFallback(t *testing.T) {
 			sql.NullString{},
 			sql.NullString{},
 			false,
+			sql.NullInt64{},  // channel_id
+			sql.NullString{}, // model_mapping_chain
+			sql.NullString{}, // billing_tier
+			sql.NullString{}, // billing_mode
 			now,
 		}})
 		require.NoError(t, err)