test(repo): cover requested model repository semantics

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

backend/internal/repository/usage_log_repo_breakdown_test.go

@@ -34,11 +34,11 @@ func TestResolveModelDimensionExpression(t *testing.T) {
 		modelType string
 		want      string
 	}{
-		{usagestats.ModelSourceRequested, "model"},
+		{usagestats.ModelSourceRequested, "COALESCE(NULLIF(TRIM(requested_model), ''), model)"},
-		{usagestats.ModelSourceUpstream, "COALESCE(NULLIF(TRIM(upstream_model), ''), model)"},
+		{usagestats.ModelSourceUpstream, "COALESCE(NULLIF(TRIM(upstream_model), ''), COALESCE(NULLIF(TRIM(requested_model), ''), model))"},
-		{usagestats.ModelSourceMapping, "(model || ' -> ' || COALESCE(NULLIF(TRIM(upstream_model), ''), model))"},
+		{usagestats.ModelSourceMapping, "(COALESCE(NULLIF(TRIM(requested_model), ''), model) || ' -> ' || COALESCE(NULLIF(TRIM(upstream_model), ''), COALESCE(NULLIF(TRIM(requested_model), ''), model)))"},
-		{"", "model"},
+		{"", "COALESCE(NULLIF(TRIM(requested_model), ''), model)"},
-		{"invalid", "model"},
+		{"invalid", "COALESCE(NULLIF(TRIM(requested_model), ''), model)"},
 	}
 
 	for _, tc := range tests {

backend/internal/repository/usage_log_repo_request_type_test.go

@@ -3,6 +3,7 @@ package repository
 import (
 	"context"
 	"database/sql"
+	"database/sql/driver"
 	"fmt"
 	"reflect"
 	"testing"
@@ -26,6 +27,7 @@ func TestUsageLogRepositoryCreateSyncRequestTypeAndLegacyFields(t *testing.T) {
 		AccountID:      3,
 		RequestID:      "req-1",
 		Model:          "gpt-5",
+		RequestedModel: "gpt-5",
 		InputTokens:    10,
 		OutputTokens:   20,
 		TotalCost:      1,
@@ -44,6 +46,7 @@ func TestUsageLogRepositoryCreateSyncRequestTypeAndLegacyFields(t *testing.T) {
 			log.AccountID,
 			log.RequestID,
 			log.Model,
+			log.RequestedModel,
 			sqlmock.AnyArg(), // upstream_model
 			sqlmock.AnyArg(), // group_id
 			sqlmock.AnyArg(), // subscription_id
@@ -104,6 +107,7 @@ func TestUsageLogRepositoryCreate_PersistsServiceTier(t *testing.T) {
 		AccountID:      3,
 		RequestID:      "req-service-tier",
 		Model:          "gpt-5.4",
+		RequestedModel: "gpt-5.4",
 		ServiceTier:    &serviceTier,
 		CreatedAt:      createdAt,
 	}
@@ -115,6 +119,7 @@ func TestUsageLogRepositoryCreate_PersistsServiceTier(t *testing.T) {
 			log.AccountID,
 			log.RequestID,
 			log.Model,
+			log.RequestedModel,
 			sqlmock.AnyArg(),
 			sqlmock.AnyArg(),
 			sqlmock.AnyArg(),
@@ -158,6 +163,75 @@ func TestUsageLogRepositoryCreate_PersistsServiceTier(t *testing.T) {
 	require.NoError(t, mock.ExpectationsWereMet())
 }
 
+func TestBuildUsageLogBestEffortInsertQuery_IncludesRequestedModelColumn(t *testing.T) {
+	prepared := prepareUsageLogInsert(&service.UsageLog{
+		UserID:         1,
+		APIKeyID:       2,
+		AccountID:      3,
+		RequestID:      "req-best-effort-query",
+		Model:          "gpt-5",
+		RequestedModel: "gpt-5",
+		CreatedAt:      time.Date(2025, 1, 3, 12, 0, 0, 0, time.UTC),
+	})
+
+	query, args := buildUsageLogBestEffortInsertQuery([]usageLogInsertPrepared{prepared})
+
+	require.Contains(t, query, "INSERT INTO usage_logs (")
+	require.Contains(t, query, "\n\t\t\tmodel,\n\t\t\trequested_model,\n\t\t\tupstream_model,")
+	require.Contains(t, query, "\n\t\t\trequest_id,\n\t\t\tmodel,\n\t\t\trequested_model,\n\t\t\tupstream_model,")
+	require.Len(t, args, len(prepared.args))
+	require.Equal(t, prepared.args[5], args[5])
+}
+
+func TestExecUsageLogInsertNoResult_PersistsRequestedModel(t *testing.T) {
+	db, mock := newSQLMock(t)
+	prepared := prepareUsageLogInsert(&service.UsageLog{
+		UserID:         1,
+		APIKeyID:       2,
+		AccountID:      3,
+		RequestID:      "req-best-effort-exec",
+		Model:          "gpt-5",
+		RequestedModel: "gpt-5",
+		CreatedAt:      time.Date(2025, 1, 4, 12, 0, 0, 0, time.UTC),
+	})
+
+	mock.ExpectExec("INSERT INTO usage_logs").
+		WithArgs(anySliceToDriverValues(prepared.args)...).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	err := execUsageLogInsertNoResult(context.Background(), db, prepared)
+	require.NoError(t, err)
+	require.NoError(t, mock.ExpectationsWereMet())
+}
+
+func TestPrepareUsageLogInsert_ArgCountMatchesTypes(t *testing.T) {
+	prepared := prepareUsageLogInsert(&service.UsageLog{
+		UserID:         1,
+		APIKeyID:       2,
+		AccountID:      3,
+		RequestID:      "req-arg-count",
+		Model:          "gpt-5",
+		RequestedModel: "gpt-5",
+		CreatedAt:      time.Date(2025, 1, 5, 12, 0, 0, 0, time.UTC),
+	})
+
+	require.Len(t, prepared.args, len(usageLogInsertArgTypes))
+}
+
+func TestCoalesceTrimmedString(t *testing.T) {
+	require.Equal(t, "fallback", coalesceTrimmedString(sql.NullString{}, "fallback"))
+	require.Equal(t, "fallback", coalesceTrimmedString(sql.NullString{Valid: true, String: "   "}, "fallback"))
+	require.Equal(t, "value", coalesceTrimmedString(sql.NullString{Valid: true, String: "value"}, "fallback"))
+}
+
+func anySliceToDriverValues(values []any) []driver.Value {
+	out := make([]driver.Value, 0, len(values))
+	for _, value := range values {
+		out = append(out, value)
+	}
+	return out
+}
+
 func TestUsageLogRepositoryListWithFiltersRequestTypePriority(t *testing.T) {
 	db, mock := newSQLMock(t)
 	repo := &usageLogRepository{sql: db}
@@ -355,6 +429,7 @@ func TestScanUsageLogRequestTypeAndLegacyFallback(t *testing.T) {
 			int64(30), // account_id
 			sql.NullString{Valid: true, String: "req-1"},
 			"gpt-5", // model
+			sql.NullString{Valid: true, String: "gpt-5"}, // requested_model
 			sql.NullString{},  // upstream_model
 			sql.NullInt64{},   // group_id
 			sql.NullInt64{},   // subscription_id
@@ -407,6 +482,7 @@ func TestScanUsageLogRequestTypeAndLegacyFallback(t *testing.T) {
 			int64(31),
 			sql.NullString{Valid: true, String: "req-2"},
 			"gpt-5",
+			sql.NullString{Valid: true, String: "gpt-5"},
 			sql.NullString{},
 			sql.NullInt64{},
 			sql.NullInt64{},
@@ -449,6 +525,7 @@ func TestScanUsageLogRequestTypeAndLegacyFallback(t *testing.T) {
 			int64(32),
 			sql.NullString{Valid: true, String: "req-3"},
 			"gpt-5.4",
+			sql.NullString{Valid: true, String: "gpt-5.4"},
 			sql.NullString{},
 			sql.NullInt64{},
 			sql.NullInt64{},