diff --git a/packages/domain/market/types.go b/packages/domain/market/types.go
index ea0f485..1367496 100644
--- a/packages/domain/market/types.go
+++ b/packages/domain/market/types.go
@@ -30,9 +30,10 @@ const (
 type Timeframe string
 
 const (
-	TimeframeDaily Timeframe = "1d"
-	TimeframeMin1  Timeframe = "1m"
-	TimeframeMin5  Timeframe = "5m"
+	TimeframeMonthly Timeframe = "1mo"
+	TimeframeDaily   Timeframe = "1d"
+	TimeframeMin1    Timeframe = "1m"
+	TimeframeMin5    Timeframe = "5m"
 )
 
 type InstrumentID string
diff --git a/packages/domain/market/types_test.go b/packages/domain/market/types_test.go
index 60d227e..fce1d76 100644
--- a/packages/domain/market/types_test.go
+++ b/packages/domain/market/types_test.go
@@ -79,6 +79,23 @@ func TestMarketVenueMetadata(t *testing.T) {
 	}
 }
 
+func TestTimeframeVocabulary(t *testing.T) {
+	cases := []struct {
+		timeframe Timeframe
+		want      string
+	}{
+		{TimeframeMonthly, "1mo"},
+		{TimeframeDaily, "1d"},
+		{TimeframeMin1, "1m"},
+		{TimeframeMin5, "5m"},
+	}
+	for _, c := range cases {
+		if string(c.timeframe) != c.want {
+			t.Errorf("timeframe %q: got %q, want %q", c.want, string(c.timeframe), c.want)
+		}
+	}
+}
+
 func TestProviderCapabilityRequireDailyBars(t *testing.T) {
 	// A KIS-like capability serving both KR and US daily bars.
 	kis := ProviderCapability{
diff --git a/services/api/internal/socket/market.go b/services/api/internal/socket/market.go
index afce715..5d5f196 100644
--- a/services/api/internal/socket/market.go
+++ b/services/api/internal/socket/market.go
@@ -207,7 +207,7 @@ func validateImportDateRange(fromValue, toValue string) error {
 
 func isValidTimeframe(t altv1.Timeframe) bool {
 	switch t {
-	case altv1.Timeframe_TIMEFRAME_DAILY, altv1.Timeframe_TIMEFRAME_MINUTE_1, altv1.Timeframe_TIMEFRAME_MINUTE_5:
+	case altv1.Timeframe_TIMEFRAME_MONTHLY, altv1.Timeframe_TIMEFRAME_DAILY, altv1.Timeframe_TIMEFRAME_MINUTE_1, altv1.Timeframe_TIMEFRAME_MINUTE_5:
 		return true
 	default:
 		return false
diff --git a/services/api/internal/socket/market_test.go b/services/api/internal/socket/market_test.go
index 9a8d617..659ee2f 100644
--- a/services/api/internal/socket/market_test.go
+++ b/services/api/internal/socket/market_test.go
@@ -167,6 +167,19 @@ func TestHandleListBarsValidation(t *testing.T) {
 	}
 }
 
+func TestIsValidTimeframeAcceptsMonthlyAndMinuteBaseline(t *testing.T) {
+	for _, tf := range []altv1.Timeframe{
+		altv1.Timeframe_TIMEFRAME_MONTHLY,
+		altv1.Timeframe_TIMEFRAME_DAILY,
+		altv1.Timeframe_TIMEFRAME_MINUTE_1,
+		altv1.Timeframe_TIMEFRAME_MINUTE_5,
+	} {
+		if !isValidTimeframe(tf) {
+			t.Errorf("expected timeframe %v to be valid", tf)
+		}
+	}
+}
+
 func TestHandleListBarsNilWorker(t *testing.T) {
 	resp, err := handleListBars(nil, validBarsRequest())
 	if err != nil {
diff --git a/services/worker/internal/socket/backtest_mapping.go b/services/worker/internal/socket/backtest_mapping.go
index e33463a..4a57ece 100644
--- a/services/worker/internal/socket/backtest_mapping.go
+++ b/services/worker/internal/socket/backtest_mapping.go
@@ -102,6 +102,8 @@ func marketToProto(m market.Market) altv1.Market {
 
 func timeframeFromProto(t altv1.Timeframe) (market.Timeframe, error) {
 	switch t {
+	case altv1.Timeframe_TIMEFRAME_MONTHLY:
+		return market.TimeframeMonthly, nil
 	case altv1.Timeframe_TIMEFRAME_DAILY:
 		return market.TimeframeDaily, nil
 	case altv1.Timeframe_TIMEFRAME_MINUTE_1:
@@ -115,6 +117,8 @@ func timeframeFromProto(t altv1.Timeframe) (market.Timeframe, error) {
 
 func timeframeToProto(t market.Timeframe) altv1.Timeframe {
 	switch t {
+	case market.TimeframeMonthly:
+		return altv1.Timeframe_TIMEFRAME_MONTHLY
 	case market.TimeframeDaily:
 		return altv1.Timeframe_TIMEFRAME_DAILY
 	case market.TimeframeMin1:
diff --git a/services/worker/internal/socket/backtest_mapping_test.go b/services/worker/internal/socket/backtest_mapping_test.go
index 39a2f3d..e12fa52 100644
--- a/services/worker/internal/socket/backtest_mapping_test.go
+++ b/services/worker/internal/socket/backtest_mapping_test.go
@@ -92,7 +92,7 @@ func TestMarketEnumRoundTrip(t *testing.T) {
 }
 
 func TestTimeframeEnumRoundTrip(t *testing.T) {
-	for _, tf := range []market.Timeframe{market.TimeframeDaily, market.TimeframeMin1, market.TimeframeMin5} {
+	for _, tf := range []market.Timeframe{market.TimeframeMonthly, market.TimeframeDaily, market.TimeframeMin1, market.TimeframeMin5} {
 		got, err := timeframeFromProto(timeframeToProto(tf))
 		if err != nil {
 			t.Fatalf("unexpected error for %q: %v", tf, err)