eighth version

internal/marketdata/loader.go

@@ -86,16 +86,24 @@ func (l Loader) LatestQuote(ctx context.Context, instrumentUID string, depth int
 	if err != nil {
 		return domain.OrderBook{}, err
 	}
-	if book.ReceivedAt.IsZero() {
-		return domain.OrderBook{}, fmt.Errorf("quote received timestamp is missing")
+	quoteTs := quoteTimestamp(book)
+	if quoteTs.IsZero() {
+		return domain.OrderBook{}, fmt.Errorf("quote timestamp is missing")
 	}
-	age := l.nowUTC().Sub(book.ReceivedAt)
+	age := l.nowUTC().Sub(quoteTs)
 	if maxAge > 0 && age > maxAge {
 		return domain.OrderBook{}, fmt.Errorf("quote age %s exceeds %s", age, maxAge)
 	}
 	return book, nil
 }
 
+func quoteTimestamp(book domain.OrderBook) time.Time {
+	if !book.Time.IsZero() {
+		return book.Time.UTC()
+	}
+	return book.ReceivedAt.UTC()
+}
+
 func (l Loader) nowUTC() time.Time {
 	if l.clock == nil {
 		return time.Now().UTC()

internal/marketdata/loader_test.go

@@ -0,0 +1,43 @@
+package marketdata
+
+import (
+	"context"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/shopspring/decimal"
+
+	"overnight-trading-bot/internal/domain"
+	"overnight-trading-bot/internal/tinvest"
+)
+
+type fixedClock struct {
+	now time.Time
+}
+
+func (c fixedClock) Now() time.Time {
+	return c.now
+}
+
+func (c fixedClock) Sleep(<-chan struct{}, time.Duration) bool {
+	return true
+}
+
+func TestLatestQuoteUsesExchangeTimestampForFreshness(t *testing.T) {
+	now := time.Date(2026, 6, 8, 18, 20, 0, 0, time.UTC)
+	gateway := tinvest.NewFakeGateway()
+	gateway.OrderBooks["uid"] = domain.OrderBook{
+		InstrumentUID: "uid",
+		Time:          now.Add(-2 * time.Second),
+		ReceivedAt:    now,
+		Bids:          []domain.OrderBookLevel{{Price: decimal.NewFromInt(99), QuantityLots: 10}},
+		Asks:          []domain.OrderBookLevel{{Price: decimal.NewFromInt(101), QuantityLots: 10}},
+	}
+	loader := NewLoader(nil, gateway)
+	loader.SetClock(fixedClock{now: now})
+	_, err := loader.LatestQuote(context.Background(), "uid", 20, time.Second)
+	if err == nil || !strings.Contains(err.Error(), "quote age") {
+		t.Fatalf("LatestQuote err=%v, want stale exchange timestamp rejection", err)
+	}
+}