Judge loss by arrival order and a deadline, one tx ring per stream

history.go

@@ -16,9 +16,12 @@ const (
 	histSlotSpan = 5 * time.Second
 	histSpan     = histSlots * histSlotSpan
 
-	// Line rate is a verdict here, not a number: the headline is smeared and
-	// briefly gated at startup, so anything close to the target counts.
-	rateOKFrac = 0.98
+	// Line rate is a verdict here, not a number: anything close to the target
+	// counts. Sub-millisecond host physics — an SMI, a DMA arbitration pause —
+	// shorts the odd display bucket by a few percent (94-97% bench-measured)
+	// and says nothing about the cable; a cable problem does not shave points,
+	// it craters the rate and brings link evidence with it.
+	rateOKFrac = 0.9
 )
 
 var faultClasses = []struct {