1 files changed, 31 insertions, 0 deletions
diff --git a/internal/casino/config_validate.go b/internal/casino/config_validate.go
index ee8e8c9..38d426d 100644
--- a/internal/casino/config_validate.go
+++ b/internal/casino/config_validate.go
@@ -141,6 +141,37 @@ func (p SlotProfile) Validate() error {
 		return fmt.Errorf("unsupported slot geometry %dx%d: the runtime evaluator supports %dx%d only",
 			profile.Rows, profile.Reels, slotGridRows, slotGridReels)
 	}
+	// A named trigger must exist, or the feature silently never fires while
+	// the RTP model also computes a zero trigger probability and reports green.
+	if profile.FreeSpinTrigger != "" {
+		found := false
+		positiveWeight := false
+		for _, symbol := range profile.Symbols {
+			if symbol.ID == profile.FreeSpinTrigger {
+				found = true
+				positiveWeight = symbol.Weight > 0
+				break
+			}
+		}
+		if !found {
+			return fmt.Errorf("free_spin_trigger %q names no symbol in symbols", profile.FreeSpinTrigger)
+		}
+		if !positiveWeight {
+			return fmt.Errorf("free_spin_trigger %q names a symbol with no reel weight, so the feature can never trigger", profile.FreeSpinTrigger)
+		}
+	}
+	// A paytable must not have a gap: evaluateSlot pays only the longest run,
+	// so Payout{3: 0.5} with no Payout[4] makes every 4-run pay zero — less
+	// than the 3-run — while the RTP model agrees and nothing else flags it.
+	// A symbol whose shorter runs also pay zero (e.g. only a 5-run pays) is a
+	// legitimate shape and is not flagged.
+	for _, symbol := range profile.Symbols {
+		for length := 4; length <= 5; length++ {
+			if symbol.Payout[length] <= 0 && symbol.Payout[length-1] > 0 {
+				return fmt.Errorf("symbol %q pays for a run of %d but not %d: a longer run would pay zero", symbol.ID, length-1, length)
+			}
+		}
+	}
 	return nil
 }