fix: harden engine across casino, economy, concurrency, security, and content

1 files changed, 24 insertions, 7 deletions

diff --git a/internal/casino/slots.go b/internal/casino/slots.go
index 075050c..64caf85 100644
--- a/internal/casino/slots.go
+++ b/internal/casino/slots.go
@@ -23,12 +23,22 @@ type SlotProfile struct {
 }
 
 type SlotSpin struct {
-	Grid         [3][5]string
+	Grid         [slotGridRows][slotGridReels]string
 	Payout       float64
 	ScatterCount int
 	Wins         []SlotWin
 }
 
+// The runtime slot evaluator is pinned to this grid: SlotSpin/SlotSnapshot
+// hold it, generateSlotSpinWithProfile fills it, and matchingLength and
+// stoppedScatters evaluate it. CalculateRTP/ValidateRTP are generic over
+// SlotProfile.Rows/Reels/Ways, so SlotProfile.Validate rejects any other
+// geometry (see config_validate.go) to keep the RTP gate honest.
+const (
+	slotGridRows  = 3
+	slotGridReels = 5
+)
+
 type SlotWin struct {
 	Symbol     string
 	Length     int
@@ -72,10 +82,12 @@ func (p SlotProfile) Normalize() SlotProfile {
 }
 
 func generateSlotSpinWithProfile(rng *rand.Rand, bet int, profile SlotProfile) *SlotSpin {
+	// SlotProfile.Normalize supplies the defaults; Validate rejects a
+	// geometry this grid cannot hold, so the bounds are exactly the grid.
 	p := profile.Normalize()
 	spin := &SlotSpin{}
-	for reel := 0; reel < p.Reels && reel < 5; reel++ {
-		for row := 0; row < p.Rows && row < 3; row++ {
+	for reel := 0; reel < p.Reels && reel < slotGridReels; reel++ {
+		for row := 0; row < p.Rows && row < slotGridRows; row++ {
 			symbol := weightedSymbol(rng, p.Symbols)
 			spin.Grid[row][reel] = symbol
 			if symbol == p.FreeSpinTrigger {
@@ -110,7 +122,7 @@ func weightedSymbol(rng *rand.Rand, symbols []SlotSymbol) string {
 	return symbols[len(symbols)-1].ID
 }
 
-func evaluateSlot(grid [3][5]string, bet int, profile SlotProfile) (float64, []SlotWin) {
+func evaluateSlot(grid [slotGridRows][slotGridReels]string, bet int, profile SlotProfile) (float64, []SlotWin) {
 	p := profile.Normalize()
 	if bet <= 0 {
 		return 0, nil
@@ -128,12 +140,12 @@ func evaluateSlot(grid [3][5]string, bet int, profile SlotProfile) (float64, []S
 	return total, wins
 }
 
-func matchingLength(grid [3][5]string, symbol string) (int, int) {
+func matchingLength(grid [slotGridRows][slotGridReels]string, symbol string) (int, int) {
 	ways := 1
 	length := 0
-	for reel := 0; reel < 5; reel++ {
+	for reel := 0; reel < slotGridReels; reel++ {
 		count := 0
-		for row := 0; row < 3; row++ {
+		for row := 0; row < slotGridRows; row++ {
 			if grid[row][reel] == symbol {
 				count++
 			}
@@ -204,6 +216,11 @@ func binomial(n, k int) float64 {
 }
 
 func ValidateRTP(profile SlotProfile, tolerance float64) error {
+	// A profile the runtime cannot play must never be certified: its RTP
+	// would describe a different game than the one actually paid.
+	if err := profile.Validate(); err != nil {
+		return err
+	}
 	if profile.TargetRTP <= 0 {
 		return nil
 	}