3 files changed, 95 insertions, 9 deletions
diff --git a/internal/validate/checks.go b/internal/validate/checks.go
index a8f973f..ccf996c 100644
--- a/internal/validate/checks.go
+++ b/internal/validate/checks.go
@@ -7,6 +7,7 @@ import (
 
 	"thehouseoficarus/internal/behavior"
 	"thehouseoficarus/internal/color"
+	"thehouseoficarus/internal/combat"
 	"thehouseoficarus/internal/world"
 )
 
@@ -292,6 +293,57 @@ func validateRoomObjectCollisions(roomID int, entries []roomObjEntry) []Issue {
 	return issues
 }
 
+// validateMobAttackTypes enforces the mob attack_types spec: a non-empty list
+// containing exactly one melee type (stab/slash/crush) plus at most one each of
+// the optional ranged/science types, with no invalid or duplicate entries.
+func validateMobAttackTypes(id string, types []string) []Issue {
+	var issues []Issue
+
+	if len(types) == 0 {
+		issues = append(issues, Issue{
+			Level:   "ERROR",
+			Type:    "reference",
+			Message: fmt.Sprintf("Mob %q: missing attack_types (must be a list with exactly one of stab/slash/crush, optionally plus ranged/science)", id),
+		})
+		return issues
+	}
+
+	meleeCount := 0
+	seen := map[string]bool{}
+	for _, t := range types {
+		if !combat.IsValidAttackType(t) {
+			issues = append(issues, Issue{
+				Level:   "ERROR",
+				Type:    "reference",
+				Message: fmt.Sprintf("Mob %q: invalid attack_types entry %q (must be stab/slash/crush/ranged/science)", id, t),
+			})
+			continue
+		}
+		if seen[t] {
+			issues = append(issues, Issue{
+				Level:   "ERROR",
+				Type:    "reference",
+				Message: fmt.Sprintf("Mob %q: duplicate attack_types entry %q", id, t),
+			})
+			continue
+		}
+		seen[t] = true
+		if combat.IsMeleeType(t) {
+			meleeCount++
+		}
+	}
+
+	if meleeCount != 1 {
+		issues = append(issues, Issue{
+			Level:   "ERROR",
+			Type:    "reference",
+			Message: fmt.Sprintf("Mob %q: attack_types must contain exactly one melee type (stab/slash/crush), found %d", id, meleeCount),
+		})
+	}
+
+	return issues
+}
+
 func validateMobs(s Source) []Issue {
 	var issues []Issue
 	itemIDs := s.Items.IDSet()
@@ -336,6 +388,10 @@ func validateMobs(s Source) []Issue {
 			})
 		}
 
+		if def.Combat != nil && def.Combat.Kind != "task" {
+			issues = append(issues, validateMobAttackTypes(id, def.Combat.AttackTypes)...)
+		}
+
 		if def.Drops.Remains != "" && !itemIDs[def.Drops.Remains] {
 			issues = append(issues, Issue{
 				Level: "ERROR",
@@ -427,7 +483,6 @@ func validateMobs(s Source) []Issue {
 func validateHazards(s Source) []Issue {
 	var issues []Issue
 	itemIDs := s.Items.IDSet()
-	validTypes := map[string]bool{"stab": true, "slash": true, "crush": true, "ranged": true, "science": true}
 
 	for id := range s.World.HazardIndex() {
 		def, err := s.World.LoadHazard(id)
@@ -439,7 +494,7 @@ func validateHazards(s Source) []Issue {
 			})
 			continue
 		}
-		if def.AttackType != "" && !validTypes[def.AttackType] {
+		if def.AttackType != "" && !combat.IsValidAttackType(def.AttackType) {
 			issues = append(issues, Issue{
 				Level:   "ERROR",
 				Type:    "reference",
diff --git a/internal/validate/grid_test.go b/internal/validate/grid_test.go
index 716cec1..e40c50b 100644
--- a/internal/validate/grid_test.go
+++ b/internal/validate/grid_test.go
@@ -141,13 +141,13 @@ func TestGrid3DTwistUpDown(t *testing.T) {
 	// path2: 1 east→A(1,0,0) up→B(1,0,1) east→C(2,0,1) south→4 wants (2,1,1)
 	// 4 already at (1,1,1) from path1 → twist.
 	rooms := map[int]string{
-		1:  "exits:\n  up: 2\n  east: 6\n",
-		2:  "exits:\n  south: 3\n  down: 1\n",
-		3:  "exits:\n  east: 4\n  north: 2\n",
-		4:  "name: four\n",
-		6:  "exits:\n  up: 7\n  west: 1\n",
-		7:  "exits:\n  east: 8\n  down: 6\n",
-		8:  "exits:\n  south: 4\n  west: 7\n",
+		1: "exits:\n  up: 2\n  east: 6\n",
+		2: "exits:\n  south: 3\n  down: 1\n",
+		3: "exits:\n  east: 4\n  north: 2\n",
+		4: "name: four\n",
+		6: "exits:\n  up: 7\n  west: 1\n",
+		7: "exits:\n  east: 8\n  down: 6\n",
+		8: "exits:\n  south: 4\n  west: 7\n",
 	}
 	issues := runGridCheck(t, rooms, 1)
 	if !containsMsg(issues, "Grid twist") {
diff --git a/internal/validate/mob_attacktype_test.go b/internal/validate/mob_attacktype_test.go
new file mode 100644
index 0000000..1464d3f
--- /dev/null
+++ b/internal/validate/mob_attacktype_test.go
@@ -0,0 +1,31 @@
+package validate
+
+import "testing"
+
+func TestValidateMobAttackTypes(t *testing.T) {
+	cases := []struct {
+		name      string
+		types     []string
+		wantError bool
+	}{
+		{"single melee", []string{"crush"}, false},
+		{"melee plus ranged", []string{"stab", "ranged"}, false},
+		{"melee plus both", []string{"slash", "ranged", "science"}, false},
+		{"empty", nil, true},
+		{"no melee", []string{"ranged"}, true},
+		{"two melee", []string{"stab", "crush"}, true},
+		{"invalid entry", []string{"crush", "magic"}, true},
+		{"duplicate", []string{"crush", "ranged", "ranged"}, true},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			issues := validateMobAttackTypes("test_mob", c.types)
+			if c.wantError && len(issues) == 0 {
+				t.Errorf("validateMobAttackTypes(%v): expected error, got none", c.types)
+			}
+			if !c.wantError && len(issues) != 0 {
+				t.Errorf("validateMobAttackTypes(%v): expected no error, got %v", c.types, issues)
+			}
+		})
+	}
+}