1 files changed, 106 insertions, 0 deletions
diff --git a/internal/validate/checks.go b/internal/validate/checks.go
index eb24721..a6eeee8 100644
--- a/internal/validate/checks.go
+++ b/internal/validate/checks.go
@@ -427,6 +427,16 @@ func validateMobs(s Source) []Issue {
 			})
 		}
 
+		// A weakness that matches no module element is dead data: the +weakness
+		// bonus can never trigger against any science module.
+		if s.ModuleElements != nil && def.Combat != nil && def.Combat.Stats.Defenses.Weakness != "" && !s.ModuleElements[def.Combat.Stats.Defenses.Weakness] {
+			issues = append(issues, Issue{
+				Level:   "WARN",
+				Type:    "reference",
+				Message: fmt.Sprintf("Mob %q: weakness %q matches no science module element (the weakness can never trigger)", id, def.Combat.Stats.Defenses.Weakness),
+			})
+		}
+
 		if !def.Protected && (def.Combat == nil || def.Combat.Stats.HP <= 0) {
 			hp := 0
 			if def.Combat != nil {
@@ -761,6 +771,15 @@ func validateCraftBlocks(s Source) []Issue {
 			}
 
 			for _, e := range c.Ingredients {
+				if len(e.Items) == 0 {
+					issues = append(issues, Issue{
+						Level: "ERROR",
+						Type:  "reference",
+						Message: fmt.Sprintf("Item %q (craft: %s): ingredient entry has no items; the recipe can never be satisfied",
+							item.ID, craftLabel),
+					})
+					continue
+				}
 				// Byproducts pair with the alternatives by index
 				// (collectByproducts reads Byproducts[j] for Items[j]), so a
 				// short or reordered list silently returns the wrong
@@ -1165,6 +1184,93 @@ func validateRoomWiring(s Source) []Issue {
 		})
 	}
 
+	// Reachability: an orphan check only catches rooms with zero inbound
+	// edges, so an entire disconnected component (every member linked only
+	// within the component) passes silently. BFS the directed exits from the
+	// configured root rooms and warn about anything with no path in, honouring
+	// ignore_unreachable.
+	reachable := make(map[int]bool)
+	var queue []int
+	for _, src := range s.RootRooms {
+		if roomIndex[src] && !reachable[src] {
+			reachable[src] = true
+			queue = append(queue, src)
+		}
+	}
+	// Transport module destinations are also legitimate entry points: a
+	// player can reach them with a module even when no exit path leads there,
+	// so they must not be reported as unreachable.
+	for _, dest := range s.ModuleDestinations {
+		if dest > 0 && roomIndex[dest] && !reachable[dest] {
+			reachable[dest] = true
+			queue = append(queue, dest)
+		}
+	}
+	for len(queue) > 0 {
+		id := queue[0]
+		queue = queue[1:]
+		room, err := s.World.LoadRoom(id)
+		if err != nil {
+			continue
+		}
+		for _, exit := range room.Exits {
+			next := exit.Room
+			if next <= 0 || reachable[next] || !roomIndex[next] {
+				continue
+			}
+			reachable[next] = true
+			queue = append(queue, next)
+		}
+	}
+	var unreachable []int
+	for id := range roomIndex {
+		if reachable[id] || ignoreTo[id] || sourceSet[id] {
+			continue
+		}
+		unreachable = append(unreachable, id)
+	}
+	if len(unreachable) > 0 {
+		sort.Ints(unreachable)
+		var strs []string
+		for _, id := range unreachable {
+			strs = append(strs, fmt.Sprintf("%d", id))
+		}
+		issues = append(issues, Issue{
+			Level: "WARN",
+			Type:  "integrity",
+			Message: fmt.Sprintf("Unreachable rooms (no exit path from a configured root room): %s",
+				strings.Join(strs, ", ")),
+		})
+	}
+
+	return issues
+}
+
+// validateModuleDestinations flags a transport module whose destination room
+// does not exist: the game assigns the id unconditionally, so the player is
+// saved into a void with no exits.
+func validateModuleDestinations(s Source) []Issue {
+	if len(s.ModuleDestinations) == 0 {
+		return nil
+	}
+	roomIndex := s.World.RoomIndex()
+	ids := make([]string, 0, len(s.ModuleDestinations))
+	for id := range s.ModuleDestinations {
+		ids = append(ids, id)
+	}
+	sort.Strings(ids)
+	var issues []Issue
+	for _, id := range ids {
+		dest := s.ModuleDestinations[id]
+		if dest <= 0 || roomIndex[dest] {
+			continue
+		}
+		issues = append(issues, Issue{
+			Level:   "ERROR",
+			Type:    "reference",
+			Message: fmt.Sprintf("Module %q: destination room %d does not exist", id, dest),
+		})
+	}
 	return issues
 }