Town-colored homes, split diagonally for mixed-culture households

Shelters now wear their town's culture color on the map (North cool-blue,
South green, West gold, East red), dimmed by wear; granaries stay green,
ruins dark. And bonds can now cross town lines: usually you pair within
your own people (that's who you're near), but a wanderer who warms to
someone from another town shacks up across cultures - the first quiet
thread of contact between two peoples. When two towns share a roof, the
house is drawn split diagonally, half each culture, visible across the map.

Mechanics: buildings track their top-two resident home-towns (recomputed
with occupancy, throttled to every 30 ticks since it's map-only); the
bonding rule dropped its same-town requirement. A 240-day run produced
126 bonds, 40 of them cross-town (East+North, West+South, all combos),
with populations still balanced - inter-cultural contact without
destabilizing the towns.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scripts/GameManager.cs

@@ -164,6 +164,14 @@ public partial class GameManager : Node2D
         return new Vector2(World.GridSize / 2f, World.GridSize / 2f);
     }
 
+    /// <summary>The soul culture of a named town (for map coloring).</summary>
+    public SoulType TownSoul(string town)
+    {
+        foreach (var t in _towns)
+            if (t.Name == town) return t.Soul;
+        return SoulType.Nature;
+    }
+
     public Vector2 TownCentroid(string town)
     {
         Vector2 sum = Vector2.Zero;
@@ -325,6 +333,48 @@ public partial class GameManager : Node2D
         Npcs.AddRange(newborns);
     }
 
+    /// <summary>
+    /// Tally which home-towns sleep under each shelter, storing the top two.
+    /// A house with residents from two towns is a mixed household — someone
+    /// shacked up across cultures — and gets drawn split on the map.
+    /// </summary>
+    private void RecomputeHouseholds()
+    {
+        var counts = new Dictionary<Building, Dictionary<string, int>>();
+
+        foreach (var npc in Npcs)
+        {
+            if (npc.State != NpcState.Resting) continue;
+            Building? at = null; float best = 6.25f;
+            foreach (var b in Buildings)
+            {
+                if (b.RestCapacity <= 0) continue;
+                float d = npc.Position.DistanceSquaredTo(b.Site);
+                if (d < best) { best = d; at = b; }
+            }
+            if (at == null) continue;
+            if (!counts.TryGetValue(at, out var byTown))
+                counts[at] = byTown = new Dictionary<string, int>();
+            byTown[npc.HomeTown] = byTown.GetValueOrDefault(npc.HomeTown) + 1;
+        }
+
+        foreach (var b in Buildings)
+        {
+            b.ResidentTownA = "";
+            b.ResidentTownB = "";
+            if (!counts.TryGetValue(b, out var byTown)) continue;
+
+            string a = "", bTown = ""; int ca = 0, cb = 0;
+            foreach (var kv in byTown)
+            {
+                if (kv.Value > ca) { bTown = a; cb = ca; a = kv.Key; ca = kv.Value; }
+                else if (kv.Value > cb) { bTown = kv.Key; cb = kv.Value; }
+            }
+            b.ResidentTownA = a;
+            b.ResidentTownB = cb > 0 ? bTown : "";
+        }
+    }
+
     /// <summary>Where the community's feet actually are — new communal
     /// buildings are founded here, not at a scripted town center.</summary>
     public Vector2 CommunityCentroid()
@@ -356,6 +406,11 @@ public partial class GameManager : Node2D
             if (at != null) at.Occupancy++;
         }
 
+        // Household composition (which cultures share each roof) — for the
+        // map only, so it's cheap and refreshed occasionally, not every tick.
+        if (TotalTicks % 30 == 0)
+            RecomputeHouseholds();
+
         TotalTicks++;
 
         foreach (var npc in Npcs)