Reintroduce multiple maps: per-map chunk directories + map_t name/mapSetMap

Move chunk assets from a single flat assetsraw/chunks (and assets/chunks)
into per-map assetsraw/maps/<map>/chunks (assets/maps/<map>/chunks), so
terrain mesh/model output no longer collides across maps sharing chunk
coordinates. map_t gains a name[MAP_NAME_MAX] field plus mapSetMap()/
mapIsLoaded() (checks name[0] == '\0') in place of the old bool loaded
flag; mapInit() now just resets state and mapSetMap() does the chunk
grid load. Updated the chunk asset tool and the map editor's dev
server/client to match.

tools/asset/chunk/__main__.py

@@ -7,7 +7,7 @@
 Generates DCF + companion DMF files from raw chunk JSON files, or upgrades
 legacy DCF files (version 1 or 2) to the current version.
 
-JSON input (assetsraw/chunks/chunk_X_Y_Z.json):
+JSON input (assetsraw/maps/<map>/chunks/chunk_X_Y_Z.json):
   {
     "tiles": [
       { "pos": [x, y, z], "type": <tile_shape_int>, "tile": <uv_tile_int> }
@@ -35,6 +35,9 @@ JSON input (assetsraw/chunks/chunk_X_Y_Z.json):
   Mesh files are located by searching under assets/meshes/ and referenced by
   path from the assets root in the DCF.
 
+  <map> is the map's name, up to 9 characters (MAP_NAME_MAX in
+  src/dusk/rpg/overworld/map.h reserves 1 byte for the null terminator).
+
   "entities" spawns things into the world when this chunk loads. A "global"
   entity is spawned via mapSpawnEntity() - globalId indexes
   ENTITY_GLOBAL_LIST (src/dusk/rpg/entity/global/entitygloballist.h) and is
@@ -53,7 +56,8 @@ JSON input (assetsraw/chunks/chunk_X_Y_Z.json):
   trigger is bitwise MAP_TRIGGER_STEP(1)|ENTER(2)|EXIT(4).
 
   Output DCF is derived automatically:
-    assetsraw/chunks/chunk_X_Y_Z.json -> assets/chunks/X_Y_Z.dcf
+    assetsraw/maps/<map>/chunks/chunk_X_Y_Z.json
+      -> assets/maps/<map>/chunks/X_Y_Z.dcf
 
 Version 5 DCF format (after 8-byte header):
   tile_t   tiles[CHUNK_WIDTH * CHUNK_HEIGHT]   (one per x/y column)
@@ -85,7 +89,7 @@ DMF format:
               Each vertex: uv[2] + pos[3] = 5 x float32 LE = 20 bytes
 
 Usage:
-  python3 -m tools.asset.chunk              # process all assetsraw/chunks/*.json
+  python3 -m tools.asset.chunk              # process all assetsraw/maps/*/chunks/*.json
   python3 -m tools.asset.chunk <file.json>  # process one JSON file
   python3 -m tools.asset.chunk <file.dcf>   # upgrade legacy (v1/v2) DCF in-place
 """
@@ -118,6 +122,10 @@ CHUNK_MESH_NAME_MAX  = 64
 CHUNK_ENTITY_SPAWN_COUNT_MAX = 8
 CHUNK_AREA_COUNT_MAX = 4
 
+# Matches MAP_NAME_MAX in src/dusk/rpg/overworld/map.h (buffer size,
+# including the null terminator - so map names are at most 9 characters).
+MAP_NAME_MAX = 10
+
 ENTITY_SPAWN_KIND_GLOBAL = 0
 ENTITY_SPAWN_KIND_ITEM   = 1
 
@@ -188,8 +196,29 @@ def write_model_json(path, mesh_rel, texture_rel, color):
   print(f'  Wrote model JSON {path}')
 
 
+def chunk_map_name(json_path):
+  """assetsraw/maps/<map>/chunks/chunk_X_Y_Z.json -> <map>
+
+  Raises ValueError if json_path isn't under that structure, or if <map>
+  is longer than MAP_NAME_MAX - 1 characters."""
+  rel = os.path.relpath(os.path.abspath(json_path), ASSETSRAW_DIR)
+  parts = rel.split(os.sep)
+  if len(parts) != 4 or parts[0] != 'maps' or parts[2] != 'chunks':
+    raise ValueError(
+      f"Chunk JSON must live at assetsraw/maps/<map>/chunks/*.json, got: "
+      f"{json_path}"
+    )
+  map_name = parts[1]
+  if len(map_name) > MAP_NAME_MAX - 1:
+    raise ValueError(
+      f"Map name too long (> {MAP_NAME_MAX - 1} characters): {map_name}"
+    )
+  return map_name
+
+
 def derive_dcf_path(json_path):
-  """assetsraw/chunks/chunk_X_Y_Z.json -> assets/chunks/X_Y_Z.dcf"""
+  """assetsraw/maps/<map>/chunks/chunk_X_Y_Z.json
+  -> assets/maps/<map>/chunks/X_Y_Z.dcf"""
   base = os.path.splitext(os.path.basename(json_path))[0]
   if base.startswith('chunk_'):
     base = base[len('chunk_'):]
@@ -351,6 +380,8 @@ def build_terrain_verts(tiles_bytes):
 
 
 def from_json(json_path, dcf_path):
+  map_name = chunk_map_name(json_path)
+
   with open(json_path) as f:
     data = json.load(f)
 
@@ -377,15 +408,17 @@ def from_json(json_path, dcf_path):
 
   dcf_base = os.path.splitext(os.path.basename(dcf_path))[0]
 
-  # Terrain mesh + model (only written if non-empty)
-  terrain_dir = os.path.join(ASSETS_DIR, 'meshes', 'chunks')
-  models_dir = os.path.join(ASSETS_DIR, 'models', 'chunks')
+  # Terrain mesh + model (only written if non-empty). Namespaced under the
+  # owning map so two maps can each have a chunk at the same (x, y, z)
+  # without their generated terrain assets colliding.
+  terrain_dir = os.path.join(ASSETS_DIR, 'maps', map_name, 'meshes', 'chunks')
+  models_dir = os.path.join(ASSETS_DIR, 'maps', map_name, 'models', 'chunks')
   os.makedirs(terrain_dir, exist_ok=True)
   os.makedirs(models_dir, exist_ok=True)
   if terrain_verts:
     dmf_name = f'chunk_{dcf_base}_0.dmf'
     write_dmf(os.path.join(terrain_dir, dmf_name), terrain_verts)
-    mesh_rel = f'meshes/chunks/{dmf_name}'
+    mesh_rel = f'maps/{map_name}/meshes/chunks/{dmf_name}'
     json_name = f'chunk_{dcf_base}_0.json'
     write_model_json(
       os.path.join(models_dir, json_name),
@@ -393,7 +426,7 @@ def from_json(json_path, dcf_path):
       'tiles.png',
       [255, 255, 255, 255]
     )
-    model_names.append(f'models/chunks/{json_name}')
+    model_names.append(f'maps/{map_name}/models/chunks/{json_name}')
     mesh_offsets.append((0.0, 0.0, 0.0))
 
   # External mesh references -> look up matching model JSON
@@ -555,22 +588,27 @@ def main():
   parser.add_argument(
     'path', nargs='?',
     help='Chunk JSON file to process, or legacy DCF file to upgrade. '
-         'If omitted, processes all assetsraw/chunks/*.json'
+         'If omitted, processes all assetsraw/maps/*/chunks/*.json'
   )
   args = parser.parse_args()
 
   if args.path is None:
-    chunks_dir = os.path.join(ASSETSRAW_DIR, 'chunks')
-    if not os.path.isdir(chunks_dir):
-      print(f"No directory found: {chunks_dir}")
+    maps_dir = os.path.join(ASSETSRAW_DIR, 'maps')
+    if not os.path.isdir(maps_dir):
+      print(f"No directory found: {maps_dir}")
       sys.exit(1)
-    json_files = sorted(
-      os.path.join(chunks_dir, f)
-      for f in os.listdir(chunks_dir)
-      if f.endswith('.json')
-    )
+    json_files = []
+    for map_name in sorted(os.listdir(maps_dir)):
+      chunks_dir = os.path.join(maps_dir, map_name, 'chunks')
+      if not os.path.isdir(chunks_dir):
+        continue
+      json_files.extend(sorted(
+        os.path.join(chunks_dir, f)
+        for f in os.listdir(chunks_dir)
+        if f.endswith('.json')
+      ))
     if not json_files:
-      print(f"No JSON files found in {chunks_dir}")
+      print(f"No JSON files found under {maps_dir}")
       sys.exit(0)
     for p in json_files:
       process_json(p)