Add zone_name to persistence schema

Adds zone_name field to PlayerData and accounts table to track which
zone a player is in. Defaults to 'overworld'. Includes migration logic
to handle existing databases without the column. Server now resolves
zone from zone_name when loading player data.

src/mudlib/server.py

@@ -263,21 +263,35 @@ async def shell(
             "stamina": 100.0,
             "max_stamina": 100.0,
             "flying": False,
+            "zone_name": "overworld",
         }
+
+    # Resolve zone from zone_name (currently only overworld exists)
+    zone_name = player_data.get("zone_name", "overworld")
+    if zone_name == "overworld":
+        player_zone = _overworld
     else:
-        # Existing player - verify spawn position is still passable
-        if not _overworld.is_passable(player_data["x"], player_data["y"]):
-            # Saved position is no longer passable, find a new one
-            start_x, start_y = find_passable_start(
-                _overworld, player_data["x"], player_data["y"]
-            )
-            player_data["x"] = start_x
-            player_data["y"] = start_y
+        # Future: lookup zone by name from a zone registry
+        log.warning(
+            "unknown zone '%s' for player '%s', defaulting to overworld",
+            zone_name,
+            player_name,
+        )
+        player_zone = _overworld
+
+    # Verify spawn position is still passable
+    if not player_zone.is_passable(player_data["x"], player_data["y"]):
+        # Saved position is no longer passable, find a new one
+        start_x, start_y = find_passable_start(
+            player_zone, player_data["x"], player_data["y"]
+        )
+        player_data["x"] = start_x
+        player_data["y"] = start_y
 
     # Create player instance
     player = Player(
         name=player_name,
-        location=_overworld,
+        location=player_zone,
         x=player_data["x"],
         y=player_data["y"],
         pl=player_data["pl"],
@@ -428,11 +442,6 @@ async def run_server() -> None:
     )
     log.info("created overworld zone (%dx%d, toroidal)", _world.width, _world.height)
 
-    # Inject world into command modules
-    mudlib.commands.fly.world = _world
-    mudlib.commands.look.world = _world
-    mudlib.combat.commands.world = _world
-
     # Load content-defined commands from TOML files
     content_dir = pathlib.Path(__file__).resolve().parents[2] / "content" / "commands"
     if content_dir.exists():

tests/test_store.py

@@ -15,6 +15,7 @@ from mudlib.store import (
     load_player_data,
     save_player,
 )
+from mudlib.zone import Zone
 
 
 @pytest.fixture
@@ -177,3 +178,86 @@ def test_password_hashing_different_salts(temp_db):
 
     # This just verifies the API works correctly - we can't easily check
     # the hashes are different without exposing internal details
+
+
+def test_save_and_load_zone_name(temp_db):
+    """save_player and load_player_data persist zone_name."""
+    create_account("Maria", "password123")
+
+    # Create a zone and player
+    zone = Zone(name="testzone", width=100, height=100)
+    player = Player(
+        name="Maria",
+        location=zone,
+        x=10,
+        y=20,
+    )
+
+    # Save and load
+    save_player(player)
+    data = load_player_data("Maria")
+
+    assert data is not None
+    assert data["zone_name"] == "testzone"
+
+
+def test_default_zone_name(temp_db):
+    """New accounts have zone_name default to 'overworld'."""
+    create_account("Noah", "password123")
+    data = load_player_data("Noah")
+
+    assert data is not None
+    assert data["zone_name"] == "overworld"
+
+
+def test_zone_name_migration(temp_db):
+    """Existing DB without zone_name column still works."""
+    # Create account, which will create default schema
+    create_account("Olivia", "password123")
+
+    # Simulate old DB by manually removing the zone_name column
+    import sqlite3
+
+    conn = sqlite3.connect(temp_db)
+    cursor = conn.cursor()
+
+    # Check if column exists and remove it
+    cursor.execute("PRAGMA table_info(accounts)")
+    columns = [row[1] for row in cursor.fetchall()]
+    if "zone_name" in columns:
+        # SQLite doesn't support DROP COLUMN directly, so recreate table
+        cursor.execute("""
+            CREATE TABLE accounts_backup AS
+            SELECT name, password_hash, salt, x, y, pl, stamina,
+                   max_stamina, flying, created_at, last_login
+            FROM accounts
+        """)
+        cursor.execute("DROP TABLE accounts")
+        cursor.execute("""
+            CREATE TABLE accounts (
+                name TEXT PRIMARY KEY COLLATE NOCASE,
+                password_hash TEXT NOT NULL,
+                salt TEXT NOT NULL,
+                x INTEGER NOT NULL DEFAULT 0,
+                y INTEGER NOT NULL DEFAULT 0,
+                pl REAL NOT NULL DEFAULT 100.0,
+                stamina REAL NOT NULL DEFAULT 100.0,
+                max_stamina REAL NOT NULL DEFAULT 100.0,
+                flying INTEGER NOT NULL DEFAULT 0,
+                created_at TEXT NOT NULL DEFAULT (datetime('now')),
+                last_login TEXT
+            )
+        """)
+        cursor.execute("""
+            INSERT INTO accounts
+            SELECT * FROM accounts_backup
+        """)
+        cursor.execute("DROP TABLE accounts_backup")
+        conn.commit()
+
+    conn.close()
+
+    # Now try to load player data - should handle missing column gracefully
+    data = load_player_data("Olivia")
+    assert data is not None
+    assert data["zone_name"] == "overworld"  # Should default