Add container support to thing template loader

Extended ThingTemplate with optional container fields (capacity, closed, locked).
When a template includes capacity, spawn_thing now creates a Container instead
of a regular Thing.

Added two example container templates:
- chest.toml: non-portable, capacity 5, starts closed
- sack.toml: portable, capacity 3, starts open

content/things/chest.toml

@@ -0,0 +1,7 @@
+name = "chest"
+description = "a sturdy wooden chest with iron bindings"
+portable = false
+capacity = 5
+closed = true
+locked = false
+aliases = ["box"]

content/things/sack.toml

@@ -0,0 +1,7 @@
+name = "sack"
+description = "a rough cloth sack with drawstring closure"
+portable = true
+capacity = 3
+closed = false
+locked = false
+aliases = ["bag"]

src/mudlib/things.py

@@ -4,6 +4,7 @@ import tomllib
 from dataclasses import dataclass, field
 from pathlib import Path
 
+from mudlib.container import Container
 from mudlib.object import Object
 from mudlib.thing import Thing
 
@@ -16,6 +17,10 @@ class ThingTemplate:
     description: str
     portable: bool = True
     aliases: list[str] = field(default_factory=list)
+    # Container fields (presence of capacity indicates a container template)
+    capacity: int | None = None
+    closed: bool = False
+    locked: bool = False
 
 
 # Module-level registry
@@ -31,6 +36,9 @@ def load_thing_template(path: Path) -> ThingTemplate:
         description=data["description"],
         portable=data.get("portable", True),
         aliases=data.get("aliases", []),
+        capacity=data.get("capacity"),
+        closed=data.get("closed", False),
+        locked=data.get("locked", False),
     )
 
 
@@ -51,6 +59,21 @@ def spawn_thing(
     y: int | None = None,
 ) -> Thing:
     """Create a Thing instance from a template at the given location."""
+    # If template has capacity, spawn a Container instead of a Thing
+    if template.capacity is not None:
+        return Container(
+            name=template.name,
+            description=template.description,
+            portable=template.portable,
+            aliases=list(template.aliases),
+            capacity=template.capacity,
+            closed=template.closed,
+            locked=template.locked,
+            location=location,
+            x=x,
+            y=y,
+        )
+
     return Thing(
         name=template.name,
         description=template.description,

tests/test_container_templates.py

@@ -0,0 +1,149 @@
+"""Tests for container template loading and spawning."""
+
+from pathlib import Path
+from tempfile import TemporaryDirectory
+
+from mudlib.container import Container
+from mudlib.thing import Thing
+from mudlib.things import load_thing_template, spawn_thing
+from mudlib.zone import Zone
+
+
+def test_load_container_template_with_capacity():
+    """load_thing_template recognizes container templates (has capacity field)."""
+    with TemporaryDirectory() as tmpdir:
+        toml_path = Path(tmpdir) / "chest.toml"
+        toml_path.write_text(
+            """
+name = "chest"
+description = "a wooden chest"
+capacity = 5
+"""
+        )
+        template = load_thing_template(toml_path)
+        assert template.name == "chest"
+        assert template.description == "a wooden chest"
+        assert hasattr(template, "capacity")
+        assert template.capacity == 5
+
+
+def test_load_container_template_with_closed():
+    """load_thing_template handles closed field."""
+    with TemporaryDirectory() as tmpdir:
+        toml_path = Path(tmpdir) / "chest.toml"
+        toml_path.write_text(
+            """
+name = "chest"
+description = "a wooden chest"
+capacity = 5
+closed = true
+"""
+        )
+        template = load_thing_template(toml_path)
+        assert template.closed is True
+
+
+def test_load_container_template_with_locked():
+    """load_thing_template handles locked field."""
+    with TemporaryDirectory() as tmpdir:
+        toml_path = Path(tmpdir) / "chest.toml"
+        toml_path.write_text(
+            """
+name = "chest"
+description = "a wooden chest"
+capacity = 5
+closed = true
+locked = true
+"""
+        )
+        template = load_thing_template(toml_path)
+        assert template.locked is True
+
+
+def test_load_container_template_defaults():
+    """Container template fields have sensible defaults."""
+    with TemporaryDirectory() as tmpdir:
+        toml_path = Path(tmpdir) / "sack.toml"
+        toml_path.write_text(
+            """
+name = "sack"
+description = "a cloth sack"
+capacity = 3
+"""
+        )
+        template = load_thing_template(toml_path)
+        assert template.capacity == 3
+        assert template.closed is False  # default: open
+        assert template.locked is False  # default: unlocked
+
+
+def test_spawn_container_from_template():
+    """spawn_thing creates a Container when template has capacity."""
+    with TemporaryDirectory() as tmpdir:
+        toml_path = Path(tmpdir) / "chest.toml"
+        toml_path.write_text(
+            """
+name = "chest"
+description = "a wooden chest"
+capacity = 5
+closed = true
+"""
+        )
+        template = load_thing_template(toml_path)
+        terrain = [["." for _ in range(10)] for _ in range(10)]
+        zone = Zone(name="test", width=10, height=10, terrain=terrain)
+
+        thing = spawn_thing(template, zone, x=5, y=5)
+
+        assert isinstance(thing, Container)
+        assert thing.name == "chest"
+        assert thing.description == "a wooden chest"
+        assert thing.capacity == 5
+        assert thing.closed is True
+        assert thing.location is zone
+
+
+def test_spawn_regular_thing_from_template_without_capacity():
+    """spawn_thing creates a regular Thing when template lacks capacity."""
+    with TemporaryDirectory() as tmpdir:
+        toml_path = Path(tmpdir) / "rock.toml"
+        toml_path.write_text(
+            """
+name = "rock"
+description = "a smooth grey rock"
+portable = true
+"""
+        )
+        template = load_thing_template(toml_path)
+        terrain = [["." for _ in range(10)] for _ in range(10)]
+        zone = Zone(name="test", width=10, height=10, terrain=terrain)
+
+        thing = spawn_thing(template, zone, x=5, y=5)
+
+        assert isinstance(thing, Thing)
+        assert not isinstance(thing, Container)
+        assert thing.name == "rock"
+        assert thing.portable is True
+
+
+def test_spawn_portable_container():
+    """spawn_thing creates a portable Container (like a sack)."""
+    with TemporaryDirectory() as tmpdir:
+        toml_path = Path(tmpdir) / "sack.toml"
+        toml_path.write_text(
+            """
+name = "sack"
+description = "a cloth sack"
+capacity = 3
+portable = true
+"""
+        )
+        template = load_thing_template(toml_path)
+        terrain = [["." for _ in range(10)] for _ in range(10)]
+        zone = Zone(name="test", width=10, height=10, terrain=terrain)
+
+        thing = spawn_thing(template, zone, x=5, y=5)
+
+        assert isinstance(thing, Container)
+        assert thing.portable is True
+        assert thing.capacity == 3