Add loot table system with LootEntry and roll_loot

LootEntry defines probabilistic item drops with min/max counts.
roll_loot takes a loot table and returns Thing instances.
MobTemplate now has loot field, parsed from TOML [[loot]] sections.

src/mudlib/loot.py

@@ -0,0 +1,34 @@
+"""Loot table system for mob drops."""
+
+import random
+from dataclasses import dataclass
+
+from mudlib.thing import Thing
+
+
+@dataclass
+class LootEntry:
+    """A single loot table entry."""
+
+    name: str
+    chance: float  # 0.0-1.0
+    min_count: int = 1
+    max_count: int = 1
+    description: str = ""
+
+
+def roll_loot(entries: list[LootEntry]) -> list[Thing]:
+    """Roll a loot table and return the resulting Things."""
+    items: list[Thing] = []
+    for entry in entries:
+        if random.random() < entry.chance:
+            count = random.randint(entry.min_count, entry.max_count)
+            for _ in range(count):
+                items.append(
+                    Thing(
+                        name=entry.name,
+                        description=entry.description,
+                        portable=True,
+                    )
+                )
+    return items

src/mudlib/mobs.py

@@ -5,6 +5,7 @@ from dataclasses import dataclass, field
 from pathlib import Path
 
 from mudlib.entity import Mob
+from mudlib.loot import LootEntry
 from mudlib.zone import Zone
 
 
@@ -18,6 +19,7 @@ class MobTemplate:
     stamina: float
     max_stamina: float
     moves: list[str] = field(default_factory=list)
+    loot: list[LootEntry] = field(default_factory=list)
 
 
 # Module-level registries
@@ -29,6 +31,19 @@ def load_mob_template(path: Path) -> MobTemplate:
     """Parse a mob TOML file into a MobTemplate."""
     with open(path, "rb") as f:
         data = tomllib.load(f)
+
+    loot_entries = []
+    for entry_data in data.get("loot", []):
+        loot_entries.append(
+            LootEntry(
+                name=entry_data["name"],
+                chance=entry_data["chance"],
+                min_count=entry_data.get("min_count", 1),
+                max_count=entry_data.get("max_count", 1),
+                description=entry_data.get("description", ""),
+            )
+        )
+
     return MobTemplate(
         name=data["name"],
         description=data["description"],
@@ -36,6 +51,7 @@ def load_mob_template(path: Path) -> MobTemplate:
         stamina=data["stamina"],
         max_stamina=data["max_stamina"],
         moves=data.get("moves", []),
+        loot=loot_entries,
     )
 
 

tests/test_loot.py

@@ -0,0 +1,102 @@
+"""Tests for loot table system."""
+
+from mudlib.loot import LootEntry, roll_loot
+from mudlib.mobs import MobTemplate, load_mob_template
+from mudlib.thing import Thing
+
+
+class TestLootEntry:
+    def test_loot_entry_fields(self):
+        entry = LootEntry(name="gold coin", chance=0.5, min_count=1, max_count=3)
+        assert entry.name == "gold coin"
+        assert entry.chance == 0.5
+
+
+class TestRollLoot:
+    def test_empty_table_returns_empty(self):
+        assert roll_loot([]) == []
+
+    def test_guaranteed_drop(self):
+        """chance=1.0 always drops."""
+        entry = LootEntry(name="gold coin", chance=1.0)
+        items = roll_loot([entry])
+        assert len(items) == 1
+        assert items[0].name == "gold coin"
+
+    def test_zero_chance_never_drops(self):
+        """chance=0.0 never drops."""
+        entry = LootEntry(name="rare gem", chance=0.0)
+        items = roll_loot([entry])
+        assert len(items) == 0
+
+    def test_count_range(self):
+        """min_count/max_count controls number of items."""
+        entry = LootEntry(name="coin", chance=1.0, min_count=3, max_count=3)
+        items = roll_loot([entry])
+        assert len(items) == 3
+        assert all(item.name == "coin" for item in items)
+
+    def test_items_are_portable_things(self):
+        entry = LootEntry(name="sword", chance=1.0, description="a rusty sword")
+        items = roll_loot([entry])
+        assert isinstance(items[0], Thing)
+        assert items[0].portable is True
+        assert items[0].description == "a rusty sword"
+
+    def test_multiple_entries(self):
+        entries = [
+            LootEntry(name="coin", chance=1.0, min_count=2, max_count=2),
+            LootEntry(name="gem", chance=1.0),
+        ]
+        items = roll_loot(entries)
+        assert len(items) == 3  # 2 coins + 1 gem
+
+
+class TestMobTemplateLoot:
+    def test_template_default_empty_loot(self):
+        t = MobTemplate(
+            name="rat", description="a rat", pl=10, stamina=10, max_stamina=10
+        )
+        assert t.loot == []
+
+    def test_load_template_with_loot(self, tmp_path):
+        toml_content = """
+name = "goblin"
+description = "a goblin"
+pl = 50.0
+stamina = 40.0
+max_stamina = 40.0
+moves = ["punch right"]
+
+[[loot]]
+name = "crude club"
+chance = 0.8
+description = "a crude wooden club"
+
+[[loot]]
+name = "gold coin"
+chance = 0.5
+min_count = 1
+max_count = 3
+"""
+        f = tmp_path / "goblin.toml"
+        f.write_text(toml_content)
+        template = load_mob_template(f)
+        assert len(template.loot) == 2
+        assert template.loot[0].name == "crude club"
+        assert template.loot[0].chance == 0.8
+        assert template.loot[1].min_count == 1
+        assert template.loot[1].max_count == 3
+
+    def test_load_template_without_loot(self, tmp_path):
+        toml_content = """
+name = "rat"
+description = "a rat"
+pl = 10.0
+stamina = 10.0
+max_stamina = 10.0
+"""
+        f = tmp_path / "rat.toml"
+        f.write_text(toml_content)
+        template = load_mob_template(f)
+        assert template.loot == []