diff --git a/tests/Aetheria.Shared.Tests/ConsumableTests.cs b/tests/Aetheria.Shared.Tests/ConsumableTests.cs
new file mode 100644
index 000000000..3fdd6aad3
--- /dev/null
+++ b/tests/Aetheria.Shared.Tests/ConsumableTests.cs
@@ -0,0 +1,152 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using CultMath;
+using GameCult.Caching;
+using Xunit;
+
+// A consumable is a cargo item with a timed effect (aetheria-release CS-R1). Its modifiers exist in the resolver
+// exactly while its effect is active: the host (Entity) initialises the effect's behaviours at activation and
+// disposes them at expiry, and ItemManager.CreateInstance is the one way a lot becomes a ConsumableItem.
+public sealed class ConsumableTests : IDisposable
+{
+    private readonly string _root = Path.Combine(Path.GetTempPath(), "aetheria-consumable-" + Guid.NewGuid().ToString("N"));
+    private string Catalog => Path.Combine(_root, "Aetheria.cc");
+    private static readonly int2 EngineCell = new int2(0, 0);
+    private static readonly int2 HoldCell = new int2(1, 1);
+
+    public ConsumableTests() => Directory.CreateDirectory(_root);
+    public void Dispose() => Directory.Delete(_root, true);
+
+    private sealed class Rig
+    {
+        public CultCache Cache;
+        public ItemManager Items;
+        public Ship Ship;
+        public EquippedItem Engine;
+        public PerformanceStat Thrust;
+        public ConsumableItemData Consumable;
+        public CultRecordKey Key;
+        public CultRecordRef<Faction> Maker;
+
+        public ConsumableItem Mint() => Assert.IsType<ConsumableItem>(Items.CreateInstance(Items.CreateLot(Consumable, Maker, .5f)));
+        public EquippedCargoBay Hold => Ship.CargoBays.Single();
+        public int InCargo => Hold.Cargo.Keys.Count(i => i is ConsumableItem);
+    }
+
+    // A ship with a thruster (Thrust 10) and a hold; the consumable doubles ThrusterData.Thrust for one second.
+    private Rig Build(bool stackable = false)
+    {
+        var thrust = new PerformanceStat { Min = 10, Max = 10 };
+        var cache = AetheriaStores.Open(Catalog, catalogWritable: true);
+        cache.Upsert(new TestCatalogGlobal { Name = "Temperament" });
+        cache.Upsert(new Faction { Name = "Maker", ShortName = "MKR" });
+        var hullShape = new Shape(3, 3);
+        foreach (var cell in hullShape.AllCoordinates) hullShape[cell] = true;
+        var hullRef = cache.Upsert(new HullData
+        {
+            Name = "Skiff", HullType = HullType.Ship, Shape = hullShape, Durability = 10,
+            Hardpoints = { new HardpointData { Type = HardpointType.Sensors, Position = EngineCell, Shape = new Shape() } }
+        });
+        var engineRef = cache.Upsert(new GearData
+        {
+            Name = "Engine", Hardpoint = HardpointType.Sensors, Shape = new Shape(), Durability = 10,
+            Behaviors = { new ThrusterData { Thrust = thrust } }
+        });
+        var interior = new Shape(1, 1);
+        foreach (var cell in interior.AllCoordinates) interior[cell] = true;
+        var holdRef = cache.Upsert(new CargoBayData { Name = "Hold", Shape = new Shape(), InteriorShape = interior, Durability = 10 });
+        var consumableRef = cache.Upsert(new ConsumableItemData
+        {
+            Name = "Overdrive", Duration = 1f, Stackable = stackable, Shape = new Shape(),
+            Behaviors =
+            {
+                new StatModifierData
+                {
+                    Stat = new StatReference { Target = nameof(ThrusterData), Stat = nameof(ThrusterData.Thrust) },
+                    Modifier = new PerformanceStat { Min = 2, Max = 2 },
+                    Type = StatModifierType.Multiplier
+                }
+            }
+        });
+        cache.FlushAsync().Wait();
+
+        var items = new ItemManager(cache, new ProvenanceLedger(), RunSaveTests.TestSettings(), _ => { });
+        var makerRef = cache.RefOf(cache.GetByName<Faction>("Maker"));
+        EquippableItem Gear(EquippableItemData design) => (EquippableItem) items.CreateInstance(items.CreateLot(design, makerRef, .5f));
+        var zone = new Zone(items, new PlanetSettings(), new ZonePack(), new GalaxyZone { Name = "Test Zone", Owner = null }, null);
+        var ship = new Ship(items, zone, Gear(cache.Get(hullRef)), new EntitySettings());
+        Assert.True(ship.TryEquip(Gear(cache.Get(engineRef)), EngineCell));
+        Assert.True(ship.TryEquip(Gear(cache.Get(holdRef)), HoldCell));
+        zone.Entities.Add(ship);
+        ship.Activate();
+        var data = cache.Get(consumableRef);
+        return new Rig
+        {
+            Cache = cache, Items = items, Ship = ship, Thrust = thrust, Consumable = data,
+            Key = items.ItemData.RefOf<ItemData>(data).Key,
+            Engine = ship.Equipment.Single(e => e.Data.Name == "Engine"),
+            Maker = makerRef
+        };
+    }
+
+    // Two ticks after activation the modifier has attached (the first tick executes it, the second applies it).
+    private static void Tick(Rig rig, int times, float dt)
+    {
+        for (var i = 0; i < times; i++) rig.Ship.Update(dt);
+    }
+
+    // The rule: a consumable's modifiers exist in the resolver exactly while its effect is active, never after.
+    // Observed at the resolved stat and at the resolver's modifier entry count, not at a flag.
+    [Fact]
+    public void AConsumableModifierBoostsUntilExpiry()
+    {
+        var rig = Build();
+        using var _ = rig.Cache;
+        var resolver = rig.Ship.Resolver;
+        Assert.Equal(10f, rig.Engine.Evaluate(rig.Thrust), 3);
+        var baseline = resolver.ModifierEntryCount;
+
+        rig.Ship.ActivateConsumable(rig.Mint());
+        Tick(rig, 2, .3f); // 0.4s of the 1s remain; the modifier has attached
+        Assert.Equal(20f, rig.Engine.Evaluate(rig.Thrust), 3);
+        Assert.True(resolver.ModifierEntryCount > baseline);
+
+        Tick(rig, 3, .3f); // 0.9s elapsed in all: expired on the third of these ticks
+        Assert.Equal(10f, rig.Engine.Evaluate(rig.Thrust), 3);
+        Assert.Equal(baseline, resolver.ModifierEntryCount);
+    }
+
+    // A lot minted through the one production path is a ConsumableItem, and a hold holding it activates it.
+    [Fact]
+    public void ABoughtConsumableActivates()
+    {
+        var rig = Build();
+        using var _ = rig.Cache;
+        Assert.True(rig.Hold.TryStore(rig.Mint()));
+        Assert.Equal(1, rig.InCargo);
+
+        Assert.True(rig.Ship.TryActivateConsumable(rig.Consumable));
+        Assert.Equal(0, rig.InCargo);
+        Assert.NotNull(rig.Ship.FindActiveConsumable(rig.Consumable));
+    }
+
+    // CS-R1: a non-stackable design allows one active effect at a time, so its Duration is its cooldown.
+    [Fact]
+    public void ANonStackableConsumableRefusesASecondActivation()
+    {
+        var rig = Build();
+        using var _ = rig.Cache;
+        Assert.True(rig.Hold.TryStore(rig.Mint()));
+        Assert.True(rig.Hold.TryStore(rig.Mint()));
+
+        Assert.True(rig.Ship.TryActivateConsumable(rig.Consumable));
+        Assert.False(rig.Ship.TryActivateConsumable(rig.Consumable));
+        Assert.Equal(1, rig.InCargo);
+
+        Tick(rig, 5, .3f); // the first effect has run out
+        Assert.True(rig.Ship.TryActivateConsumable(rig.Consumable));
+        Assert.Equal(0, rig.InCargo);
+    }
+}