NEO-69: Fix Bugbot pre-flight and output rollback issues.

Simulate input removal before output capacity checks, roll back partial
outputs on store-missing, and add tests for slot-freeing craft success.

docs/plans/NEO-69-implementation-plan.md

@@ -65,7 +65,7 @@
 
 4. **Pre-flight inputs (read-only):** For each input row, required amount = **`row.Quantity * quantity`**. Sum held quantity in the correct container (bag vs equipment via catalog **`inventorySlotKind`**) from current snapshot. Any shortfall → **`insufficient_materials`** without mutations.
 
-5. **Pre-flight outputs (read-only, kickoff decision):** Clone current snapshot; for each output row with scaled quantity, simulate **`TryAddStack`** placement rules (merge + fill empty slots, catalog **`stackMax`**, equipment routing) on the clone. If any output cannot be fully placed → **`inventory_full`** without mutations. Implementation: add **`PlayerInventoryOperations.CanPlaceStack(snapshot, itemId, quantity, registry)`** (or equivalent simulate helper) to avoid duplicating merge/fill logic.
+5. **Pre-flight outputs (read-only, kickoff decision):** Clone current snapshot; **simulate removing all scaled inputs** on the clone, then simulate each scaled output add. If any output cannot be fully placed → **`inventory_full`** without mutations. Implementation: **`TrySimulateRemoveStack`** + **`TrySimulateAddStack`** on `PlayerInventoryOperations`.
 
 6. **Commit mutations (only after steps 4–5 pass):**
    - **Remove inputs:** foreach input row, **`TryRemoveStack`** scaled quantity. (Should succeed given pre-flight; defensive deny **`insufficient_materials`** if not.)

docs/reviews/2026-05-24-NEO-69.md

@@ -49,6 +49,12 @@ None.
 
 - Nit: Compensating helpers discard rollback outcomes (`_ = TryAddStack` / `TryRemoveStack`) — same as gather engine; acceptable for prototype.
 
+## Bugbot follow-up (PR #103)
+
+1. ~~**Output pre-flight ignores input removal** — simulate output placement on snapshot with inputs still present; false `inventory_full` when input removal would free slots.~~ **Done.** Pre-flight now **`TrySimulateRemoveStack`** all inputs on clone before output simulation; test **`TryCraft_WhenBagFullWithScrapInputs_ShouldSucceedByFreeingInputSlots`**.
+
+2. ~~**Missing output rollback in store-missing branch** — output-add `StoreMissing` restored inputs but not partial outputs.~~ **Done.** `CompensatingRemoveOutputs` added before input restore on that path.
+
 ## Verification
 
 ```bash

server/NeonSprawl.Server.Tests/Game/Crafting/CraftOperationsTests.cs

@@ -119,14 +119,13 @@ public sealed class CraftOperationsTests
     }
 
     [Fact]
-    public void TryCraft_WhenBagFullForOutput_ShouldDenyWithInventoryFullWithoutConsumingInputs()
+    public void TryCraft_WhenBagFullWithScrapInputs_ShouldSucceedByFreeingInputSlots()
     {
         // Arrange
         using var factory = new InMemoryWebApplicationFactory();
         var deps = ResolveCraftDependencies(factory);
         SeedStack(deps, "scrap_metal_bulk", 5);
         FillBagExcept(deps, occupiedSlots: 1);
-        deps.InventoryStore.TryGetSnapshot(PlayerId, out var beforeInventory);
 
         // Act
         var result = CraftOperations.TryCraft(
@@ -141,10 +140,42 @@ public sealed class CraftOperationsTests
             deps.LevelCurve,
             deps.PerkUnlockEngine);
 
+        // Assert
+        deps.InventoryStore.TryGetSnapshot(PlayerId, out var inventory);
+        Assert.True(result.Success);
+        Assert.Equal(0, CountBagItem(inventory!, "scrap_metal_bulk"));
+        Assert.Equal(1, CountBagItem(inventory!, "refined_plate_stock"));
+    }
+
+    [Fact]
+    public void TryCraft_MakePrototypeArmor_WhenEquipmentOccupied_ShouldDenyWithInventoryFull()
+    {
+        // Arrange
+        using var factory = new InMemoryWebApplicationFactory();
+        var deps = ResolveCraftDependencies(factory);
+        SeedStack(deps, "refined_plate_stock", 8);
+        SeedStack(deps, "scrap_metal_bulk", 5);
+        SeedStack(deps, "prototype_armor_shell", 1);
+        deps.InventoryStore.TryGetSnapshot(PlayerId, out var beforeInventory);
+
+        // Act
+        var result = CraftOperations.TryCraft(
+            PlayerId,
+            "make_prototype_armor",
+            quantity: 1,
+            deps.RecipeRegistry,
+            deps.ItemRegistry,
+            deps.InventoryStore,
+            deps.SkillRegistry,
+            deps.XpStore,
+            deps.LevelCurve,
+            deps.PerkUnlockEngine);
+
         // Assert
         deps.InventoryStore.TryGetSnapshot(PlayerId, out var afterInventory);
         Assert.False(result.Success);
         Assert.Equal(CraftReasonCodes.InventoryFull, result.ReasonCode);
+        Assert.Equal(8, CountBagItem(afterInventory!, "refined_plate_stock"));
         Assert.Equal(5, CountBagItem(afterInventory!, "scrap_metal_bulk"));
         Assert.Equal(TotalBagQuantity(beforeInventory!), TotalBagQuantity(afterInventory!));
     }

server/NeonSprawl.Server/Game/Crafting/CraftOperations.cs

@@ -57,6 +57,14 @@ public static class CraftOperations
         }
 
         var simulated = CloneSnapshot(snapshot);
+        foreach (var input in scaledInputs)
+        {
+            if (!PlayerInventoryOperations.TrySimulateRemoveStack(ref simulated, input.ItemId, input.Quantity, itemRegistry))
+            {
+                return Deny(CraftReasonCodes.InsufficientMaterials);
+            }
+        }
+
         foreach (var output in scaledOutputs)
         {
             if (!PlayerInventoryOperations.TrySimulateAddStack(ref simulated, output.ItemId, output.Quantity, itemRegistry))
@@ -102,6 +110,7 @@ public static class CraftOperations
 
             if (addOutcome.Kind == PlayerInventoryMutationKind.StoreMissing)
             {
+                CompensatingRemoveOutputs(playerId, outputsApplied, itemRegistry, inventoryStore);
                 CompensatingRestoreInputs(playerId, scaledInputs, itemRegistry, inventoryStore);
                 return Deny(CraftReasonCodes.InventoryStoreMissing);
             }

server/NeonSprawl.Server/Game/Items/PlayerInventoryOperations.cs

@@ -187,6 +187,54 @@ public static class PlayerInventoryOperations
         return true;
     }
 
+    /// <summary>
+    /// Simulates removing <paramref name="quantity"/> from a snapshot clone without persisting (NEO-69 craft pre-flight).
+    /// </summary>
+    public static bool TrySimulateRemoveStack(
+        ref PlayerInventorySnapshot snapshot,
+        string itemId,
+        int quantity,
+        IItemDefinitionRegistry registry)
+    {
+        if (quantity <= 0)
+        {
+            return false;
+        }
+
+        var lookup = itemId.Trim();
+        if (lookup.Length == 0 || !registry.TryGetDefinition(lookup, out var def))
+        {
+            return false;
+        }
+
+        var container = PlayerInventorySnapshot.ContainerFromSlotKind(def.InventorySlotKind);
+        var slots = PlayerInventorySnapshot.CloneSlots(snapshot.GetSlots(container));
+        if (CountQuantity(slots, def.Id) < quantity)
+        {
+            return false;
+        }
+
+        var remaining = quantity;
+        for (var i = 0; i < slots.Length && remaining > 0; i++)
+        {
+            var slot = slots[i];
+            if (slot.IsEmpty || !string.Equals(slot.ItemId, def.Id, StringComparison.Ordinal))
+            {
+                continue;
+            }
+
+            var take = Math.Min(remaining, slot.Quantity);
+            var left = slot.Quantity - take;
+            slots[i] = left <= 0
+                ? new InventorySlotState(slot.SlotIndex, null, 0)
+                : new InventorySlotState(slot.SlotIndex, def.Id, left);
+            remaining -= take;
+        }
+
+        snapshot = snapshot.WithSlots(container, slots);
+        return true;
+    }
+
     private static PlayerInventoryMutationOutcome Deny(string playerId, IPlayerInventoryStore store, string reasonCode)
     {
         // --- Telemetry hook site (NEO-56): future E9.M1 catalog event `inventory_transfer_denied` ---