NEO-55: address code review suggestions for inventory HTTP

Add remove round-trip and invalid_quantity API tests, Bruno remove request,
dependency register NEO-55 footnote, and strike-through review follow-ups.

bruno/neon-sprawl-server/inventory/Post inventory remove.bru

@@ -0,0 +1,41 @@
+meta {
+  name: POST inventory remove
+  type: http
+  seq: 4
+}
+
+docs {
+  NEO-55: remove stack via mutationKind remove. Run Post inventory add first on a fresh server,
+  or expect applied true when dev-local-1 already holds scrap_metal_bulk.
+}
+
+post {
+  url: {{baseUrl}}/game/players/dev-local-1/inventory
+  body: json
+  auth: none
+}
+
+body:json {
+  {
+    "schemaVersion": 1,
+    "mutationKind": "remove",
+    "itemId": "scrap_metal_bulk",
+    "quantity": 2
+  }
+}
+
+tests {
+  test("remove returns 200 with applied true and reduced quantity", function () {
+    expect(res.getStatus()).to.equal(200);
+    const body = res.getBody();
+    expect(body.schemaVersion).to.equal(1);
+    expect(body.applied).to.equal(true);
+    expect(body.reasonCode).to.equal(null);
+    expect(body.inventory).to.be.an("object");
+    const scrap = body.inventory.bagSlots.find((s) => s.itemId === "scrap_metal_bulk");
+    if (scrap) {
+      expect(scrap.quantity).to.be.a("number");
+      expect(scrap.quantity).to.be.at.least(0);
+    }
+  });
+}

bruno/neon-sprawl-server/inventory/folder.bru

@@ -1,3 +1,10 @@
 meta {
   name: inventory
 }
+
+docs {
+  NEO-55 inventory HTTP. Run GET first on a fresh dev server for empty 24+1 grid.
+  POST add/remove mutate dev-local-1; cumulative stacks from prior manual runs can make
+  Post inventory add assertions use at.least(5). Restart server (or truncate DB in Postgres
+  mode) for a clean inventory baseline.
+}

docs/decomposition/modules/module_dependency_register.md

@@ -48,7 +48,7 @@ Fleshed-out scope, contracts, and integration notes live in **per-module documen
 | E3.M4 | SinkAndDurabilityLifecycle | E3.M3, E8.M3 | DurabilityState, ItemSinkEvent, RepairCostRule | Pre-production | Planned |
 | E3.M5 | EconomyBalancePolicy | E3.M4, E9.M2 | EconomyPolicy, PriceBandRule, FaucetSinkRatio | Pre-production | Planned |
 
-**E3.M3 note:** Epic 3 **Slice 1** backlog in Linear ([Epic 3 — Crafting, Gathering, and Itemization Economy](https://linear.app/neon-sprawl/project/epic-3-crafting-gathering-and-itemization-economy-65785ed05bc2)): [NEO-50](https://linear.app/neon-sprawl/issue/NEO-50) → [NEO-56](https://linear.app/neon-sprawl/issue/NEO-56); label **`E3.M3`**. See [E3M3-prototype-backlog.md](../../plans/E3M3-prototype-backlog.md), [E3_M3_ItemizationAndInventorySchema.md](E3_M3_ItemizationAndInventorySchema.md). **NEO-50** (content + CI), **NEO-51** (server fail-fast load), **NEO-52** (`IItemDefinitionRegistry` + DI), **NEO-53** (`GET /game/world/item-definitions`), and **NEO-54** (inventory store + stack/slot rules engine) moved the register row to **In Progress**; later slices update the alignment table as they land.
+**E3.M3 note:** Epic 3 **Slice 1** backlog in Linear ([Epic 3 — Crafting, Gathering, and Itemization Economy](https://linear.app/neon-sprawl/project/epic-3-crafting-gathering-and-itemization-economy-65785ed05bc2)): [NEO-50](https://linear.app/neon-sprawl/issue/NEO-50) → [NEO-56](https://linear.app/neon-sprawl/issue/NEO-56); label **`E3.M3`**. See [E3M3-prototype-backlog.md](../../plans/E3M3-prototype-backlog.md), [E3_M3_ItemizationAndInventorySchema.md](E3_M3_ItemizationAndInventorySchema.md). **NEO-50** (content + CI), **NEO-51** (server fail-fast load), **NEO-52** (`IItemDefinitionRegistry` + DI), **NEO-53** (`GET /game/world/item-definitions`), **NEO-54** (inventory store + stack/slot rules engine), and **NEO-55** (`GET`/`POST /game/players/{id}/inventory`) moved the register row to **In Progress**; later slices update the alignment table as they land.
 
 ### Epic 4 — World Topology
 

docs/reviews/2026-05-23-NEO-55.md

@@ -19,11 +19,11 @@ NEO-55 adds versioned **`GET` / `POST /game/players/{id}/inventory`** with DTOs,
 | [`docs/plans/NEO-55-implementation-plan.md`](../plans/NEO-55-implementation-plan.md) | **Matches** — single POST + `mutationKind`, fixed 24+1 slot arrays, `applied`/`reasonCode`/snapshot echo, status mapping, Bruno + README, no manual QA doc per kickoff; acceptance checklist complete. |
 | [`docs/decomposition/modules/E3_M3_ItemizationAndInventorySchema.md`](../decomposition/modules/E3_M3_ItemizationAndInventorySchema.md) | **Matches** — NEO-55 HTTP bullet under **Related implementation slices**. |
 | [`docs/decomposition/modules/documentation_and_implementation_alignment.md`](../decomposition/modules/documentation_and_implementation_alignment.md) | **Matches** — E3.M3 row notes NEO-55 landed with README + Bruno pointers; NEO-56 telemetry still planned. |
-| [`docs/decomposition/modules/module_dependency_register.md`](../decomposition/modules/module_dependency_register.md) | **Partially matches** — E3.M3 **In Progress** is correct; **E3.M3 note** footnote still lists through **NEO-54** only (NEO-55 not mentioned). |
+| [`docs/decomposition/modules/module_dependency_register.md`](../decomposition/modules/module_dependency_register.md) | **Matches** — E3.M3 **In Progress**; footnote lists NEO-50–NEO-55. |
 | [`docs/decomposition/modules/client_server_authority.md`](../decomposition/modules/client_server_authority.md) | **Matches** — inventory mutations remain server-authoritative; HTTP is read/apply surface only. |
 | [`server/README.md`](../../server/README.md) | **Matches** — Player inventory section documents GET/POST shapes, curl examples, reason codes, persistence; NEO-54 deferral removed. |
 
-Register/tracking: alignment table updated; optional footnote extension for NEO-55 in dependency register.
+Register/tracking: alignment table and dependency register footnote updated for NEO-55.
 
 ## Blocking issues
 
@@ -31,19 +31,19 @@ None.
 
 ## Suggestions
 
-1. **Dependency register footnote (optional)** — Extend the **E3.M3 note** in [`module_dependency_register.md`](../decomposition/modules/module_dependency_register.md) to mention **NEO-55** (inventory HTTP) alongside NEO-50–NEO-54, matching the alignment table and prior NEO-54 review pattern.
+1. ~~**Dependency register footnote (optional)** — Extend the **E3.M3 note** in [`module_dependency_register.md`](../decomposition/modules/module_dependency_register.md) to mention **NEO-55** (inventory HTTP) alongside NEO-50–NEO-54, matching the alignment table and prior NEO-54 review pattern.~~ **Done.**
 
-2. **POST remove happy path (optional)** — Integration tests cover add success and remove deny (`insufficient_quantity`) but not add-then-remove success. A short round-trip test would lock the full POST contract for both `mutationKind` values.
+2. ~~**POST remove happy path (optional)** — Integration tests cover add success and remove deny (`insufficient_quantity`) but not add-then-remove success. A short round-trip test would lock the full POST contract for both `mutationKind` values.~~ **Done.** — `PostInventory_ShouldApplyRemove_AfterAdd_WithUpdatedSnapshot` in `PlayerInventoryApiTests.cs`.
 
-3. **`invalid_quantity` HTTP smoke (optional)** — Engine returns `invalid_quantity` for non-positive quantity; no HTTP test asserts **200** + `applied: false` + that code. Low risk (engine tested in NEO-54) but would complete the documented reason-code surface at the API layer.
+3. ~~**`invalid_quantity` HTTP smoke (optional)** — Engine returns `invalid_quantity` for non-positive quantity; no HTTP test asserts **200** + `applied: false` + that code. Low risk (engine tested in NEO-54) but would complete the documented reason-code surface at the API layer.~~ **Done.** — `PostInventory_ShouldDenyNonPositiveQuantity_WithInvalidQuantity` in `PlayerInventoryApiTests.cs`.
 
 ## Nits
 
-- Nit: **`Post inventory add.bru`** uses `expect(scrap.quantity).to.be.at.least(5)` — correct for a cumulative dev server, but an exact `=== 5` assertion would fail if prior manual runs left stacks. Acceptable for prototype Bruno; document “fresh dev player” in folder docs if flakes appear.
+- ~~Nit: **`Post inventory add.bru`** uses `expect(scrap.quantity).to.be.at.least(5)` — correct for a cumulative dev server, but an exact `=== 5` assertion would fail if prior manual runs left stacks. Acceptable for prototype Bruno; document “fresh dev player” in folder docs if flakes appear.~~ **Done.** — `folder.bru` docs note fresh-server baseline and cumulative stacks.
 
 - Nit: Plan referenced a **`BuildSnapshot`** helper name (NEO-37 mirror); implementation uses **`MapSnapshot`** — behavior is equivalent, naming only.
 
-- Nit: No Bruno request for **`remove`** happy path — plan minimum (one deny) is met via `invalid_item`; a remove-after-add Bruno would complement manual QA.
+- ~~Nit: No Bruno request for **`remove`** happy path — plan minimum (one deny) is met via `invalid_item`; a remove-after-add Bruno would complement manual QA.~~ **Done.** — `Post inventory remove.bru` (seq 4).
 
 ## Verification
 

server/NeonSprawl.Server.Tests/Game/Items/PlayerInventoryApiTests.cs

@@ -139,6 +139,54 @@ public sealed class PlayerInventoryApiTests
         Assert.Equal(10, occupied[0].Quantity);
     }
 
+    [Fact]
+    public async Task PostInventory_ShouldApplyRemove_AfterAdd_WithUpdatedSnapshot()
+    {
+        // Arrange
+        await using var factory = new InMemoryWebApplicationFactory();
+        var client = factory.CreateClient();
+
+        // Act
+        _ = await client.PostAsJsonAsync(
+            "/game/players/dev-local-1/inventory",
+            Mutation("add", "scrap_metal_bulk", quantity: 10));
+        var response = await client.PostAsJsonAsync(
+            "/game/players/dev-local-1/inventory",
+            Mutation("remove", "scrap_metal_bulk", quantity: 4));
+
+        // Assert
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        var body = await response.Content.ReadFromJsonAsync<PlayerInventoryMutationResponse>();
+        Assert.NotNull(body);
+        Assert.True(body!.Applied);
+        Assert.Null(body.ReasonCode);
+        var occupied = body.Inventory.BagSlots.Where(static s => s.Quantity > 0).ToList();
+        Assert.Single(occupied);
+        Assert.Equal("scrap_metal_bulk", occupied[0].ItemId);
+        Assert.Equal(6, occupied[0].Quantity);
+    }
+
+    [Fact]
+    public async Task PostInventory_ShouldDenyNonPositiveQuantity_WithInvalidQuantity()
+    {
+        // Arrange
+        await using var factory = new InMemoryWebApplicationFactory();
+        var client = factory.CreateClient();
+
+        // Act
+        var response = await client.PostAsJsonAsync(
+            "/game/players/dev-local-1/inventory",
+            Mutation("add", "scrap_metal_bulk", quantity: 0));
+
+        // Assert
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        var body = await response.Content.ReadFromJsonAsync<PlayerInventoryMutationResponse>();
+        Assert.NotNull(body);
+        Assert.False(body!.Applied);
+        Assert.Equal(PlayerInventoryReasonCodes.InvalidQuantity, body.ReasonCode);
+        Assert.All(body.Inventory.BagSlots, static slot => Assert.Equal(0, slot.Quantity));
+    }
+
     [Fact]
     public async Task PostInventory_ShouldDenyUnknownItem_WithInvalidItem_AndLeaveInventoryEmpty()
     {