feat(contracts): add transport-neutral inventory contracts

- WHY: align inventory capability contracts with protocol-agnostic integration boundaries
- WHAT: add contract conventions, grpc adapter surfaces, and blueprint descriptor consumption
- RULE: enforce building-block to blueprint dependency direction

docs/architecture/inventory-contract-boundary.puml

@@ -3,15 +3,23 @@ skinparam packageStyle rectangle
 
 package "building-block-inventory" {
   package "BuildingBlock.Inventory.Contracts" {
+    class Conventions
     class Requests
     class Responses
+    interface Adapters
+    class Grpc
     interface Abstractions
   }
 }
 
+package "blueprint-platform" {
+  interface IBlueprintPackageContract
+}
+
 package "furniture-service" as FurnitureService
 package "furniture-bff" as FurnitureBff
 
+Conventions ..> IBlueprintPackageContract
 FurnitureService --> Requests
 FurnitureService --> Responses
 FurnitureBff --> Requests

docs/contracts/inventory-contract-catalog.md

@@ -4,14 +4,18 @@
 
 - `BuildingBlock.Inventory.Contracts`
 
-## Current Contract Groups
+## Contract Groups
 
+- `Conventions`: transport-neutral request/response and envelope conventions.
 - `Requests`: capability request shapes for inventory use cases.
 - `Responses`: capability response shapes for inventory use cases.
 - `Abstractions`: marker abstractions for inventory contract ownership.
+- `Adapters`: protocol adapter boundaries.
+- `Grpc`: gRPC contract shapes for adapter translation.
 
 ## Ownership Boundary
 
 - This repository owns inventory capability contracts only.
+- Contract metadata consumes `Core.Blueprint.Common.Contracts` and does not redefine Blueprint contracts.
 - Implementation details stay in furniture-service, furniture-bff, or furniture-dal.
 - Identity abstractions are out of scope and remain Thalos-owned.

docs/contracts/inventory-versioning-policy.md

@@ -6,7 +6,12 @@
 - Breaking changes require a new major package version.
 - Deprecated members should remain for at least one release cycle.
 
+## Blueprint Compatibility
+
+- Package descriptor metadata is implemented via `IBlueprintPackageContract` from `Core.Blueprint.Common.Contracts`.
+- Inventory contracts consume Blueprint common contract primitives rather than redefining them.
+
 ## Compatibility Notes
 
 - Consumer repositories (`furniture-service`, `furniture-bff`) should update contracts explicitly.
-- Transport adapters remain outside this contracts package.
+- Protocol adapters remain edge concerns; inventory contracts remain transport-neutral.

src/BuildingBlock.Inventory.Contracts/Adapters/IInventoryGrpcContractAdapter.cs

@@ -0,0 +1,25 @@
+using BuildingBlock.Inventory.Contracts.Grpc;
+using BuildingBlock.Inventory.Contracts.Requests;
+using BuildingBlock.Inventory.Contracts.Responses;
+
+namespace BuildingBlock.Inventory.Contracts.Adapters;
+
+/// <summary>
+/// Defines adapter boundary for gRPC contract translation.
+/// </summary>
+public interface IInventoryGrpcContractAdapter
+{
+    /// <summary>
+    /// Maps transport-neutral request into gRPC contract shape.
+    /// </summary>
+    /// <param name="request">Transport-neutral inventory lookup request.</param>
+    /// <returns>gRPC contract request shape.</returns>
+    InventoryItemLookupGrpcContract ToGrpcRequest(InventoryItemLookupRequest request);
+
+    /// <summary>
+    /// Maps gRPC contract response data into transport-neutral response.
+    /// </summary>
+    /// <param name="contract">gRPC contract response shape.</param>
+    /// <returns>Transport-neutral inventory lookup response.</returns>
+    InventoryItemLookupResponse FromGrpcResponse(InventoryItemLookupGrpcContract contract);
+}

src/BuildingBlock.Inventory.Contracts/BuildingBlock.Inventory.Contracts.csproj

@@ -4,4 +4,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\blueprint-platform\src\Core.Blueprint.Common\Core.Blueprint.Common.csproj" />
+  </ItemGroup>
 </Project>

src/BuildingBlock.Inventory.Contracts/Conventions/IInventoryContractRequest.cs

@@ -0,0 +1,9 @@
+namespace BuildingBlock.Inventory.Contracts.Conventions;
+
+/// <summary>
+/// Defines transport-neutral request contract shape for inventory capability operations.
+/// </summary>
+/// <typeparam name="TResponse">Response contract type.</typeparam>
+public interface IInventoryContractRequest<out TResponse>
+{
+}

src/BuildingBlock.Inventory.Contracts/Conventions/InventoryContractEnvelope.cs

@@ -0,0 +1,8 @@
+namespace BuildingBlock.Inventory.Contracts.Conventions;
+
+/// <summary>
+/// Defines transport-neutral envelope metadata for inventory contract messages.
+/// </summary>
+/// <param name="ContractVersion">Contract schema version.</param>
+/// <param name="CorrelationId">Correlation identifier for cross-service tracing.</param>
+public sealed record InventoryContractEnvelope(string ContractVersion, string CorrelationId);

src/BuildingBlock.Inventory.Contracts/Conventions/InventoryPackageContract.cs

@@ -0,0 +1,15 @@
+using Core.Blueprint.Common.Contracts;
+
+namespace BuildingBlock.Inventory.Contracts.Conventions;
+
+/// <summary>
+/// Defines package descriptor metadata for inventory contracts package.
+/// </summary>
+public sealed class InventoryPackageContract : IBlueprintPackageContract
+{
+    /// <inheritdoc />
+    public BlueprintPackageDescriptor Descriptor { get; } = new(
+        "BuildingBlock.Inventory.Contracts",
+        PackageVersionPolicy.Minor,
+        ["Core.Blueprint.Common"]);
+}

src/BuildingBlock.Inventory.Contracts/Grpc/InventoryItemLookupGrpcContract.cs

@@ -0,0 +1,7 @@
+namespace BuildingBlock.Inventory.Contracts.Grpc;
+
+/// <summary>
+/// Defines minimal gRPC contract shape for adapter-level translation.
+/// </summary>
+/// <param name="ItemCode">External item identifier.</param>
+public sealed record InventoryItemLookupGrpcContract(string ItemCode);

src/BuildingBlock.Inventory.Contracts/Requests/InventoryItemLookupRequest.cs

@@ -1,7 +1,13 @@
+using BuildingBlock.Inventory.Contracts.Conventions;
+
 namespace BuildingBlock.Inventory.Contracts.Requests;
 
 /// <summary>
-/// Represents the contract request to lookup an inventory item.
+/// Represents the transport-neutral contract request to lookup an inventory item.
 /// </summary>
+/// <param name="Envelope">Contract envelope metadata.</param>
 /// <param name="ItemCode">External item identifier.</param>
-public sealed record InventoryItemLookupRequest(string ItemCode);
+public sealed record InventoryItemLookupRequest(
+    InventoryContractEnvelope Envelope,
+    string ItemCode)
+    : IInventoryContractRequest<Responses.InventoryItemLookupResponse>;

src/BuildingBlock.Inventory.Contracts/Responses/InventoryItemLookupResponse.cs

@@ -1,8 +1,14 @@
+using BuildingBlock.Inventory.Contracts.Conventions;
+
 namespace BuildingBlock.Inventory.Contracts.Responses;
 
 /// <summary>
-/// Represents the contract response for an inventory item lookup.
+/// Represents the transport-neutral contract response for an inventory item lookup.
 /// </summary>
+/// <param name="Envelope">Contract envelope metadata.</param>
 /// <param name="ItemCode">External item identifier.</param>
 /// <param name="QuantityAvailable">Current quantity available.</param>
-public sealed record InventoryItemLookupResponse(string ItemCode, int QuantityAvailable);
+public sealed record InventoryItemLookupResponse(
+    InventoryContractEnvelope Envelope,
+    string ItemCode,
+    int QuantityAvailable);

tests/BuildingBlock.Inventory.Contracts.UnitTests/ContractShapeTests.cs

@@ -1,24 +1,42 @@
+using BuildingBlock.Inventory.Contracts.Conventions;
 using BuildingBlock.Inventory.Contracts.Requests;
 using BuildingBlock.Inventory.Contracts.Responses;
+using Core.Blueprint.Common.Contracts;
 
 namespace BuildingBlock.Inventory.Contracts.UnitTests;
 
 public class ContractShapeTests
 {
     [Fact]
-    public void InventoryItemLookupRequest_WhenCreated_StoresItemCode()
+    public void InventoryItemLookupRequest_WhenCreated_StoresTransportNeutralData()
     {
-        var request = new InventoryItemLookupRequest("SKU-001");
+        var envelope = new InventoryContractEnvelope("1.0.0", "corr-123");
+        var request = new InventoryItemLookupRequest(envelope, "SKU-001");
 
+        Assert.Equal("1.0.0", request.Envelope.ContractVersion);
+        Assert.Equal("corr-123", request.Envelope.CorrelationId);
         Assert.Equal("SKU-001", request.ItemCode);
     }
 
     [Fact]
-    public void InventoryItemLookupResponse_WhenCreated_StoresContractData()
+    public void InventoryItemLookupResponse_WhenCreated_StoresTransportNeutralData()
     {
-        var response = new InventoryItemLookupResponse("SKU-001", 5);
+        var envelope = new InventoryContractEnvelope("1.0.0", "corr-123");
+        var response = new InventoryItemLookupResponse(envelope, "SKU-001", 5);
 
+        Assert.Equal("1.0.0", response.Envelope.ContractVersion);
+        Assert.Equal("corr-123", response.Envelope.CorrelationId);
         Assert.Equal("SKU-001", response.ItemCode);
         Assert.Equal(5, response.QuantityAvailable);
     }
+
+    [Fact]
+    public void InventoryPackageContract_WhenCreated_UsesBlueprintDescriptorContract()
+    {
+        IBlueprintPackageContract contract = new InventoryPackageContract();
+
+        Assert.Equal("BuildingBlock.Inventory.Contracts", contract.Descriptor.PackageId);
+        Assert.Equal(PackageVersionPolicy.Minor, contract.Descriptor.VersionPolicy);
+        Assert.Contains("Core.Blueprint.Common", contract.Descriptor.DependencyPackageIds);
+    }
 }