Initial commit: Add project files

src/KArtSell.BuildingBlocks/Versioning/VersionSet.cs

@@ -0,0 +1,32 @@
+namespace KArtSell.BuildingBlocks.Versioning;
+
+/// <summary>
+/// Immutable identity of the data, model, configuration and code used for a decision.
+/// Values are opaque, approved identifiers or SHA-256 digests; they are never inferred from the client.
+/// </summary>
+public sealed record VersionSet(
+    string DatasetId,
+    string DataHash,
+    string ModelVersion,
+    string ConfigVersion,
+    string CodeSha,
+    string ContractVersion)
+{
+    public void EnsureValid()
+    {
+        EnsureNotBlank(DatasetId, nameof(DatasetId));
+        EnsureNotBlank(DataHash, nameof(DataHash));
+        EnsureNotBlank(ModelVersion, nameof(ModelVersion));
+        EnsureNotBlank(ConfigVersion, nameof(ConfigVersion));
+        EnsureNotBlank(CodeSha, nameof(CodeSha));
+        EnsureNotBlank(ContractVersion, nameof(ContractVersion));
+    }
+
+    private static void EnsureNotBlank(string value, string name)
+    {
+        if (string.IsNullOrWhiteSpace(value))
+        {
+            throw new ArgumentException($"{name} must be an approved, non-blank identifier.", name);
+        }
+    }
+}