Card liquefication

SVSim.Database/Repositories/Card/ICardInventoryRepository.cs

@@ -0,0 +1,44 @@
+namespace SVSim.Database.Repositories.Card;
+
+/// <summary>
+/// Mutating operations on a viewer's card inventory (destruct, create, protect…).
+/// Read-only catalog queries live on <see cref="ICardRepository"/>.
+/// </summary>
+public interface ICardInventoryRepository
+{
+    /// <summary>
+    /// Validate-then-mutate destruct of owned cards. Atomic: all validation runs before any
+    /// mutation, and the mutation phase is wrapped in an explicit DB transaction so a mid-flight
+    /// EF failure rolls back currency + inventory + deck-strip together.
+    /// </summary>
+    /// <param name="viewerId">Authenticated viewer.</param>
+    /// <param name="destructCounts">cardId → num_to_destruct. Empty dict is rejected by the caller.</param>
+    /// <returns>
+    ///   <see cref="DestructResult"/> with post-state totals on success, or a
+    ///   <see cref="DestructError"/> when validation fails. On error nothing is written.
+    /// </returns>
+    Task<DestructOutcome> DestructCards(long viewerId, IReadOnlyDictionary<long, int> destructCounts);
+}
+
+/// <summary>
+/// Either a success payload or an error code. Discriminated by which field is set.
+/// </summary>
+public sealed record DestructOutcome(DestructResult? Result, DestructError? Error)
+{
+    public bool IsSuccess => Result is not null;
+
+    public static DestructOutcome Ok(DestructResult r) => new(r, null);
+    public static DestructOutcome Fail(DestructError e) => new(null, e);
+}
+
+public sealed record DestructResult(
+    ulong NewRedEtherTotal,
+    IReadOnlyDictionary<long, int> NewOwnedCounts);   // cardId → post-destruct Count
+
+public enum DestructError
+{
+    UnknownCard,
+    NotDestructible,
+    CardProtected,
+    InsufficientCards,
+}