feat(load-index): emit data.card_master_hash on mismatch (tier-1 freshness gate)

SVSim.EmulatedEntrypoint/Controllers/LoadController.cs

@@ -48,11 +48,13 @@ public class LoadController : SVSimController
     private readonly IViewerMissionStateService _missionState;
     private readonly SVSimDbContext _db;
     private readonly IInventoryService _inv;
+    private readonly ICardMasterPayloadProvider _cardMaster;
 
     public LoadController(IViewerRepository viewerRepository, IGlobalsRepository globalsRepository,
         IGameConfigService config,
         IBattlePassService battlePass, IViewerMissionStateService missionState,
-        SVSimDbContext db, IInventoryService inv)
+        SVSimDbContext db, IInventoryService inv,
+        ICardMasterPayloadProvider cardMaster)
     {
         _viewerRepository = viewerRepository;
         _globalsRepository = globalsRepository;
@@ -61,6 +63,7 @@ public class LoadController : SVSimController
         _missionState = missionState;
         _db = db;
         _inv = inv;
+        _cardMaster = cardMaster;
     }
 
     [HttpPost("index")]
@@ -163,7 +166,7 @@ public class LoadController : SVSimController
         var deviceHeader = Request.Headers["DEVICE"].FirstOrDefault();
         int deviceType = int.TryParse(deviceHeader, out int parsed) ? parsed : 0;
 
-        return new IndexResponse
+        var response = new IndexResponse
         {
             UserTutorial = new UserTutorial { TutorialStep = viewer.MissionData.TutorialState },
             UserInfo = new UserInfo(deviceType, viewer),
@@ -259,6 +262,21 @@ public class LoadController : SVSimController
             DeckFormat = Format.Rotation,
             CardSetIdForResourceDlView = rotation.CardSetIdForResourceDlView,
         };
+
+        // Emit card_master_hash only when the client's local copy differs from the configured
+        // hash (presence-only client check — Wizard/CardMaster.cs:20). Emitting on every boot
+        // would force a 1.27 MB redownload every boot. Empty request hash = fresh client = mismatch.
+        if (_cardMaster.IsAvailable)
+        {
+            var cardMasterCfg = _config.Get<CardMasterConfig>();
+            if (cardMasterCfg.EnableServing &&
+                !string.Equals(request.CardMasterHash, cardMasterCfg.CurrentHash, StringComparison.Ordinal))
+            {
+                response.CardMasterHash = cardMasterCfg.CurrentHash;
+            }
+        }
+
+        return response;
     }
 
     /// <summary>

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/IndexResponse.cs

@@ -42,6 +42,23 @@ public class IndexResponse
     [Key("deck_format")]
     public Format DeckFormat { get; set; } = Format.Rotation;
 
+    /// <summary>
+    /// Freshness trigger for the card-master refresh flow (Wizard/CardMaster.cs:18-30).
+    /// Nullable + global <c>WhenWritingNull</c> means absence on the wire when the request
+    /// already matches <c>CardMasterConfig.CurrentHash</c>. Presence (any value) tells the
+    /// client to call <c>POST /immutable_data/card_master</c> with this echoed back; the
+    /// client treats the string as opaque.
+    /// <para>
+    /// Lives on the inner <c>data</c> payload, NOT <c>data_headers</c> — verified by
+    /// <c>LoadDetail.cs:414</c> constructing <c>new CardMaster.UpdateInfo(jsonData)</c>
+    /// from the inner data, and the 2026-06-03 capture at
+    /// <c>data_dumps/captures/traffic_prod_allstars_freepack.ndjson</c>.
+    /// </para>
+    /// </summary>
+    [JsonPropertyName("card_master_hash")]
+    [Key("card_master_hash")]
+    public string? CardMasterHash { get; set; }
+
     #endregion
 
     #region Basic User Data