quests: QuestMetrics helpers, README quests section

README.md

@@ -53,7 +53,7 @@ stack.
 | `Auth` | `AuthService` | `LoginWithDeviceAsync`, `RefreshAsync`, `Logout`, `AuthStateChanged` |
 | `Player` | `PlayerService` | `GetProfileAsync` |
 | `BattlePass` | `BattlePassService` | `GetProgressAsync`, `AddXpAsync`, `ClaimRewardAsync`, `PurchasePremiumAsync` |
-| `Quests` | `QuestsService` | `ListAsync`, `ClaimAsync` |
+| `Quests` | `QuestsService` | `ListAsync`, `ClaimAsync`, `ReportProgressAsync` |
 | `Stores` | `StoresService` | `ListAsync`, `GetAsync`, `PurchaseAsync` |
 | `Inventory` | `InventoryService` | `GetAsync` |
 | `Leaderboards` | `LeaderboardsService` | `FindBySlug(slug)` → handle: `SubmitAsync`, `ListAsync` |
@@ -62,6 +62,30 @@ stack.
 | `Storage` | `StorageService` | `GetAsync`, `ListAllAsync`, `SaveAsync`, `DeleteAsync` |
 | `Realtime` | `RealtimeService` | `ConnectAsync`, `DisconnectAsync` |
 
+## Quests
+
+`client.Quests` covers the player's global quests — list with per-objective
+progress, claim, and metric reports. These are distinct from scenario quest
+nodes, which advance through `QuestSession` (`Scenario.OnQuest`).
+
+```csharp
+var quests = await client.Quests.ListAsync();
+foreach (var quest in quests)
+{
+    if (quest.Status == "completed")
+        await client.Quests.ClaimAsync(quest.Id);
+}
+
+// Custom metrics advance matching objectives server-side; the call returns
+// the ids of quests completed by this report.
+var completedIds = await client.Quests.ReportProgressAsync("kills", 1);
+```
+
+Purchase metrics are reported automatically by store purchases;
+`QuestMetrics.PurchaseOffer(offerId)` / `QuestMetrics.PurchaseItem(itemId)`
+name the format (`purchase.offer:<offerId>`, `purchase.item:<itemId>`) so
+quest configs and client code agree on it.
+
 ## Sessions
 
 Every API call goes through the client's session pipeline: a 401 triggers a

Services/QuestMetrics.cs

@@ -0,0 +1,16 @@
+namespace RudderSdk.Core;
+
+/// <summary>
+/// Builders for the quest metric strings known to the platform. Purchase
+/// metrics are reported automatically by the shop purchase fan-out; any other
+/// metric is a custom string reported via
+/// <see cref="QuestsService.ReportProgressAsync"/>.
+/// </summary>
+public static class QuestMetrics
+{
+    /// <summary>Metric for purchasing a store offer; auto-reported on purchase.</summary>
+    public static string PurchaseOffer(string offerId) => $"purchase.offer:{offerId}";
+
+    /// <summary>Metric for purchasing a catalog item; auto-reported on purchase.</summary>
+    public static string PurchaseItem(string itemId) => $"purchase.item:{itemId}";
+}