diff --git a/BattlePass/AddBattlePassXpRequest.cs b/BattlePass/AddBattlePassXpRequest.cs
index 42d193c..f53f35e 100644
--- a/BattlePass/AddBattlePassXpRequest.cs
+++ b/BattlePass/AddBattlePassXpRequest.cs
@@ -14,8 +14,8 @@ public class AddBattlePassXpRequest
     [JsonProperty("runId")]
     public string? RunId { get; set; }
 
-    [JsonProperty("scenarioId")]
-    public string? ScenarioId { get; set; }
+    [JsonProperty("scenarioSlug")]
+    public string? ScenarioSlug { get; set; }
 
     [JsonProperty("source")]
     public string? Source { get; set; }
diff --git a/BattlePass/ClaimBattlePassRewardRequest.cs b/BattlePass/ClaimBattlePassRewardRequest.cs
index 51dd9fd..adfee1a 100644
--- a/BattlePass/ClaimBattlePassRewardRequest.cs
+++ b/BattlePass/ClaimBattlePassRewardRequest.cs
@@ -14,8 +14,8 @@ public class ClaimBattlePassRewardRequest
     [JsonProperty("runId")]
     public string? RunId { get; set; }
 
-    [JsonProperty("scenarioId")]
-    public string? ScenarioId { get; set; }
+    [JsonProperty("scenarioSlug")]
+    public string? ScenarioSlug { get; set; }
 
     [JsonProperty("track")]
     public string? Track { get; set; }
diff --git a/BattlePass/GetBattlePassProgressRequest.cs b/BattlePass/GetBattlePassProgressRequest.cs
index 6f633ea..426d254 100644
--- a/BattlePass/GetBattlePassProgressRequest.cs
+++ b/BattlePass/GetBattlePassProgressRequest.cs
@@ -8,7 +8,7 @@ public class GetBattlePassProgressRequest
     [JsonProperty("nodeId")]
     public string? NodeId { get; set; }
 
-    [JsonProperty("scenarioId")]
-    public string? ScenarioId { get; set; }
+    [JsonProperty("scenarioSlug")]
+    public string? ScenarioSlug { get; set; }
 
 }
diff --git a/BattlePass/PurchaseBattlePassPremiumRequest.cs b/BattlePass/PurchaseBattlePassPremiumRequest.cs
index 6208bf0..b360952 100644
--- a/BattlePass/PurchaseBattlePassPremiumRequest.cs
+++ b/BattlePass/PurchaseBattlePassPremiumRequest.cs
@@ -14,7 +14,7 @@ public class PurchaseBattlePassPremiumRequest
     [JsonProperty("runId")]
     public string? RunId { get; set; }
 
-    [JsonProperty("scenarioId")]
-    public string? ScenarioId { get; set; }
+    [JsonProperty("scenarioSlug")]
+    public string? ScenarioSlug { get; set; }
 
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3366285..4fd1108 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,36 @@
 # Changelog
 
+## 2.0.0
+
+Breaking change — major bump, required by the backend environments release.
+Every project now has exactly two environments, `staging` and `prod`, and the
+SDK key you configure decides which one the player belongs to. The environment
+never appears in the client API: it is resolved at login and carried inside the
+access and refresh tokens. Tokens issued before this release have no
+environment claim and are rejected with 401, so the first call after the
+backend upgrade refreshes, fails, clears the stored tokens and raises
+`AuthService.AuthStateChanged` with `RudderAuthState.SignedOut`. Log the player
+in again with `Auth.LoginWithDeviceAsync` / `LoginWithCustomAsync`.
+
+Quests, scenarios and offers are addressed by their slug instead of their id,
+because ids differ between staging and prod while slugs are stable. Renamed
+accordingly: `Quest.Id` is now `Quest.Slug`, `QuestsService.ClaimAsync` takes a
+quest slug, `ReportProgressAsync` returns the slugs of the completed quests
+(`ReportQuestProgressResponse.CompletedQuestSlugs`), `StoresService.PurchaseAsync`
+takes an offer slug and `Offer` carries a `Slug`, `QuestMetrics.PurchaseOffer`
+builds its metric from the offer slug, and every scenario-scoped type exposes
+`ScenarioSlug` instead of `ScenarioId` — `PendingEffect`, the effect objects,
+`ScenarioCompletedEffect`, `ScenarioFailedEffect`, the battle pass requests and
+`BattlePassService.GetProgressAsync`. Leaderboards, items and stores already
+used slugs and are unchanged.
+
+Also shipped here, previously committed but never published: the effects client
+reconciles against every `GET /sdk/v1/scenarios/pending` response, so a run that
+disappears server-side (finished elsewhere, expired after a promote) now emits
+`OnScenarioCompleted` instead of lingering; and `run_not_active` joins
+`unknown_run` and `run_expired` as a terminal rejection that drops the run and
+emits `OnScenarioFailed`.
+
 ## 1.0.0
 
 Breaking change — major bump. The local scenario engine is replaced by a
diff --git a/Quests/ClaimQuestRequest.cs b/Quests/ClaimQuestRequest.cs
index 8e11b6f..312a7db 100644
--- a/Quests/ClaimQuestRequest.cs
+++ b/Quests/ClaimQuestRequest.cs
@@ -5,7 +5,7 @@ namespace RudderSdk.Core.Models.Quests;
 
 public class ClaimQuestRequest
 {
-    [JsonProperty("questId")]
-    public string? QuestId { get; set; }
+    [JsonProperty("questSlug")]
+    public string? QuestSlug { get; set; }
 
 }
diff --git a/Quests/Quest.cs b/Quests/Quest.cs
index b87ce9c..e11bfd8 100644
--- a/Quests/Quest.cs
+++ b/Quests/Quest.cs
@@ -7,9 +7,6 @@ namespace RudderSdk.Core.Models.Quests;
 
 public class Quest
 {
-    [JsonProperty("id")]
-    public string? Id { get; set; }
-
     [JsonProperty("name")]
     public string? Name { get; set; }
 
@@ -19,6 +16,9 @@ public class Quest
     [JsonProperty("rewards")]
     public List<Reward>? Rewards { get; set; }
 
+    [JsonProperty("slug")]
+    public string? Slug { get; set; }
+
     [JsonProperty("status")]
     public string? Status { get; set; }
 
diff --git a/Quests/ReportQuestProgressResponse.cs b/Quests/ReportQuestProgressResponse.cs
index ef90c2e..777978a 100644
--- a/Quests/ReportQuestProgressResponse.cs
+++ b/Quests/ReportQuestProgressResponse.cs
@@ -6,7 +6,7 @@ namespace RudderSdk.Core.Models.Quests;
 
 public class ReportQuestProgressResponse
 {
-    [JsonProperty("completedQuestIds")]
-    public List<string>? CompletedQuestIds { get; set; }
+    [JsonProperty("completedQuestSlugs")]
+    public List<string>? CompletedQuestSlugs { get; set; }
 
 }
diff --git a/README.md b/README.md
index de95f95..c599e4a 100644
--- a/README.md
+++ b/README.md
@@ -73,7 +73,7 @@ var quests = await client.Quests.ListAsync();
 foreach (var quest in quests)
 {
     if (quest.Status == "completed")
-        await client.Quests.ClaimAsync(quest.Id);
+        await client.Quests.ClaimAsync(quest.Slug);
 }
 
 // Custom metrics advance matching objectives server-side; the call returns
@@ -82,8 +82,8 @@ 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
+`QuestMetrics.PurchaseOffer(offerSlug)` / `QuestMetrics.PurchaseItem(itemId)`
+name the format (`purchase.offer:<offerSlug>`, `purchase.item:<itemId>`) so
 quest configs and client code agree on it.
 
 ## Sessions
diff --git a/Rudder.Core.csproj b/Rudder.Core.csproj
index 022768d..40e94a9 100644
--- a/Rudder.Core.csproj
+++ b/Rudder.Core.csproj
@@ -6,7 +6,7 @@
     <AssemblyName>Rudder.Core</AssemblyName>
     <RootNamespace>RudderSdk.Core</RootNamespace>
     <PackageId>Rudder.Core</PackageId>
-    <Version>1.0.0</Version>
+    <Version>2.0.0</Version>
     <Authors>Rudder</Authors>
     <Description>Rudder LiveOps client SDK for .NET: auth, player, stores, battle pass, quests, leaderboards, inventory, remote config, scenarios and storage.</Description>
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
diff --git a/Scenarios/HandleScenarioCallbackRequest.cs b/Scenarios/HandleScenarioCallbackRequest.cs
index 922875b..515a713 100644
--- a/Scenarios/HandleScenarioCallbackRequest.cs
+++ b/Scenarios/HandleScenarioCallbackRequest.cs
@@ -14,7 +14,7 @@ public class HandleScenarioCallbackRequest
     [JsonProperty("runId")]
     public string? RunId { get; set; }
 
-    [JsonProperty("scenarioId")]
-    public string? ScenarioId { get; set; }
+    [JsonProperty("scenarioSlug")]
+    public string? ScenarioSlug { get; set; }
 
 }
diff --git a/Scenarios/PendingEffect.cs b/Scenarios/PendingEffect.cs
index bac2d18..4160922 100644
--- a/Scenarios/PendingEffect.cs
+++ b/Scenarios/PendingEffect.cs
@@ -16,8 +16,8 @@ public class PendingEffect
     [JsonProperty("runId")]
     public string RunId { get; set; } = null!;
 
-    [JsonProperty("scenarioId")]
-    public string ScenarioId { get; set; } = null!;
+    [JsonProperty("scenarioSlug")]
+    public string ScenarioSlug { get; set; } = null!;
 
     [JsonProperty("type")]
     public string Type { get; set; } = null!;
diff --git a/Scenarios/UpdateScenarioCounterRequest.cs b/Scenarios/UpdateScenarioCounterRequest.cs
index 1457c0d..c36f269 100644
--- a/Scenarios/UpdateScenarioCounterRequest.cs
+++ b/Scenarios/UpdateScenarioCounterRequest.cs
@@ -17,7 +17,7 @@ public class UpdateScenarioCounterRequest
     [JsonProperty("runId")]
     public string? RunId { get; set; }
 
-    [JsonProperty("scenarioId")]
-    public string? ScenarioId { get; set; }
+    [JsonProperty("scenarioSlug")]
+    public string? ScenarioSlug { get; set; }
 
 }
diff --git a/Services/BattlePassService.cs b/Services/BattlePassService.cs
index 5662b32..41292c6 100644
--- a/Services/BattlePassService.cs
+++ b/Services/BattlePassService.cs
@@ -24,11 +24,11 @@ public sealed class BattlePassService
     internal BattlePassService(RudderClient client) => _client = client;
 
     /// <summary>Reads current progress: xp, level, premium ownership, claimed tiers.</summary>
-    public Task<GetBattlePassProgressResponse> GetProgressAsync(string scenarioId, string nodeId, CancellationToken cancellationToken = default)
+    public Task<GetBattlePassProgressResponse> GetProgressAsync(string scenarioSlug, string nodeId, CancellationToken cancellationToken = default)
         => _client.SendAsync<GetBattlePassProgressRequest, GetBattlePassProgressResponse>(
             "POST",
             "/sdk/v1/battlepass/progress",
-            new GetBattlePassProgressRequest { ScenarioId = scenarioId, NodeId = nodeId },
+            new GetBattlePassProgressRequest { ScenarioSlug = scenarioSlug, NodeId = nodeId },
             cancellationToken);
 
     /// <summary>Credits xp and returns the new xp/level and level-up flags.</summary>
diff --git a/Services/Effects/BattlePassEffect.cs b/Services/Effects/BattlePassEffect.cs
index a7ce69b..5aff93c 100644
--- a/Services/Effects/BattlePassEffect.cs
+++ b/Services/Effects/BattlePassEffect.cs
@@ -26,7 +26,7 @@ public sealed class BattlePassEffect
     public string RunId => _handle.RunId;
 
     /// <summary>Scenario id.</summary>
-    public string ScenarioId => _handle.ScenarioId;
+    public string ScenarioSlug => _handle.ScenarioSlug;
 
     /// <summary>Node id.</summary>
     public string NodeId => _handle.NodeId;
@@ -39,13 +39,13 @@ public sealed class BattlePassEffect
 
     /// <summary>Reads current progress (xp, level, premium ownership, claimed tiers) for this node.</summary>
     public Task<GetBattlePassProgressResponse> GetProgressAsync(CancellationToken cancellationToken = default)
-        => _battlePass.GetProgressAsync(_handle.ScenarioId, _handle.NodeId, cancellationToken);
+        => _battlePass.GetProgressAsync(_handle.ScenarioSlug, _handle.NodeId, cancellationToken);
 
     /// <summary>Credits xp from a configured source.</summary>
     public Task<AddBattlePassXpResponse> AddXpAsync(string source, long amount, CancellationToken cancellationToken = default)
         => _battlePass.AddXpAsync(new AddBattlePassXpRequest
         {
-            ScenarioId = _handle.ScenarioId,
+            ScenarioSlug = _handle.ScenarioSlug,
             NodeId = _handle.NodeId,
             RunId = _handle.RunId,
             Source = source,
@@ -59,7 +59,7 @@ public sealed class BattlePassEffect
     public Task<ClaimBattlePassRewardResponse> ClaimRewardAsync(int level, string track, CancellationToken cancellationToken = default)
         => _battlePass.ClaimRewardAsync(new ClaimBattlePassRewardRequest
         {
-            ScenarioId = _handle.ScenarioId,
+            ScenarioSlug = _handle.ScenarioSlug,
             NodeId = _handle.NodeId,
             RunId = _handle.RunId,
             Level = level,
@@ -71,7 +71,7 @@ public sealed class BattlePassEffect
     {
         var response = await _battlePass.PurchasePremiumAsync(new PurchaseBattlePassPremiumRequest
         {
-            ScenarioId = _handle.ScenarioId,
+            ScenarioSlug = _handle.ScenarioSlug,
             NodeId = _handle.NodeId,
             RunId = _handle.RunId,
             IdempotencyKey = Guid.NewGuid().ToString()
diff --git a/Services/Effects/BattlePassLevelEffect.cs b/Services/Effects/BattlePassLevelEffect.cs
index 0bb0507..d1975da 100644
--- a/Services/Effects/BattlePassLevelEffect.cs
+++ b/Services/Effects/BattlePassLevelEffect.cs
@@ -19,7 +19,7 @@ public sealed class BattlePassLevelEffect
     public string RunId => _handle.RunId;
 
     /// <summary>Scenario id.</summary>
-    public string ScenarioId => _handle.ScenarioId;
+    public string ScenarioSlug => _handle.ScenarioSlug;
 
     /// <summary>Node id.</summary>
     public string NodeId => _handle.NodeId;
diff --git a/Services/Effects/LeaderboardEffect.cs b/Services/Effects/LeaderboardEffect.cs
index cee667d..b64f992 100644
--- a/Services/Effects/LeaderboardEffect.cs
+++ b/Services/Effects/LeaderboardEffect.cs
@@ -15,7 +15,7 @@ public sealed class LeaderboardEffect
     public string RunId => _handle.RunId;
 
     /// <summary>Scenario id.</summary>
-    public string ScenarioId => _handle.ScenarioId;
+    public string ScenarioSlug => _handle.ScenarioSlug;
 
     /// <summary>Node id.</summary>
     public string NodeId => _handle.NodeId;
diff --git a/Services/Effects/NotificationEffect.cs b/Services/Effects/NotificationEffect.cs
index af986d1..8314441 100644
--- a/Services/Effects/NotificationEffect.cs
+++ b/Services/Effects/NotificationEffect.cs
@@ -15,7 +15,7 @@ public sealed class NotificationEffect
     public string RunId => _handle.RunId;
 
     /// <summary>Scenario id.</summary>
-    public string ScenarioId => _handle.ScenarioId;
+    public string ScenarioSlug => _handle.ScenarioSlug;
 
     /// <summary>Node id.</summary>
     public string NodeId => _handle.NodeId;
diff --git a/Services/Effects/QuestEffect.cs b/Services/Effects/QuestEffect.cs
index c3ece16..7fb6281 100644
--- a/Services/Effects/QuestEffect.cs
+++ b/Services/Effects/QuestEffect.cs
@@ -20,7 +20,7 @@ public sealed class QuestEffect
     public string RunId => _handle.RunId;
 
     /// <summary>Scenario id.</summary>
-    public string ScenarioId => _handle.ScenarioId;
+    public string ScenarioSlug => _handle.ScenarioSlug;
 
     /// <summary>Node id.</summary>
     public string NodeId => _handle.NodeId;
diff --git a/Services/Effects/ScenarioCompletedEffect.cs b/Services/Effects/ScenarioCompletedEffect.cs
index 267275b..b7fcf59 100644
--- a/Services/Effects/ScenarioCompletedEffect.cs
+++ b/Services/Effects/ScenarioCompletedEffect.cs
@@ -3,15 +3,15 @@ namespace RudderSdk.Core;
 /// <summary>Payload of <see cref="EffectsService.OnScenarioCompleted"/>.</summary>
 public sealed class ScenarioCompletedEffect
 {
-    internal ScenarioCompletedEffect(string runId, string scenarioId)
+    internal ScenarioCompletedEffect(string runId, string scenarioSlug)
     {
         RunId = runId;
-        ScenarioId = scenarioId;
+        ScenarioSlug = scenarioSlug;
     }
 
     /// <summary>Server-issued run id.</summary>
     public string RunId { get; }
 
     /// <summary>Scenario id.</summary>
-    public string ScenarioId { get; }
+    public string ScenarioSlug { get; }
 }
diff --git a/Services/Effects/ScenarioFailedEffect.cs b/Services/Effects/ScenarioFailedEffect.cs
index 2c833a7..c2e0d55 100644
--- a/Services/Effects/ScenarioFailedEffect.cs
+++ b/Services/Effects/ScenarioFailedEffect.cs
@@ -5,10 +5,10 @@ namespace RudderSdk.Core;
 /// <summary>Payload of <see cref="EffectsService.OnScenarioFailed"/>.</summary>
 public sealed class ScenarioFailedEffect
 {
-    internal ScenarioFailedEffect(string runId, string scenarioId, string nodeId, Exception exception)
+    internal ScenarioFailedEffect(string runId, string scenarioSlug, string nodeId, Exception exception)
     {
         RunId = runId;
-        ScenarioId = scenarioId;
+        ScenarioSlug = scenarioSlug;
         NodeId = nodeId;
         Exception = exception;
     }
@@ -17,7 +17,7 @@ public sealed class ScenarioFailedEffect
     public string RunId { get; }
 
     /// <summary>Scenario id.</summary>
-    public string ScenarioId { get; }
+    public string ScenarioSlug { get; }
 
     /// <summary>Node the failure happened at.</summary>
     public string NodeId { get; }
diff --git a/Services/Effects/StoreOfferEffect.cs b/Services/Effects/StoreOfferEffect.cs
index 084acc8..19a4ab4 100644
--- a/Services/Effects/StoreOfferEffect.cs
+++ b/Services/Effects/StoreOfferEffect.cs
@@ -15,7 +15,7 @@ public sealed class StoreOfferEffect
     public string RunId => _handle.RunId;
 
     /// <summary>Scenario id.</summary>
-    public string ScenarioId => _handle.ScenarioId;
+    public string ScenarioSlug => _handle.ScenarioSlug;
 
     /// <summary>Node id.</summary>
     public string NodeId => _handle.NodeId;
diff --git a/Services/Effects/WaitEffect.cs b/Services/Effects/WaitEffect.cs
index 28c7d57..6bf165d 100644
--- a/Services/Effects/WaitEffect.cs
+++ b/Services/Effects/WaitEffect.cs
@@ -18,7 +18,7 @@ public sealed class WaitEffect
     public string RunId => _handle.RunId;
 
     /// <summary>Scenario id.</summary>
-    public string ScenarioId => _handle.ScenarioId;
+    public string ScenarioSlug => _handle.ScenarioSlug;
 
     /// <summary>Node id.</summary>
     public string NodeId => _handle.NodeId;
diff --git a/Services/EffectsService.cs b/Services/EffectsService.cs
index dbb7f02..4cd0811 100644
--- a/Services/EffectsService.cs
+++ b/Services/EffectsService.cs
@@ -101,7 +101,7 @@ public sealed class EffectsService
                 var key = (effect.RunId, effect.NodeId);
                 if (_seen.ContainsKey(key))
                     continue;
-                _seen[key] = effect.ScenarioId;
+                _seen[key] = effect.ScenarioSlug;
 
                 if (string.Equals(effect.Type, EffectTypes.Wait, StringComparison.Ordinal))
                 {
@@ -126,7 +126,7 @@ public sealed class EffectsService
                 "/sdk/v1/scenarios/callback",
                 new HandleScenarioCallbackRequest
                 {
-                    ScenarioId = source.ScenarioId,
+                    ScenarioSlug = source.ScenarioSlug,
                     NodeId = source.NodeId,
                     Handle = handle,
                     RunId = source.RunId
@@ -136,13 +136,13 @@ public sealed class EffectsService
             ForgetWait(source.RunId, source.NodeId);
             var next = ReadEffect(response?.Effect);
             if (next == null)
-                Emit(OnScenarioCompleted, new ScenarioCompletedEffect(source.RunId, source.ScenarioId));
+                Emit(OnScenarioCompleted, new ScenarioCompletedEffect(source.RunId, source.ScenarioSlug));
             else
                 Ingest(new[] { next });
         }
         catch (Exception ex) when (IsDefinitiveRejection(ex))
         {
-            DropRun(source.RunId, source.ScenarioId, source.NodeId, ex);
+            DropRun(source.RunId, source.ScenarioSlug, source.NodeId, ex);
         }
     }
 
@@ -159,7 +159,7 @@ public sealed class EffectsService
                 "/sdk/v1/scenarios/counter",
                 new UpdateScenarioCounterRequest
                 {
-                    ScenarioId = source.ScenarioId,
+                    ScenarioSlug = source.ScenarioSlug,
                     NodeId = source.NodeId,
                     CounterKey = counterKey,
                     Amount = amount,
@@ -173,13 +173,13 @@ public sealed class EffectsService
             ForgetWait(source.RunId, source.NodeId);
             var next = ReadEffect(response.Effect);
             if (next == null)
-                Emit(OnScenarioCompleted, new ScenarioCompletedEffect(source.RunId, source.ScenarioId));
+                Emit(OnScenarioCompleted, new ScenarioCompletedEffect(source.RunId, source.ScenarioSlug));
             else
                 Ingest(new[] { next });
         }
         catch (Exception ex) when (IsDefinitiveRejection(ex))
         {
-            DropRun(source.RunId, source.ScenarioId, source.NodeId, ex);
+            DropRun(source.RunId, source.ScenarioSlug, source.NodeId, ex);
         }
         catch (Exception ex)
         {
@@ -274,14 +274,14 @@ public sealed class EffectsService
                     OnScenarioFailed,
                     new ScenarioFailedEffect(
                         effect.RunId,
-                        effect.ScenarioId,
+                        effect.ScenarioSlug,
                         effect.NodeId,
                         new Exception($"Unsupported scenario node type '{effect.Type}'")));
                 break;
         }
     }
 
-    private void DropRun(string runId, string scenarioId, string nodeId, Exception exception)
+    private void DropRun(string runId, string scenarioSlug, string nodeId, Exception exception)
     {
         lock (_gate)
         {
@@ -299,7 +299,7 @@ public sealed class EffectsService
             }
         }
 
-        Emit(OnScenarioFailed, new ScenarioFailedEffect(runId, scenarioId, nodeId, exception));
+        Emit(OnScenarioFailed, new ScenarioFailedEffect(runId, scenarioSlug, nodeId, exception));
     }
 
     private void Reconcile(IEnumerable<PendingEffect>? effects)
@@ -424,7 +424,7 @@ internal sealed class EffectHandle
 
     public string RunId => _effect.RunId;
 
-    public string ScenarioId => _effect.ScenarioId;
+    public string ScenarioSlug => _effect.ScenarioSlug;
 
     public string NodeId => _effect.NodeId;
 
diff --git a/Services/QuestMetrics.cs b/Services/QuestMetrics.cs
index c30ade5..ef7349d 100644
--- a/Services/QuestMetrics.cs
+++ b/Services/QuestMetrics.cs
@@ -9,7 +9,7 @@ namespace RudderSdk.Core;
 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}";
+    public static string PurchaseOffer(string offerSlug) => $"purchase.offer:{offerSlug}";
 
     /// <summary>Metric for purchasing a catalog item; auto-reported on purchase.</summary>
     public static string PurchaseItem(string itemId) => $"purchase.item:{itemId}";
diff --git a/Services/QuestsService.cs b/Services/QuestsService.cs
index 9fa6080..c89c991 100644
--- a/Services/QuestsService.cs
+++ b/Services/QuestsService.cs
@@ -27,11 +27,11 @@ public sealed class QuestsService
     }
 
     /// <summary>Claims a completed quest's rewards (idempotent server-side).</summary>
-    public Task<ClaimQuestResponse> ClaimAsync(string questId, CancellationToken cancellationToken = default)
+    public Task<ClaimQuestResponse> ClaimAsync(string questSlug, CancellationToken cancellationToken = default)
         => _client.SendAsync<ClaimQuestRequest, ClaimQuestResponse>(
             "POST",
             "/sdk/v1/quests/claim",
-            new ClaimQuestRequest { QuestId = questId },
+            new ClaimQuestRequest { QuestSlug = questSlug },
             cancellationToken);
 
     /// <summary>Reports progress for a metric and returns the ids of quests completed by this report.</summary>
@@ -43,6 +43,6 @@ public sealed class QuestsService
             new ReportQuestProgressRequest { Metric = metric, Amount = amount },
             cancellationToken).ConfigureAwait(false);
 
-        return response?.CompletedQuestIds ?? new List<string>();
+        return response?.CompletedQuestSlugs ?? new List<string>();
     }
 }
diff --git a/Services/StoresService.cs b/Services/StoresService.cs
index 0e366e7..93470f0 100644
--- a/Services/StoresService.cs
+++ b/Services/StoresService.cs
@@ -35,17 +35,17 @@ public sealed class StoresService
     /// </summary>
     public Task<PurchaseOfferResponse> PurchaseAsync(
         string storeSlug,
-        string offerId,
+        string offerSlug,
         string? idempotencyKey = null,
         CancellationToken cancellationToken = default)
     {
         return _client.SendAsync<PurchaseOfferRequest, PurchaseOfferResponse>(
             "POST",
-            "/sdk/v1/stores/" + Url.Encode(storeSlug) + "/offers/" + Url.Encode(offerId) + "/purchase",
+            "/sdk/v1/stores/" + Url.Encode(storeSlug) + "/offers/" + Url.Encode(offerSlug) + "/purchase",
             new PurchaseOfferRequest
             {
                 StoreSlug = storeSlug,
-                OfferId = offerId,
+                OfferSlug = offerSlug,
                 IdempotencyKey = idempotencyKey ?? Guid.NewGuid().ToString()
             },
             cancellationToken);
diff --git a/Stores/Offer.cs b/Stores/Offer.cs
index 5f9d9e3..dc616a1 100644
--- a/Stores/Offer.cs
+++ b/Stores/Offer.cs
@@ -25,6 +25,9 @@ public class Offer
     [JsonProperty("price")]
     public OfferPrice? Price { get; set; }
 
+    [JsonProperty("slug")]
+    public string? Slug { get; set; }
+
     [JsonProperty("updatedAt")]
     public DateTimeOffset? UpdatedAt { get; set; }
 
diff --git a/Stores/PurchaseOfferRequest.cs b/Stores/PurchaseOfferRequest.cs
index c72a45b..6d48627 100644
--- a/Stores/PurchaseOfferRequest.cs
+++ b/Stores/PurchaseOfferRequest.cs
@@ -8,8 +8,8 @@ public class PurchaseOfferRequest
     [JsonProperty("idempotencyKey")]
     public string? IdempotencyKey { get; set; }
 
-    [JsonProperty("offerId")]
-    public string? OfferId { get; set; }
+    [JsonProperty("offerSlug")]
+    public string? OfferSlug { get; set; }
 
     [JsonProperty("storeSlug")]
     public string? StoreSlug { get; set; }
diff --git a/skills/rudder-csharp-sdk/SKILL.md b/skills/rudder-csharp-sdk/SKILL.md
index 8fb22f1..ce85b65 100644
--- a/skills/rudder-csharp-sdk/SKILL.md
+++ b/skills/rudder-csharp-sdk/SKILL.md
@@ -82,7 +82,7 @@ realtime websocket client in Rudder.Core.
 Important cross-cutting facts:
 
 - Battle pass state is tied to a scenario battle-pass node: every
-  `BattlePassService` call carries `ScenarioId`/`NodeId` (mutations also
+  `BattlePassService` call carries `ScenarioSlug`/`NodeId` (mutations also
   `RunId`). During a scenario run, `BattlePassEffect` supplies them — prefer
   the effect API inside a run.
 - Global quests (`client.Quests`) are distinct from scenario quest nodes
diff --git a/skills/rudder-csharp-sdk/reference/auth.md b/skills/rudder-csharp-sdk/reference/auth.md
index d644b7a..99ece49 100644
--- a/skills/rudder-csharp-sdk/reference/auth.md
+++ b/skills/rudder-csharp-sdk/reference/auth.md
@@ -24,6 +24,19 @@ public void Logout();              // drops the stored session, fires SignedOut
 `RudderAuthState`: `SignedIn`, `SignedOut`. The event fires after a
 successful login and after logout or a failed token refresh.
 
+## Environments
+
+A project has two environments, `staging` and `prod`. The SDK key configured
+in `RudderClientOptions.ProjectKey` belongs to one of them, so the environment
+is resolved at login and carried inside the access and refresh tokens; nothing
+in the client API takes an environment argument, and a player created in one
+environment is invisible in the other. Content released only to `staging` is
+empty for a `prod` key and vice versa.
+
+Tokens issued before SDK 2.0.0 carry no environment claim and are rejected with
+401. The refresh pipeline then fails, clears the store and fires
+`AuthStateChanged(SignedOut)` — log the player in again.
+
 ## Endpoints
 
 - `POST /sdk/v1/authorization/device` — body `{key, deviceId, region,
diff --git a/skills/rudder-csharp-sdk/reference/battlepass.md b/skills/rudder-csharp-sdk/reference/battlepass.md
index ad6aa86..26fe69a 100644
--- a/skills/rudder-csharp-sdk/reference/battlepass.md
+++ b/skills/rudder-csharp-sdk/reference/battlepass.md
@@ -6,7 +6,7 @@ Source: `Services/BattlePassService.cs`,
 (generated DTOs).
 
 Battle pass state is tied to a scenario battle-pass node, so every call
-carries `ScenarioId`/`NodeId` (mutations also `RunId`). Inside a scenario run,
+carries `ScenarioSlug`/`NodeId` (mutations also `RunId`). Inside a scenario run,
 `Effects.OnBattlePass` hands you a `BattlePassEffect` that supplies these
 ids — prefer it over calling the service directly.
 
@@ -18,7 +18,7 @@ public const string TrackPremium = "premium";
 
 // POST /sdk/v1/battlepass/progress
 public Task<GetBattlePassProgressResponse> GetProgressAsync(
-    string scenarioId, string nodeId, CancellationToken cancellationToken = default);
+    string scenarioSlug, string nodeId, CancellationToken cancellationToken = default);
 
 // POST /sdk/v1/battlepass/xp
 public Task<AddBattlePassXpResponse> AddXpAsync(
@@ -40,7 +40,7 @@ public Task<PurchaseBattlePassPremiumResponse> PurchasePremiumAsync(
 public class GetBattlePassProgressRequest
 {
     public string? NodeId { get; set; }     // "nodeId"
-    public string? ScenarioId { get; set; } // "scenarioId"
+    public string? ScenarioSlug { get; set; } // "scenarioSlug"
 }
 
 public class AddBattlePassXpRequest
@@ -48,7 +48,7 @@ public class AddBattlePassXpRequest
     public long? Amount { get; set; }       // "amount"
     public string? NodeId { get; set; }     // "nodeId"
     public string? RunId { get; set; }      // "runId"
-    public string? ScenarioId { get; set; } // "scenarioId"
+    public string? ScenarioSlug { get; set; } // "scenarioSlug"
     public string? Source { get; set; }     // "source"
 }
 
@@ -57,7 +57,7 @@ public class ClaimBattlePassRewardRequest
     public int? Level { get; set; }         // "level"
     public string? NodeId { get; set; }     // "nodeId"
     public string? RunId { get; set; }      // "runId"
-    public string? ScenarioId { get; set; } // "scenarioId"
+    public string? ScenarioSlug { get; set; } // "scenarioSlug"
     public string? Track { get; set; }      // "track" — TrackFree / TrackPremium
 }
 
@@ -66,7 +66,7 @@ public class PurchaseBattlePassPremiumRequest
     public string? IdempotencyKey { get; set; } // "idempotencyKey"
     public string? NodeId { get; set; }         // "nodeId"
     public string? RunId { get; set; }          // "runId"
-    public string? ScenarioId { get; set; }     // "scenarioId"
+    public string? ScenarioSlug { get; set; }     // "scenarioSlug"
 }
 ```
 
@@ -116,7 +116,7 @@ Raised via `Effects.OnBattlePass`. Bound to the node's scenario/node/run ids:
 
 ```csharp
 public string RunId { get; }
-public string ScenarioId { get; }
+public string ScenarioSlug { get; }
 public string NodeId { get; }
 public T Get<T>(string key, T defaultValue = default!);
 
diff --git a/skills/rudder-csharp-sdk/reference/quests.md b/skills/rudder-csharp-sdk/reference/quests.md
index 0c4f767..4444f16 100644
--- a/skills/rudder-csharp-sdk/reference/quests.md
+++ b/skills/rudder-csharp-sdk/reference/quests.md
@@ -14,10 +14,10 @@ scenarios.md.
 public Task<IReadOnlyList<Quest>> ListAsync(CancellationToken cancellationToken = default);
 
 // POST /sdk/v1/quests/claim — claims a completed quest's rewards (idempotent server-side)
-public Task<ClaimQuestResponse> ClaimAsync(string questId, CancellationToken cancellationToken = default);
+public Task<ClaimQuestResponse> ClaimAsync(string questSlug, CancellationToken cancellationToken = default);
 
 // POST /sdk/v1/quests/progress — reports progress for a metric; returns the
-// ids of quests completed by THIS report
+// slugs of quests completed by THIS report
 public Task<IReadOnlyList<string>> ReportProgressAsync(
     string metric, long amount, CancellationToken cancellationToken = default);
 ```
@@ -27,7 +27,7 @@ public Task<IReadOnlyList<string>> ReportProgressAsync(
 ```csharp
 public static class QuestMetrics
 {
-    public static string PurchaseOffer(string offerId);  // "purchase.offer:{offerId}"
+    public static string PurchaseOffer(string offerSlug);  // "purchase.offer:{offerSlug}"
     public static string PurchaseItem(string itemId);    // "purchase.item:{itemId}"
 }
 ```
@@ -40,10 +40,10 @@ metric is a custom string passed to `ReportProgressAsync`.
 ```csharp
 public class Quest
 {
-    public string? Id { get; set; }                              // "id"
     public string? Name { get; set; }                            // "name"
     public List<QuestObjectiveProgress>? Objectives { get; set; }// "objectives"
     public List<Reward>? Rewards { get; set; }                   // "rewards"
+    public string? Slug { get; set; }                            // "slug" — stable across environments
     public string? Status { get; set; }                          // "status"
 }
 
diff --git a/skills/rudder-csharp-sdk/reference/scenarios.md b/skills/rudder-csharp-sdk/reference/scenarios.md
index 176e88a..4af909f 100644
--- a/skills/rudder-csharp-sdk/reference/scenarios.md
+++ b/skills/rudder-csharp-sdk/reference/scenarios.md
@@ -78,7 +78,7 @@ client.Effects.OnNotification += n =>
 await client.Scenario.TriggerAsync("level_complete");
 ```
 
-Every effect exposes `RunId`, `ScenarioId`, `NodeId`, `Data` (`JObject`),
+Every effect exposes `RunId`, `ScenarioSlug`, `NodeId`, `Data` (`JObject`),
 and `Get<T>(key, defaultValue)` for reading node data. Completion methods
 have an `Async` variant (awaitable) and a fire-and-forget variant.
 
@@ -156,7 +156,7 @@ Scenario quest node — distinct from global `client.Quests`.
 public string Name { get; }                         // node data "name"
 public IReadOnlyList<JObject> Objectives { get; }   // node data "objectives"
 
-// POST /sdk/v1/scenarios/counter  {scenarioId, nodeId, runId, counterKey, amount}
+// POST /sdk/v1/scenarios/counter  {scenarioSlug, nodeId, runId, counterKey, amount}
 public Task ReportProgressAsync(string objectiveId, long amount = 1, CancellationToken ct = default);
 public void ReportProgress(string objectiveId, long amount = 1);
 ```
@@ -166,7 +166,7 @@ completed counter response may carry the next `PendingEffect`.
 
 ### `BattlePassEffect`
 
-Bound to this node's `ScenarioId` / `NodeId` / `RunId` — prefer these over
+Bound to this node's `ScenarioSlug` / `NodeId` / `RunId` — prefer these over
 calling `client.BattlePass` by hand. See also reference/battlepass.md.
 
 ```csharp
@@ -199,13 +199,13 @@ configured level.
 public sealed class ScenarioCompletedEffect
 {
     public string RunId { get; }
-    public string ScenarioId { get; }
+    public string ScenarioSlug { get; }
 }
 
 public sealed class ScenarioFailedEffect
 {
     public string RunId { get; }
-    public string ScenarioId { get; }
+    public string ScenarioSlug { get; }
     public string NodeId { get; }
     public Exception Exception { get; }
 }
@@ -219,7 +219,7 @@ advanced a wait, the run expired, or another device completed it.
 ## Reliability
 
 - Completion methods POST `/sdk/v1/scenarios/callback` with
-  `{scenarioId, runId, nodeId, handle}` using the handles `output`,
+  `{scenarioSlug, runId, nodeId, handle}` using the handles `output`,
   `onPurchase`, `onDecline`, `onEnd`, `onClaim`, `onComplete`, `onLevelUp`,
   `onPremiumPurchase`. A non-null `effect` in the response is ingested as
   the next node; a null/missing effect completes the run.
@@ -243,7 +243,7 @@ public class PendingEffect
     public JToken Data { get; set; }
     public string NodeId { get; set; }
     public string RunId { get; set; }
-    public string ScenarioId { get; set; }
+    public string ScenarioSlug { get; set; }
     public string Type { get; set; }
     public DateTimeOffset? WaitDeadline { get; set; }
 }
@@ -257,7 +257,7 @@ public class HandleScenarioCallbackRequest
     public string? Handle { get; set; }
     public string? NodeId { get; set; }
     public string? RunId { get; set; }
-    public string? ScenarioId { get; set; }
+    public string? ScenarioSlug { get; set; }
 }
 public class HandleScenarioCallbackResponse { public JToken? Effect { get; set; } }
 
@@ -267,7 +267,7 @@ public class UpdateScenarioCounterRequest
     public string? CounterKey { get; set; }
     public string? NodeId { get; set; }
     public string? RunId { get; set; }
-    public string? ScenarioId { get; set; }
+    public string? ScenarioSlug { get; set; }
 }
 public class UpdateScenarioCounterResponse
 {
diff --git a/skills/rudder-csharp-sdk/reference/stores.md b/skills/rudder-csharp-sdk/reference/stores.md
index 7f175b1..3fbed95 100644
--- a/skills/rudder-csharp-sdk/reference/stores.md
+++ b/skills/rudder-csharp-sdk/reference/stores.md
@@ -14,11 +14,11 @@ public Task<IReadOnlyList<Store>> ListAsync(CancellationToken cancellationToken
 // GET /sdk/v1/stores/{slug}
 public Task<Store> GetAsync(string slug, CancellationToken cancellationToken = default);
 
-// POST /sdk/v1/stores/{storeSlug}/offers/{offerId}/purchase
+// POST /sdk/v1/stores/{storeSlug}/offers/{offerSlug}/purchase
 // When idempotencyKey is null a random GUID is generated; pass a stable key to
 // make retries safe.
 public Task<PurchaseOfferResponse> PurchaseAsync(
-    string storeSlug, string offerId, string? idempotencyKey = null,
+    string storeSlug, string offerSlug, string? idempotencyKey = null,
     CancellationToken cancellationToken = default);
 ```
 
@@ -44,6 +44,7 @@ public class Store
 public class Offer
 {
     public string? Id { get; set; }                  // "id"
+    public string? Slug { get; set; }                // "slug" — stable across environments
     public string? Name { get; set; }                // "name"
     public OfferPrice? Price { get; set; }           // "price"
     public List<OfferContent>? Contents { get; set; }// "contents"
@@ -65,5 +66,5 @@ public class PurchaseOfferResponse
 
 `PurchaseOfferResponse.Error` carries a business error string when
 `Success` is false — check the flag instead of relying on exceptions alone.
-Purchases also auto-report quest metrics (`purchase.offer:{offerId}`) — see
+Purchases also auto-report quest metrics (`purchase.offer:{offerSlug}`) — see
 quests.md.
diff --git a/tests/Rudder.Core.Tests/ScenarioServiceTests.cs b/tests/Rudder.Core.Tests/ScenarioServiceTests.cs
index 094e632..3a75a82 100644
--- a/tests/Rudder.Core.Tests/ScenarioServiceTests.cs
+++ b/tests/Rudder.Core.Tests/ScenarioServiceTests.cs
@@ -103,7 +103,7 @@ public sealed class ScenarioServiceTests
 
         Assert.NotNull(completed);
         Assert.Equal("run-1", completed!.RunId);
-        Assert.Equal("scenario-1", completed.ScenarioId);
+        Assert.Equal("scenario-1", completed.ScenarioSlug);
     }
 
     [Fact]
@@ -522,7 +522,7 @@ public sealed class ScenarioServiceTests
         return new PendingEffect
         {
             RunId = runId,
-            ScenarioId = "scenario-1",
+            ScenarioSlug = "scenario-1",
             NodeId = nodeId,
             Type = type,
             Data = data == null ? new JObject() : JObject.FromObject(data),