NEO-146: fix in-memory create/complete lock ordering

Nest player and instance locks in TryCreateActive, TryMarkComplete, and
TryClearInstance so concurrent create and complete cannot leave a stale
active index or mismatched snapshot.

docs/plans/NEO-146-implementation-plan.md

@@ -68,7 +68,7 @@ Durable per-player **`ContractInstance`** rows (active/completed) and append-onl
 - **Types:** `ContractInstanceStatus`, `ContractInstanceState`, `ContractInstanceIds`, `ContractInstanceReasonCodes`, `ContractOutcomeRow`, `ContractOutcomeIds`.
 - **Stores:** `IContractInstanceStore` / `IContractOutcomeStore`; in-memory + Postgres (`V011`, `V012`) when connection string set; partial unique index + app-level one-active enforcement.
 - **DI:** `AddContractInstanceStores` in `Program.cs`; in-memory override in `InMemoryWebApplicationFactory`.
-- **Tests:** `InMemoryContractInstanceStoreTests`, `InMemoryContractOutcomeStoreTests`, Postgres persistence integration tests; host DI smoke (`871` tests green).
+- **Tests:** `InMemoryContractInstanceStoreTests`, `InMemoryContractOutcomeStoreTests`, Postgres persistence integration tests; host DI smoke (`872` tests green).
 - **In-memory outcome guard:** `InMemoryContractOutcomeStore.TryAppend` denies when **`IContractInstanceStore.TryGet`** is false (Postgres FK + player/instance SQL guard parity).
 - **Docs:** `server/README.md` contract instance + outcome store sections.
 - **Bruno:** `bruno/neon-sprawl-server/contract-stores/` health smoke (startup-only; no contract HTTP in E7M4-03).

server/NeonSprawl.Server.Tests/Game/Contracts/InMemoryContractInstanceStoreTests.cs

@@ -227,6 +227,44 @@ public sealed class InMemoryContractInstanceStoreTests
         Assert.False(created);
     }
 
+    [Fact]
+    public async Task TryCreateActiveAndTryMarkComplete_ShouldKeepActiveIndexConsistent_WhenRacingOnSameInstanceId()
+    {
+        // Arrange
+        var store = CreateStore();
+        // Act
+        await Task.WhenAll(
+            Enumerable.Range(0, 32).Select(i => Task.Run(() =>
+            {
+                if (i % 2 == 0)
+                {
+                    _ = store.TryCreateActive(
+                        PlayerId,
+                        InstanceId,
+                        TemplateId,
+                        SeedBucket,
+                        IssuedAt,
+                        out _);
+                    return;
+                }
+
+                _ = store.TryMarkComplete(PlayerId, InstanceId, CompletedAt, out _);
+            })));
+
+        // Assert
+        if (store.TryGetActiveForPlayer(PlayerId, out var active))
+        {
+            Assert.True(store.TryGet(PlayerId, active.ContractInstanceId, out var row));
+            Assert.Equal(ContractInstanceStatus.Active, row.Status);
+        }
+
+        if (store.TryGet(PlayerId, InstanceId, out var final) &&
+            final.Status == ContractInstanceStatus.Completed)
+        {
+            Assert.False(store.TryGetActiveForPlayer(PlayerId, out _));
+        }
+    }
+
     [Fact]
     public async Task Host_ShouldResolveContractInstanceStoresFromDi()
     {

server/NeonSprawl.Server/Game/Contracts/InMemoryContractInstanceStore.cs

@@ -153,36 +153,39 @@ public sealed class InMemoryContractInstanceStore(IOptions<GamePositionOptions>
 
         lock (instanceLocks.GetOrAdd(PlayerLockKey(player), _ => new object()))
         {
-            if (activeInstanceByPlayer.TryGetValue(player, out var existingActiveId))
+            lock (instanceLocks.GetOrAdd(ContractInstanceIds.MakeInstanceKey(player, instanceId), _ => new object()))
             {
-                if (byInstanceId.TryGetValue(existingActiveId, out var existingActive) &&
-                    existingActive.Status == ContractInstanceStatus.Active)
+                if (activeInstanceByPlayer.TryGetValue(player, out var existingActiveId))
                 {
-                    snapshot = existingActive.ToSnapshot();
+                    if (byInstanceId.TryGetValue(existingActiveId, out var existingActive) &&
+                        existingActive.Status == ContractInstanceStatus.Active)
+                    {
+                        snapshot = existingActive.ToSnapshot();
+                        return false;
+                    }
+
+                    activeInstanceByPlayer.TryRemove(player, out _);
+                }
+
+                if (byInstanceId.TryGetValue(instanceId, out var existing))
+                {
+                    snapshot = existing.ToSnapshot();
                     return false;
                 }
 
-                activeInstanceByPlayer.TryRemove(player, out _);
+                var row = new InstanceRow(
+                    instanceId,
+                    normalizedTemplateId,
+                    player,
+                    ContractInstanceStatus.Active,
+                    normalizedSeedBucket,
+                    issuedAt,
+                    null);
+                byInstanceId[instanceId] = row;
+                activeInstanceByPlayer[player] = instanceId;
+                snapshot = row.ToSnapshot();
+                return true;
             }
-
-            if (byInstanceId.TryGetValue(instanceId, out var existing))
-            {
-                snapshot = existing.ToSnapshot();
-                return false;
-            }
-
-            var row = new InstanceRow(
-                instanceId,
-                normalizedTemplateId,
-                player,
-                ContractInstanceStatus.Active,
-                normalizedSeedBucket,
-                issuedAt,
-                null);
-            byInstanceId[instanceId] = row;
-            activeInstanceByPlayer[player] = instanceId;
-            snapshot = row.ToSnapshot();
-            return true;
         }
     }
 
@@ -207,30 +210,33 @@ public sealed class InMemoryContractInstanceStore(IOptions<GamePositionOptions>
             return false;
         }
 
-        lock (instanceLocks.GetOrAdd(lockKey, _ => new object()))
+        lock (instanceLocks.GetOrAdd(PlayerLockKey(player), _ => new object()))
         {
-            if (!byInstanceId.TryGetValue(instanceId, out var row) ||
-                !string.Equals(row.PlayerId, player, StringComparison.Ordinal))
+            lock (instanceLocks.GetOrAdd(lockKey, _ => new object()))
             {
-                return false;
-            }
+                if (!byInstanceId.TryGetValue(instanceId, out var row) ||
+                    !string.Equals(row.PlayerId, player, StringComparison.Ordinal))
+                {
+                    return false;
+                }
 
-            if (row.Status == ContractInstanceStatus.Completed)
-            {
+                if (row.Status == ContractInstanceStatus.Completed)
+                {
+                    snapshot = row.ToSnapshot();
+                    return false;
+                }
+
+                if (row.Status != ContractInstanceStatus.Active)
+                {
+                    snapshot = row.ToSnapshot();
+                    return false;
+                }
+
+                row.MarkCompleted(completedAt);
+                activeInstanceByPlayer.TryRemove(player, out _);
                 snapshot = row.ToSnapshot();
-                return false;
+                return true;
             }
-
-            if (row.Status != ContractInstanceStatus.Active)
-            {
-                snapshot = row.ToSnapshot();
-                return false;
-            }
-
-            row.MarkCompleted(completedAt);
-            activeInstanceByPlayer.TryRemove(player, out _);
-            snapshot = row.ToSnapshot();
-            return true;
         }
     }
 
@@ -250,21 +256,24 @@ public sealed class InMemoryContractInstanceStore(IOptions<GamePositionOptions>
             return false;
         }
 
-        lock (instanceLocks.GetOrAdd(lockKey, _ => new object()))
+        lock (instanceLocks.GetOrAdd(PlayerLockKey(player), _ => new object()))
         {
-            if (!byInstanceId.TryGetValue(instanceId, out var row) ||
-                !string.Equals(row.PlayerId, player, StringComparison.Ordinal))
+            lock (instanceLocks.GetOrAdd(lockKey, _ => new object()))
             {
-                return false;
-            }
+                if (!byInstanceId.TryGetValue(instanceId, out var row) ||
+                    !string.Equals(row.PlayerId, player, StringComparison.Ordinal))
+                {
+                    return false;
+                }
 
-            _ = byInstanceId.TryRemove(instanceId, out _);
-            if (row.Status == ContractInstanceStatus.Active)
-            {
-                activeInstanceByPlayer.TryRemove(player, out _);
-            }
+                _ = byInstanceId.TryRemove(instanceId, out _);
+                if (row.Status == ContractInstanceStatus.Active)
+                {
+                    activeInstanceByPlayer.TryRemove(player, out _);
+                }
 
-            return true;
+                return true;
+            }
         }
     }
 }