NEO-32: prune expired cooldown entries on TryGetCooldownEndUtc

bruno/neon-sprawl-server/cooldown-snapshot/Get cooldown snapshot.bru

@@ -4,6 +4,10 @@ meta {
   seq: 1
 }
 
+docs {
+  NEO-32: expired slot entries are pruned when building the snapshot (server-side store hygiene).
+}
+
 get {
   url: {{baseUrl}}/game/players/dev-local-1/cooldown-snapshot
   body: none

docs/reviews/2026-04-30-NEO-32.md

@@ -35,7 +35,7 @@ The branch delivers the planned NEO-32 slice: authoritative in-memory per-player
 
 1. **C# AAA layout on new integration tests** — `CooldownSnapshotApiTests.GetCooldownSnapshot_ShouldExposeSlotEnd_WhenCastAccepted_ThenClear_WhenAdvancedPastDuration` and the two new cooldown tests in `AbilityCastApiTests` bundle HTTP calls and `FakeClock.Advance` inside a single `// Act` block. Per [csharp-style](.cursor/rules/csharp-style.md#unit-and-integration-tests-arrange-act-assert), split so **Act** is only the invocations under assertion (or use clearly separated Act steps per phase) and keep clock advances in Arrange or interleaved with labeled sections. Low priority but keeps CI lint/review consistency for future edits.
 
-2. **Stale cooldown entries in the in-memory store** — `TryGetCooldownEndUtc` does not prune expired ends; `BuildSnapshot` omits them from JSON, so wire behavior is correct. Expired rows linger until `IsOnCooldown` runs (e.g. next cast to that slot). For a long-lived prototype process this is negligible; if you ever extend GET-heavy paths, consider pruning in `TryGetCooldownEndUtc` or snapshot build for symmetry with `IsOnCooldown`.
+2. ~~**Stale cooldown entries in the in-memory store** — `TryGetCooldownEndUtc` does not prune expired ends; `BuildSnapshot` omits them from JSON, so wire behavior is correct. Expired rows linger until `IsOnCooldown` runs (e.g. next cast to that slot). For a long-lived prototype process this is negligible; if you ever extend GET-heavy paths, consider pruning in `TryGetCooldownEndUtc` or snapshot build for symmetry with `IsOnCooldown`.~~ **Done.** `TryGetCooldownEndUtc` now takes `DateTimeOffset now` and shares pruning with `IsOnCooldown`; `InMemoryPlayerAbilityCooldownStoreTests` covers prune-on-read.
 
 ## Nits
 

server/NeonSprawl.Server.Tests/Game/AbilityInput/InMemoryPlayerAbilityCooldownStoreTests.cs

@@ -0,0 +1,41 @@
+using NeonSprawl.Server.Game.AbilityInput;
+using Xunit;
+
+namespace NeonSprawl.Server.Tests.Game.AbilityInput;
+
+public sealed class InMemoryPlayerAbilityCooldownStoreTests
+{
+    [Fact]
+    public void TryGetCooldownEndUtc_ShouldReturnEnd_WhenNowBeforeCooldownEnd()
+    {
+        // Arrange
+        var store = new InMemoryPlayerAbilityCooldownStore();
+        var t0 = new DateTimeOffset(2026, 4, 30, 12, 0, 0, TimeSpan.Zero);
+        store.StartCooldown("p1", 2, t0, TimeSpan.FromSeconds(3));
+
+        // Act
+        var has = store.TryGetCooldownEndUtc("p1", 2, t0 + TimeSpan.FromSeconds(1), out var endUtc);
+
+        // Assert
+        Assert.True(has);
+        Assert.Equal(t0 + TimeSpan.FromSeconds(3), endUtc);
+    }
+
+    [Fact]
+    public void TryGetCooldownEndUtc_ShouldPruneAndReturnFalse_WhenNowAtOrAfterEnd()
+    {
+        // Arrange
+        var store = new InMemoryPlayerAbilityCooldownStore();
+        var t0 = new DateTimeOffset(2026, 4, 30, 12, 0, 0, TimeSpan.Zero);
+        store.StartCooldown("p1", 0, t0, TimeSpan.FromSeconds(3));
+        var after = t0 + TimeSpan.FromSeconds(5);
+
+        // Act
+        var pruned = store.TryGetCooldownEndUtc("p1", 0, after, out _);
+        var second = store.TryGetCooldownEndUtc("p1", 0, after, out _);
+
+        // Assert
+        Assert.False(pruned);
+        Assert.False(second);
+    }
+}

server/NeonSprawl.Server/Game/AbilityInput/CooldownSnapshotApi.cs

@@ -32,7 +32,7 @@ public static class CooldownSnapshotApi
         for (var i = 0; i < HotbarLoadoutResponse.SlotCountV1; i++)
         {
             DateTimeOffset? end = null;
-            if (cooldowns.TryGetCooldownEndUtc(playerId, i, out var endUtc) && endUtc > now)
+            if (cooldowns.TryGetCooldownEndUtc(playerId, i, now, out var endUtc))
             {
                 end = endUtc;
             }

server/NeonSprawl.Server/Game/AbilityInput/IPlayerAbilityCooldownStore.cs

@@ -9,6 +9,6 @@ public interface IPlayerAbilityCooldownStore
     /// <summary>Sets cooldown end for a slot to <paramref name="now"/> + <paramref name="duration"/>.</summary>
     void StartCooldown(string playerId, int slotIndex, DateTimeOffset now, TimeSpan duration);
 
-    /// <summary>Gets stored end instant for the slot when an entry exists (may be in the past).</summary>
-    bool TryGetCooldownEndUtc(string playerId, int slotIndex, out DateTimeOffset endUtc);
+    /// <summary>Gets active cooldown end when <paramref name="now"/> is strictly before that end; removes expired entries (same hygiene as <see cref="IsOnCooldown"/>).</summary>
+    bool TryGetCooldownEndUtc(string playerId, int slotIndex, DateTimeOffset now, out DateTimeOffset endUtc);
 }

server/NeonSprawl.Server/Game/AbilityInput/InMemoryPlayerAbilityCooldownStore.cs

@@ -9,6 +9,29 @@ public sealed class InMemoryPlayerAbilityCooldownStore : IPlayerAbilityCooldownS
 
     public bool IsOnCooldown(string playerId, int slotIndex, DateTimeOffset now)
     {
+        return TryGetActiveCooldownEnd(playerId, slotIndex, now, out _);
+    }
+
+    public void StartCooldown(string playerId, int slotIndex, DateTimeOffset now, TimeSpan duration)
+    {
+        var perSlot = ends.GetOrAdd(playerId, _ => new ConcurrentDictionary<int, DateTimeOffset>());
+        perSlot[slotIndex] = now + duration;
+    }
+
+    public bool TryGetCooldownEndUtc(string playerId, int slotIndex, DateTimeOffset now, out DateTimeOffset endUtc)
+    {
+        return TryGetActiveCooldownEnd(playerId, slotIndex, now, out endUtc);
+    }
+
+    /// <summary>Shared read path: returns true with <paramref name="endUtc"/> when cooldown is active; removes slot entry when <paramref name="now"/> &gt;= stored end.</summary>
+    private static bool TryGetActiveCooldownEnd(
+        ConcurrentDictionary<string, ConcurrentDictionary<int, DateTimeOffset>> ends,
+        string playerId,
+        int slotIndex,
+        DateTimeOffset now,
+        out DateTimeOffset endUtc)
+    {
+        endUtc = default;
         if (!ends.TryGetValue(playerId, out var perSlot))
         {
             return false;
@@ -25,23 +48,12 @@ public sealed class InMemoryPlayerAbilityCooldownStore : IPlayerAbilityCooldownS
             return false;
         }
 
+        endUtc = end;
         return true;
     }
 
-    public void StartCooldown(string playerId, int slotIndex, DateTimeOffset now, TimeSpan duration)
+    private bool TryGetActiveCooldownEnd(string playerId, int slotIndex, DateTimeOffset now, out DateTimeOffset endUtc)
     {
-        var perSlot = ends.GetOrAdd(playerId, _ => new ConcurrentDictionary<int, DateTimeOffset>());
-        perSlot[slotIndex] = now + duration;
-    }
-
-    public bool TryGetCooldownEndUtc(string playerId, int slotIndex, out DateTimeOffset endUtc)
-    {
-        endUtc = default;
-        if (!ends.TryGetValue(playerId, out var perSlot))
-        {
-            return false;
-        }
-
-        return perSlot.TryGetValue(slotIndex, out endUtc);
+        return TryGetActiveCooldownEnd(ends, playerId, slotIndex, now, out endUtc);
     }
 }