NEO-95: add player combat HP store and NPC attack resolve

Wire telegraph-complete damage into AdvanceAll and expose GET
/game/players/{id}/combat-health for session player HP read model.

server/NeonSprawl.Server/Game/Combat/CombatTargetFixtureApi.cs

@@ -1,4 +1,6 @@
+using Microsoft.Extensions.Options;
 using NeonSprawl.Server.Game.Npc;
+using NeonSprawl.Server.Game.PositionState;
 
 namespace NeonSprawl.Server.Game.Combat;
 
@@ -9,7 +11,13 @@ public static class CombatTargetFixtureApi
     {
         app.MapPost(
             "/game/__dev/combat-targets-fixture",
-            (CombatTargetFixtureRequest? body, ICombatEntityHealthStore healthStore, IThreatStateStore threatStore, INpcRuntimeStateStore runtimeStore) =>
+            (
+                CombatTargetFixtureRequest? body,
+                ICombatEntityHealthStore healthStore,
+                IThreatStateStore threatStore,
+                INpcRuntimeStateStore runtimeStore,
+                IPlayerCombatHealthStore playerHealthStore,
+                IOptions<GamePositionOptions> gameOptions) =>
             {
                 if (body is null || body.SchemaVersion != CombatTargetFixtureRequest.CurrentSchemaVersion)
                 {
@@ -27,6 +35,12 @@ public static class CombatTargetFixtureApi
                 AggroOperations.ClearAllPrototypeHolders(threatStore);
                 NpcRuntimeOperations.ResetAllPrototypeRows(runtimeStore);
 
+                var devPlayerId = gameOptions.Value.DevPlayerId;
+                if (!playerHealthStore.TryResetToFull(devPlayerId, out _))
+                {
+                    return Results.NotFound();
+                }
+
                 return Results.Json(
                     new CombatTargetFixtureResponse
                     {

server/NeonSprawl.Server/Game/Combat/IPlayerCombatHealthStore.cs

@@ -0,0 +1,25 @@
+namespace NeonSprawl.Server.Game.Combat;
+
+/// <summary>
+/// Session in-memory player combat HP for incoming NPC damage (NEO-95).
+/// No Postgres persistence in Epic 5 Slice 2.
+/// </summary>
+public interface IPlayerCombatHealthStore
+{
+    /// <summary>
+    /// Reads the current snapshot for a player. Lazy-initializes HP to
+    /// <see cref="PlayerCombatHealthDefaults.MaxHp"/> on first access.
+    /// </summary>
+    bool TryGet(string? playerId, out PlayerCombatHealthSnapshot snapshot);
+
+    /// <summary>
+    /// Applies non-negative NPC attack damage. Lazy-initializes on first access.
+    /// Floors <see cref="PlayerCombatHealthSnapshot.CurrentHp"/> at zero.
+    /// </summary>
+    bool TryApplyDamage(string? playerId, int damage, out PlayerCombatHealthSnapshot snapshot);
+
+    /// <summary>
+    /// Restores a player to full HP. Creates the row when absent (dev fixture + tests).
+    /// </summary>
+    bool TryResetToFull(string? playerId, out PlayerCombatHealthSnapshot snapshot);
+}

server/NeonSprawl.Server/Game/Combat/InMemoryPlayerCombatHealthStore.cs

@@ -0,0 +1,91 @@
+using System.Collections.Concurrent;
+
+namespace NeonSprawl.Server.Game.Combat;
+
+/// <summary>Thread-safe in-memory session player combat HP; empty at startup — lazy rows only (NEO-95).</summary>
+public sealed class InMemoryPlayerCombatHealthStore : IPlayerCombatHealthStore
+{
+    private readonly ConcurrentDictionary<string, int> currentHpById = new(StringComparer.Ordinal);
+
+    private readonly ConcurrentDictionary<string, object> idLocks = new(StringComparer.Ordinal);
+
+    /// <inheritdoc />
+    public bool TryGet(string? playerId, out PlayerCombatHealthSnapshot snapshot)
+    {
+        var key = NormalizePlayerId(playerId);
+        if (key.Length == 0)
+        {
+            snapshot = default;
+            return false;
+        }
+
+        lock (idLocks.GetOrAdd(key, _ => new object()))
+        {
+            EnsureRowInitialized(key);
+            snapshot = CreateSnapshot(key, currentHpById[key]);
+            return true;
+        }
+    }
+
+    /// <inheritdoc />
+    public bool TryApplyDamage(string? playerId, int damage, out PlayerCombatHealthSnapshot snapshot)
+    {
+        snapshot = default;
+        if (damage < 0)
+        {
+            return false;
+        }
+
+        var key = NormalizePlayerId(playerId);
+        if (key.Length == 0)
+        {
+            return false;
+        }
+
+        lock (idLocks.GetOrAdd(key, _ => new object()))
+        {
+            EnsureRowInitialized(key);
+            var current = currentHpById[key];
+            var next = Math.Max(0, current - damage);
+            currentHpById[key] = next;
+            snapshot = CreateSnapshot(key, next);
+            return true;
+        }
+    }
+
+    /// <inheritdoc />
+    public bool TryResetToFull(string? playerId, out PlayerCombatHealthSnapshot snapshot)
+    {
+        var key = NormalizePlayerId(playerId);
+        if (key.Length == 0)
+        {
+            snapshot = default;
+            return false;
+        }
+
+        lock (idLocks.GetOrAdd(key, _ => new object()))
+        {
+            currentHpById[key] = PlayerCombatHealthDefaults.MaxHp;
+            snapshot = CreateSnapshot(key, PlayerCombatHealthDefaults.MaxHp);
+            return true;
+        }
+    }
+
+    private void EnsureRowInitialized(string normalizedId)
+    {
+        if (!currentHpById.ContainsKey(normalizedId))
+        {
+            currentHpById[normalizedId] = PlayerCombatHealthDefaults.MaxHp;
+        }
+    }
+
+    private static PlayerCombatHealthSnapshot CreateSnapshot(string playerId, int currentHp) =>
+        new(
+            playerId,
+            PlayerCombatHealthDefaults.MaxHp,
+            currentHp,
+            currentHp <= 0);
+
+    private static string NormalizePlayerId(string? playerId) =>
+        playerId?.Trim().ToLowerInvariant() ?? string.Empty;
+}

server/NeonSprawl.Server/Game/Combat/NpcAttackOperations.cs

@@ -0,0 +1,44 @@
+using NeonSprawl.Server.Game.Npc;
+
+namespace NeonSprawl.Server.Game.Combat;
+
+/// <summary>Deterministic NPC telegraph-complete damage resolve (NEO-95).</summary>
+public static class NpcAttackOperations
+{
+    /// <summary>
+    /// Applies catalog <paramref name="attackDamage"/> to <paramref name="holderPlayerId"/> when
+    /// the threat row still names that holder for <paramref name="npcInstanceId"/>.
+    /// </summary>
+    public static bool TryResolveTelegraphComplete(
+        string npcInstanceId,
+        string holderPlayerId,
+        int attackDamage,
+        IPlayerCombatHealthStore playerHealthStore,
+        IThreatStateStore threatStore)
+    {
+        if (attackDamage <= 0)
+        {
+            return true;
+        }
+
+        if (string.IsNullOrWhiteSpace(holderPlayerId) ||
+            !threatStore.TryGet(npcInstanceId, out var threat) ||
+            string.IsNullOrEmpty(threat.AggroHolderPlayerId) ||
+            !string.Equals(threat.AggroHolderPlayerId, holderPlayerId, StringComparison.Ordinal))
+        {
+            return false;
+        }
+
+        if (!playerHealthStore.TryApplyDamage(holderPlayerId, attackDamage, out var snapshot))
+        {
+            return false;
+        }
+
+        if (snapshot.Defeated)
+        {
+            // TODO(E9.M1): player_death
+        }
+
+        return true;
+    }
+}

server/NeonSprawl.Server/Game/Combat/PlayerCombatHealthApi.cs

@@ -0,0 +1,38 @@
+using NeonSprawl.Server.Game.PositionState;
+
+namespace NeonSprawl.Server.Game.Combat;
+
+/// <summary>Maps <c>GET /game/players/{id}/combat-health</c> (NEO-95).</summary>
+public static class PlayerCombatHealthApi
+{
+    public static WebApplication MapPlayerCombatHealthApi(this WebApplication app)
+    {
+        app.MapGet(
+            "/game/players/{id}/combat-health",
+            (string id, IPositionStateStore positions, IPlayerCombatHealthStore playerHealthStore) =>
+            {
+                if (!positions.TryGetPosition(id, out _))
+                {
+                    return Results.NotFound();
+                }
+
+                if (!playerHealthStore.TryGet(id, out var snapshot))
+                {
+                    return Results.NotFound();
+                }
+
+                return Results.Json(BuildResponse(snapshot));
+            });
+
+        return app;
+    }
+
+    internal static PlayerCombatHealthResponse BuildResponse(in PlayerCombatHealthSnapshot snapshot) =>
+        new()
+        {
+            PlayerId = snapshot.PlayerId,
+            MaxHp = snapshot.MaxHp,
+            CurrentHp = snapshot.CurrentHp,
+            Defeated = snapshot.Defeated,
+        };
+}

server/NeonSprawl.Server/Game/Combat/PlayerCombatHealthDefaults.cs

@@ -0,0 +1,8 @@
+namespace NeonSprawl.Server.Game.Combat;
+
+/// <summary>Prototype session player combat HP defaults (E5M2-09 / NEO-95).</summary>
+public static class PlayerCombatHealthDefaults
+{
+    /// <summary>Lazy-init max HP for session player combat rows.</summary>
+    public const int MaxHp = 100;
+}

server/NeonSprawl.Server/Game/Combat/PlayerCombatHealthDtos.cs

@@ -0,0 +1,24 @@
+using System.Text.Json.Serialization;
+
+namespace NeonSprawl.Server.Game.Combat;
+
+/// <summary>JSON body for <c>GET /game/players/{id}/combat-health</c> (NEO-95).</summary>
+public sealed class PlayerCombatHealthResponse
+{
+    public const int CurrentSchemaVersion = 1;
+
+    [JsonPropertyName("schemaVersion")]
+    public int SchemaVersion { get; init; } = CurrentSchemaVersion;
+
+    [JsonPropertyName("playerId")]
+    public required string PlayerId { get; init; }
+
+    [JsonPropertyName("maxHp")]
+    public required int MaxHp { get; init; }
+
+    [JsonPropertyName("currentHp")]
+    public required int CurrentHp { get; init; }
+
+    [JsonPropertyName("defeated")]
+    public required bool Defeated { get; init; }
+}

server/NeonSprawl.Server/Game/Combat/PlayerCombatHealthServiceCollectionExtensions.cs

@@ -0,0 +1,12 @@
+namespace NeonSprawl.Server.Game.Combat;
+
+/// <summary>Registers session player combat health store (NEO-95).</summary>
+public static class PlayerCombatHealthServiceCollectionExtensions
+{
+    /// <summary>Registers <see cref="IPlayerCombatHealthStore"/> as an in-memory singleton.</summary>
+    public static IServiceCollection AddPlayerCombatHealthStore(this IServiceCollection services)
+    {
+        services.AddSingleton<IPlayerCombatHealthStore, InMemoryPlayerCombatHealthStore>();
+        return services;
+    }
+}

server/NeonSprawl.Server/Game/Combat/PlayerCombatHealthSnapshot.cs

@@ -0,0 +1,12 @@
+namespace NeonSprawl.Server.Game.Combat;
+
+/// <summary>Authoritative HP snapshot for a session player (NEO-95).</summary>
+/// <param name="PlayerId">Normalized lowercase player id.</param>
+/// <param name="MaxHp">Prototype session max HP.</param>
+/// <param name="CurrentHp">Current HP after NPC damage; floored at zero.</param>
+/// <param name="Defeated"><c>true</c> when <paramref name="CurrentHp"/> is zero.</param>
+public readonly record struct PlayerCombatHealthSnapshot(
+    string PlayerId,
+    int MaxHp,
+    int CurrentHp,
+    bool Defeated);

server/NeonSprawl.Server/Game/Npc/NpcRuntimeOperations.cs

@@ -1,3 +1,5 @@
+using NeonSprawl.Server.Game.Combat;
+
 namespace NeonSprawl.Server.Game.Npc;
 
 /// <summary>Deterministic prototype NPC behavior state machine + lazy tick advance (NEO-93).</summary>
@@ -14,6 +16,7 @@ public static class NpcRuntimeOperations
         INpcRuntimeStateStore runtimeStore,
         IThreatStateStore threatStore,
         INpcBehaviorDefinitionRegistry behaviorRegistry,
+        IPlayerCombatHealthStore playerHealthStore,
         double maxDeltaSeconds = DefaultMaxDeltaSeconds)
     {
         if (maxDeltaSeconds <= 0)
@@ -32,7 +35,8 @@ public static class NpcRuntimeOperations
                     nowUtc,
                     runtimeStore,
                     threatStore,
-                    behaviorRegistry);
+                    behaviorRegistry,
+                    playerHealthStore);
             }
 
             runtimeStore.LastAdvancedUtc = nowUtc;
@@ -50,7 +54,8 @@ public static class NpcRuntimeOperations
                     nowUtc,
                     runtimeStore,
                     threatStore,
-                    behaviorRegistry);
+                    behaviorRegistry,
+                    playerHealthStore);
             }
 
             return;
@@ -68,7 +73,8 @@ public static class NpcRuntimeOperations
                 windowEnd,
                 runtimeStore,
                 threatStore,
-                behaviorRegistry);
+                behaviorRegistry,
+                playerHealthStore);
         }
 
         runtimeStore.LastAdvancedUtc = windowEnd;
@@ -84,7 +90,8 @@ public static class NpcRuntimeOperations
         DateTimeOffset windowEnd,
         INpcRuntimeStateStore runtimeStore,
         IThreatStateStore threatStore,
-        INpcBehaviorDefinitionRegistry behaviorRegistry)
+        INpcBehaviorDefinitionRegistry behaviorRegistry,
+        IPlayerCombatHealthStore playerHealthStore)
     {
         if (!PrototypeNpcRegistry.TryGet(npcInstanceId, out var entry) ||
             !behaviorRegistry.TryGetDefinition(entry.BehaviorDefId, out var behavior))
@@ -102,7 +109,7 @@ public static class NpcRuntimeOperations
             return;
         }
 
-        if (!TryHasAggroHolder(npcInstanceId, threatStore, out _))
+        if (!TryHasAggroHolder(npcInstanceId, threatStore, out var aggroHolderPlayerId))
         {
             if (snapshot.BehaviorState != NpcBehaviorState.Idle || snapshot.ActiveTelegraph is not null)
             {
@@ -130,7 +137,7 @@ public static class NpcRuntimeOperations
         var cursor = windowStart;
         while (cursor < windowEnd)
         {
-            if (!TryHasAggroHolder(npcInstanceId, threatStore, out _))
+            if (!TryHasAggroHolder(npcInstanceId, threatStore, out aggroHolderPlayerId))
             {
                 WriteIdle(runtimeStore, npcInstanceId);
                 return;
@@ -176,24 +183,36 @@ public static class NpcRuntimeOperations
                     }
 
                     cursor = phaseEnd;
+                    NpcAttackOperations.TryResolveTelegraphComplete(
+                        npcInstanceId,
+                        aggroHolderPlayerId,
+                        behavior.AttackDamage,
+                        playerHealthStore,
+                        threatStore);
                     WriteState(
                         runtimeStore,
                         npcInstanceId,
                         NpcBehaviorState.Recover,
                         cursor,
                         activeTelegraph: null);
-                    // telemetry: telegraph_fired / npc_state_transition (NEO-96); logical attack_execute → recover (NEO-95 applies attackDamage)
+                    // telemetry: telegraph_fired / npc_state_transition (NEO-96); logical attack_execute → recover
                     break;
                 }
 
                 case NpcBehaviorState.AttackExecute:
+                    NpcAttackOperations.TryResolveTelegraphComplete(
+                        npcInstanceId,
+                        aggroHolderPlayerId,
+                        behavior.AttackDamage,
+                        playerHealthStore,
+                        threatStore);
                     WriteState(
                         runtimeStore,
                         npcInstanceId,
                         NpcBehaviorState.Recover,
                         cursor,
                         activeTelegraph: null);
-                    // telemetry: npc_state_transition (NEO-96); NEO-95 applies attackDamage here
+                    // telemetry: npc_state_transition (NEO-96)
                     break;
 
                 case NpcBehaviorState.Recover:

server/NeonSprawl.Server/Game/Npc/NpcRuntimeSnapshotWorldApi.cs

@@ -1,3 +1,5 @@
+using NeonSprawl.Server.Game.Combat;
+
 namespace NeonSprawl.Server.Game.Npc;
 
 /// <summary>Maps <c>GET /game/world/npc-runtime-snapshot</c> (NEO-94).</summary>
@@ -11,10 +13,16 @@ public static class NpcRuntimeSnapshotWorldApi
                 TimeProvider clock,
                 INpcRuntimeStateStore runtimeStore,
                 IThreatStateStore threatStore,
-                INpcBehaviorDefinitionRegistry behaviorRegistry) =>
+                INpcBehaviorDefinitionRegistry behaviorRegistry,
+                IPlayerCombatHealthStore playerHealthStore) =>
             {
                 var now = clock.GetUtcNow();
-                NpcRuntimeOperations.AdvanceAll(now, runtimeStore, threatStore, behaviorRegistry);
+                NpcRuntimeOperations.AdvanceAll(
+                    now,
+                    runtimeStore,
+                    threatStore,
+                    behaviorRegistry,
+                    playerHealthStore);
                 return Results.Json(BuildSnapshot(now, runtimeStore, threatStore, behaviorRegistry));
             });
 

server/NeonSprawl.Server/Program.cs

@@ -27,6 +27,7 @@ builder.Services.AddAbilityDefinitionCatalog(builder.Configuration);
 builder.Services.AddNpcBehaviorDefinitionCatalog(builder.Configuration);
 builder.Services.AddThreatStateStore();
 builder.Services.AddNpcRuntimeStateStore();
+builder.Services.AddPlayerCombatHealthStore();
 builder.Services.AddMasteryCatalog(builder.Configuration);
 
 var app = builder.Build();
@@ -59,6 +60,7 @@ app.MapAbilityDefinitionsWorldApi();
 app.MapNpcBehaviorDefinitionsWorldApi();
 app.MapCombatTargetsWorldApi();
 app.MapNpcRuntimeSnapshotWorldApi();
+app.MapPlayerCombatHealthApi();
 app.MapResourceNodeDefinitionsWorldApi();
 app.MapPlayerInventoryApi();
 app.MapPlayerCraftApi();