Map events apart from the map: map_events/<map>/*.json of any mod merged by id (RpgMapEventResolver, RpgMapEventMerge); item Icon look for events; rpg_walk checks a pickup across leaving the map and loading a save

src/Data/RpgMap.cs

@@ -16,7 +16,10 @@ namespace Cthangover.Mods.Rpg
     /// <para/>
     /// Files declare <c>"Kind": "rpg_map"</c>. Layers are parsed by
     /// <see cref="RpgMapGrid"/>; a dependent mod replaces a whole map by id, the
-    /// usual entity override.
+    /// usual entity override. The map file holds only the ground: what stands on it
+    /// (NPCs, doors, chests, pickups) are events in <c>map_events/&lt;id&gt;/</c> of any
+    /// mod, merged by <see cref="RpgMapEventResolver"/>, so a mod adds to another
+    /// mod's map without replacing it.
     /// </summary>
     [EntityKind("rpg_map")]
     public class RpgMap : IIdentifiable
@@ -49,8 +52,6 @@ namespace Cthangover.Mods.Rpg
         /// <summary>Where the player appears when entering the map without a teleport target.</summary>
         public RpgTeleport Spawn { get; set; } = new();
 
-        /// <summary>Events placed on the map.</summary>
-        public List<RpgMapEvent> Events { get; set; } = new();
 
         /// <summary>Random battles; null for a safe map.</summary>
         public RpgEncounterTable Encounters { get; set; }

src/Data/RpgMapEvent.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Text.Json.Serialization;
 
 namespace Cthangover.Mods.Rpg
 {
@@ -7,7 +8,7 @@ namespace Cthangover.Mods.Rpg
     /// RPG Maker events: an NPC, a sign, a chest, a door. What it looks like and
     /// what it does are independent:
     /// <list type="bullet">
-    /// <item>look — a charset <see cref="Sprite"/>, or one atlas <see cref="Tile"/>, or nothing (an invisible trigger);</item>
+    /// <item>look — a charset <see cref="Sprite"/>, or one atlas <see cref="Tile"/>, or an item <see cref="Icon"/>, or nothing (an invisible trigger);</item>
     /// <item>effect — a <see cref="Teleport"/>, handled natively, or a dialog built
     /// from a <see cref="Scenario"/> file followed by inline <see cref="Commands"/>
     /// (the full scenario DSL, so <c>action rpg.battle …</c>, <c>flag …</c>, quests).</item>
@@ -15,6 +16,9 @@ namespace Cthangover.Mods.Rpg
     /// A <see cref="Condition"/> in the scenario condition language hides the
     /// event while false; it is re-checked whenever game state changes, so a
     /// defeated boss (<c>flag boss_dead 1</c>) disappears at once.
+    /// <para/>
+    /// Events are stored apart from their map, in <c>map_events/&lt;map&gt;/*.json</c>
+    /// of any mod (<see cref="RpgMapEventResolver"/>).
     /// </summary>
     public class RpgMapEvent
     {
@@ -33,13 +37,19 @@ namespace Cthangover.Mods.Rpg
         /// <summary>Atlas index of the map's tileset drawn as the event when it has no sprite; -1 for none.</summary>
         public int Tile { get; set; } = -1;
 
+        /// <summary>
+        /// Picture in the <c>items</c> group (what an item's <c>Sprite</c> names), drawn fitted into the
+        /// cell when the event has neither a sprite nor a tile: an item lying on the ground.
+        /// </summary>
+        public string Icon { get; set; }
+
         /// <summary>Initial facing of a sprite.</summary>
         public RpgDirection Dir { get; set; } = RpgDirection.Down;
 
         /// <summary>When the event fires.</summary>
         public RpgEventTrigger Trigger { get; set; } = RpgEventTrigger.Action;
 
-        /// <summary>The event occupies its cell. Null means "solid when it is visible" (a sprite or a tile).</summary>
+        /// <summary>The event occupies its cell. Null means "solid when it is visible" (a sprite, a tile or an icon).</summary>
         public bool? Solid { get; set; }
 
         /// <summary>Scenario path inside the <c>scenarios</c> group (extension optional), played as a dialog.</summary>
@@ -54,7 +64,15 @@ namespace Cthangover.Mods.Rpg
         /// <summary>Scenario condition; the event exists only while it is true.</summary>
         public string Condition { get; set; }
 
+        /// <summary>Mod the event was read from (set by the event resolver, not stored).</summary>
+        [JsonIgnore]
+        public string ModId { get; set; }
+
+        /// <summary>Mod-relative path of the file the event was read from (set by the event resolver, not stored).</summary>
+        [JsonIgnore]
+        public string File { get; set; }
+
         /// <summary>Effective solidity: explicit value, else whether the event is drawn.</summary>
-        public bool IsSolid => Solid ?? (!string.IsNullOrEmpty(Sprite) || Tile >= 0);
+        public bool IsSolid => Solid ?? (!string.IsNullOrEmpty(Sprite) || Tile >= 0 || !string.IsNullOrEmpty(Icon));
     }
 }

src/Data/RpgMapEventFile.cs

@@ -0,0 +1,15 @@
+using System.Collections.Generic;
+
+namespace Cthangover.Mods.Rpg
+{
+    /// <summary>
+    /// One file of map events, <c>map_events/&lt;map id&gt;/&lt;any name&gt;.json</c>:
+    /// <c>{"Events": [ … ]}</c>. The folder names the map, so a file holds the events
+    /// of one map, and a mod may split them over as many files as it likes.
+    /// </summary>
+    public class RpgMapEventFile
+    {
+        /// <summary>The events of the file, in drawing order.</summary>
+        public List<RpgMapEvent> Events { get; set; } = new();
+    }
+}

src/Data/RpgMapEventMerge.cs

@@ -0,0 +1,53 @@
+using System;
+using System.Collections.Generic;
+
+namespace Cthangover.Mods.Rpg
+{
+    /// <summary>
+    /// Builds the event list of every map from event files read in mod load order.
+    /// A new id is appended; an id already present (ignoring case) is replaced in
+    /// place, so the later file wins and keeps the original's drawing order. Mods
+    /// load after their dependencies, so the engine's replacement rule holds:
+    /// ship the same event id and declare <c>depends</c> on the owner to replace
+    /// it, ship a new id to add to any mod's map.
+    /// <para/>
+    /// Pure data, so the merge rules are tested without a mod set.
+    /// </summary>
+    public class RpgMapEventMerge
+    {
+        /// <summary>Events per map id (case-insensitive).</summary>
+        public Dictionary<string, List<RpgMapEvent>> Maps { get; } = new(StringComparer.OrdinalIgnoreCase);
+
+        /// <summary>
+        /// Adds the events of one file of <paramref name="modId"/> for map <paramref name="map"/>;
+        /// each event gets <see cref="RpgMapEvent.ModId"/> and <see cref="RpgMapEvent.File"/>.
+        /// Returns the ids that replaced an earlier event.
+        /// </summary>
+        public List<string> Add(string map, string modId, string file, IEnumerable<RpgMapEvent> events)
+        {
+            var replaced = new List<string>();
+            if (!Maps.TryGetValue(map, out var list))
+            {
+                list = new List<RpgMapEvent>();
+                Maps[map] = list;
+            }
+
+            foreach (var mapEvent in events ?? Array.Empty<RpgMapEvent>())
+            {
+                if (mapEvent == null || string.IsNullOrWhiteSpace(mapEvent.Id))
+                    continue;
+                mapEvent.ModId = modId;
+                mapEvent.File = file;
+                var index = list.FindIndex(e => string.Equals(e.Id, mapEvent.Id, StringComparison.OrdinalIgnoreCase));
+                if (index < 0)
+                {
+                    list.Add(mapEvent);
+                    continue;
+                }
+                list[index] = mapEvent;
+                replaced.Add(mapEvent.Id);
+            }
+            return replaced;
+        }
+    }
+}

src/Data/RpgMapEventResolver.cs

@@ -0,0 +1,93 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Text.Json;
+using Cthangover.Core.Mods;
+using Cthangover.Core.Mods.Resolvers;
+using Cthangover.Core.Utils;
+
+namespace Cthangover.Mods.Rpg
+{
+    /// <summary>
+    /// Collects map events from <c>map_events/&lt;map id&gt;/**/*.json</c> of every
+    /// loaded mod in load order (files of one mod sorted by path), then from the
+    /// studio overlays, and merges them per map with <see cref="RpgMapEventMerge"/>.
+    /// <para/>
+    /// Events live apart from the map file (<c>maps/&lt;id&gt;.json</c> holds only
+    /// tiles, collision, spawn and encounters) so that any mod can put its own NPC,
+    /// chest or quest trigger on another mod's map without replacing the map, and
+    /// so that drawing and placing do not fight over one big file. Events of a map
+    /// no mod defines are kept and simply never shown.
+    /// </summary>
+    public class RpgMapEventResolver : ModAssetResolver
+    {
+        /// <summary>Group folder of event files.</summary>
+        public const string Directory = "map_events";
+
+        private Dictionary<string, List<RpgMapEvent>> cache;
+
+        /// <inheritdoc />
+        public override string Id => "rpg_map_events";
+
+        /// <summary>Events per map id, merged; cached until the next mod reload or <see cref="ClearCache"/>.</summary>
+        public Dictionary<string, List<RpgMapEvent>> Collect()
+        {
+            Context.Initialize();
+            if (cache != null)
+                return cache;
+
+            var merge = new RpgMapEventMerge();
+            foreach (var modId in Context.GetOrderedModIds())
+                CollectMod(Context.Mods[modId].FileProvider, modId, merge);
+            foreach (var overlay in ModOverlays.All)
+                CollectMod(overlay.Value, overlay.Key, merge);
+
+            cache = merge.Maps;
+            GameLogger.Log("RPG", $"map events: {cache.Values.Sum(l => l.Count)} event(s) on {cache.Count} map(s)");
+            return cache;
+        }
+
+        /// <inheritdoc />
+        public override void ClearCache() => cache = null;
+
+        private void CollectMod(IModFileProvider provider, string modId, RpgMapEventMerge merge)
+        {
+            foreach (var mapDir in provider.ListFiles(Directory).Where(e => e.EndsWith("/")).OrderBy(e => e, System.StringComparer.Ordinal))
+            {
+                var map = mapDir.TrimEnd('/');
+                map = map.Substring(map.LastIndexOf('/') + 1);
+                var files = new List<string>();
+                ListJson(provider, mapDir.TrimEnd('/'), files);
+                foreach (var file in files.OrderBy(f => f, System.StringComparer.Ordinal))
+                    ReadFile(provider, modId, map, file, merge);
+            }
+        }
+
+        private static void ListJson(IModFileProvider provider, string dir, List<string> files)
+        {
+            foreach (var entry in provider.ListFiles(dir))
+            {
+                if (entry.EndsWith("/"))
+                    ListJson(provider, entry.TrimEnd('/'), files);
+                else if (entry.EndsWith(".json", System.StringComparison.OrdinalIgnoreCase))
+                    files.Add(entry);
+            }
+        }
+
+        private void ReadFile(IModFileProvider provider, string modId, string map, string file, RpgMapEventMerge merge)
+        {
+            var text = Context.ReadResolvedText(modId, file, provider);
+            if (string.IsNullOrWhiteSpace(text))
+                return;
+            try
+            {
+                var data = JsonSerializer.Deserialize<RpgMapEventFile>(text, JsonOptionsProvider.ReadOptions);
+                foreach (var id in merge.Add(map, modId, file, data?.Events))
+                    GameLogger.Log("RPG", $"map '{map}': event '{id}' replaced by mod '{modId}' ({file})");
+            }
+            catch (JsonException ex)
+            {
+                GameLogger.Log("RPG", $"map events '{modId}/{file}': broken JSON: {ex.Message}", LogLevel.Error);
+            }
+        }
+    }
+}

src/Data/RpgMapEvents.cs

@@ -0,0 +1,19 @@
+using System.Collections.Generic;
+using Cthangover.Core.Mods;
+
+namespace Cthangover.Mods.Rpg
+{
+    /// <summary>Access to the merged map events of <see cref="RpgMapEventResolver"/>.</summary>
+    public static class RpgMapEvents
+    {
+        /// <summary>The events of a map (an empty list when it has none); the list is shared, do not change it.</summary>
+        public static IReadOnlyList<RpgMapEvent> Of(string map)
+        {
+            var maps = ModManager.Instance.GetResolver<RpgMapEventResolver>()?.Collect();
+            return map != null && maps != null && maps.TryGetValue(map, out var list) ? list : new List<RpgMapEvent>();
+        }
+
+        /// <summary>Forgets the collected events, so the next <see cref="Of"/> reads the files again (after an editor save).</summary>
+        public static void Invalidate() => ModManager.Instance.GetResolver<RpgMapEventResolver>()?.ClearCache();
+    }
+}

src/World/RpgActor.cs

@@ -79,6 +79,25 @@ namespace Cthangover.Mods.Rpg
             AddChild(sprite);
         }
 
+        /// <summary>
+        /// Shows an item picture fitted into three quarters of the cell and centred on it,
+        /// so an icon of any size lies on the ground like a tile-sized object.
+        /// </summary>
+        public void UseIcon(Texture2D texture)
+        {
+            if (texture == null)
+                return;
+            var fit = tileSize * 0.75f / Mathf.Max(1, Mathf.Max(texture.GetWidth(), texture.GetHeight()));
+            sprite = new Sprite2D
+            {
+                Texture = texture,
+                Position = new Vector2(tileSize, tileSize) / 2f,
+                Scale = new Vector2(fit, fit),
+                TextureFilter = TextureFilterEnum.Linear,
+            };
+            AddChild(sprite);
+        }
+
         /// <summary>Puts the actor on a cell at once, stopping any step.</summary>
         public void Place(Vector2I cell, RpgDirection facing)
         {

src/World/RpgTextures.cs

@@ -8,7 +8,8 @@ namespace Cthangover.Mods.Rpg
     /// Image lookup of the RPG world: tileset atlases in the <c>tilesets</c> file
     /// group, charsets in <c>charsets</c>. Both are file groups (last mod wins),
     /// not texture groups, so their names never collide with backgrounds or
-    /// icons. Decoded textures are kept for the life of one world, which builds
+    /// icons; item pictures for <see cref="RpgMapEvent.Icon"/> come from the
+    /// <c>items</c> group the inventory uses. Decoded textures are kept for the life of one world, which builds
     /// and owns an instance; the editor keeps its own.
     /// </summary>
     public class RpgTextures
@@ -19,6 +20,9 @@ namespace Cthangover.Mods.Rpg
         /// <summary>File group of charset images.</summary>
         public const string CharsetGroup = "charsets";
 
+        /// <summary>File group of item pictures (an item's <c>Sprite</c>).</summary>
+        public const string IconGroup = "items";
+
         private readonly Dictionary<string, Texture2D> cache = new();
 
         /// <summary>Tileset atlas image, or null (logged by the loader).</summary>
@@ -27,6 +31,9 @@ namespace Cthangover.Mods.Rpg
         /// <summary>Charset image, or null.</summary>
         public Texture2D Charset(string path) => Load(CharsetGroup, path);
 
+        /// <summary>Item picture, or null.</summary>
+        public Texture2D Icon(string path) => Load(IconGroup, path);
+
         private Texture2D Load(string group, string path)
         {
             if (string.IsNullOrWhiteSpace(path))

src/World/RpgWorldView.cs

@@ -66,7 +66,7 @@ namespace Cthangover.Mods.Rpg
             AddChild(actorLayer);
             AddChild(BuildLayer(RpgLayer.Front, tileSet));
 
-            foreach (var mapEvent in map.Events ?? new List<RpgMapEvent>())
+            foreach (var mapEvent in RpgMapEvents.Of(map.ID))
                 AddEventActor(mapEvent);
             RefreshEvents();
 
@@ -227,6 +227,8 @@ namespace Cthangover.Mods.Rpg
                 actor.UseCharset(textures.Charset(mapEvent.Sprite));
             else if (mapEvent.Tile >= 0 && Tileset != null)
                 actor.UseTile(atlas, RpgTileSetBuilder.AtlasCoords(Tileset, mapEvent.Tile));
+            else if (!string.IsNullOrEmpty(mapEvent.Icon))
+                actor.UseIcon(textures.Icon(mapEvent.Icon));
             actor.Place(new Vector2I(mapEvent.X, mapEvent.Y), mapEvent.Dir);
             actorLayer.AddChild(actor);
             eventActors[mapEvent.Id] = actor;

test_suites/walk/manifest.json

@@ -1,6 +1,6 @@
 {
   "name": "RPG Walk Test",
-  "description": "Integration test of the rpg mod on the rpg_demo game: real WASD/E key events walk the hero, collide, read a sign, turn an NPC, go through a door teleport, flip events by a story flag, fight a battle that returns to the same cell with the win flag set. Activated by --itest=rpg_walk with --game=rpg_demo --new; --shots=<dir> saves screenshots (windowed runs only).",
+  "description": "Integration test of the rpg mod on the rpg_demo game: real WASD/E key events walk the hero, collide, read a sign, turn an NPC, go through a door teleport, flip events by a story flag, fight a battle that returns to the same cell with the win flag set. A pickup the suite adds to the village through its own map_events file is picked up and must stay gone after leaving the map and coming back, and after a save is loaded. Activated by --itest=rpg_walk with --game=rpg_demo --new; --shots=<dir> saves screenshots (windowed runs only).",
   "sources": [
     "src/*.cs"
   ],

test_suites/walk/map_events/rpg_village/rpg_walk_test.json

@@ -0,0 +1,19 @@
+{
+  "Events": [
+    {
+      "Id": "rpg_walk_mushroom",
+      "X": 18,
+      "Y": 14,
+      "Icon": "rpg_demo/forest_mushroom",
+      "Trigger": "Touch",
+      "Solid": false,
+      "Commands": [
+        "ptext \"Found: a mushroom\"",
+        "action item.add id=rpg_demo/mushroom count=1",
+        "flag rpg_village_rpg_walk_mushroom_taken 1",
+        "end"
+      ],
+      "Condition": "rpg_village_rpg_walk_mushroom_taken != 1"
+    }
+  ]
+}

test_suites/walk/src/RpgWalkTestDriver.cs

@@ -6,6 +6,7 @@ using Cthangover.Core.Factories.Impls;
 using Cthangover.Core.Games;
 using Cthangover.Core.Scenes;
 using Cthangover.Core.Settings;
+using Cthangover.Core.Items;
 using Cthangover.Core.Utils;
 using Cthangover.Mods.Interface.View;
 using Godot;
@@ -17,6 +18,13 @@ namespace Cthangover.Mods.Rpg.Tests
     /// <see cref="Input.ParseInputEvent"/>, so the world reads them exactly as
     /// it reads a keyboard (physical keys, held state, unhandled action key).
     /// <para/>
+    /// A pickup is checked across map rebuilds: the suite's own
+    /// <c>map_events/rpg_village/rpg_walk_test.json</c> lays a mushroom on the demo's
+    /// village (an event added by another mod, shaped like the map editor's
+    /// pickups); it is picked up, the player leaves the map and comes back, then
+    /// saves, loads and comes back again — it must never reappear nor give a
+    /// second item.
+    /// <para/>
     /// One step per timer tick; a step either waits (returns without
     /// advancing) or checks and moves on. A failed check is recorded and the
     /// run goes on; an exception ends it. Result line:
@@ -31,12 +39,18 @@ namespace Cthangover.Mods.Rpg.Tests
         private const string House = "rpg_elder_house";
         private const string WinFlag = "rpg_test_win";
         private const string SaveSlot = "slot_9901";
+        private const string PickupId = "rpg_walk_mushroom";
+        private const string PickupFlag = "rpg_village_rpg_walk_mushroom_taken";
+        private const string Mushroom = "rpg_demo/mushroom";
+
+        private static readonly Vector2I PickupCell = new(18, 14);
 
         private readonly string shotsDir;
         private readonly List<string> failures = new();
         private int passed;
         private int step;
         private int waitTicks;
+        private int mushroomsBefore;
         private double elapsed;
 
         /// <summary>Creates the driver; <paramref name="shotsDir"/> null disables screenshots.</summary>
@@ -51,6 +65,10 @@ namespace Cthangover.Mods.Rpg.Tests
 
         private static RpgWorldView View => RpgWorldHost.Current?.View;
 
+        private static IInventory Inventory => GameData.Instance.Runtime.Inventory;
+
+        private static string Flag(string name) => GameData.Instance.Runtime.Flags.TryGetValue(name, out var value) ? value : null;
+
         private void Tick()
         {
             if (step < 0)
@@ -142,17 +160,63 @@ namespace Cthangover.Mods.Rpg.Tests
                 case 9:
                     if (AdvanceDialog())
                         return;
+                    // A pickup this suite adds to the demo's village (map_events of another mod).
+                    mushroomsBefore = Inventory.CheckCount(Mushroom);
+                    Check(View.FindEvent(PickupId)?.Visible == true, "a test mod's map_events file adds a pickup to the demo's village");
+                    View.PlacePlayer(PickupCell.X - 1, PickupCell.Y, RpgDirection.Right);
+                    Press(Key.D, true);
+                    Next();
+                    return;
+                case 10:
+                    if (View.Player.Cell.X < PickupCell.X)
+                        return;
+                    Press(Key.D, false);
+                    Next();
+                    return;
+                case 11:
+                    // Stepping on the pickup starts its dialog; the flag is set when it ends.
+                    if (AdvanceDialog() || Flag(PickupFlag) != "1")
+                        return;
+                    Check(Inventory.CheckCount(Mushroom) == mushroomsBefore + 1, $"stepping on the pickup adds the item, {Inventory.CheckCount(Mushroom)} now");
+                    Check(View.FindEvent(PickupId)?.Visible == false, "the picked item leaves the map");
+                    RpgWorldHost.Teleport(new RpgTeleport { Map = House, X = 6, Y = 8, Dir = RpgDirection.Up });
+                    Next();
+                    return;
+                case 12:
+                    if (View?.Map?.ID != House || GodotSceneService.IsTransitioning || AdvanceDialog())
+                        return;
+                    RpgWorldHost.Teleport(new RpgTeleport { Map = Village, X = PickupCell.X - 1, Y = PickupCell.Y, Dir = RpgDirection.Right });
+                    Next();
+                    return;
+                case 13:
+                    if (View?.Map?.ID != Village || GodotSceneService.IsTransitioning || AdvanceDialog())
+                        return;
+                    CheckPickupGone("after leaving the map and coming back");
+                    Press(Key.D, true);
+                    Next();
+                    return;
+                case 14:
+                    if (View.Player.Cell.X < PickupCell.X)
+                        return;
+                    Press(Key.D, false);
+                    Next();
+                    return;
+                case 15:
+                    if (View.Player.IsMoving || ++waitTicks < 5)
+                        return;
+                    Check(RpgInput.FindDialogBox()?.IsRunning != true && Inventory.CheckCount(Mushroom) == mushroomsBefore + 1,
+                        "stepping on the empty cell again gives nothing");
                     View.PlacePlayer(6, 7, RpgDirection.Up);
                     Press(Key.W, true);
                     Next();
                     return;
-                case 10:
+                case 16:
                     if (!View.Player.IsMoving && View.Map.ID == Village)
                         return;
                     Press(Key.W, false);
                     Next();
                     return;
-                case 11:
+                case 17:
                     if (View?.Map?.ID != House)
                         return;
                     if (AdvanceDialog())
@@ -163,14 +227,14 @@ namespace Cthangover.Mods.Rpg.Tests
                     ScenarioCondition.SetFlag("rpg_wolf_dead", "1");
                     Next();
                     return;
-                case 12:
+                case 18:
                     Check(View.FindEvent("elder_quest")?.Visible == false && View.FindEvent("elder_thanks")?.Visible == true, "a story flag swaps the elder's events at once");
                     ScenarioCondition.SetFlag("rpg_wolf_dead", "0");
                     Check(RpgBattleService.Start("rpg_slime", WinFlag), "a battle starts from the map");
                     Godot.Engine.TimeScale = 4;
                     Next();
                     return;
-                case 13:
+                case 19:
                     if (GetTree().CurrentScene is not BattleSceneContext battle)
                         return;
                     // The core's auto turn only passes, so the hero would lose: once the
@@ -184,14 +248,14 @@ namespace Cthangover.Mods.Rpg.Tests
                     battle.ShowWinground();
                     Next();
                     return;
-                case 14:
+                case 20:
                     if (GetTree().Root.FindChild("ContinueButton", true, false) is not Button button || !button.IsVisibleInTree())
                         return;
                     Shot("victory");
                     button.EmitSignal(BaseButton.SignalName.Pressed);
                     Next();
                     return;
-                case 15:
+                case 21:
                     if (View?.Map?.ID != House || GodotSceneService.IsTransitioning)
                         return;
                     Godot.Engine.TimeScale = 1;
@@ -202,19 +266,27 @@ namespace Cthangover.Mods.Rpg.Tests
                     GameSession.OpenMainMenu(GetTree());
                     Next();
                     return;
-                case 16:
+                case 22:
                     if (RpgWorldHost.Current != null || ++waitTicks < 5)
                         return;
                     Check(GameSession.LoadAndEnter(this, SaveSlot), "the save loads");
                     Next();
                     return;
-                case 17:
+                case 23:
                     if (View?.Map?.ID != House || GodotSceneService.IsTransitioning || ++waitTicks < 5)
                         return;
                     Shot("loaded");
                     var dialog = RpgInput.FindDialogBox();
                     Check(dialog != null && !dialog.IsRunning && !dialog.IsVisibleInTree(), $"no dialog box after loading (running={dialog?.IsRunning}, visible={dialog?.IsVisibleInTree()})");
                     Check(View.Player.Cell == new Vector2I(6, 8), $"the loaded game puts the player on the saved cell, got {View.Player.Cell}");
+                    Check(Flag(PickupFlag) == "1" && Inventory.CheckCount(Mushroom) == mushroomsBefore + 1, "the save keeps the pickup's flag and the picked item");
+                    RpgWorldHost.Teleport(new RpgTeleport { Map = Village, X = PickupCell.X - 1, Y = PickupCell.Y, Dir = RpgDirection.Right });
+                    Next();
+                    return;
+                case 24:
+                    if (View?.Map?.ID != Village || GodotSceneService.IsTransitioning || AdvanceDialog())
+                        return;
+                    CheckPickupGone("after loading the save");
                     SaveService.DeleteSave(SaveSlot);
                     Finish();
                     return;
@@ -237,6 +309,15 @@ namespace Cthangover.Mods.Rpg.Tests
             }
         }
 
+        /// <summary>The map was built again (a teleport or a load): the picked item must stay gone and give nothing.</summary>
+        private void CheckPickupGone(string when)
+        {
+            var pickup = View.FindEvent(PickupId);
+            Check(pickup != null && !pickup.Visible, $"the picked item does not come back {when}");
+            Check(View.EventAt(PickupCell, RpgEventTrigger.Touch) == null, $"its cell has no pickup to step on {when}");
+            Check(Inventory.CheckCount(Mushroom) == mushroomsBefore + 1, $"the inventory still holds exactly the one picked item {when}");
+        }
+
         /// <summary>Advances a running dialog with the action key; true while it is still running.</summary>
         private bool AdvanceDialog()
         {

tests/RpgStateTests.cs

@@ -57,7 +57,6 @@ namespace Cthangover.Mods.Rpg.Tests
         {
             var json = @"{""Id"":""m"",""Tileset"":""village"",""Width"":2,""Height"":1,
                 ""Spawn"":{""X"":1,""Y"":0,""Dir"":""left""},
-                ""Events"":[{""Id"":""door"",""X"":0,""Y"":0,""Trigger"":""touch"",""Teleport"":{""Map"":""x"",""X"":3,""Y"":4,""Dir"":""Up""}}],
                 ""Encounters"":{""Steps"":20,""Groups"":[""slime""]}}";
 
             var map = JsonSerializer.Deserialize<RpgMap>(json, Cthangover.Core.Utils.JsonOptionsProvider.ReadOptions);
@@ -65,12 +64,62 @@ namespace Cthangover.Mods.Rpg.Tests
 
             ModAssert.Equal("m", again.ID, "id");
             ModAssert.Equal("Left", again.Spawn.Dir.ToString(), "spawn facing, read in any case");
+            ModAssert.Equal(20, again.Encounters.Steps, "encounter steps");
+            ModAssert.Equal("slime", again.Encounters.Groups[0], "encounter group");
+            ModAssert.Equal(2, again.Zoom, "zoom default");
+        }
+
+        [ModTest("state/event_file_round_trip")]
+        static void EventFileRoundTrip(ModTestContext ctx)
+        {
+            var json = @"{""Events"":[
+                {""Id"":""door"",""X"":0,""Y"":0,""Trigger"":""touch"",""Teleport"":{""Map"":""x"",""X"":3,""Y"":4,""Dir"":""Up""}},
+                {""Id"":""herb"",""X"":2,""Y"":1,""Icon"":""rpg_demo/forest_mushroom"",""Commands"":[""end""],""Condition"":""herb != 1""}]}";
+
+            var file = JsonSerializer.Deserialize<RpgMapEventFile>(json, Cthangover.Core.Utils.JsonOptionsProvider.ReadOptions);
+            file.Events[0].ModId = "some_mod";
+            var text = JsonSerializer.Serialize(file);
+            var again = JsonSerializer.Deserialize<RpgMapEventFile>(text, Cthangover.Core.Utils.JsonOptionsProvider.ReadOptions);
+
+            ModAssert.Equal(2, again.Events.Count, "both events");
             ModAssert.Equal("Touch", again.Events[0].Trigger.ToString(), "trigger");
             ModAssert.Equal("x", again.Events[0].Teleport.Map, "teleport map");
             ModAssert.Equal(4, again.Events[0].Teleport.Y, "teleport y");
             ModAssert.False(again.Events[0].IsSolid, "an invisible event does not block");
-            ModAssert.Equal(20, again.Encounters.Steps, "encounter steps");
-            ModAssert.Equal(2, again.Zoom, "zoom default");
+            ModAssert.Equal("rpg_demo/forest_mushroom", again.Events[1].Icon, "icon");
+            ModAssert.True(again.Events[1].IsSolid, "an icon is drawn, so it blocks unless told otherwise");
+            ModAssert.Equal("herb != 1", again.Events[1].Condition, "condition");
+            ModAssert.Equal("end", again.Events[1].Commands[0], "commands");
+            ModAssert.False(text.Contains("some_mod"), "where an event came from is not written");
+        }
+
+        [ModTest("state/event_merge_adds_and_replaces")]
+        static void EventMergeAddsAndReplaces(ModTestContext ctx)
+        {
+            var merge = new RpgMapEventMerge();
+            merge.Add("village", "base_game", "map_events/village/events.json", new[]
+            {
+                new RpgMapEvent { Id = "elder", X = 1, Y = 1 },
+                new RpgMapEvent { Id = "sign", X = 2, Y = 1 },
+                new RpgMapEvent { Id = " " }
+            });
+            var replaced = merge.Add("VILLAGE", "quest_mod", "map_events/village/quest.json", new[]
+            {
+                new RpgMapEvent { Id = "Elder", X = 5, Y = 5 },
+                new RpgMapEvent { Id = "quest_giver", X = 3, Y = 3 }
+            });
+            merge.Add("forest", "quest_mod", "map_events/forest/a.json", null);
+
+            var village = merge.Maps["village"];
+            ModAssert.Equal(3, village.Count, "an event without an id is skipped, a new id is added");
+            ModAssert.Equal(1, replaced.Count, "one replacement reported");
+            ModAssert.Equal("Elder", replaced[0], "the replacing id");
+            ModAssert.Equal(5, village[0].X, "the later mod's event replaces in place (any case)");
+            ModAssert.Equal("quest_mod", village[0].ModId, "the replacement remembers its mod");
+            ModAssert.Equal("sign", village[1].Id, "the others keep their order");
+            ModAssert.Equal("base_game", village[1].ModId, "and their mod");
+            ModAssert.Equal("map_events/village/quest.json", village[2].File, "an added event remembers its file");
+            ModAssert.Equal(0, merge.Maps["forest"].Count, "a file without events adds nothing");
         }
     }
 }