From a406660e78451ee69331f309f045a9880b3b7ebb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lancelot=20de=20Ferri=C3=A8re?= <wraitii@gmail.com>
Date: Mon, 10 Aug 2026 09:15:14 +0200
Subject: [PATCH] Fix a ModifiersManager bug when changing player entities

The cache invalidation was incorrectly using forEach, which failed to invalidate the cache.
This never actually caused a bug because the game currently does not silently swap active player entities.
---
 .../simulation/components/ModifiersManager.js |  3 +-
 .../components/tests/test_ModifiersManager.js | 49 +++++++++++++++++++
 2 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/binaries/data/mods/public/simulation/components/ModifiersManager.js b/binaries/data/mods/public/simulation/components/ModifiersManager.js
index fe58c301a7..dfdd11292d 100644
--- a/binaries/data/mods/public/simulation/components/ModifiersManager.js
+++ b/binaries/data/mods/public/simulation/components/ModifiersManager.js
@@ -198,7 +198,8 @@ ModifiersManager.prototype.OnGlobalPlayerEntityChanged = function(msg)
 
 	if (msg.from != INVALID_PLAYER && this.playerEntitiesCached.has(msg.from))
 	{
-		this.playerEntitiesCached.get(msg.from).forEach(propName => this.InvalidateCache(propName, msg.from));
+		const playerCache = this.playerEntitiesCached.get(msg.from);
+		playerCache.forEach((_, propName) => this.InvalidateCache(propName, msg.from, playerCache));
 		this.playerEntitiesCached.delete(msg.from);
 	}
 };
diff --git a/binaries/data/mods/public/simulation/components/tests/test_ModifiersManager.js b/binaries/data/mods/public/simulation/components/tests/test_ModifiersManager.js
index bfc4ef644b..c7f46edf01 100644
--- a/binaries/data/mods/public/simulation/components/tests/test_ModifiersManager.js
+++ b/binaries/data/mods/public/simulation/components/tests/test_ModifiersManager.js
@@ -248,3 +248,52 @@ TS_ASSERT_EQUALS(ApplyValueModificationsToEntity("Test_D", 10, 5), 16);
 	Engine.PostMessage = oldPostMessage;
 	Engine.BroadcastMessage = oldBroadcastMessage;
 })();
+
+(function Test_PlayerEntityChangeInvalidatesCachedEntities()
+{
+	const PLAYER_ID = 1;
+	const OLD_PLAYER_ENTITY = 40;
+	const NEW_PLAYER_ENTITY = 41;
+	const TEST_ENTITY = 42;
+	const PROPERTY_NAME = "Test_PlayerEntityChange";
+
+	let playerEntity = OLD_PLAYER_ENTITY;
+	AddMock(SYSTEM_ENTITY, IID_PlayerManager, {
+		"GetPlayerByID": () => playerEntity
+	});
+	AddMock(OLD_PLAYER_ENTITY, IID_Player, {
+		"GetPlayerID": () => PLAYER_ID
+	});
+	AddMock(NEW_PLAYER_ENTITY, IID_Player, {
+		"GetPlayerID": () => PLAYER_ID
+	});
+	AddMock(TEST_ENTITY, IID_Ownership, {
+		"GetOwner": () => PLAYER_ID
+	});
+	AddMock(TEST_ENTITY, IID_Identity, {
+		"GetClassesList": () => "Unit"
+	});
+
+	const cmp = ConstructComponent(SYSTEM_ENTITY, "ModifiersManager", {});
+	cmp.Init();
+	cmp.OnGlobalPlayerEntityChanged({
+		"player": PLAYER_ID,
+		"from": INVALID_ENTITY,
+		"to": OLD_PLAYER_ENTITY
+	});
+	cmp.AddModifier(PROPERTY_NAME, "old player modifier", [{
+		"affects": ["Unit"],
+		"add": 10
+	}], OLD_PLAYER_ENTITY);
+
+	TS_ASSERT_EQUALS(cmp.ApplyModifiers(PROPERTY_NAME, 5, TEST_ENTITY), 15);
+
+	playerEntity = NEW_PLAYER_ENTITY;
+	cmp.OnGlobalPlayerEntityChanged({
+		"player": PLAYER_ID,
+		"from": OLD_PLAYER_ENTITY,
+		"to": NEW_PLAYER_ENTITY
+	});
+
+	TS_ASSERT_EQUALS(cmp.ApplyModifiers(PROPERTY_NAME, 5, TEST_ENTITY), 5);
+})();