From d5afe8de5450f2c7da611f6c36a91c8b0d68da39 Mon Sep 17 00:00:00 2001
From: Ivan Savenko <saven.ivan@gmail.com>
Date: Wed, 26 Nov 2025 21:04:47 +0200
Subject: [PATCH] Fix chain disabling of mods with soft dependencies

Happens if:
- Main mod that player attempts to disable has submods
- There is another mod that has soft-depend on such submod

This leads to scenario where submod is never added to load order, and
neither is another mod since it can only be added after submod.

Now mods (including submods) with known missing dependencies will be
dropped from load order immediately, allowing mods with soft-depends on
them to be added to load order
---
 lib/modding/ModManager.cpp | 44 +++++++++++++++++++++++++++-----------
 1 file changed, 32 insertions(+), 12 deletions(-)

diff --git a/lib/modding/ModManager.cpp b/lib/modding/ModManager.cpp
index 01e961197..9a6bc11e9 100644
--- a/lib/modding/ModManager.cpp
+++ b/lib/modding/ModManager.cpp
@@ -767,35 +767,45 @@ void ModDependenciesResolver::tryAddMods(TModList modsToResolve, const ModsStora
 	std::set<TModID> resolvedModIDs(activeMods.begin(), activeMods.end()); // Use a set for validation for performance reason, but set does not keep order of elements
 	std::set<TModID> notResolvedModIDs(modsToResolve.begin(), modsToResolve.end()); // Use a set for validation for performance reason
 
+	enum class ModResolveStatus {
+		RESOLVED, // ok - mod can be added to load order
+		WAITING, // maybe - wait for more iterations before deciding
+		BROKEN // fail - this mod definitely can't be loaded
+	};
+
 	// Mod is resolved if it has no dependencies or all its dependencies are already resolved
-	auto isResolved = [&](const ModDescription & mod) -> bool
+	auto isResolved = [&](const ModDescription & mod) -> ModResolveStatus
 	{
 		if (mod.isTranslation() && CGeneralTextHandler::getPreferredLanguage() != mod.getBaseLanguage())
-			return false;
+			return ModResolveStatus::BROKEN;
 
 		if(!mod.isCompatible())
-			return false;
-
-		if(mod.getDependencies().size() > resolvedModIDs.size())
-			return false;
+			return ModResolveStatus::BROKEN;
 
 		for(const TModID & dependency : mod.getDependencies())
+		{
 			if(!vstd::contains(resolvedModIDs, dependency))
-				return false;
+			{
+				if (vstd::contains(notResolvedModIDs, dependency))
+					return ModResolveStatus::WAITING;
+				else
+					return ModResolveStatus::BROKEN;
+			}
+		}
 
 		for(const TModID & softDependency : mod.getSoftDependencies())
 			if(vstd::contains(notResolvedModIDs, softDependency))
-				return false;
+				return ModResolveStatus::WAITING;
 
 		for(const TModID & conflict : mod.getConflicts())
 			if(vstd::contains(resolvedModIDs, conflict))
-				return false;
+				return ModResolveStatus::BROKEN;
 
 		for(const TModID & reverseConflict : resolvedModIDs)
 			if(vstd::contains(storage.getMod(reverseConflict).getConflicts(), mod.getID()))
-				return false;
+				return ModResolveStatus::BROKEN;
 
-		return true;
+		return ModResolveStatus::RESOLVED;
 	};
 
 	while(true)
@@ -803,7 +813,9 @@ void ModDependenciesResolver::tryAddMods(TModList modsToResolve, const ModsStora
 		std::set<TModID> resolvedOnCurrentTreeLevel;
 		for(auto it = modsToResolve.begin(); it != modsToResolve.end();) // One iteration - one level of mods tree
 		{
-			if(isResolved(storage.getMod(*it)))
+			ModResolveStatus status = isResolved(storage.getMod(*it));
+
+			if (status == ModResolveStatus::RESOLVED)
 			{
 				resolvedOnCurrentTreeLevel.insert(*it); // Not to the resolvedModIDs, so current node children will be resolved on the next iteration
 				assert(!vstd::contains(sortedValidMods, *it));
@@ -811,6 +823,14 @@ void ModDependenciesResolver::tryAddMods(TModList modsToResolve, const ModsStora
 				it = modsToResolve.erase(it);
 				continue;
 			}
+			if (status == ModResolveStatus::BROKEN)
+			{
+				resolvedOnCurrentTreeLevel.insert(*it);
+				brokenMods.push_back(*it);
+				it = modsToResolve.erase(it);
+				continue;
+			}
+
 			it++;
 		}
 		if(!resolvedOnCurrentTreeLevel.empty())