From 4e535df3b29c7a454cc78023dcb21bd344a0ca77 Mon Sep 17 00:00:00 2001
From: Alistair-Afton <AlistairDev@gmx.de>
Date: Wed, 16 Sep 2026 16:12:04 +0200
Subject: [PATCH] gui/mod-manager: warn when a preset is missing new vanilla
 mods

When Bay12 adds a new vanilla mod, existing presets silently exclude it
since the preset modlist predates it. Presets now record the set of
installed vanilla mod ids when saved or overwritten. On load, the
current vanilla set is compared against the recorded set and a warning
lists any new vanilla mods the preset does not include. The recorded
set is refreshed on every load so the warning fires only once per new
mod. Presets saved before this change record the current set silently
on their first load, since intentionally excluded vanilla mods cannot
be distinguished from missing ones.

Fixes DFHack/dfhack#5839
---
 changelog.txt       |  2 ++
 gui/mod-manager.lua | 65 ++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 64 insertions(+), 3 deletions(-)

diff --git a/changelog.txt b/changelog.txt
index 1ed30ae501..dcbcbee297 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -32,6 +32,8 @@ Template for new versions:
 
 ## New Features
 
+- `gui/mod-manager`: warn when loading a preset that doesn't include vanilla mods that were added to the game after the preset was saved
+
 ## Fixes
 - `bodyswap`: fix "invalid argument count" when the target unit has no nemesis record
 - `fix/loyaltycascade`: guard against citizens that are not historical figures and emit a warning.
diff --git a/gui/mod-manager.lua b/gui/mod-manager.lua
index a3a745963d..ed6ef8c886 100644
--- a/gui/mod-manager.lua
+++ b/gui/mod-manager.lua
@@ -161,6 +161,19 @@ local function get_active_modlist(viewscreen)
     return t
 end
 
+-- ids of the vanilla mods currently installed with the base game, so presets
+-- can detect when Bay12 adds a new vanilla mod that the preset doesn't cover
+function get_vanilla_mod_ids(viewscreen)
+    local fields = get_modlist_fields("base_available", viewscreen)
+    local ids = {}
+    for i, v in ipairs(fields.id) do
+        if vanilla(fields.src_dir[i]) then
+            table.insert(ids, v.value)
+        end
+    end
+    return ids
+end
+
 --- @return string[]
 --- @return { id: string, new: string }[]
 local function swap_modlist(viewscreen, modlist)
@@ -204,7 +217,11 @@ ModmanageMenu.ATTRS {
 local function save_new_preset(preset_name)
     local viewscreen = get_any_moddable_viewscreen()
     local modlist = get_active_modlist(viewscreen)
-    table.insert(presets_file.data, { name = preset_name, modlist = modlist })
+    table.insert(presets_file.data, {
+        name = preset_name,
+        modlist = modlist,
+        vanilla_mods = get_vanilla_mod_ids(viewscreen),
+    })
     presets_file:write()
 end
 
@@ -225,6 +242,7 @@ local function overwrite_preset(idx)
     local viewscreen = get_any_moddable_viewscreen()
     local modlist = get_active_modlist(viewscreen)
     presets_file.data[idx].modlist = modlist
+    presets_file.data[idx].vanilla_mods = get_vanilla_mod_ids(viewscreen)
     presets_file:write()
 end
 
@@ -272,7 +290,32 @@ local function load_preset(idx, unset_default_on_failure)
     end
 
     local viewscreen = get_any_moddable_viewscreen()
-    local modlist = presets_file.data[idx].modlist
+    local preset = presets_file.data[idx]
+    local modlist = preset.modlist
+
+    -- detect vanilla mods that were added to the base game after this preset
+    -- last recorded the vanilla mod set and that the preset doesn't include
+    local in_modlist = {}
+    for _, v in ipairs(modlist) do
+        in_modlist[v.id] = true
+    end
+    local vanilla_ids = get_vanilla_mod_ids(viewscreen)
+    local new_vanilla = {}
+    if preset.vanilla_mods then
+        local recorded = {}
+        for _, id in ipairs(preset.vanilla_mods) do
+            recorded[id] = true
+        end
+        for _, id in ipairs(vanilla_ids) do
+            if not recorded[id] and not in_modlist[id] then
+                table.insert(new_vanilla, id)
+            end
+        end
+    end
+    -- update the recorded set so the warning only fires once per new mod
+    preset.vanilla_mods = vanilla_ids
+    presets_file:write()
+
     local failures, changes = swap_modlist(viewscreen, modlist)
     local text = {}
 
@@ -309,7 +352,23 @@ local function load_preset(idx, unset_default_on_failure)
         end
     end
 
-    if failed or changed then
+    if #new_vanilla > 0 then
+        if failed or changed then
+            table.insert(text, NEWLINE) -- just to separate the sections
+        end
+        table.insert(text, {
+            text='New vanilla mods are not included in the preset.',
+            pen=COLOR_YELLOW,
+        })
+        table.insert(text, NEWLINE)
+        table.insert(text, NEWLINE)
+        for _, v in ipairs(new_vanilla) do
+            table.insert(text, ('- %s'):format(v))
+            table.insert(text, NEWLINE)
+        end
+    end
+
+    if failed or changed or #new_vanilla > 0 then
         dialogs.showMessage("Warning", text)
     end
 end