nix-config/.agents/skills/nix-config-umu-game/SKILL.md

name, description

name	description
nix-config-umu-game	Use when installing a Windows game launcher (二次元 / gacha or any non-Steam game) on a NixOS desktop via umu-launcher, given an installer URL or an .exe, or when such a launcher opens an invisible, transparent, black, or empty window under Wine.

Installing a Windows game launcher with umu

The bundled scripts/umu-install.nu renders the files in scripts/templates/. It creates a prefix, runs the installer, and writes launchers. Use the Nix DW-Proton default unless research identifies a specific installed release; then select it with PROTONPATH and pin that path in the game's conf. Every per-game detail lives under ~/Games/, never in this repo.

Bundled files

Path	What
scripts/umu-install.nu	installer and template renderer
scripts/templates/*.tpl	non-executable templates; placeholders use @NAME@
scripts/tests/test_install.py	offline regression tests

Layout

Path	What
~/Games/global.conf	optional, sourced by every game before its own conf
~/Games/<name>/prefix	the Wine prefix (WINEPREFIX)
~/Games/<name>/conf	optional per-game overrides (ENABLE_MANGOHUD=0, ...)
~/Games/<name>/prelaunch	optional executable, run before every launch
~/Games/<name>/run	generated launcher
~/Games/<name>/exec	generated helper: exec <exe-or-tool> [args...]
~/Games/<name>/<name>.desktop	generated desktop entry
~/Games/<name>/uninstall	generated: drop the desktop entry and (with y) the dir

Run, from the repo root:

nu .agents/skills/nix-config-umu-game/scripts/umu-install.nu <name> <setup.exe> <launcher> [gameid] [setup-args...]

<launcher> is relative to the prefix and GAMEID defaults to umu-default. At install, PROTONPATH resolves from $PROTONPATH, $UMU_PROTONPATH (the Nix-provided DW-Proton), then Steam's per-user compatibilitytools.d. At launch, the generated run script checks the current $PROTONPATH and $UMU_PROTONPATH before its saved default. A game's conf is sourced after those defaults, so set PROTONPATH there to pin a particular installed version across launches.

Procedure

1. Research first. Mandatory before inventing any fix: a documented fix beats a custom patch every time. Check the game's Lutris installer YAML as data only (https://lutris.net/api/installers/<game-slug> encodes winetricks verbs, write_file content, and prelaunch_command; do not install or run Lutris), then ProtonDB (protondb.com/app/<id>), Steam Community / r/linux_gaming threads, and GitHub issues for the launcher and Proton. Record whether reports require a Proton family and exact release. If no exact release is required, use the Nix-provided DW-Proton default. If one is required, inspect $UMU_PROTONPATH and installed Steam tools under ~/.local/share/Steam/compatibilitytools.d/ or ~/.steam/root/compatibilitytools.d/; select the matching installed path with PROTONPATH. Prefix the installer command with PROTONPATH="<selected-tool-directory>" and set the same value in the game's conf to pin it across launches; otherwise the runtime Nix UMU_PROTONPATH may take precedence. If the required release is absent from Nix and Steam, stop and ask the user before downloading it from elsewhere. Do not substitute a different release or use ProtonPlus/Lutris to fetch one.
2. Slug. Pick a lowercase <name> (e.g. wuthering-waves).
3. GAMEID. The umu database maps a title to a GAMEID whose protonfixes add CJK fonts, drop the SteamOS/SteamDeck vars, and keep Wine's Documents inside the prefix. Without it some games save into the host home or the wrong prefix. Fetch https://raw.githubusercontent.com/Open-Wine-Components/umu-database/main/umu-database.csv, match the title, and use its umu-<id>; if nothing matches, leave the default.
4. Download. curl -fL <url> -o ~/Games/<name>/setup.exe. The CN store pages are JS/token driven, so the user normally supplies the URL or the file itself.
5. Install. Run the bundled script. The first run also downloads umu's Steam runtime and the protonfix fonts, so it is slow. The installer is usually a GUI the user clicks through, but extra args after [gameid] go to setup.exe, so try a silent flag first (/S, /quiet, --silent); if it ignores them, fall back to clicking. On some CN installers the last page auto-starts the launcher. The script writes run/exec even if the installer exits non-zero, so a killed installer is not fatal.
6. Find the launcher. If <launcher> is only known after install, locate it under ~/Games/<name>/prefix/drive_c and set LAUNCHER in ~/Games/<name>/conf. Re-running the installer script invokes setup.exe again; only do so if that installer is known to handle reruns.
7. Per-game fix. Port step 1 findings into ~/Games/<name>/prelaunch (bash, chmod +x): winetricks verbs via ~/Games/<name>/exec winetricks <verbs>, file patches or registry tweaks via ~/Games/<name>/exec. Never commit the fix to this repo.
8. Re-run every launch, not once. A launcher that self-updates overwrites files it patches, so those patches belong in prelaunch.
9. Verify. ~/Games/<name>/run must open a visible launcher window. MangoHud is enabled by default with FPS and frame time at the top-left; set ENABLE_MANGOHUD=0 in conf to disable it, or override MANGOHUD_CONFIG. Re-running prelaunch must be idempotent. The launcher may then download the game body itself (tens of GB) -- that is the launcher's job, not this skill's, so the install is done once the window is usable. ENABLE_LOG=1 captures last-run.log when something misbehaves.

Invisible / transparent launcher window

A WebView2/.NET (WPF) launcher that shows an empty or fully transparent window is rendering with AllowsTransparency. Fix the DLL, not Wine:

1. find ~/Games/<name>/prefix/drive_c -iname 'launcher_main.dll' (usually under a X.Y.Z.W version dir).
2. Rename that WPF property in place, keeping the byte length so PE offsets stay valid: bbe -e 's/\x12AllowsTransparency/\x09IsEnabled\x1bA\x00\x03AAAAA/' <dll>.
3. Put it in ~/Games/<name>/prelaunch so it is re-applied on every launch, because a launcher self-update restores the original DLL. Restart the launcher after patching.

Half-width tile instead of fullscreen

Niri tiles a new window into a column of default-column-width { proportion 0.500000; } (50%), and a launcher that only opens a large borderless window cannot take over the screen by itself: with a 4K panel at scale 1.5 Niri's logical space is 2560x1440, so a window asking for the physical 3840x2160 becomes an ordinary half-width tile. Nothing is broken -- the umu app-id is just not covered by a rule.

Every umu/Proton game reports steam_app_<GAMEID>. In this repo home/linux/gui/niri/conf/windowrules.kdl matches app-id="^steam_app_[0-9]+$" and sets open-fullscreen true, so games open fullscreen without a per-game rule. niri validate checks the live config, Mod+Shift+F (fullscreen-window) toggles an already-open window, and setting the in-game resolution to the compositor's logical size (2560x1440 here) avoids the mismatch too.

A launcher shares that app id with its game, so the rule also catches the launcher's own windows: a helper that is still untitled while it maps, and the announcement popup (公告 / Announcement), which on this launcher renders as a pure white rectangle. Fullscreening either one buries the UI that opened it, so both are excluded. A window rule applies when a window opens, so an already-open offender needs Mod+Shift+F on it or a relaunch; drop open-fullscreen true altogether if a launcher keeps surprising you -- the game then costs one Mod+Shift+F per session instead.

Mojibake that is not a missing font

Latin-looking garbage such as 我已阅读 where the launcher should say 我已阅读并同意, while other Chinese on the same window renders fine, is UTF-8 decoded as Windows-1252. Confirm the pattern:

python3 -c "print('我已阅读并同意'.encode('utf-8').decode('cp1252','replace'))"

If that prints exactly what the launcher shows, the bug is identified and you can stop here.

The string itself is fine and so are the fonts: the same launcher renders 请输入手机号 and 登录 correctly, and the garbled label exists as correct UTF-16 in KRSDKEx.dll. The bytes are simply decoded with a single-byte Western codepage.

This is not the prefix locale. Setting LANG=zh_CN.UTF-8 in ~/Games/<name>/conf does change the prefix (verified in this repo: "ACP" went 1252 -> 936 and "LocaleName" en-US -> zh-CN), and the garbling stayed byte-for-byte identical. The launcher decodes those bytes as Latin-1 no matter what Windows codepage it is told to use, so this is an upstream bug in its own text pipeline: report it, or accept it -- the launcher still works. LANG is nevertheless the lever for the prefix locale, not LC_ALL: Proton clears LC_ALL unless HOST_LC_ALL is set.

So: check the bytes first, do not install more CJK fonts, and do not promise a locale fix.

Silent install

umu-install.nu <name> <setup.exe> <launcher> <gameid> /S passes /S to the installer. Not all installers honour it; try /quiet or --silent too, then fall back to the GUI.

Desktop entry and persistence

The script also writes ~/.local/share/applications/<name>.desktop (and a copy at ~/Games/<name>/<name>.desktop), so the game shows up in the desktop launcher. Under an impermanence setup both ~/Games and ~/.local/share/applications must be in the host's preservation.preserveAt list; in this repo ~/Games and .local/share/umu already are, and hosts/idols-ai/preservation.nix now persists .local/share/applications too.

Uninstall

Run ~/Games/<name>/uninstall: it removes the desktop entry and then asks before deleting ~/Games/<name> (prefix + game files). To keep the game and only drop the menu entry, delete the .desktop file by hand.

Optimize the launch

~/Games/<name>/conf (or ~/Games/global.conf) is a shell file the generated run sources. Defaults are ENABLE_MANGOHUD=1, MANGOHUD_CONFIG="fps=1,frametime=1,position=top-left", ENABLE_GAMEMODE=0, ENABLE_GAMESCOPE=0, GAMESCOPE_ARGS="-f", and ENABLE_LOG=0. Set ENABLE_MANGOHUD=0 to hide the overlay, ENABLE_GAMESCOPE=1 + GAMESCOPE_ARGS="-f -w 3840 -h 2160" for the handheld / multi-monitor case, ENABLE_GAMEMODE=1 for GameMode, and ENABLE_LOG=1 to capture the run. A dGPU wrapper still goes outside: nvidia-offload ~/Games/<name>/run. Shader caches are kept in ~/Games/<name>/shader-cache.

Escape hatches

• ~/Games/<name>/exec <exe-or-tool> [args...] runs anything in the prefix with the right env: an absolute path to a game exe or repair tool, or a bare Wine tool (winecfg, explorer, regedit, uninstaller), which it runs as umu-run <Proton's wine> <tool>. Both forms are handed to umu-run, so they execute inside umu's Steam runtime container -- that is what makes them work on a non-FHS distro like NixOS, where Proton's wine cannot start on its own.
• ~/Games/<name>/run <game args> passes extra args to the launcher.
• Kill a stuck prefix with pkill -f '/Games/<name>/prefix', or rm -f ~/Games/<name>/prefix/pfx.lock.

Common mistakes

• Committing a game name, URL, or patch to this repo instead of ~/Games/<name>/.
• Patching once instead of in prelaunch -- the next launcher self-update undoes it.
• Dropping the GAMEID -- the in-game CJK fonts and the save location go wrong.
• Installing more CJK fonts when the text is mojibake -- decode the bytes first (see above).
• Expecting umu to fetch DW-Proton: it only auto-manages GE-Proton / UMU-Proton; use Nix or Steam installed paths. Ask the user before obtaining a required release from elsewhere.
• Running a Wine tool without umu. umu-run winecfg does not work -- umu only special-cases winetricks -- and $PROTONPATH/files/bin/wine winecfg fails on any non-FHS distro (on NixOS the 32-bit loader it needs lives only inside the Steam runtime container). Use ~/Games/<name>/exec winecfg; exec goes through umu-run, which provides that container.
• Waiting for the game download before calling the install done: the launcher's own download is out of scope here.
• On NixOS a game needing 32-bit or Vulkan needs hardware.graphics.enable32Bit, and Steam is a module rather than a package -- see the nix-config-desktop skill.

Prior art

ESKAP3/umu-skeleton (filesystem-as-game-manager, global.conf, tools), gizmo-ds/endfield-run (-exec installer), Septa-Serpenta-Seraph/Vesper (umu + GAMEID notes), joshsymonds/nix-config (research-first debugging), olafkfreund/nixarchy (NixOS gaming skill).

Regression tests

From the repo root:

python3 .agents/skills/nix-config-umu-game/scripts/tests/test_install.py

Requires python3, nu, bash, and shellcheck. Uses temporary homes and a stub umu-run; no game downloads, Wine windows, or changes to existing games. It checks template permissions, rendered shell syntax and lint, installer arguments and failures, configuration precedence, prelaunch, logging, launch wrappers, literal paths, runtime Proton overrides, tool routing, and uninstall confirmation.