Linux install never runs the shader compatibility scan; missing report is treated as a failed scan, so FSR/RenderScale is silently disabled and the Extra tab always shows Native

[Petyok]

Optimum version: 0.3.14 (source zip from 2026-08-27; the same tag before the 2026-09-01 update)
Install method: ./scripts/install-linux.sh --install-dir ~/Applications/optimum --non-interactive
Host: Arch Linux, Vintage Story 1.22.7, Intel HD 6000 (Mesa 26.2), .NET 10.0.11

Summary

On Linux the installed client never runs the shader compatibility scan, so <dataPath>/.optimum/shader-compatibility.json is never written. The game-side loader treats a missing report as a failed scan, which silently disables every optional shader feature — including RenderScale (FSR). The result for the user: the Extra tab always shows Render Scale = Native, changing the dropdown does nothing (and looks like "settings reset on every restart"), and FSR is never active. No warning anywhere.

The Windows package (built off-platform with make package-win) behaves correctly: Optimum.exe is the real launcher, the scan runs, the report is written, FSR works.

Evidence

1. The Linux install has no runtime launcher.

$ file ~/Applications/optimum/Optimum
ELF 64-bit LSB pie executable, x86-64 ...
$ strings ~/Applications/optimum/Optimum | grep -m1 '\.dll$'
Vintagestory.dll                      # apphost for the game, not for Optimum.dll
$ ls ~/Applications/optimum | grep -i '^Optimum'
Optimum  Optimum.Api.Contracts.dll  Optimum.desktop  optimum-launch.sh   # no Optimum.dll

install-linux.sh patches the assemblies in place at install time (Patching VintagestoryLib.vanilla.dll... in the install log; VintagestoryLib.vanilla.dll sits next to the patched VintagestoryLib.dll). ShaderCompatibilityScanner.Scan() / SaveReport() live in Optimum.Launcher/Program.cs, so with no launcher process they never execute.

2. Consequently the data path has no launcher state at all:

$ ls -a ~/.config/VintagestoryData/.optimum/     # after several weeks of use
ls: cannot access ...: No such file or directory
$ find ~ -name shader-compatibility.json -o -name optimum-launcher.log    # nothing

3. Game side: a missing report equals a failed scan.

sources/VintagestoryApi/Config/OptimumConfig.cs, LoadShaderCompatibilityReport():

_shaderCompatibilityScanFailed = true;          // pessimistic default
...
if (!File.Exists(reportPath)) return;           // ← missing file leaves ScanFailed == true

and

public static bool IsShaderFeatureDisabled(string feature) =>
    _shaderCompatibilityScanFailed || _shaderCompatibilityDisabledFeatures.Contains(feature);

public static float EffectiveRenderScale => IsShaderFeatureDisabled("RenderScale") ? 1.0f : RenderScale;

So ClientSettings.OptimumRenderScale is forced to 1.0 at startup regardless of ModConfig/optimum.json (mine has "RenderScale": 0.67), the Extra tab renders "Native", and onOptimumRenderScaleChanged returns early:

if (OptimumConfig.IsShaderFeatureDisabled("RenderScale")) return;

which the user perceives as "the setting resets every time I relaunch".

Repro

1. Install on Linux via install-linux.sh.
2. Put "RenderScale": 0.67 into <dataPath>/ModConfig/optimum.json (or pick Performance in the Extra tab).
3. Launch, open Settings → Extra: Render Scale shows Native. Change it, restart: still Native. No log line explains why.

Workaround that confirms the diagnosis

Hand-writing the report the scanner would have produced for this mod set (CarryOn = Harmony render hooks, no external shader assets):

{ "ScanFailed": false, "Fingerprint": null,
  "DisabledFeatures": ["EntityLightBatch","EntityShaderStateCache","MapPageCache","Oit","ShaderPreprocessParallel"] }

into ~/.config/VintagestoryData/.optimum/shader-compatibility.json → next launch the Extra tab shows Performance, the choice persists, and FSR is visibly active. Measured on a 15 W Broadwell-U (i5-5350U + HD 6000): in singleplayer the CPU cores stopped dipping to 500 MHz under load (the iGPU no longer starves the shared package power budget), package temperature median 81 °C / max 87 °C over 7 minutes, zero thermal-throttle events, no stutter.

Suggested fixes

1. Linux packaging: either ship and use the launcher (as on Windows/macOS) so the scan runs, or run ShaderCompatibilityScanner once from install-linux.sh / optimum-launch.sh and write the report into the data path. Note the scan has to be repeated when the mod set changes, which argues for the launcher route.
2. Loader semantics: a missing report should not be reported as ScanFailed = true. Options: treat "no report" as "nothing disabled" (matches the Windows behaviour when the scan finds conflicts=0), or keep the pessimistic default but log a clear warning and show a hint in the Extra tab ("shader scan not run — FSR disabled") instead of silently rendering Native and ignoring the dropdown.

Happy to test a patched build on Linux — this box reproduces it deterministically.