Fix VFS not intercepting writes for games on SD card

pressure-vessel's default sharing of /run/media and home uses non-recursive
bind mounts that don't propagate FUSE submounts into the container. The
shouldExposeMountPointToPressureVessel function excluded all paths under /run
(isSystemRootPath) and under /run/media (pressureVesselSharesByDefault), so
the fuse.mo2linux mount point was never added to PRESSURE_VESSEL_FILESYSTEMS_RW.

Inside the container, the game saw the real SD card Data directory instead of
the FUSE overlay, so all VFS writes (shader cache, config files, overwrite)
bypassed staging entirely — VFS_staging stayed empty and write-heavy mods like
Community Shaders logged "Failed to save shader" on every compile.

Internal-drive games were unaffected because pressure-vessel's home directory
handling is recursive and propagates FUSE submounts correctly.

Fix: detect fuse.mo2linux in the mountinfo scan and always add it to
PRESSURE_VESSEL_FILESYSTEMS_RW regardless of its parent path classification.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/src/protonlauncher.cpp b/src/src/protonlauncher.cpp
index f6059e3..e8c2a89 100644
--- a/src/src/protonlauncher.cpp
+++ b/src/src/protonlauncher.cpp
@@ -169,6 +169,14 @@ bool shouldExposeMountPointToPressureVessel(const QString& mountPoint,
                                             const QString& fsType,
                                             const QString& source)
 {
+  // Always expose our VFS FUSE mount explicitly.  pressure-vessel's default
+  // sharing of /run/media (and home) uses non-recursive bind mounts that do
+  // not propagate FUSE submounts into the container — games on SD card end up
+  // writing to the real game directory and bypassing the VFS entirely.
+  if (fsType == QStringLiteral("fuse.mo2linux")) {
+    return !mountPoint.isEmpty() && mountPoint != "/";
+  }
+
   if (mountPoint.isEmpty() || mountPoint == "/" ||
       pressureVesselSharesByDefault(mountPoint) ||
       isSystemRootPath(mountPoint)) {