An opt-in second Steam client (Steam settings, Steam client: x86-64): Valve's
x86-64 Linux client, unchanged, runs under FEX in its own home with its own
game library and the same sign-in. Linux builds run directly, so titles such
as Team Fortress 2 and Half-Life use their Linux versions; Windows games use
DroidDeck-Proton as on arm64. The arm64 client stays the default.
- droiddeck-steam-x64: FEX and the x86-64 rootfs from DroidDeck-Components
(sha256-pinned), client install and sync from Valve's CDN, sign-in shared
with the arm64 client, its web helper on the GPU (ANGLE GL over FEX's GL
thunk, zink, Turnip), Proton wrappers for the arm64 client's tools,
DroidDeck direct for Linux builds, SD-card library (x86-64/ beside the
arm64 one), repair.
- FEX 2610 built by build-fex.yml with thunks and three patches: an openat2
fallback without openat2 (proot), newer-clang thunkgen, MAP_32BIT
exhaustion returning ENOMEM. libblsession resolves RESOLVE_IN_ROOT paths
inside the root.
- Session: x86-64 gating, shortcuts and compatibility tools per client,
logs from the client that ran.
- App: client setting with the FEX version, an x86-64 chip on the Games
header, the active client's library, art, storage, downloads, repair,
Offline Mode, Decky, desktop mode, optional VAC diagnostics; per-client
state for art, the content log, repair and leftovers.
- Strings in every locale.
- Review fixes: the library cache is saved only by the newest scan; an
abandoned session's Steam logs come from the client it recorded; distinct
VAC console names; FEXInterpreter in CPU pinning; clearer VAC hint in
pl, ru, uk, cs and bg.
The session's proot runs with -i <app uid>, and the rootfs names that uid
root, so the client calls itself root while geteuid() returns the app's
uid. The read-only retry required geteuid() == 0 and never ran: the
Proton Experimental (ARM64) update still failed with Missing file
permissions on wineopenxr.dll (2026-09-26 16:07, 2,471 read-only files).
Also recognise the client by the path it was started by: the kernel's
/proc/self/exe names proot's loader for every process in the session.
The client runs as proot's root, which the kernel does not see, and
leaves many content files read-only; an update that rewrites one was
refused (EACCES) and cancelled with "Missing file permissions"
(Proton Experimental (ARM64), wineopenxr.dll). For the client's own
processes, a refused write-open of a file the app owns now gets the
owner's write bit - on the file, or on the directory a new file goes
into - and one more try. Games and Wine keep ordinary permissions.
MaxsTechReview