saphid--frame-control/docs/apks.md

Installing APKs (Lepton)

The confidence labels are the same as in ssh.md. Android apps run in Lepton, Valve's Waydroid-based container. Lepton is built for games, not general Android use (GamingOnLinux).

VR streaming clients: WiVRn 26.9 and ALVR 20.14.1 install, but both fail OpenXR instance creation on the checked Frame because its Android runtime lacks XR_KHR_convert_timespec_time (verified 2026-09-28, SteamOS 0.4.1, BUILD_ID 20260925.6191901). They are not Frame Control dependencies. See the feasibility results and options.

Install from the Mac: one app, one Lepton instance (verified 2026-09-25)

Use Frame Control's Android apps section (search, Install, Test, Report), drop an .apk on Send to Frame, or:

./scripts/install-apk.sh some-app.apk            # own instance, Steam shortcut
python3 ui/frame_android.py list|launch|stop|remove|probe <package>

Each APK becomes its own app, the way T3 Code is set up (see the instance section below), instead of going into Lepton Development:

1. ui/frame_apk.py reads the package, label, version, ABIs and icon (a stdlib parser of the binary manifest and resource table, so no Android SDK). APKs that need API > 30 or have no arm64-v8a build are refused.
2. The APK, frame/android/lepton-app.sh (as launch.sh), instance.id, meta.json, the icon and the lepton-show-flatscreen marker go to ~/Applications/Android/<package>/ on the Frame.
3. A non-Steam shortcut is added through Steam's CEF debug port (frame/android/steam_shortcuts.py), with no Steam restart.
4. Launching the shortcut runs Lepton directly with SteamAppId set to the instance id (2800000000 + crc32(package) % 70000000). That's a "steamlaunch" context, so app data in compatdata/<id>/internal survives restarts and updates, and each app gets its own SteamVR panel. Several can run at once alongside Lepton Development, each in its own container (lepton-steamlaunch-<id>, ADB on 5556, 5557, …).

Verified with AntennaPod and Tabletop Tools: installed in about 7 s, launched from the shortcut, stopped, and relaunched with their data intact. ADB and Lepton Development aren't involved.

--dev keeps the old path: ADB into Lepton Development over an SSH tunnel (first free Mac port from 15555), which starts Lepton Development if needed. Apps installed that way are deleted when it exits (see below). No pairing or "Allow debugging?" prompt is needed for either path.

Lepton Development must be installed once. Over SSH, ssh frame 'steam steam://install/3056000' queues it, but the install still needs to be confirmed or started in the headset.

When an app needs a newer Android

Lepton is Android 11 (API 30), with arm64-v8a only. If Frame Control refuses an APK, it shows compatible versions from F-Droid's main and archive repos and IzzyOnDroid. It shows at most eight version names, newest first, preferring an arm64-only build, and says how many compatible builds it found in total. Each index is reduced to its compatible builds once a day and cached (about 16 MB). The first lookup takes about 30 s and 100 MB of memory; later ones are instant. Choose Install to download a listed version, verify its SHA-256 against the index, and install it as its own app.

You can also inspect a file or look up a package from the command line:

python3 ui/frame_android.py info some-app.apk
python3 ui/frame_android.py versions some-app.apk
python3 ui/frame_android.py versions org.example.app

The search links open APKMirror, APKPure, Uptodown, F-Droid and GitHub. Pick a version whose minimum is Android 11 or lower and that has an arm64-v8a build (or no native code). Frame Control does not fetch APKs from those search sites. Older versions may lack fixes, and being installable does not guarantee an app will run: see the missing services below. Android may refuse a downgrade or an update signed by a different publisher; removing the app deletes its data.

Installed apps disappear when Lepton Development closes (verified 2026-09-25)

Lepton Development runs in a throwaway "dev" context. When it exits for any reason (you close it, or it crashes), the launcher script ~/.local/share/Steam/steamapps/common/Lepton/lepton calls clear_baked_app_data "non steamlaunch container" and deletes every app installed over ADB. The journal shows Clearing baked app data due to non steamlaunch container, and pm list packages -3 is empty afterwards.

The script skips the wipe when LEPTON_NO_CLEANUP is set (liblepton/liblepton.sh, clear_baked_app_data). To keep your apps, set Lepton Development's Steam launch options to:

LEPTON_NO_CLEANUP=1 %command%

(Steam → Library → Lepton Development → Properties → Launch Options.) Inferred from the script, not yet tested across a restart.

Which APKs work (verified 2026-09-25, SteamOS build 20260922.6101926)

Lepton is LineageOS 18.1 (lepton_arm64_only): Android 11, API 30, abilist=arm64-v8a only, Mesa (Turnip, Adreno 750) with GLES 3.2 and Vulkan 1.4. About 30 F-Droid apps were installed and opened on the Frame to check each rule. The results are in the compatibility database (see compat-db/README.md).

Won't install (the installer refuses):

Rule	Seen on device
minSdkVersion > 30	INSTALL_FAILED_OLDER_SDK: Requires newer sdk version #33 (current version is #30)
Native code without arm64-v8a (32-bit ARM or x86 only)	INSTALL_FAILED_NO_MATCHING_ABIS

Crash on launch. Lepton has no clipboard system service, so getSystemService(CLIPBOARD_SERVICE) returns null:

What	Result
Jetpack Compose UI < 1.11	Crashes as soon as a Compose screen appears: null cannot be cast to non-null type android.content.ClipboardManager in AndroidComposeView. Seen with 1.5, 1.6, 1.7, 1.8 and 1.10 apps.
Jetpack Compose UI 1.11, 1.12, 1.13	Works. Six apps opened fine, including Aurora Store and NewPipe.
Old Compose, but the first screen uses classic Views	Opens (FoCal, Compose 1.3), and crashes only on Compose screens
SDL2 apps, including Kivy	Crash: SDL calls ClipboardManager.addPrimaryClipChangedListener at start-up
Godot 4.3	Crashes (clipboard cast). Godot 4.6.1 works.

Works: classic Android Views apps, Flutter (2 of 2), libGDX (2 of 2), Compose 1.11+, Firebase-using apps. React Native: 2 of 3 opened; one (controlloid) died with SIGSEGV on the Hermes JS thread. A Qt 6 app (AusweisApp) failed on a missing libc++ symbol.

Missing pieces: an app may open but fail when you use one of these:

• No Google Play Services.
• No activity for VIEW of web links, OPEN_DOCUMENT/GET_CONTENT (no file picker), IMAGE_CAPTURE, or text-to-speech. WebView (Chromium 152) is there.
• No Downloads or Contacts providers.
• Missing system services also include accessibility, vibrator, phone, print, usb, nfc and autofill. The declared features lack touchscreen.multitouch, bluetooth_le and telephony.
• No on-screen keyboard (IME) is installed. How text entry reaches Android apps in the headset hasn't been checked.

Lepton itself can crash. Three times during testing, the graphics HAL (android.hardware.graphics.composer@2.1-service) aborted right after an app crashed. SurfaceFlinger died, the whole lepton-dev container exited, and the installed apps were wiped (see above). A retry of the same app worked, so it's intermittent rather than app-specific.

How good are the predictions? In a random sample of 12 apps rated "Should work", all 12 installed, opened and were still running 12 s later (two needed a retry because Lepton crashed mid-install). "Opened" isn't the same as fully working: see the missing pieces above.

Catalogue and compatibility reports

Frame Control's Android apps section lists every F-Droid app with a verdict: Works on Frame, Should work, Might work, Probably crashes, or Won't work, with the reasons. As of 2026-09-25 that's 30 working, 3,323 should work, 223 might work, 723 probably crash (mostly Compose < 1.11) and 156 won't install. Each app is rated on its newest version that Lepton can install, because F-Droid often publishes separate per-ABI builds and the newest is frequently x86_64. Install downloads the APK (SHA-256 checked against the F-Droid index) and sets it up as its own instance.

No ProtonDB-style database for sideloaded Android apps on the Frame existed as of 2026-09-25. Steam Frame Hub collects community reports for Steam games only and has no public API, and Valve's "Great on Frame" badges and each Steam app's recommended_runtime (for example lepton-stable) also cover Steam games only (VR.org). So Frame Control keeps its own. Your reports are saved on your Mac; the maintainer's copy also syncs them to a private Lakebed database. Test records whether the app stays up in its own instance, and Report (for any APK, F-Droid or not) records whether it worked, how it was run, where it came from, and notes, each with the SteamOS and Lepton build ids. See compat-db/README.md and apk-catalog/README.md.

In-headset app store: F-Droid 1.17 (verified 2026-09-25)

F-Droid 1.23 uses an old Compose and crashes on launch. F-Droid 1.17.2, the newest archived build without Compose, runs, loads the full catalogue (the first repo update takes about 90s), and can install apps. F-Droid 2.0 uses Compose 1.12, so it should work, but it hasn't been tried. The catalogue's Install button for F-Droid installs 1.17.2. To let F-Droid install apps without a settings prompt, with the tunnel open:

adb -s $S shell appops set org.fdroid.fdroid REQUEST_INSTALL_PACKAGES allow

Handy commands

Open a tunnel by hand (use any free local port):

ssh -f -N -M -S /tmp/frame-adb.sock -L 127.0.0.1:15555:127.0.0.1:5555 frame
adb connect 127.0.0.1:15555
S=127.0.0.1:15555
# when done: adb disconnect $S; ssh -S /tmp/frame-adb.sock -O exit frame

Then:

adb -s $S shell pm list packages -3              # installed third-party apps
adb -s $S shell monkey -p <pkg> -c android.intent.category.LAUNCHER 1
# If monkey exits with -5 (it did for T3 Code), start the activity directly:
adb -s $S shell am start -W -n "$(adb -s $S shell cmd package resolve-activity --brief -c android.intent.category.LAUNCHER <pkg> | tail -n 1)"
adb -s $S logcat -d -b crash                      # why an app died
adb -s $S uninstall <pkg>
adb -s $S exec-out screencap -p > shot.png        # the Lepton window

Reaching a Mac service from Lepton (T3 Code v2, verified 2026-09-25)

Lepton runs in podman with pasta networking. It has its own loopback, so a port on the Frame's 127.0.0.1 isn't visible as 127.0.0.1 inside Android. But pasta runs with --map-gw, so the gateway address inside Lepton (192.168.1.1 on the home network) maps to the Frame host's loopback.

T3 Code v2 on the Mac listens only on 127.0.0.1:3873. To reach it:

1. Keep ssh -N -R 127.0.0.1:3873:127.0.0.1:3873 frame running on the Mac, for example from a LaunchAgent with KeepAlive, so launchd restarts it if it drops.
2. In the app on the Frame, the environment host is 192.168.1.1:3873.

The app on the Frame was built from the T3 Code v2 nightly source with expo prebuild and gradlew assembleRelease -PreactNativeArchitectures=arm64-v8a, using Homebrew openjdk@17 and the android-commandlinetools SDK. It's signed with the debug key.

To pair again, issue a one-time code on the Mac and type it into Add environment:

A="/Applications/T3 Code (V2 Preview).app"
ELECTRON_RUN_AS_NODE=1 "$A/Contents/MacOS/T3 Code (Alpha)" \
  "$A/Contents/Resources/app.asar/apps/server/dist/bin.mjs" \
  auth pairing create --base-dir "$HOME/.t3-v2" --ttl 15m --label "Steam Frame"

The app is deleted whenever Lepton Development closes (see above), so reinstall it afterwards or set LEPTON_NO_CLEANUP=1. The gateway address comes from the Frame's network when Lepton starts. On a different network, check it with adb shell ip route and edit the host.

Lepton Development forgets apps; give an app its own instance (verified 2026-09-25)

Lepton Development wipes every installed app when it exits. Its launcher logs Clearing baked app data due to non steamlaunch container, unless LEPTON_NO_CLEANUP is set. A Steam-style launch (with SteamAppId set) is a "steamlaunch" context and keeps its data:

• App data lives in STEAM_COMPAT_DATA_PATH/internal/<package> (symlinked to /data/data/<package>) and survives everything, including APK updates.
• STEAM_COMPAT_DATA_PATH/baked is Lepton's Android snapshot. It's rebuilt when the APK changes, or when the app exits within 30 seconds of starting.
• STEAM_COMPAT_DATA_PATH must be under ~/.local/share/Steam (use steamapps/compatdata/<id>). Only that tree is mounted in the container. Put it anywhere else and the symlinks dangle, so the app crashes with ENOENT on its first file write.
• Lepton runs apps headless unless an empty lepton-show-flatscreen file sits next to the APK (STEAM_COMPAT_INSTALL_PATH).
• Several instances can run at once. Each gets ADB on 5555 + offset (podman ps --format "{{.Names}} {{.Labels.adb_port}}").
• Outside Steam, Lepton's setpgid --foreground re-exec fails with no terminal. Set IS_PARENT=true and start it with setsid --wait.

frame/t3code/launch.sh does all this for T3 Code (context steamlaunch-2873873873; ADB is the first free 5555 + n, e.g. 5557). It needs the Steam client running (it mounts ~/.steam/steam.pipe).

T3 Code in the Steam library (verified 2026-09-25). The wrapper lives on the Frame at ~/Applications/T3Code/launch.sh, with t3code.apk and the flatscreen marker next to it. It's a non-Steam shortcut called "T3 Code" (shortcut app id 3130509679). Launching it from Steam gets its own SteamVR panel, valve.steam.desktopgame.3130509679, and opens already paired.

• The shortcut was added without restarting Steam, through Steam's CEF debug port (127.0.0.1:8080 on the Frame, target SharedJSContext): SteamClient.Apps.AddShortcut(name, exe, "", ""), then SetShortcutName and SetShortcutStartDir. steam steam://addnonsteamgame/<path> only logged the URL and added nothing.
• To launch it over SSH: steam steam://rungameid/13445436691150012416, which is (3130509679 << 32) | 0x02000000.
• Steam sets STEAM_FOSSILIZE_DUMP_PATH for shortcut launches but not STEAM_COMPAT_SHADER_PATH. Lepton then dies with "unbound variable", so the wrapper sets both.
• To update T3, replace t3code.apk. Lepton rebuilds its snapshot on the next launch, and the pairing survives.

Crashing apps can take down the headset session (verified 2026-09-25)

Some apps crash Android's graphics composer HAL, which kills the Lepton container. On 2026-09-25 a batch crash-test also coincided with steamvr.service restarting "on client request", which stops and SIGKILLs gamescope-session. After one of those kills, gamescope crash-looped about once a second on rendervulkan.cpp:2181 ... Assertion '!modifiers.empty()' because it kept attaching to the SteamVR processes orphaned from the dead session. The fix without sudo was to for p in vrdashboard vrcompositor vrserver; do pkill -TERM -x $p; done (pkill takes one pattern). The next session then started SteamVR fresh and recovered within a minute.

Android display: resolution, UI scale, text size (verified 2026-09-25, SteamOS 0.3.0, build 20260922.6101926)

Each running Lepton instance has its own ADB port on the Frame, assigned at launch: 5555 is Lepton Development, and own-instance apps take the next free port (T3 Code was on 5557). Find them with ss -ltn (5555–5599) and identify each with pm list packages -3. Both instances reported Physical size: 1920x1080. Their densities were 180 dpi (Lepton Development) and 213 dpi (T3 Code), and settings get system font_scale returned null (1.0).

These all apply immediately and read back as set. Tested on Lepton Development only:

adb -s $S shell wm size 2560x1440         # or: wm size reset
adb -s $S shell wm density 240            # or: wm density reset
adb -s $S shell settings put system font_scale 1.15
adb -s $S shell settings delete system font_scale

After a wm reset, Android writes font_scale=1.0 back asynchronously, so a single delete that follows one reads back 1.0. A second delete a second later leaves it null. Frame Control's Android display card does this for you (/api/android/display).

Inferred, not yet checked in the headset: a bigger Android resolution with density scaled to match (2560×1440 at 4/3 of the density) gives sharper text, because gamescope scales Lepton's surface to fit the same panel. Also unverified: whether the settings survive the app or its Lepton instance relaunching. Lepton Development rebuilds its Android data on exit, so there they probably don't.

Expansion files and save backups

SideQuest-inspired CLI helpers install local OBB files into an already-running app instance and back up/restore a stopped instance's private app data. See SideQuest features and limits for commands, archive scope and verification status. These paths have offline coverage; real Frame storage and permissions remain unverified. They do not change APK install or launch behavior.