Installer: check free space; README: what the Frame's SteamOS provides

A survey of a Steam Frame (SteamOS 0.4.3, build 20260930) found podman
5.5.2 set up for rootless use (subuid/subgid for steamos, crun, overlay
storage in the home folder) running aarch64 containers natively, plus
every tool the installer uses there (bash, python3, rsync, curl, tar,
bsdtar, unzip, sftp-server; no 7-Zip, which bsdtar covers). It also found
a nearly full home partition, which is what would break a build first.

- The installer checks the work folder has room before starting: about
  20 GB for a first build, 5 once Dawn is built, plus the disc's
  extraction. Short of it, it points at --work-dir on the SD card.
- Before copying the disc to the Frame it checks the destination has room
  for it, pointing at --frame-disc on the card otherwise.
- $USER may be unset (cron, some containers); the message falls back to
  id -un rather than tripping set -u.
- README: building on the Frame is confirmed to work with SteamOS's own
  podman, with the work folder on the SD card when home is short; the
  sizes involved are given where they matter.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019HBRGKTE1GnN2ah8gcZKr3

Launcher/steam-frame-install.sh

@@ -160,6 +160,22 @@ fi
 [[ "$jobs" =~ ^[1-9][0-9]*$ ]] || fail "--jobs must be a positive number"
 note "$jobs parallel compiles"
 
+# Room for the build. A first one (the toolchain, Dawn's source and build, the game's build) takes
+# about 20 GB; later ones reuse Dawn. Extracting a disc image takes about 5 GB more, plus the
+# archive's size while one is unpacked. Running out halfway is worse than stopping here.
+need_gb=20
+[[ -f "$work_dir/dawn/package/aurora-dawn.json" ]] && need_gb=5
+if [[ -n "$disc" && -f "$disc" && ! -f "$work_dir/disc/sys/main.dol" ]]; then
+    need_gb=$(( need_gb + 5 + $(du -k "$disc" | cut -f1) / 1024 / 1024 ))
+fi
+free_gb=$(( $(df -Pk "$work_dir" | awk 'NR == 2 { print $4 }') / 1024 / 1024 ))
+if (( free_gb < need_gb )); then
+    fail "$work_dir has $free_gb GB free; this run needs about $need_gb GB. Free some space, or put
+    the work folder on a bigger drive with --work-dir (on the Frame, a mounted card such as
+    --work-dir /run/media/${USER:-$(id -un)}/<card>/wiicompiled-frame)."
+fi
+note "$free_gb GB free in $work_dir"
+
 # ---------------------------------------------------------------------------------------------
 # The source: the tree this script is in, an explicit --source, or a release kept in the work dir.
 if [[ -z "$source_dir" && -z "$release" && -n "$script_dir" && -f "$script_dir/../runtime/CMakeLists.txt" ]]; then
@@ -474,11 +490,20 @@ EOF
 )
 if [[ "$has_disc" != yes ]]; then
     [[ -n "$disc_dir" ]] || fail "the Frame has no disc at $frame_disc yet: pass --disc"
-    on_frame "$frame_disc_path" <<'EOF' || fail "cannot write $frame_disc on the Frame. SteamOS's system is read-only:
-    pick a folder in the home folder (the default, wiicompiled/disc) or on a mounted card."
+    # The folder must be writable, and have room for the disc (prints its free space in KB).
+    frame_free_kb=$(on_frame "$frame_disc_path" <<'EOF'
 [[ "$1" = /* ]] && d=$1 || d="$HOME/$1"
-mkdir -p "$(dirname "$d")" 2>/dev/null && [[ -w "$(dirname "$d")" ]] && rm -rf "$d.partial"
+mkdir -p "$(dirname "$d")" 2>/dev/null && [[ -w "$(dirname "$d")" ]] && rm -rf "$d.partial" &&
+    df -Pk "$(dirname "$d")" | awk 'NR == 2 { print $4 }'
 EOF
+    ) || fail "cannot write $frame_disc on the Frame. SteamOS's system is read-only: pick a folder in
+    the home folder (the default, wiicompiled/disc) or on a mounted card."
+    disc_kb=$(du -sk "$disc_dir" | cut -f1)
+    if (( frame_free_kb < disc_kb + 1024 * 1024 )); then
+        fail "the Frame has $(( frame_free_kb / 1024 / 1024 )) GB free where the disc goes and the disc
+    needs $(( disc_kb / 1024 / 1024 + 1 )) GB. Free some space, or put it on a mounted card with
+    --frame-disc /run/media/<user>/<card>/wiicompiled-disc."
+    fi
     note "copying the extracted disc to $frame_disc (a few GB)"
     copy_to_frame "$disc_dir" "$frame_disc_path.partial"
     on_frame "$frame_disc_path" <<'EOF'

README.md

@@ -82,7 +82,8 @@ curl -fsSL https://raw.githubusercontent.com/mitch030504/Wiicompiled_VR_Frame/op
   [Frame Control](https://github.com/saphid/frame-control), pass `--frame frame` instead: its SSH
   key answers to that name.
 - Everything it builds lives in `~/wiicompiled-frame` (`--work-dir` to change that): the toolchain,
-  Dawn, the source, the extracted disc and the build log, `build.log`.
+  Dawn, the source, the extracted disc and the build log, `build.log`. A first build needs about
+  20 GB there, and the script checks for it before starting.
 - It runs as many compiles at once as fit in memory (a quarter of your memory in GB). If the machine
   still freezes, run it again with a lower `--jobs`, such as `--jobs 2`.
 - If it stops for any reason, the same command picks up where it left off.
@@ -100,7 +101,7 @@ Everything it puts on the Frame is in your home folder, where it survives SteamO
 | Where | What |
 | --- | --- |
 | `~/devkit-game/WiiCompiled/` | the game |
-| `~/wiicompiled/disc/` | your extracted disc (`--frame-disc` puts it elsewhere in your home folder or on a mounted card) |
+| `~/wiicompiled/disc/` | your extracted disc, about 4.5 GB (`--frame-disc` puts it elsewhere in your home folder or on the SD card, `/run/media/steamos/<card>/...`) |
 | `~/.local/share/WiiCompiled/` | `Config.toml`, saves and logs, written by the game itself |
 | Steam's library | the **WiiCompiled** shortcut, made through Valve's devkit tools in `~/devkit-utils` |
 
@@ -312,21 +313,26 @@ is open.
 
 ## Other ways to build
 
-**On the Frame itself.** This needs podman, which has to come with SteamOS: its system is read-only,
-and anything installed into it with `pacman` (after switching the read-only mode off) is gone at the
-next update, so don't. The script checks and says so if it is missing; then build on a PC as above.
-If it is there, run the script over SSH (`ssh steamos@<frame-ip>`) or in a Desktop Mode terminal:
+**On the Frame itself.** SteamOS on the Frame (0.4.3, September 2026) comes with podman 5.5, set
+up for rootless containers with its storage in the home folder, so the install script runs there
+natively, with no emulation and nothing installed into the read-only system. Don't add tools to
+SteamOS with `pacman`: that means switching the read-only mode off, and the next update undoes it.
+The script checks for podman and stops with a pointer to building on a PC if an image lacks it.
+
+The first build needs about 20 GB in its work folder, and podman's storage
+(`~/.local/share/containers`) grows by about 1.5 GB for the build container. If the home folder is
+short of that (the script checks), put the work folder on the SD card, which SteamOS mounts under
+`/run/media/<user>/<card>` (on the Frame the user is `steamos`). Over SSH
+(`ssh steamos@<frame-ip>`) or in a Desktop Mode terminal:
 
 ```bash
 curl -fsSL https://raw.githubusercontent.com/mitch030504/Wiicompiled_VR_Frame/openxr-work/Launcher/steam-frame-install.sh \
-    | bash -s -- --disc "/path/to/Mario Kart Wii.wbfs" --frame local
+    | bash -s -- --disc "/path/to/Mario Kart Wii.wbfs" --frame local --work-dir /run/media/steamos/<card>/wiicompiled-frame
 ```
 
-It is native ARM64, so no emulation, but the Frame has less memory and cooling than a PC; keep it
-on its charger. Everything stays in your home folder: the container image and its packages in
-podman's storage (`~/.local/share/containers`), the toolchain, Dawn and the build in
-`~/wiicompiled-frame` (about 20 GB), and the game reads the disc straight from
-`~/wiicompiled-frame/disc`. By hand, the
+Leave out `--work-dir` to keep it in `~/wiicompiled-frame`. With 15 GB of memory the Frame runs three
+compiles at once; it has less cooling than a PC, so keep it on its charger. The game then reads the
+disc straight from the work folder's `disc`. By hand, the
 steps under [Building by hand](#building-by-hand) work the same in a container started without
 `--platform linux/arm64`, with `nodtool-linux-aarch64` in place of `nodtool-linux-x86_64`.