diff --git a/.github/workflows/checks.yml b/.github/workflows/checks.yml
index 51eea2d..314bf4f 100644
--- a/.github/workflows/checks.yml
+++ b/.github/workflows/checks.yml
@@ -71,3 +71,15 @@ jobs:
           cd ios
           udid=$(xcrun simctl list devices available -j | python3 -c 'import json,sys; d=json.load(sys.stdin)["devices"]; print(next(x["udid"] for r in d for x in d[r] if x["name"].startswith("iPhone")))')
           xcodebuild -project FrameControl.xcodeproj -scheme FrameControl -destination "platform=iOS Simulator,id=$udid" CODE_SIGNING_ALLOWED=NO test
+
+  # End-to-end tests against the fake Frame (tests/fakeframe): Arch Linux ARM
+  # in Docker, on a native arm64 runner like the headset. See docs/testing.md.
+  e2e:
+    runs-on: ubuntu-24.04-arm
+    timeout-minutes: 30
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install zsh
+        run: sudo apt-get update -qq && sudo apt-get install -y -qq zsh
+      - name: End-to-end tests
+        run: scripts/e2e.sh
diff --git a/.gitignore b/.gitignore
index ad5b005..d89ecc2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,4 @@ apk-catalog/data/cache/
 apk-catalog/data/index-v2.json*
 compat-db/.env.lakebed.server
 compat-db/.lakebed/
+tests/smoke/results/
diff --git a/README.md b/README.md
index 93cabeb..5f25235 100644
--- a/README.md
+++ b/README.md
@@ -195,6 +195,7 @@ Frame's software fits together, all checked against a real headset and labelled
 | [SSH](docs/ssh.md) · [Streaming](docs/streaming.md) · [Files](docs/file-transfer.md) · [Panels](docs/panels.md) · [Tailscale](docs/tailscale.md) | Topic notes |
 | [Frame Control for iPhone](docs/iphone.md) | The iPhone and iPad app, how it runs the server on the Frame, pairing |
 | [Recovery and OS images](docs/recovery-and-images.md) | Where to download the Frame's OS, what's inside, testing without the headset |
+| [Testing](docs/testing.md) | Unit tests, end-to-end tests against a fake Frame in Docker, and the headset smoke test |
 | [Open questions](docs/open-questions.md) | What's still unchecked |
 
 <details>
@@ -221,6 +222,7 @@ Frame's software fits together, all checked against a real headset and labelled
 
 ```sh
 python3 -m unittest discover -s tests   # server tests; no headset needed
+scripts/e2e.sh                          # end-to-end against a fake Frame (Linux with Docker)
 cd app && npm install && npm start      # run the app from the checkout
 ```
 
diff --git a/docs/testing.md b/docs/testing.md
new file mode 100644
index 0000000..e70a4a7
--- /dev/null
+++ b/docs/testing.md
@@ -0,0 +1,142 @@
+# Testing
+
+Frame Control is tested in three layers, from fast and fake to slow and real.
+A fourth, a SteamOS VM, may come later ([issue #6](https://github.com/saphid/steam-frame/issues/6)).
+
+| Layer | Runs | Needs | Covers |
+|---|---|---|---|
+| Unit tests (`tests/*.py`) | `python3 -m unittest discover -s tests` | Nothing | Parsing, validation, request guards; SSH and HTTP are mocked |
+| Fake Frame (`tests/e2e`) | `scripts/e2e.sh` | Linux with Docker | The real server and scripts against a container that behaves like a Frame |
+| Headset smoke test | `scripts/frame-smoke.sh` | A Frame on the `frame` alias | Install, launch and remove on the real device, recorded with its BUILD_ID |
+
+## Unit tests
+
+```sh
+python3 -m unittest discover -s tests
+```
+
+About 120 tests, a few seconds, on Python 3.9 and newer. GitHub Actions runs
+them on macOS, Windows and Linux. They don't pick up `tests/e2e`.
+
+## The fake Frame
+
+`tests/fakeframe/` builds a container that stands in for the headset, and a
+second one for the computer Frame Control runs on. `scripts/e2e.sh` builds
+both, starts them with `docker compose`, runs `tests/e2e` in the host
+container and takes everything down, exiting with the tests' status:
+
+```sh
+scripts/e2e.sh                                   # everything, about 2 minutes plus the first build
+scripts/e2e.sh test_titles                       # one module
+scripts/e2e.sh test_faults.Faults.test_disk_full # one test
+FAKEFRAME_KEEP=1 scripts/e2e.sh                  # leave it running afterwards
+```
+
+It needs a Linux host with Docker and `docker compose`, and zsh. The images
+are `fakeframe-frame` and `fakeframe-host`; the compose project, network and
+volumes are `fakeframe-e2e*`. CI runs it on a native arm64 runner
+(`ubuntu-24.04-arm`, the `e2e` job in `.github/workflows/checks.yml`).
+
+The host container exists because OpenSSH reads `~/.ssh/config` from the
+passwd home directory, not `$HOME`. There, `ssh frame` reaches the fake Frame
+through the same `Host frame` block `ui/frame_connect.py` writes, the
+repository is mounted read-only at `/repo`, and each test module starts the
+real `ui/server.py` (Python 3.9) and talks to it over HTTP with the headers
+its guards want.
+
+### What's real and what's fake
+
+| On the fake Frame | |
+|---|---|
+| Arch Linux (`archlinux:base`, or `menci/archlinuxarm:base` on arm64), user `steamos`, `/etc/os-release` with BUILD_ID 20260922.6101926 | Real OS, Frame's identity |
+| `sshd` with key and password logins, `rsync`, `python3` | Real |
+| Valve's steamos-devkit-service on port 32000 and its hooks, vendored unmodified in `tests/fakeframe/steamos-devkit-service` | Real; only its `dbus` import (for mDNS through systemd-resolved) is a stand-in that logs the registration |
+| Valve's devkit-utils, copied over by Frame Control itself | Real |
+| **fakesteam**: `~/.steam/steam.pid`, `steam.token` and the `steam.pipe` FIFO; answers `approve-ssh-key`, `create-shortcut`, `run-game`, `list-shortcuts` and `delete-shortcut` with the response files devkit-utils waits for; takes `steam://rungameid`, `install` and `store` URLs | Fake |
+| DevTools on `127.0.0.1:8080` with a `SharedJSContext` target. The JavaScript Frame Control sends runs for real in Node against stand-in `SteamClient`, `appStore` and `downloadsStore` objects (`cef_shim.js`), so async functions, optional chaining and `Map`s behave as in Steam's CEF | The JS engine is real; the objects are fake |
+| `steam`, `wpctl`, `flatpak`, `podman`, `nmcli`, `qdbus6`, `gamescopectl`, SteamOS's `steamos-enable-sshd` helper, and Lepton's launcher | Stubs that record their calls |
+| Battery, charger and thermal zones under `/sys/class` | Files the supervisor writes. `/sys` is read-only in a container and Docker's AppArmor profile refuses writes under it, so each folder is a volume mounted twice: over `/sys/class/...` for `frame_status.py` to read, and under `/var/lib/fakeframe/sys` for the supervisor to write |
+| `vrserver` and `plasmashell` | Renamed `sleep` processes, so the status page and the clipboard find them |
+
+Every fake behaviour copied from the device has a comment citing the doc or
+observation and the BUILD_ID it came from; anything not seen on a headset is
+marked as a guess. The fake keeps its state in `/var/lib/fakeframe/state.json`
+(shortcuts, devkit titles, compat tool mapping, launches, pairing requests,
+Lepton instances, volume, Flatpaks, clipboard) and logs stub calls to
+`calls.jsonl` beside it.
+
+Native programs really run: a launched aarch64 title executes on an arm64
+host, and an x86-64 one on x86-64 (the container shares the host's kernel).
+Proton titles are recorded with the command Steam would run, not run.
+
+### Fault switches
+
+`fakeframe-ctl` works over SSH (`ssh frame fakeframe-ctl help`) and from the
+host container (`FAKEFRAME_CTL=http://fakeframe:9999`), so a test can flip a
+switch while SSH is down:
+
+| Command | Effect |
+|---|---|
+| `pairing on\|off` | Steam's **Pair new host** screen open or not; off gives the device's 403 text |
+| `answer approve\|deny\|timeout` | How the pairing prompt is answered |
+| `steam on\|off` | Steam client running (pid file, pipe, DevTools) |
+| `sleep on\|off` | Headset asleep: ports 22 and 32000 accept and never answer, so SSH times out |
+| `sshd on\|off` | sshd stopped: new connections are refused, open ones stay |
+| `devkit-service on\|off` | Port 32000 closed |
+| `disk-full on\|off` | Fills the small (64 MB) filesystem on `~/devkit-game` |
+| `runtime NAME installed\|missing` | Proton, the Steam Linux Runtimes, Lepton |
+| `battery KEY=VALUE...` | e.g. `capacity=15 status=Discharging current_now=-900000` |
+| `keys harness\|none`, `authorized-keys` | Set or read `~/.ssh/authorized_keys` |
+| `reset`, `state`, `calls [TOOL]` | Start over; read the state and call log |
+
+### What the fake can't show
+
+- Rendering: the headset view, desktop capture content, live video, SteamVR,
+  gamescope and panels. The capture stub returns a placeholder PNG.
+- Proton and FEX: whether a Windows or x86-64 program actually runs.
+- Android: there's no Android in the Lepton stand-in, so no ADB, display
+  settings, probes or app crashes.
+- The real Steam client's UI and anything it does that isn't modelled, and
+  mDNS discovery.
+- `sudo` and the power buttons, Tailscale, and the Windows and macOS sides of
+  the app (the host container is Linux, so the `rsync` paths are tested and the
+  `scp` fallback isn't).
+
+## Headset smoke test
+
+```sh
+scripts/frame-smoke.sh           # needs `ssh frame` to work without a password
+scripts/frame-smoke.sh --pair    # also pairs a throwaway key: approve it in the headset
+```
+
+It checks `properties.json` and the status, then installs, launches and
+removes three tiny titles built from bytes by `tests/smoke/tiny_programs.py`
+(an ARM64 and an x86-64 static Linux program that sleep for five seconds, and
+an x86-64 `.exe` that exits at once), keeping what Steam logged about each.
+Everything it installs is removed again, also after a failure. Results go to
+`tests/smoke/results/<time>-<BUILD_ID>.json` (not committed) with a summary on
+screen; it exits 0 when every step passed, 1 if one failed, 2 if the headset
+isn't reachable.
+
+`--pair` asks the devkit service to pair a new RSA key, which needs someone
+in the headset to open **Settings → Developer → Pair new host** and approve
+it; the key is checked and then taken out of `authorized_keys` again.
+
+## When the device disagrees with the fake
+
+The fake is only as good as what's been seen on a headset. When the smoke
+test (or anyone) finds the Frame doing something else:
+
+1. Record what the device did, with the date and BUILD_ID, in the doc that
+   covers it (`docs/sideloading.md`, `docs/ssh.md` and so on).
+2. Change the fake to match, with a comment citing that observation. The
+   behaviours are in `tests/fakeframe/rootfs/usr/local/lib/fakeframe/`
+   (`fakesteam.py` for Steam, `cef_shim.js` for DevTools, `init.py` for the
+   switches, the stubs in `rootfs/usr/local/bin`).
+3. Run `scripts/e2e.sh`. If the app is wrong, the tests now fail the way the
+   device did; fix the app and add a unit test.
+
+For example, on 2026-09-27 the smoke test found that Steam's `create-shortcut`
+refuses ids with a hyphen (`missing/invalid arguments`), which the fake had
+accepted. The fake now refuses them the same way, and Frame Control makes ids
+Steam accepts.
diff --git a/scripts/e2e.sh b/scripts/e2e.sh
new file mode 100755
index 0000000..2c0b1ed
--- /dev/null
+++ b/scripts/e2e.sh
@@ -0,0 +1,64 @@
+#!/usr/bin/env zsh
+# Linux host with Docker: run the end-to-end tests against the fake Frame.
+# Builds the fake Frame and host images (tests/fakeframe), starts them with
+# docker compose, runs tests/e2e in the host container, prints the results
+# and takes everything down again. Exits with the tests' status (2 if the
+# harness itself didn't come up). See docs/testing.md.
+#
+# Usage: scripts/e2e.sh [TEST...]     e.g. scripts/e2e.sh test_titles test_faults.Faults.test_disk_full
+# Env:   FAKEFRAME_BASE   base image (default: archlinux:base, or menci/archlinuxarm:base on arm64)
+#        FAKEFRAME_KEEP=1 leave the containers running afterwards
+set -uo pipefail
+
+root=${0:A:h:h}
+cd "$root" || exit 2
+case $(uname -m) in
+  x86_64|amd64) base=archlinux:base ;;
+  aarch64|arm64) base=menci/archlinuxarm:base ;;
+  *) print -u2 "No Arch Linux base image known for $(uname -m); set FAKEFRAME_BASE"; exit 2 ;;
+esac
+base=${FAKEFRAME_BASE:-$base}
+compose=(docker compose -p fakeframe-e2e -f tests/fakeframe/compose.yaml)
+started=$SECONDS
+
+print "==> Building fakeframe-frame (from $base) and fakeframe-host"
+docker build -q --build-arg BASE="$base" -t fakeframe-frame -f tests/fakeframe/Containerfile tests/fakeframe || exit 2
+docker build -q -t fakeframe-host -f tests/fakeframe/host.Containerfile tests/fakeframe || exit 2
+
+logs() {
+  print "\n==> Fake Frame logs"
+  $compose logs --no-color --tail 80 fakeframe
+  $compose exec -T fakeframe sh -c 'for f in /var/log/fakeframe/*.log; do echo "--- $f"; tail -n 40 "$f"; done' 2>/dev/null
+  print "\n==> ui/server.py log"
+  $compose exec -T host sh -c 'tail -n 80 /tmp/fakeframe-e2e-server.log' 2>/dev/null
+}
+
+finish() {
+  if [[ ${FAKEFRAME_KEEP:-0} == 1 ]]; then
+    print "==> Left running: ${(j: :)compose} exec host bash"
+  else
+    $compose down -v --remove-orphans >/dev/null 2>&1
+  fi
+}
+trap finish EXIT
+
+$compose down -v --remove-orphans >/dev/null 2>&1
+print "==> Starting the fake Frame and the host"
+if ! $compose up -d --wait; then
+  logs
+  exit 2
+fi
+print "==> Up after $(( SECONDS - started )) s; running tests/e2e"
+
+if (( $# )); then
+  args=(-v "$@")
+else
+  args=(discover -v -s .)
+fi
+tests_started=$SECONDS
+$compose exec -T -w /repo/tests/e2e host python3 -m unittest "${args[@]}"
+rc=$?
+(( rc == 0 )) || logs
+print "\n==> tests/e2e: $([[ $rc == 0 ]] && echo passed || echo "FAILED (exit $rc)") in $(( SECONDS - tests_started )) s" \
+      "($(( SECONDS - started )) s with builds)"
+exit $rc
diff --git a/scripts/frame-smoke.sh b/scripts/frame-smoke.sh
new file mode 100755
index 0000000..8d8872a
--- /dev/null
+++ b/scripts/frame-smoke.sh
@@ -0,0 +1,8 @@
+#!/usr/bin/env zsh
+# Mac or Linux: the headset smoke test. Installs, launches and removes tiny
+# test titles on the Frame (the `frame` alias) and records the results with
+# its BUILD_ID under tests/smoke/results/. See docs/testing.md.
+#
+# Usage: scripts/frame-smoke.sh [--pair]   (--pair needs you in the headset to approve)
+set -euo pipefail
+exec python3 "${0:A:h:h}/tests/smoke/frame_smoke.py" "$@"
diff --git a/tests/e2e/harness.py b/tests/e2e/harness.py
new file mode 100644
index 0000000..9a0818d
--- /dev/null
+++ b/tests/e2e/harness.py
@@ -0,0 +1,198 @@
+"""Plumbing for the end-to-end tests against the fake Frame (tests/fakeframe).
+
+scripts/e2e.sh runs these inside the compose `host` container, where
+`ssh frame` reaches the fake Frame and FAKEFRAME_CTL is its control port.
+Each test starts from `fakeframe-ctl reset` and drives the real ui/server.py
+(started once, on a free port) over HTTP, then checks the fake's state.
+Without FRAME_E2E=1 every test here is skipped.
+"""
+import atexit
+import http.client
+import json
+import os
+import socket
+import subprocess
+import sys
+import tempfile
+import time
+import unittest
+import urllib.request
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[2]
+sys.path[:0] = [str(ROOT / 'ui'), str(ROOT / 'tests'), str(ROOT / 'tests' / 'smoke')]
+
+ENABLED = os.environ.get('FRAME_E2E') == '1'
+CTL = os.environ.get('FAKEFRAME_CTL', 'http://fakeframe:9999').rstrip('/')
+FAKE_HOST = os.environ.get('FAKEFRAME_HOST', 'fakeframe')
+HOME = '/home/steamos'
+SERVER_LOG = os.path.join(tempfile.gettempdir(), 'fakeframe-e2e-server.log')
+
+
+def require():
+    """Call at module level: skips the module unless the fake Frame is up."""
+    if not ENABLED:
+        raise unittest.SkipTest('needs the fake Frame: run scripts/e2e.sh (sets FRAME_E2E=1)')
+
+
+# ---- the fake Frame's control port --------------------------------------------
+
+def _ctl_request(path, body=None, timeout=60):
+    data = json.dumps(body).encode() if body is not None else None
+    req = urllib.request.Request(CTL + path, data=data, headers={'Content-Type': 'application/json'})
+    with urllib.request.urlopen(req, timeout=timeout) as r:
+        return json.load(r)
+
+
+def ctl(*args):
+    out = _ctl_request('/ctl', {'args': list(args)})
+    if 'error' in out:
+        raise AssertionError(f'fakeframe-ctl {" ".join(args)}: {out["error"]}')
+    return out
+
+
+def state():
+    return _ctl_request('/state')
+
+
+def calls(tool=None):
+    return _ctl_request('/calls' + (f'?{tool}' if tool else ''))
+
+
+def wait_for(check, timeout=30, what='a condition', every=0.3):
+    """Poll check() until it returns something truthy; returns that."""
+    deadline = time.monotonic() + timeout
+    last = None
+    while time.monotonic() < deadline:
+        last = check()
+        if last:
+            return last
+        time.sleep(every)
+    raise AssertionError(f'timed out after {timeout}s waiting for {what} (last: {last!r})')
+
+
+def reset():
+    ctl('reset')
+    wait_for(lambda: _ctl_request('/ping')['ok'], 30, 'the fake Frame to come back after reset')
+
+
+def ssh(cmd, check=True, timeout=30):
+    """Run cmd on the fake Frame through the `frame` alias, as Frame Control does."""
+    r = subprocess.run(['ssh', '-o', 'BatchMode=yes', '-o', 'ConnectTimeout=5', 'frame', cmd],
+                       capture_output=True, text=True, stdin=subprocess.DEVNULL, timeout=timeout)
+    if check and r.returncode != 0:
+        raise AssertionError(f'ssh frame {cmd!r} exited {r.returncode}: {r.stderr.strip()}')
+    return r.stdout
+
+
+def exists(path):
+    return ssh(f'test -e {path} && echo yes || echo no').strip() == 'yes'
+
+
+# ---- the real server ----------------------------------------------------------
+
+class Server:
+    proc = None
+    port = None
+
+    @classmethod
+    def start(cls):
+        if cls.proc and cls.proc.poll() is None:
+            return
+        with socket.socket() as s:
+            s.bind(('127.0.0.1', 0))
+            cls.port = s.getsockname()[1]
+        env = dict(os.environ, FRAME_CONTROL_LOCAL_LINKS='1')
+        log = open(SERVER_LOG, 'ab')
+        cls.proc = subprocess.Popen([sys.executable, str(ROOT / 'ui' / 'server.py'), '--port', str(cls.port)],
+                                    cwd=str(ROOT), env=env, stdin=subprocess.DEVNULL, stdout=log, stderr=log)
+        log.close()
+        atexit.register(cls.stop)
+        wait_for(lambda: cls._up(), 20, 'ui/server.py to listen')
+
+    @classmethod
+    def _up(cls):
+        try:
+            return api('GET', '/api/host')[0] == 200
+        except OSError:
+            return False
+
+    @classmethod
+    def stop(cls):
+        if cls.proc and cls.proc.poll() is None:
+            cls.proc.terminate()
+            try:
+                cls.proc.wait(10)
+            except subprocess.TimeoutExpired:
+                cls.proc.kill()
+
+
+def api(method, path, body=None, raw=None, headers=None, timeout=120):
+    """One request to the server with the headers its guards want. -> (status, JSON or bytes, headers)."""
+    conn = http.client.HTTPConnection('127.0.0.1', Server.port, timeout=timeout)
+    try:
+        hdrs = {'X-Frame-UI': '1', **(headers or {})}   # Host is 127.0.0.1:<port>, which it accepts
+        data = raw if raw is not None else (json.dumps(body).encode() if body is not None else None)
+        if data is not None and 'Content-Type' not in hdrs:
+            hdrs['Content-Type'] = 'application/json'
+        conn.request(method, path, body=data, headers=hdrs)
+        r = conn.getresponse()
+        payload = r.read()
+        if r.getheader('Content-Type', '').startswith('application/json'):
+            payload = json.loads(payload)
+        return r.status, payload, dict(r.getheaders())
+    finally:
+        conn.close()
+
+
+def ok(method, path, body=None, **kw):
+    status, out, _ = api(method, path, body, **kw)
+    if status != 200:
+        raise AssertionError(f'{method} {path} -> {status}: {out}')
+    return out
+
+
+def upload(path, mode, name=None):
+    with open(path, 'rb') as f:
+        data = f.read()
+    return api('POST', '/api/upload', raw=data, headers={
+        'X-Filename': name or os.path.basename(path), 'X-Mode': mode, 'Content-Type': 'application/octet-stream'})
+
+
+def wait_title_job(token, timeout=180):
+    def done():
+        job = ok('GET', f'/api/titles/job?token={token}')
+        return job if job['done'] else None
+    return wait_for(done, timeout, f'title install job {token}', every=0.5)
+
+
+def install_title(path, **options):
+    """Upload (or, for a folder, inspect by path) and install; returns (plan, finished job)."""
+    if os.path.isdir(path):
+        staged = ok('POST', '/api/titles', {'action': 'inspect', 'path': path})
+    else:
+        status, staged, _ = upload(path, 'title')
+        if status != 200:
+            raise AssertionError(f'upload -> {status}: {staged}')
+    started = ok('POST', '/api/titles', {'action': 'install', 'token': staged['token'], **options})
+    return staged['plan'], wait_title_job(started['job'])
+
+
+def launches(kind=None):
+    return [r for r in state()['launches'] if kind is None or r['kind'] == kind]
+
+
+class FrameTestCase(unittest.TestCase):
+    """Starts the server once and the fake Frame afresh for every test."""
+
+    @classmethod
+    def setUpClass(cls):
+        Server.start()
+
+    def setUp(self):
+        reset()
+        self.tmp = tempfile.mkdtemp(prefix='fakeframe-e2e-')
+        self.addCleanup(subprocess.run, ['rm', '-rf', self.tmp])
+
+    def path(self, *parts):
+        return os.path.join(self.tmp, *parts)
diff --git a/tests/e2e/test_android.py b/tests/e2e/test_android.py
new file mode 100644
index 0000000..b2b5373
--- /dev/null
+++ b/tests/e2e/test_android.py
@@ -0,0 +1,76 @@
+"""An APK as its own Lepton instance (ui/frame_android.py): the shortcut goes in
+through the fake Steam client's DevTools port, the launch through `steam`,
+Lepton's launcher and podman."""
+import unittest
+
+import harness
+from harness import HOME, exists, ok, state, upload, wait_for
+from test_frame_apk import apk, manifest, resources
+
+harness.require()
+
+PKG = 'com.example.fakeframe'
+APP_DIR = f'{HOME}/Applications/Android/{PKG}'
+
+
+class AndroidApps(harness.FrameTestCase):
+    def build_apk(self, min_sdk=26):
+        arsc = resources({(1, '', 0): {0: 1, 1: 2}, (2, '', 640): {0: 4}})
+        data = apk({'AndroidManifest.xml': manifest(PKG, 0x7f010000, 0x7f010001, min_sdk),
+                    'resources.arsc': arsc, 'res/icon_hi.png': b'\x89PNG fake icon',
+                    'lib/arm64-v8a/libgame.so': b''})
+        path = self.path('fake-app.apk')
+        with open(path, 'wb') as f:
+            f.write(data)
+        return path
+
+    def test_install_launch_stop_remove(self):
+        status, out, _ = upload(self.build_apk(), 'apk')
+        self.assertEqual(status, 200, out)
+        meta = out['app']
+        self.assertEqual((meta['package'], meta['label'], meta['version']), (PKG, 'App label', '2.1'))
+        shortcut = next(s for s in state()['steam']['shortcuts'] if s['appid'] == meta['shortcut'])
+        self.assertEqual(shortcut['name'], 'App label')
+        self.assertEqual(shortcut['exe'], f'{APP_DIR}/launch.sh')
+        self.assertEqual(shortcut['start_dir'], APP_DIR)
+        self.assertEqual(shortcut['icon'], f'{APP_DIR}/icon.png')
+        for f in ('app.apk', 'launch.sh', 'instance.id', 'meta.json', 'icon.png', 'lepton-show-flatscreen'):
+            self.assertTrue(exists(f'{APP_DIR}/{f}'), f)
+        self.assertEqual(meta['game_id'], (meta['shortcut'] << 32) | 0x02000000)
+
+        ok('POST', '/api/android', {'action': 'launch', 'package': PKG})
+        ctr = f"lepton-steamlaunch-{meta['instance']}"
+        running = wait_for(lambda: state()['lepton'].get(ctr), 20, 'the Lepton instance')
+        self.assertTrue(running['flatscreen'])
+        self.assertGreaterEqual(running['port'], 5556)
+        call = next(c for c in harness.calls('lepton') if 'env' in c)
+        self.assertEqual(call['env']['SteamAppId'], str(meta['instance']))
+        self.assertTrue(call['env']['STEAM_COMPAT_DATA_PATH'].startswith(f'{HOME}/.local/share/Steam/'))
+        apps = ok('GET', '/api/android')['apps']
+        self.assertEqual([(a['package'], a['running']) for a in apps], [(PKG, True)])
+
+        ok('POST', '/api/android', {'action': 'stop', 'package': PKG})
+        wait_for(lambda: ctr not in state()['lepton'], 15, 'the instance to stop')
+        ok('POST', '/api/android', {'action': 'remove', 'package': PKG})
+        self.assertEqual(state()['steam']['shortcuts'], [])
+        self.assertFalse(exists(APP_DIR))
+        self.assertFalse(exists(f"{HOME}/.local/share/Steam/steamapps/compatdata/{meta['instance']}"))
+
+    def test_reinstall_reuses_the_shortcut(self):
+        first = upload(self.build_apk(), 'apk')[1]['app']
+        second = upload(self.build_apk(), 'apk')[1]['app']
+        self.assertEqual(first['shortcut'], second['shortcut'])
+        self.assertEqual(len(state()['steam']['shortcuts']), 1)
+
+    def test_launch_without_lepton_installed_fails_on_the_frame(self):
+        meta = upload(self.build_apk(), 'apk')[1]['app']
+        harness.ctl('runtime', 'lepton', 'missing')
+        ok('POST', '/api/android', {'action': 'launch', 'package': PKG})
+        run = wait_for(lambda: next((r for r in state()['launches'] if r.get('appid') == meta['shortcut']
+                                     and r.get('exit') is not None), None), 20, 'launch.sh to exit')
+        self.assertEqual(run['exit'], 1)   # launch.sh: "Lepton isn't installed (Steam app 3056000)"
+        self.assertEqual(state()['lepton'], {})
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/tests/e2e/test_device.py b/tests/e2e/test_device.py
new file mode 100644
index 0000000..5888ce0
--- /dev/null
+++ b/tests/e2e/test_device.py
@@ -0,0 +1,86 @@
+"""Status, Steam library, volume, clipboard, Flatpaks and the desktop capture,
+through the server against the fake Frame."""
+import unittest
+
+import harness
+from harness import api, ctl, launches, ok, state, wait_for
+
+harness.require()
+
+
+class Device(harness.FrameTestCase):
+    def test_status(self):
+        s = ok('GET', '/api/status')
+        self.assertEqual(s['hostname'], 'frame')
+        self.assertEqual(s['os'], {'version': '0.3.0', 'build': '20260922.6101926', 'variant': 'vr'})
+        b = s['battery']
+        self.assertEqual((b['percent'], b['status'], b['health']), (76, 'Charging', 'Good'))
+        self.assertAlmostEqual(b['watts'], 9.62, places=1)
+        self.assertAlmostEqual(b['tempC'], 31.2, places=3)
+        self.assertEqual(s['power'], {'type': 'C PD [PD_PPS]', 'watts': 20.0})
+        self.assertEqual(s['temp'], 41.5)
+        self.assertEqual(s['wifi'], {'ssid': 'Fake:Frame Wi-Fi', 'signal': 72})
+        self.assertEqual(s['volume'], {'level': 0.4, 'muted': False})
+        self.assertEqual(s['services'], {'steamvr': True, 'desktop': True, 'lepton': False, 'rdp': False})
+        # Runtimes and Lepton are Steam "apps" too; the status hides them.
+        self.assertEqual([g['name'] for g in s['games']], ['Beat Saber'])
+        self.assertIsNotNone(s['disk']['home'])
+
+        ctl('battery', 'capacity=15', 'status=Discharging', 'current_now=-900000')
+        b = ok('GET', '/api/status')['battery']
+        self.assertEqual((b['percent'], b['status']), (15, 'Discharging'))
+        self.assertLess(b['watts'], 0)
+
+    def test_volume_and_mute(self):
+        ok('POST', '/api/volume', {'level': 0.55, 'muted': True})
+        self.assertEqual(state()['volume'], {'level': 0.55, 'muted': True})
+        self.assertEqual(ok('GET', '/api/status')['volume'], {'level': 0.55, 'muted': True})
+        status, out, _ = api('POST', '/api/volume', {'level': 2})
+        self.assertEqual(status, 400, out)
+
+    def test_clipboard_goes_to_klipper(self):
+        text = 'héllo from the e2e tests\nline two, with a trailing newline\n'
+        out = ok('POST', '/api/clipboard', {'text': text})
+        # ${#text} counts bytes or characters depending on the session's locale.
+        self.assertRegex(out['message'], r'^copied via Klipper \(\d+ chars\)$')
+        self.assertEqual(state()['clipboard'], [text])
+
+    def test_flatpak_install_and_remove(self):
+        ok('POST', '/api/flatpak', {'id': 'org.videolan.VLC', 'action': 'install'})
+        self.assertEqual([f['id'] for f in ok('GET', '/api/status')['flatpaks']], ['org.videolan.VLC'])
+        ok('POST', '/api/flatpak', {'id': 'org.videolan.VLC', 'action': 'uninstall'})
+        self.assertEqual(state()['flatpaks'], [])
+        status, out, _ = api('POST', '/api/flatpak', {'id': 'org.example.missing', 'action': 'install'})
+        self.assertEqual(status, 502)
+        self.assertIn('Nothing matches org.example.missing', out['error'])
+
+    def test_desktop_capture(self):
+        status, png, headers = api('GET', '/api/screenshot')
+        self.assertEqual(status, 200, png)
+        self.assertTrue(png.startswith(b'\x89PNG\r\n\x1a\n'))
+        self.assertEqual(headers.get('X-Capture-Source'), 'gamescope')
+
+    def test_steam_library_and_installs(self):
+        owned = ok('GET', '/api/steam/owned')
+        self.assertEqual(owned['country'], 'AU')
+        games = {g['id']: g for g in owned['games']}
+        self.assertEqual(set(games), {2379780, 274190, 620980})
+        self.assertEqual((games[2379780]['frame'], games[620980]['installed']), (3, True))
+        # Balatro queues at once; Broforce stops at the options dialog, which
+        # frame_steam.py accepts with ContinueInstall().
+        for appid, name in ((2379780, 'Balatro'), (274190, 'Broforce')):
+            out = ok('POST', '/api/steam', {'appid': appid, 'action': 'install'})
+            self.assertEqual(out, {'state': 'downloading', 'message': f'{name} is queued to download on the Frame'})
+        self.assertEqual(ok('GET', '/api/steam/owned')['download']['appid'], 274190)
+
+    def test_launch_and_store_page(self):
+        ok('POST', '/api/launch', {'appid': 620980})
+        run = wait_for(lambda: launches('rungameid'), 10, 'the launch to reach Steam')[-1]
+        self.assertEqual((run['appid'], run['started']), (620980, True))
+        ok('POST', '/api/steam', {'appid': 1145360, 'action': 'store'})
+        wait_for(lambda: state()['steam']['pages'], 10, 'the store page')
+        self.assertEqual(state()['steam']['pages'][0]['title'], 'Hades on Steam')
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/tests/e2e/test_faults.py b/tests/e2e/test_faults.py
new file mode 100644
index 0000000..b42d4e2
--- /dev/null
+++ b/tests/e2e/test_faults.py
@@ -0,0 +1,94 @@
+"""What Frame Control does when the headset misbehaves: Steam not running,
+the headset asleep or with sshd off, and a full disk."""
+import os
+import subprocess
+import sys
+import time
+import unittest
+import zipfile
+
+import harness
+import tiny_programs
+from harness import HOME, ROOT, api, ctl, exists, install_title, ok, state, wait_for
+
+harness.require()
+
+
+class Faults(harness.FrameTestCase):
+    def exe(self):
+        return tiny_programs.write(self.tmp, 'exe')
+
+    def test_steam_not_running_then_install_again(self):
+        ctl('steam', 'off')
+        _, job = install_title(self.exe())
+        # steam-client-create-shortcut's own words, passed on by frame_titles.
+        self.assertEqual(job['error'], "Uploaded, but Steam didn't register it: The Steam client is not running. "
+                                       "Registration did not complete. With Steam running on the Frame, "
+                                       "install it again.")
+        self.assertTrue(exists(f'{HOME}/devkit-game/fc_smoke_exe/fc-smoke-exe.exe'))   # the files stay
+        self.assertEqual(state()['devkit_games'], {})
+        status, out, _ = api('GET', '/api/steam/owned')
+        self.assertEqual(status, 502)
+        self.assertIn("Steam's UI isn't answering", out['error'])
+
+        ctl('steam', 'on')
+        wait_for(lambda: harness._ctl_request('/ping')['ok'], 20, 'Steam to start')
+        _, job = install_title(self.exe())
+        self.assertIsNone(job['error'], job)
+        self.assertIn('fc_smoke_exe', state()['devkit_games'])
+
+    def test_launch_with_steam_stopped(self):
+        _, job = install_title(self.exe())
+        self.assertIsNone(job['error'], job)
+        ctl('steam', 'off')
+        status, out, _ = api('POST', '/api/titles', {'action': 'launch', 'id': 'fc_smoke_exe'})
+        self.assertEqual(status, 502, out)
+        self.assertIn('steam.pid', out['error'])
+        self.assertEqual(harness.launches(), [])
+
+    def test_headset_asleep(self):
+        ok('GET', '/api/status')                        # a shared connection is up
+        ctl('sleep', 'on')
+        t0 = time.monotonic()
+        status, out, _ = api('GET', '/api/status', timeout=90)
+        took = time.monotonic() - t0
+        self.assertEqual(status, 502, out)
+        self.assertRegex(out['error'], r'[Tt]imed out')
+        self.assertLess(took, 40)                       # ConnectTimeout, not a hang
+        ctl('sleep', 'off')
+        # The next request after waking gets through again.
+        wait_for(lambda: api('GET', '/api/status', timeout=60)[0] == 200, 60, 'status after waking')
+
+    def test_sshd_stopped(self):
+        ok('GET', '/api/titles')                        # the server's shared connection is up
+        ctl('sshd', 'off')
+        # Stopping sshd keeps open sessions (Arch's sshd.service kills only the
+        # listener), so the server carries on over its shared connection...
+        self.assertEqual(api('GET', '/api/titles')[0], 200)
+        # ...while anything that connects afresh is refused.
+        out = subprocess.run([sys.executable, str(ROOT / 'ui' / 'frame_titles.py'), 'list'],
+                             capture_output=True, text=True, timeout=60)
+        self.assertEqual(out.returncode, 1)
+        self.assertIn('Connection refused', out.stderr)
+        ctl('sshd', 'on')
+        wait_for(lambda: subprocess.run([sys.executable, str(ROOT / 'ui' / 'frame_titles.py'), 'list'],
+                                        capture_output=True, timeout=60).returncode == 0, 30, 'sshd to be back')
+
+    def test_disk_full(self):
+        path = self.path('Big Game.zip')
+        with zipfile.ZipFile(path, 'w') as z:
+            z.writestr('Big Game/BigGame.exe', tiny_programs.pe_x86_64())
+            z.writestr('Big Game/data.pak', os.urandom(2 * 1024 * 1024))
+        ctl('disk-full', 'on')
+        _, job = install_title(path)
+        self.assertIn('No space left on device', job['error'] or '', job)
+        # A first install that failed part-way leaves nothing behind.
+        self.assertFalse(exists(f'{HOME}/devkit-game/Big_Game'))
+        self.assertEqual(state()['devkit_games'], {})
+        ctl('disk-full', 'off')
+        _, job = install_title(path)
+        self.assertIsNone(job['error'], job)
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/tests/e2e/test_pairing.py b/tests/e2e/test_pairing.py
new file mode 100644
index 0000000..aaf1ecf
--- /dev/null
+++ b/tests/e2e/test_pairing.py
@@ -0,0 +1,111 @@
+"""Setting up the connection: ui/frame_connect.py against Valve's real
+steamos-devkit-service on the fake Frame, and its password fallback."""
+import json
+import os
+import stat
+import subprocess
+import sys
+import unittest
+import urllib.request
+
+import harness
+from harness import FAKE_HOST, ROOT, ctl, state, wait_for
+
+harness.require()
+
+
+class Pairing(harness.FrameTestCase):
+    def setUp(self):
+        super().setUp()
+        ctl('keys', 'none')             # a computer the headset doesn't know yet
+
+    def connect(self, askpass=None):
+        """Start frame_connect.py FAKE_HOST with no terminal, as the app's setup window would."""
+        env = {k: v for k, v in os.environ.items() if not k.startswith('SSH_ASKPASS')}
+        if askpass:
+            script = self.path('askpass')
+            with open(script, 'w') as f:
+                f.write(f'#!/bin/sh\necho {askpass}\n')
+            os.chmod(script, stat.S_IRWXU)
+            env.update(SSH_ASKPASS=script, SSH_ASKPASS_REQUIRE='force')
+        return subprocess.Popen([sys.executable, str(ROOT / 'ui' / 'frame_connect.py'), FAKE_HOST],
+                                stdin=subprocess.DEVNULL, stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
+                                text=True, env=env, start_new_session=True)
+
+    def finish(self, proc, timeout=120):
+        out, _ = proc.communicate(timeout=timeout)
+        return proc.returncode, out
+
+    def authorized_keys(self):
+        return ctl('authorized-keys')['text']
+
+    def test_service_properties_and_announcement(self):
+        # docs/ssh.md: properties.json answers "login": "steamos" on the Frame.
+        with urllib.request.urlopen(f'http://{FAKE_HOST}:32000/properties.json', timeout=10) as r:
+            props = json.load(r)
+        self.assertEqual(props['login'], 'steamos')
+        self.assertEqual(props['devkit1'], ['devkit-1'])
+        # At start the service announces _steamos-devkit._tcp under the Frame's hostname.
+        ctl('devkit-service', 'off')
+        ctl('devkit-service', 'on')
+        reg = wait_for(lambda: [c for c in harness.calls('resolve1') if c['method'] == 'RegisterService'],
+                       15, 'the mDNS registration')
+        self.assertEqual(reg[0]['args'][:3], ['frame', 'frame', '_steamos-devkit._tcp'])
+        self.assertEqual(reg[0]['args'][3], 32000)
+
+    def test_pairing_mode_refusal_then_approval(self):
+        proc = self.connect()
+        # The first /register is refused: "Pair new host" isn't open.
+        wait_for(lambda: any(r['answer'] == 'not in pairing mode' for r in state()['pairing_requests']),
+                 30, 'a refused pairing request')
+        ctl('pairing', 'on')            # the user opens Settings > Developer > Pair new host
+        rc, out = self.finish(proc)
+        self.assertEqual(rc, 0, out)
+        self.assertIn('paired; key login OK', out)
+        answers = [r['answer'] for r in state()['pairing_requests']]
+        self.assertEqual(answers[-1], 'approve')
+        self.assertIn('not in pairing mode', answers)
+        self.assertIn('frame-control@', state()['pairing_requests'][-1]['request'])
+        # The hook turned sshd on and installed the RSA key for steamos.
+        self.assertTrue(harness.calls('steamos-enable-sshd'))
+        keys = self.authorized_keys()
+        self.assertRegex(keys, r'(?m)^ssh-rsa \S+ frame-control@\S+$')
+        self.assertNotIn('900b919520e4cf601998a71eec318fec', keys)  # the magic phrase isn't stored
+
+    def test_denied_request_falls_back_to_the_password(self):
+        ctl('pairing', 'on')
+        ctl('answer', 'deny')
+        rc, out = self.finish(self.connect())   # no password to give: the fallback can't finish
+        self.assertEqual(rc, 1, out)
+        self.assertIn('devkit pairing failed: the pairing request was denied', out)
+        self.assertIn('falling back to the password', out)
+        self.assertNotIn('ssh-rsa', self.authorized_keys())
+
+    def test_service_down_uses_the_password(self):
+        ctl('devkit-service', 'off')
+        rc, out = self.finish(self.connect(askpass='frame'))
+        self.assertEqual(rc, 0, out)
+        self.assertIn('devkit service not reachable on port 32000', out)
+        self.assertIn('key login OK', out)
+        with open(os.path.expanduser('~/.ssh/id_ed25519_frame.pub')) as f:
+            ours = f.read().split()[1]
+        self.assertIn(ours, self.authorized_keys())
+
+    def test_prompt_left_unanswered_times_out(self):
+        # approve-ssh-key waits 30 s for Steam, then says so.
+        ctl('pairing', 'on')
+        ctl('answer', 'timeout')
+        rc, out = self.finish(self.connect(), timeout=150)
+        self.assertEqual(rc, 1, out)
+        self.assertIn('timeout - Steam did not respond to the pairing request', out)
+
+    def test_steam_not_running(self):
+        ctl('pairing', 'on')
+        ctl('steam', 'off')
+        rc, out = self.finish(self.connect())
+        self.assertEqual(rc, 1, out)
+        self.assertIn('devkit pairing failed: Steam is not running', out)
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/tests/e2e/test_titles.py b/tests/e2e/test_titles.py
new file mode 100644
index 0000000..c07bc0b
--- /dev/null
+++ b/tests/e2e/test_titles.py
@@ -0,0 +1,191 @@
+"""Sideloaded titles (ui/frame_titles.py) through the server's HTTP API, against
+Valve's devkit-utils talking to the fake Steam client."""
+import hashlib
+import http.server
+import json
+import os
+import platform
+import subprocess
+import sys
+import threading
+import unittest
+import zipfile
+
+import harness
+import tiny_programs
+from harness import HOME, ROOT, ctl, exists, install_title, launches, ok, ssh, state, wait_for
+
+harness.require()
+
+GAMES = f'{HOME}/devkit-game'
+# The host container shares the fake Frame's kernel, so a native program of this
+# machine's architecture really runs there; the other one fails to exec.
+NATIVE = {'aarch64': 'arm64', 'arm64': 'arm64', 'x86_64': 'x86_64'}.get(platform.machine())
+
+
+class Titles(harness.FrameTestCase):
+    def game_zip(self, name='Cool Game-v1.2-win64.zip', extra=b''):
+        path = self.path(name)
+        with zipfile.ZipFile(path, 'w') as z:
+            z.writestr('Cool Game/CoolGame.exe', tiny_programs.pe_x86_64())
+            z.writestr('Cool Game/CoolGame_Data/level0', b'level data' + extra)
+        return path
+
+    def folder(self, kind, name):
+        os.makedirs(self.path(name))
+        return tiny_programs.write(self.path(name), kind), self.path(name)
+
+    def assert_installed(self, gid, runtime, target):
+        game = state()['devkit_games'][gid]
+        self.assertEqual(game['settings']['compat_tool'], runtime)
+        self.assertEqual(game['argv'], [target])
+        steam = state()['steam']
+        shortcut = next(s for s in steam['shortcuts'] if s['devkit_gameid'] == gid)
+        self.assertEqual(steam['compat_tools'][str(shortcut['appid'])], runtime)
+        self.assertEqual(ssh(f'stat -c %a {GAMES}/{gid}/{target}').strip(), '755')
+        listed = {t['id']: t for t in ok('GET', '/api/titles')['titles']}
+        self.assertEqual(listed[gid]['runtime'], runtime)
+        self.assertTrue(listed[gid]['frame_control'])
+        return shortcut
+
+    def test_zip_with_a_windows_exe(self):
+        plan, job = install_title(self.game_zip())
+        self.assertEqual((plan['name'], plan['id'], plan['target']), ('Cool Game', 'Cool_Game', 'CoolGame.exe'))
+        self.assertEqual(plan['runtime'], 'proton-experimental')
+        self.assertIsNone(job['error'], job)
+        self.assertEqual(job['title']['runtime_label'], 'Proton Experimental')
+        self.assert_installed('Cool_Game', 'proton-experimental', 'CoolGame.exe')
+        game = state()['devkit_games']['Cool_Game']
+        self.assertEqual(game['settings'], {'steam_play': '1', 'steam_play_debug': '0',
+                                            'steam_play_debug_version': '2019', 'compat_tool': 'proton-experimental'})
+        self.assertTrue(exists(f'{GAMES}/Cool_Game/CoolGame_Data/level0'))
+        self.assertTrue(exists(f'{HOME}/devkit-utils/.frame-control-stamp'))
+
+    def test_folder_with_an_arm64_build_runs_natively(self):
+        _, folder = self.folder('arm64', 'Tiny Arm Game')
+        plan, job = install_title(folder)
+        self.assertEqual(plan['runtime'], 'SteamLinuxRuntime_4-arm64')
+        self.assertIsNone(job['error'], job)
+        self.assert_installed('Tiny_Arm_Game', 'SteamLinuxRuntime_4-arm64', 'fc-smoke-arm64')
+        ok('POST', '/api/titles', {'action': 'launch', 'id': 'Tiny_Arm_Game'})
+        run = launches('devkit')[-1]
+        # No runtime prefix: Steam ran the aarch64 build directly on the Frame.
+        self.assertEqual(run['command'], f'{GAMES}/Tiny_Arm_Game/fc-smoke-arm64')
+        if NATIVE == 'arm64':
+            self.assertIsNotNone(run['pid'], run)
+            done = wait_for(lambda: launches('devkit')[-1].get('exit') is not None and launches('devkit')[-1],
+                            20, 'the arm64 test program to exit')
+            self.assertEqual(done['exit'], 0)
+        else:
+            self.assertIn('Exec format error', run.get('exec_error', ''), run)
+
+    def test_single_exe_upload_launch_and_remove(self):
+        exe = tiny_programs.write(self.tmp, 'exe')
+        plan, job = install_title(exe)
+        self.assertEqual(plan['id'], 'fc_smoke_exe')
+        self.assertIsNone(job['error'], job)
+        shortcut = self.assert_installed('fc_smoke_exe', 'proton-experimental', 'fc-smoke-exe.exe')
+
+        ok('POST', '/api/titles', {'action': 'launch', 'id': 'fc_smoke_exe'})
+        run = launches('devkit')[-1]
+        self.assertTrue(run['started'])
+        self.assertEqual(run['command'], f'proton waitforexitandrun "{GAMES}/fc_smoke_exe/fc-smoke-exe.exe"')
+        prefix = f"{HOME}/.local/share/Steam/steamapps/compatdata/{shortcut['appid']}"
+        self.assertTrue(exists(prefix))
+
+        ok('POST', '/api/titles', {'action': 'remove', 'id': 'fc_smoke_exe'})
+        after = state()
+        self.assertNotIn('fc_smoke_exe', after['devkit_games'])
+        self.assertEqual(after['steam']['shortcuts'], [])
+        for gone in (f'{GAMES}/fc_smoke_exe', prefix, *(f'{GAMES}/fc_smoke_exe-{k}.json'
+                                                        for k in ('argv', 'env', 'settings', 'framecontrol'))):
+            self.assertFalse(exists(gone), gone)
+        self.assertEqual(ok('GET', '/api/titles')['titles'], [])
+
+    def test_names_steam_would_refuse_are_made_safe(self):
+        # Steam's create-shortcut takes ^[A-Za-z_][A-Za-z0-9_.]+$ only (device, 2026-09-27).
+        exe = self.path('2048-Deluxe.exe')
+        with open(exe, 'wb') as f:
+            f.write(tiny_programs.pe_x86_64())
+        plan, job = install_title(exe)
+        self.assertEqual(plan['id'], '_2048_Deluxe')
+        self.assertIsNone(job['error'], job)
+        self.assert_installed('_2048_Deluxe', 'proton-experimental', '2048-Deluxe.exe')
+
+    def test_x86_64_linux_build_needs_a_runtime_the_frame_lacks(self):
+        _, folder = self.folder('x86_64', 'Tiny PC Game')
+        plan, job = install_title(folder)
+        self.assertEqual(plan['runtime'], 'SteamLinuxRuntime_4')
+        self.assertIsNone(job['error'], job)
+        appid = self.assert_installed('Tiny_PC_Game', 'SteamLinuxRuntime_4', 'fc-smoke-x86_64')['appid']
+        # Steam answers the launch, then doesn't start it (docs/sideloading.md).
+        ok('POST', '/api/titles', {'action': 'launch', 'id': 'Tiny_PC_Game'})
+        run = launches('devkit')[-1]
+        self.assertFalse(run['started'])
+        self.assertEqual(run['message'], f'Tool 4183110 "Steam Linux Runtime 4.0" is found for appID {appid}, '
+                                         'but is not installed')
+        # With the runtime installed, it starts.
+        ctl('runtime', 'SteamLinuxRuntime_4', 'installed')
+        ok('POST', '/api/titles', {'action': 'launch', 'id': 'Tiny_PC_Game'})
+        run = launches('devkit')[-1]
+        self.assertTrue(run['started'])
+        if NATIVE == 'x86_64':
+            done = wait_for(lambda: launches('devkit')[-1].get('exit') is not None and launches('devkit')[-1],
+                            20, 'the x86-64 test program to exit')
+            self.assertEqual(done['exit'], 0)
+
+    def test_reinstall_with_another_runtime_keeps_one_shortcut(self):
+        zip_path = self.game_zip()
+        _, first = install_title(zip_path)
+        self.assertIsNone(first['error'], first)
+        appid = state()['devkit_games']['Cool_Game']['appid']
+        _, second = install_title(zip_path, runtime='proton-stable')
+        self.assertIsNone(second['error'], second)
+        self.assert_installed('Cool_Game', 'proton-stable', 'CoolGame.exe')
+        steam = state()['steam']
+        self.assertEqual([s['appid'] for s in steam['shortcuts']], [appid])
+        meta = json.loads(ssh(f'cat {GAMES}/Cool_Game-framecontrol.json'))
+        self.assertEqual(meta['runtime'], 'proton-stable')
+
+    def test_install_link_with_a_local_manifest(self):
+        # frame-control://install?manifest=... as a website would link it, served from
+        # this computer (FRAME_CONTROL_LOCAL_LINKS=1 lets http://127.0.0.1 through).
+        site = self.path('site')
+        os.makedirs(site)
+        with open(self.game_zip('linkgame-win64.zip'), 'rb') as f:
+            data = f.read()
+        with open(os.path.join(site, 'linkgame-win64.zip'), 'wb') as f:
+            f.write(data)
+        class Files(http.server.SimpleHTTPRequestHandler):
+            def __init__(self, *args):
+                super().__init__(*args, directory=site)
+
+            def log_message(self, *args):
+                pass
+        httpd = http.server.ThreadingHTTPServer(('127.0.0.1', 0), Files)
+        threading.Thread(target=httpd.serve_forever, daemon=True).start()
+        self.addCleanup(httpd.shutdown)
+        base = f'http://127.0.0.1:{httpd.server_address[1]}'
+        with open(os.path.join(site, 'manifest.json'), 'w') as f:
+            json.dump({'schema': 'framedrop.install/v1', 'name': 'Link Game',
+                       'files': [{'url': f'{base}/linkgame-win64.zip', 'sha256': hashlib.sha256(data).hexdigest(),
+                                  'size': len(data), 'exe': 'Cool Game/CoolGame.exe'}]}, f)
+
+        check = ok('POST', '/api/webinstall/check', {'manifest': f'{base}/manifest.json'})
+        self.assertEqual((check['name'], check['kind'], check['size']), ('Link Game', 'title', len(data)))
+        job_id = ok('POST', '/api/webinstall/start', {'id': check['id']})['job']
+        job = wait_for(lambda: (lambda j: j if j['phase'] in ('done', 'error') else None)(
+            ok('GET', f'/api/webinstall/job?id={job_id}')), 120, 'the link install')
+        self.assertEqual(job['phase'], 'done', job)
+        self.assert_installed('Link_Game', 'proton-experimental', 'CoolGame.exe')
+
+    def test_command_line_lists_what_the_app_installed(self):
+        install_title(self.game_zip())
+        out = subprocess.run([sys.executable, str(ROOT / 'ui' / 'frame_titles.py'), 'list'],
+                             capture_output=True, text=True, timeout=60)
+        self.assertEqual(out.returncode, 0, out.stderr)
+        self.assertEqual([t['id'] for t in json.loads(out.stdout)], ['Cool_Game'])
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/tests/fakeframe/Containerfile b/tests/fakeframe/Containerfile
new file mode 100644
index 0000000..ce1f2e0
--- /dev/null
+++ b/tests/fakeframe/Containerfile
@@ -0,0 +1,40 @@
+# The fake Steam Frame: Arch Linux (SteamOS's base) with sshd, rsync, python3,
+# Valve's steamos-devkit-service and hooks, a fake Steam client and stubs for
+# the Frame-only commands Frame Control runs. See docs/testing.md.
+#
+# BASE: archlinux:base on x86_64, menci/archlinuxarm:base on arm64 (a daily
+# Arch Linux ARM build); scripts/e2e.sh picks one from `uname -m`.
+ARG BASE=archlinux:base
+FROM ${BASE}
+
+RUN (pacman-key --init && pacman-key --populate) >/dev/null 2>&1; \
+    pacman -Syu --noconfirm --needed openssh rsync python nodejs curl iproute2 procps-ng util-linux \
+    && pacman -Scc --noconfirm
+
+# The Frame's user is steamos (docs/ssh.md). Its password stands in for the
+# Developer Mode password.
+RUN useradd -m -u 1000 -s /bin/bash steamos \
+    && echo 'steamos:frame' | chpasswd \
+    && ssh-keygen -A
+
+# Valve's service and hooks where the service looks for them. It runs as
+# steamos, so it lists one user and properties.json says "login": "steamos",
+# as the Frame's does (docs/ssh.md, verified 2026-09-26, BUILD_ID 20260922.6101926).
+COPY steamos-devkit-service/src/steamos-devkit-service.py /usr/lib/steamos-devkit/
+COPY steamos-devkit-service/hooks/ /usr/share/steamos-devkit/hooks/
+COPY rootfs/ /
+
+# /etc/os-release, pointed at /usr/lib/os-release, carries the Frame's
+# VERSION_ID 0.3.0, VARIANT_ID vr and BUILD_ID 20260922.6101926 (docs/apks.md).
+RUN ln -sf ../usr/lib/os-release /etc/os-release \
+    && chmod 755 /usr/share/steamos-devkit/hooks/approve-ssh-key /usr/share/steamos-devkit/hooks/install-ssh-key \
+      /usr/share/steamos-devkit/hooks/devkit-1-identify /usr/local/bin/* /usr/local/lib/fakeframe/*.py \
+      /usr/bin/steamos-polkit-helpers/steamos-enable-sshd \
+    && mkdir -p /usr/local/lib/fakeframe/bin /var/lib/fakeframe /var/log/fakeframe /home/steamos/devkit-game \
+    && cp /usr/bin/sleep /usr/local/lib/fakeframe/bin/vrserver \
+    && cp /usr/bin/sleep /usr/local/lib/fakeframe/bin/plasmashell \
+    && chmod 1777 /var/lib/fakeframe /var/log/fakeframe \
+    && chown -R steamos:steamos /home/steamos
+
+EXPOSE 22 32000 9999
+CMD ["python3", "/usr/local/lib/fakeframe/init.py"]
diff --git a/tests/fakeframe/compose.yaml b/tests/fakeframe/compose.yaml
new file mode 100644
index 0000000..089321c
--- /dev/null
+++ b/tests/fakeframe/compose.yaml
@@ -0,0 +1,54 @@
+# The fake Frame and the computer Frame Control runs on, for tests/e2e.
+# scripts/e2e.sh builds the two images, brings this up, runs the tests in
+# `host` and takes it down again.
+name: fakeframe-e2e
+services:
+  fakeframe:
+    image: fakeframe-frame
+    pull_policy: never
+    hostname: frame               # the Frame's default hostname (docs/ssh.md)
+    init: true
+    tmpfs:
+      # Small, so `fakeframe-ctl disk-full on` can fill it.
+      - /home/steamos/devkit-game:size=64m,mode=0755,exec
+    volumes:
+      - keys:/keys
+      # frame_status.py reads the battery and thermal zones from /sys, which is
+      # read-only in a container (and docker's AppArmor profile refuses writes
+      # under /sys even to a mount there). So each folder is a volume mounted
+      # twice: over /sys/class/... for reading, and under /var/lib/fakeframe/sys
+      # where the supervisor writes it (fakeframe-ctl battery).
+      - power:/sys/class/power_supply
+      - power:/var/lib/fakeframe/sys/power_supply
+      - thermal:/sys/class/thermal
+      - thermal:/var/lib/fakeframe/sys/thermal
+    environment:
+      FAKEFRAME_PAIRING_MODE: ${FAKEFRAME_PAIRING_MODE:-0}
+    healthcheck:
+      test: ["CMD", "fakeframe-ctl", "ping"]
+      interval: 2s
+      timeout: 10s
+      retries: 60
+  host:
+    image: fakeframe-host
+    pull_policy: never
+    init: true
+    depends_on:
+      fakeframe:
+        condition: service_healthy
+    volumes:
+      - ../..:/repo:ro
+      - keys:/keys:ro
+    environment:
+      FAKEFRAME_CTL: http://fakeframe:9999
+      FAKEFRAME_HOST: fakeframe
+      FRAME_E2E: "1"
+    healthcheck:
+      test: ["CMD", "test", "-f", "/home/tester/.ready"]
+      interval: 1s
+      timeout: 5s
+      retries: 120
+volumes:
+  keys:
+  power:
+  thermal:
diff --git a/tests/fakeframe/host.Containerfile b/tests/fakeframe/host.Containerfile
new file mode 100644
index 0000000..bfdc7b5
--- /dev/null
+++ b/tests/fakeframe/host.Containerfile
@@ -0,0 +1,14 @@
+# The computer Frame Control runs on, for the e2e tests: Python 3.9 (the
+# oldest the app supports), the OpenSSH client and rsync, and nothing else.
+# The repository is mounted read-only at /repo (compose.yaml). OpenSSH reads
+# ~/.ssh/config from the passwd home, not $HOME, which is why this is a
+# container of its own rather than a HOME override on the machine running the tests.
+FROM python:3.9-slim-bookworm
+RUN apt-get update && apt-get install -y --no-install-recommends openssh-client rsync procps \
+    && rm -rf /var/lib/apt/lists/* \
+    && useradd -m -u 1000 -s /bin/bash tester
+COPY host/entrypoint.sh /usr/local/bin/fakeframe-host
+ENV PYTHONDONTWRITEBYTECODE=1 PYTHONUNBUFFERED=1
+USER tester
+WORKDIR /repo
+CMD ["fakeframe-host"]
diff --git a/tests/fakeframe/host/entrypoint.sh b/tests/fakeframe/host/entrypoint.sh
new file mode 100755
index 0000000..b4727c0
--- /dev/null
+++ b/tests/fakeframe/host/entrypoint.sh
@@ -0,0 +1,25 @@
+#!/bin/bash
+# The computer side of the harness: tester's ~/.ssh as Frame Control's setup
+# leaves it (ui/frame_connect.py's own config block), pointing `frame` at the
+# fake Frame, with the harness key the fake trusts.
+set -euo pipefail
+host=${FAKEFRAME_HOST:-fakeframe}
+for _ in $(seq 1 240); do
+  [ -s /keys/id_ed25519_frame.pub ] && break
+  sleep 0.5
+done
+mkdir -p -m 700 ~/.ssh
+install -m 600 /keys/id_ed25519_frame ~/.ssh/id_ed25519_frame
+install -m 644 /keys/id_ed25519_frame.pub ~/.ssh/id_ed25519_frame.pub
+python3 - "$host" > ~/.ssh/config <<'PY'
+import sys
+sys.path.insert(0, '/repo/ui')
+import frame_connect
+print('\n'.join(frame_connect.config_block(sys.argv[1])))
+PY
+chmod 600 ~/.ssh/config
+until ssh-keyscan -T 2 "$host" > ~/.ssh/known_hosts 2>/dev/null && [ -s ~/.ssh/known_hosts ]; do
+  sleep 1
+done
+touch ~/.ready
+exec sleep infinity
diff --git a/tests/fakeframe/rootfs/etc/ssh/sshd_config b/tests/fakeframe/rootfs/etc/ssh/sshd_config
new file mode 100644
index 0000000..74bc0f9
--- /dev/null
+++ b/tests/fakeframe/rootfs/etc/ssh/sshd_config
@@ -0,0 +1,21 @@
+# The fake Frame's sshd. With Developer Mode on, the Frame takes key logins and
+# the Developer Mode password for `steamos` (docs/ssh.md); the fake's password
+# is "frame". MaxSessions leaves room for Frame Control's shared connection.
+Port 22
+HostKey /etc/ssh/ssh_host_ed25519_key
+HostKey /etc/ssh/ssh_host_rsa_key
+HostKey /etc/ssh/ssh_host_ecdsa_key
+PermitRootLogin no
+PubkeyAuthentication yes
+AuthorizedKeysFile .ssh/authorized_keys
+PasswordAuthentication yes
+KbdInteractiveAuthentication no
+UsePAM no
+PrintMotd no
+MaxSessions 64
+MaxStartups 64:30:128
+# OpenSSH 9.8+ penalises an address after failed logins by refusing it for a
+# while. The pairing tests fail logins on purpose, so the fake turns that off.
+# (Whether the Frame's sshd penalises is unchecked.)
+PerSourcePenalties no
+Subsystem sftp /usr/lib/ssh/sftp-server
diff --git a/tests/fakeframe/rootfs/usr/bin/steamos-polkit-helpers/steamos-enable-sshd b/tests/fakeframe/rootfs/usr/bin/steamos-polkit-helpers/steamos-enable-sshd
new file mode 100755
index 0000000..8386d15
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/bin/steamos-polkit-helpers/steamos-enable-sshd
@@ -0,0 +1,14 @@
+#!/usr/bin/env python3
+"""Stub for SteamOS's polkit helper, which approve-ssh-key runs once a pairing
+is approved: asks the fake Frame's supervisor to (re)start sshd."""
+import json
+import sys
+import urllib.request
+
+sys.path.insert(0, '/usr/local/lib/fakeframe')
+import fakeframe_state as fs  # noqa: E402
+
+fs.log('steamos-enable-sshd')
+req = urllib.request.Request('http://127.0.0.1:9999/ctl', data=json.dumps({'args': ['sshd', 'on']}).encode(),
+                             headers={'Content-Type': 'application/json'})
+urllib.request.urlopen(req, timeout=10).read()
diff --git a/tests/fakeframe/rootfs/usr/lib/os-release b/tests/fakeframe/rootfs/usr/lib/os-release
new file mode 100644
index 0000000..baac582
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/lib/os-release
@@ -0,0 +1,9 @@
+NAME="SteamOS"
+PRETTY_NAME="SteamOS"
+ID=steamos
+ID_LIKE=arch
+LOGO=steamos
+HOME_URL="https://www.steampowered.com/"
+VERSION_ID=0.3.0
+VARIANT_ID=vr
+BUILD_ID=20260922.6101926
diff --git a/tests/fakeframe/rootfs/usr/local/bin/fakeframe-ctl b/tests/fakeframe/rootfs/usr/local/bin/fakeframe-ctl
new file mode 100755
index 0000000..bdbb02b
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/local/bin/fakeframe-ctl
@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+"""Flip the fake Frame's fault switches and read its state; `fakeframe-ctl help`.
+
+Talks to the supervisor's control port, so it works the same over SSH
+(`ssh frame fakeframe-ctl steam off`) and from the host container with
+FAKEFRAME_CTL=http://fakeframe:9999.
+"""
+import json
+import os
+import sys
+import urllib.error
+import urllib.request
+
+url = os.environ.get('FAKEFRAME_CTL', 'http://127.0.0.1:9999').rstrip('/')
+req = urllib.request.Request(url + '/ctl', data=json.dumps({'args': sys.argv[1:]}).encode(),
+                             headers={'Content-Type': 'application/json'})
+try:
+    with urllib.request.urlopen(req, timeout=60) as r:
+        out = json.load(r)
+except urllib.error.HTTPError as e:
+    out = json.load(e)
+except OSError as e:
+    sys.exit(f'fakeframe-ctl: control port not answering ({e})')
+if 'usage' in out:
+    print(out['usage'])
+elif 'error' in out:
+    sys.exit(f"fakeframe-ctl: {out['error']}")
+else:
+    print(json.dumps(out, indent=1))
+    if sys.argv[1:2] == ['ping'] and not out.get('ok'):
+        sys.exit(1)
diff --git a/tests/fakeframe/rootfs/usr/local/bin/flatpak b/tests/fakeframe/rootfs/usr/local/bin/flatpak
new file mode 100755
index 0000000..1d9d510
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/local/bin/flatpak
@@ -0,0 +1,38 @@
+#!/usr/bin/env python3
+"""Stub for flatpak: --user installs and removals, and `list`, kept in the state file.
+Nothing is downloaded; an app id containing "missing" fails like an unknown ref."""
+import sys
+
+sys.path.insert(0, '/usr/local/lib/fakeframe')
+import fakeframe_state as fs  # noqa: E402
+
+args = sys.argv[1:]
+fs.log('flatpak', args=args)
+words = [a for a in args if not a.startswith('-')]
+cmd = words[0] if words else ''
+if cmd == 'remote-add':
+    pass
+elif cmd == 'install':
+    app = words[-1]
+    if 'missing' in app:
+        sys.exit(f'error: Nothing matches {app} in remote flathub')
+    with fs.update() as s:
+        if not any(f['id'] == app for f in s['flatpaks']):
+            s['flatpaks'].append({'id': app, 'name': app.rsplit('.', 1)[-1], 'version': '1.0', 'installation': 'user'})
+    print(f'Installing {app}\nInstallation complete.')
+elif cmd == 'uninstall':
+    app = words[-1]
+    with fs.update() as s:
+        before = len(s['flatpaks'])
+        s['flatpaks'] = [f for f in s['flatpaks'] if f['id'] != app]
+        gone = len(s['flatpaks']) < before
+    if not gone:
+        sys.exit(f'error: {app}/*unspecified*/*unspecified* not installed')
+    print('Uninstall complete.')
+elif cmd == 'list':
+    for f in fs.read()['flatpaks']:
+        print('\t'.join((f['id'], f['name'], f['version'], f['installation'])))
+elif cmd == 'run':
+    pass
+else:
+    sys.exit(f'flatpak stub: unsupported {args}')
diff --git a/tests/fakeframe/rootfs/usr/local/bin/gamescopectl b/tests/fakeframe/rootfs/usr/local/bin/gamescopectl
new file mode 100755
index 0000000..6ba57c0
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/local/bin/gamescopectl
@@ -0,0 +1,26 @@
+#!/usr/bin/env python3
+"""Stub for gamescopectl: `screenshot FILE` writes a small PNG, as gamescope does
+(asynchronously on the Frame, which server.SCREENSHOT waits out)."""
+import struct
+import sys
+import zlib
+
+sys.path.insert(0, '/usr/local/lib/fakeframe')
+import fakeframe_state as fs  # noqa: E402
+
+args = sys.argv[1:]
+fs.log('gamescopectl', args=args)
+if len(args) != 2 or args[0] != 'screenshot':
+    sys.exit(f'gamescopectl stub: unsupported {args}')
+
+
+def chunk(kind, data):
+    return struct.pack('>I', len(data)) + kind + data + struct.pack('>I', zlib.crc32(kind + data))
+
+
+w, h = 64, 36
+rows = b''.join(b'\0' + b''.join(bytes((x * 4, y * 7, 160)) for x in range(w)) for y in range(h))
+png = (b'\x89PNG\r\n\x1a\n' + chunk(b'IHDR', struct.pack('>IIBBBBB', w, h, 8, 2, 0, 0, 0))
+       + chunk(b'IDAT', zlib.compress(rows)) + chunk(b'IEND', b''))
+with open(args[1], 'wb') as f:
+    f.write(png)
diff --git a/tests/fakeframe/rootfs/usr/local/bin/nmcli b/tests/fakeframe/rootfs/usr/local/bin/nmcli
new file mode 100755
index 0000000..d416776
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/local/bin/nmcli
@@ -0,0 +1,11 @@
+#!/usr/bin/env python3
+"""Stub for nmcli: the Wi-Fi network frame_status.py reads with
+`nmcli -t -f active,ssid,signal dev wifi` (':' inside fields escaped as '\\:')."""
+import sys
+
+sys.path.insert(0, '/usr/local/lib/fakeframe')
+import fakeframe_state as fs  # noqa: E402
+
+fs.log('nmcli', args=sys.argv[1:])
+print('yes:Fake\\:Frame Wi-Fi:72')
+print('no:Neighbours:31')
diff --git a/tests/fakeframe/rootfs/usr/local/bin/podman b/tests/fakeframe/rootfs/usr/local/bin/podman
new file mode 100755
index 0000000..a996bf3
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/local/bin/podman
@@ -0,0 +1,47 @@
+#!/usr/bin/env python3
+"""Stub for podman, for the fake Lepton instances (lepton.py): ps, stop, exec.
+`podman ps --format "{{.Names}} {{.Labels.adb_port}}"` lists what's running,
+as frame_android.running_instances reads it (docs/apks.md)."""
+import os
+import sys
+import time
+
+sys.path.insert(0, '/usr/local/lib/fakeframe')
+import fakeframe_state as fs  # noqa: E402
+
+
+def alive(c):
+    try:
+        os.kill(c['pid'], 0)
+        return True
+    except OSError:
+        return False
+
+
+args = sys.argv[1:]
+fs.log('podman', args=args)
+cmd = args[0] if args else ''
+containers = {n: c for n, c in fs.read()['lepton'].items() if alive(c)}
+if cmd == 'ps':
+    for name, c in sorted(containers.items()):
+        print(f"{name} {c['port']}")
+elif cmd == 'stop':
+    name = args[-1]
+    c = containers.get(name)
+    if not c:
+        sys.exit(f'Error: no container with name or ID "{name}" found: no such container')
+    os.kill(c['pid'], 15)
+    for _ in range(50):
+        if not alive(c):
+            break
+        time.sleep(0.1)
+    print(name)
+elif cmd == 'exec':
+    name, rest = args[1], ' '.join(args[2:])
+    if name not in containers:
+        sys.exit(f'Error: no container with name or ID "{name}" found: no such container')
+    if 'pidof' in rest:
+        print(4242)                   # the app is "up"; there's no Android to ask
+    # logcat and anything else: nothing to report
+else:
+    sys.exit(f'podman stub: unsupported {args}')
diff --git a/tests/fakeframe/rootfs/usr/local/bin/qdbus6 b/tests/fakeframe/rootfs/usr/local/bin/qdbus6
new file mode 100755
index 0000000..c1afafb
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/local/bin/qdbus6
@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+"""Stub for qdbus6: records Klipper setClipboardContents calls, the way
+Frame Control sends text to the headset desktop's clipboard (server.PASTE,
+verified 2026-09-25)."""
+import os
+import sys
+
+sys.path.insert(0, '/usr/local/lib/fakeframe')
+import fakeframe_state as fs  # noqa: E402
+
+args = sys.argv[1:]
+fs.log('qdbus6', args=args[:3], bus=os.environ.get('DBUS_SESSION_BUS_ADDRESS'))
+if args[:3] == ['org.kde.klipper', '/klipper', 'org.kde.klipper.klipper.setClipboardContents'] and len(args) == 4:
+    if not os.environ.get('DBUS_SESSION_BUS_ADDRESS'):
+        sys.exit('Could not connect to D-Bus server')
+    with fs.update() as s:
+        s['clipboard'].append(args[3])
+else:
+    sys.exit(f'qdbus6 stub: unsupported {args}')
diff --git a/tests/fakeframe/rootfs/usr/local/bin/steam b/tests/fakeframe/rootfs/usr/local/bin/steam
new file mode 100755
index 0000000..0ce1613
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/local/bin/steam
@@ -0,0 +1,26 @@
+#!/usr/bin/env python3
+"""Stub for SteamOS's `steam` command: hands steam:// URLs to the running client.
+
+On the Frame, `steam steam://rungameid/N` over SSH starts the game in the
+running client (docs/apks.md, docs/steam-games.md, 2026-09-25). How the real
+wrapper passes the URL on isn't documented; this writes it as a line on
+~/.steam/steam.pipe, which fakesteam reads (guess).
+"""
+import os
+import sys
+
+sys.path.insert(0, '/usr/local/lib/fakeframe')
+import fakeframe_state as fs  # noqa: E402
+
+args = sys.argv[1:]
+running = fs.steam_pid() is not None
+fs.log('steam', args=args, client_running=running)
+if not running:
+    # The real command would start the Steam client; this one can't.
+    print('steam: the Steam client is not running', file=sys.stderr)
+    sys.exit(0)
+fd = os.open(os.path.expanduser('~/.steam/steam.pipe'), os.O_RDWR)
+try:
+    os.write(fd, (' '.join(args) + '\n').encode())
+finally:
+    os.close(fd)
diff --git a/tests/fakeframe/rootfs/usr/local/bin/wpctl b/tests/fakeframe/rootfs/usr/local/bin/wpctl
new file mode 100755
index 0000000..a423110
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/local/bin/wpctl
@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+"""Stub for PipeWire's wpctl: the default sink's volume and mute, kept in the state file.
+Output format as wpctl prints it: "Volume: 0.40" plus " [MUTED]"."""
+import sys
+
+sys.path.insert(0, '/usr/local/lib/fakeframe')
+import fakeframe_state as fs  # noqa: E402
+
+args = sys.argv[1:]
+fs.log('wpctl', args=args)
+if len(args) == 2 and args[0] == 'get-volume':
+    v = fs.read()['volume']
+    print(f"Volume: {v['level']:.2f}" + (' [MUTED]' if v['muted'] else ''))
+elif len(args) == 3 and args[0] == 'set-volume':
+    with fs.update() as s:
+        s['volume']['level'] = max(0.0, min(1.5, float(args[2])))
+elif len(args) == 3 and args[0] == 'set-mute':
+    with fs.update() as s:
+        s['volume']['muted'] = args[2] == 'toggle' and not s['volume']['muted'] or args[2] == '1'
+else:
+    sys.exit(f'wpctl stub: unsupported {args}')
diff --git a/tests/fakeframe/rootfs/usr/local/lib/fakeframe/cef_shim.js b/tests/fakeframe/rootfs/usr/local/lib/fakeframe/cef_shim.js
new file mode 100644
index 0000000..e50f3cf
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/local/lib/fakeframe/cef_shim.js
@@ -0,0 +1,157 @@
+// The fake Steam client's JavaScript context ("SharedJSContext"), for fakesteam's
+// DevTools server. fakesteam sends one JSON request per line on stdin:
+//   {"id": N, "expression": "...", "awaitPromise": true, "steam": {...state...}}
+// and gets one line back: {"id": N, "result": <CDP Runtime.evaluate result>, "steam": {...}}.
+// The expression runs for real in a V8 context holding the objects below, so
+// whatever JavaScript Frame Control sends (async functions, optional chaining,
+// Map) behaves as it would in Steam's CEF; only the objects are stand-ins.
+//
+// Shapes copy what was seen through the Frame's DevTools port on 2026-09-25
+// (docs/steam-games.md and docs/apks.md, BUILD_ID 20260922.6101926):
+// appStore.allApps, a Map in downloadsStore.m_DownloadOverview keyed by client
+// id with "0" for this machine, SteamClient.Installs.GetInstallManagerInfo /
+// ContinueInstall, SteamClient.User.GetIPCountry, and SteamClient.Apps.AddShortcut
+// + SetShortcutName / SetShortcutStartDir for non-Steam shortcuts.
+'use strict';
+const vm = require('vm');
+const readline = require('readline');
+
+const SHORTCUT_TYPE = 1073741824;  // app_type of a non-Steam shortcut, as steam_shortcuts.py filters
+
+function newShortcutId(steam) {
+  // Real shortcut ids are 32-bit with the top bit set (T3 Code's was 3130509679).
+  steam.next_shortcut = (steam.next_shortcut || 0) + 1;
+  return (0x80000000 + ((steam.next_shortcut * 2654435761) >>> 1)) >>> 0;
+}
+
+function build(steam) {
+  const findShortcut = id => steam.shortcuts.find(s => s.appid === Number(id));
+  const gameOverview = a => ({
+    appid: a.appid, display_name: a.display_name, sort_as: a.display_name, app_type: 1,
+    steam_hw_compat_category_packed: a.packed || 0, vr_supported: !!a.vr, vr_only: !!a.vr_only,
+    size_on_disk: String(a.installed ? a.size : 0), minutes_playtime_forever: a.minutes || 0,
+    rt_last_time_played: a.last_played || 0,
+    local_per_client_data: {
+      installed: !!a.installed, display_status: a.display_status ?? (a.installed ? 1 : 0),
+      status_percentage: a.status_percentage ?? 0,
+    },
+  });
+  const shortcutOverview = s => ({
+    appid: s.appid, display_name: s.name, sort_as: s.name, app_type: SHORTCUT_TYPE,
+    local_per_client_data: { installed: true, display_status: 1, status_percentage: 0 },
+  });
+  const allApps = () => [...steam.apps.map(gameOverview), ...steam.shortcuts.map(shortcutOverview)];
+
+  const im = () => steam.install_manager;
+  const queue = appid => {
+    // State 14: Steam queued the download (Balatro on the Frame, docs/steam-games.md).
+    const app = steam.apps.find(a => a.appid === appid);
+    Object.assign(im(), { eInstallState: 14, currentAppID: appid });
+    if (app) {
+      steam.download = { update_appid: appid, update_state: 'Downloading', paused: false,
+                         update_is_install: true, overall_percent_complete: 0,
+                         overall_estimated_time_remaining_sec: 7, update_network_bytes_per_second: 9500000 };
+    }
+  };
+
+  return {
+    appStore: {
+      get allApps() { return allApps(); },
+      GetAppOverviewByAppID(id) { return allApps().find(a => a.appid === Number(id)) || null; },
+    },
+    downloadsStore: {
+      get m_DownloadOverview() { return steam.download ? new Map([['0', { ...steam.download }]]) : new Map(); },
+    },
+    SteamClient: {
+      Apps: {
+        async AddShortcut(name, exe, launchOptions, cmdLine) {
+          const appid = newShortcutId(steam);
+          const base = String(exe).split('/').pop();
+          steam.shortcuts.push({ appid, name: base, exe: String(exe), start_dir: '', icon: '',
+                                 launch_options: String(launchOptions || ''), devkit_gameid: null });
+          return appid;
+        },
+        SetShortcutName(id, name) { const s = findShortcut(id); if (s) s.name = String(name); },
+        SetShortcutStartDir(id, dir) { const s = findShortcut(id); if (s) s.start_dir = String(dir); },
+        SetShortcutIcon(id, icon) { const s = findShortcut(id); if (s) s.icon = String(icon); },
+        SetShortcutExe(id, exe) { const s = findShortcut(id); if (s) s.exe = String(exe); },
+        RemoveShortcut(id) {
+          steam.shortcuts = steam.shortcuts.filter(s => s.appid !== Number(id));
+          delete steam.compat_tools[String(id)];
+        },
+      },
+      Installs: {
+        async GetInstallManagerInfo() {
+          const i = im();
+          return { eInstallState: i.eInstallState, currentAppID: i.currentAppID,
+                   nDiskSpaceRequired: i.nDiskSpaceRequired, nDiskSpaceAvailable: i.nDiskSpaceAvailable,
+                   eAppError: i.eAppError ?? 0, errorDetail: i.errorDetail ?? '' };
+        },
+        // Broforce stopped at state 7 and ContinueInstall() queued it (docs/steam-games.md).
+        ContinueInstall() { if (im().eInstallState === 7) queue(im().currentAppID); },
+        CancelInstall() { Object.assign(im(), { eInstallState: 16 }); },
+        // Calling OpenInstallWizard directly did nothing on the Frame: the state stayed 0.
+        OpenInstallWizard() {},
+      },
+      User: {
+        async GetIPCountry() { return steam.country; },
+      },
+    },
+  };
+}
+
+// What CDP's Runtime.evaluate returns with returnByValue.
+function remote(value) {
+  if (value === undefined) return { type: 'undefined' };
+  if (value === null) return { type: 'object', subtype: 'null', value: null };
+  const type = typeof value;
+  if (type === 'object') return { type: 'object', value: JSON.parse(JSON.stringify(value)) };
+  if (type === 'function') return { type: 'function', description: String(value) };
+  return { type, value, description: String(value) };
+}
+
+function exception(err, inPromise) {
+  // Chrome puts the stack in description; its first line is enough here.
+  const description = err && err.name ? `${err.name}: ${err.message}` : String(err);
+  return {
+    result: { type: 'object', subtype: 'error', className: (err && err.name) || 'Error', description },
+    exceptionDetails: {
+      exceptionId: 1, text: inPromise ? 'Uncaught (in promise)' : 'Uncaught', lineNumber: 0, columnNumber: 0,
+      exception: { type: 'object', subtype: 'error', className: (err && err.name) || 'Error', description },
+    },
+  };
+}
+
+async function evaluate(req) {
+  const steam = req.steam;
+  const ctx = vm.createContext(build(steam));
+  let value;
+  try {
+    value = vm.runInContext(req.expression, ctx, { timeout: 5000 });
+  } catch (err) {
+    return exception(err, false);
+  }
+  if (req.awaitPromise && value && typeof value.then === 'function') {
+    try {
+      value = await value;
+    } catch (err) {
+      return exception(err, true);
+    }
+  }
+  try {
+    return { result: remote(value) };
+  } catch (err) {
+    return exception(err, false);
+  }
+}
+
+// One request at a time: fakesteam holds the state lock around each.
+const rl = readline.createInterface({ input: process.stdin });
+let chain = Promise.resolve();
+rl.on('line', line => {
+  chain = chain.then(async () => {
+    const req = JSON.parse(line);
+    const result = await evaluate(req);
+    process.stdout.write(JSON.stringify({ id: req.id, result, steam: req.steam }) + '\n');
+  });
+});
diff --git a/tests/fakeframe/rootfs/usr/local/lib/fakeframe/fakeframe_state.py b/tests/fakeframe/rootfs/usr/local/lib/fakeframe/fakeframe_state.py
new file mode 100755
index 0000000..707f5dc
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/local/lib/fakeframe/fakeframe_state.py
@@ -0,0 +1,183 @@
+"""Shared state of the fake Frame: one JSON file plus a log of stub calls.
+
+Every fake part (the supervisor, fakesteam, the command stubs) reads and
+writes /var/lib/fakeframe/state.json through update(), which holds an
+exclusive flock, so separate processes never lose each other's changes.
+Tests read the file over SSH (`fakeframe-ctl state`) or the control port.
+"""
+import contextlib
+import fcntl
+import json
+import os
+import time
+
+DIR = '/var/lib/fakeframe'
+STATE = os.path.join(DIR, 'state.json')
+CALLS = os.path.join(DIR, 'calls.jsonl')
+LOCK = os.path.join(DIR, 'state.lock')
+
+HOME = '/home/steamos'
+STEAM_ROOT = HOME + '/.local/share/Steam'
+DEVKIT_GAMES = HOME + '/devkit-game'
+LEPTON = STEAM_ROOT + '/steamapps/common/Lepton/lepton'
+
+# Compat tools and the Steam app ids of their depots. 4183110 is the id Steam
+# printed on the Frame for "Steam Linux Runtime 4.0" (docs/sideloading.md,
+# BUILD_ID 20260922.6101926); Lepton Development is 3056000 (docs/apks.md).
+# The others are placeholders: nothing in Frame Control reads them.
+RUNTIME_APPIDS = {'proton-experimental': 1493710, 'proton-stable': 3658110,
+                  'SteamLinuxRuntime_4-arm64': 4183120, 'SteamLinuxRuntime_4': 4183110,
+                  'lepton': 3056000}
+RUNTIME_NAMES = {'proton-experimental': 'Proton Experimental', 'proton-stable': 'Proton 11.0',
+                 'SteamLinuxRuntime_4-arm64': 'Steam Linux Runtime 4.0 (arm64)',
+                 'SteamLinuxRuntime_4': 'Steam Linux Runtime 4.0', 'lepton': 'Lepton Development'}
+
+
+def default_state():
+    return {
+        'switches': {
+            'pairing_mode': False,      # Steam Settings > Developer > Pair new host open or not
+            'pairing_answer': 'approve',  # approve | deny | timeout
+            'steam': True,              # Steam client running
+            'asleep': False,            # headset asleep: ports 22 and 32000 accept but never answer
+            'sshd': True,
+            'devkit_service': True,
+            'disk_full': False,
+        },
+        # Which compat tools are installed. On the Frame the x86-64 Steam Linux
+        # Runtime 4.0 wasn't, and a devkit title didn't install it (docs/sideloading.md,
+        # 2026-09-26, BUILD_ID 20260922.6101926).
+        'runtimes': {'proton-experimental': True, 'proton-stable': True,
+                     'SteamLinuxRuntime_4-arm64': True, 'SteamLinuxRuntime_4': False, 'lepton': True},
+        # /sys/class/power_supply values, in the units the kernel uses (µV, µA, tenths
+        # of °C), as frame_status.py reads them (paths verified on build 20260922; its
+        # docstring gives the charger type 'C PD [PD_PPS]' at 20 W as seen on the Frame).
+        'battery': {'capacity': 76, 'status': 'Charging', 'voltage_now': 7700000, 'current_now': 1250000,
+                    'time_to_full_now': 2520, 'temp': 312, 'health': 'Good',
+                    'charger': {'online': 1, 'usb_type': 'C PD [PD_PPS]', 'voltage_now': 9000000,
+                                'current_now': 2220000}},
+        'thermal_mc': [41500, 38250],   # thermal_zone*/temp, millidegrees C
+        'volume': {'level': 0.4, 'muted': False},
+        'flatpaks': [],
+        'clipboard': [],
+        'steam': {
+            'country': 'AU',            # GetIPCountry() answered "AU" (docs/steam-games.md)
+            'next_shortcut': 0,
+            # A few owned games. Balatro went straight to install state 14 and
+            # Broforce stopped at 7 on the Frame (docs/steam-games.md, 2026-09-25,
+            # BUILD_ID 20260922.6101926); `wizard` makes the fake do the same.
+            'apps': [
+                {'appid': 2379780, 'display_name': 'Balatro', 'installed': False, 'size': 67000000,
+                 'packed': 3 << 8 | 3, 'vr': False, 'wizard': 14},
+                {'appid': 274190, 'display_name': 'Broforce', 'installed': False, 'size': 600000000,
+                 'packed': 0 << 8 | 2, 'vr': False, 'wizard': 7},
+                {'appid': 620980, 'display_name': 'Beat Saber', 'installed': True, 'size': 4200000000,
+                 'packed': 3 << 8 | 1, 'vr': True, 'vr_only': True, 'wizard': 14},
+            ],
+            'shortcuts': [],            # {appid, name, exe, start_dir, icon, devkit_gameid}
+            'compat_tools': {},         # shortcut appid (str) -> compat tool alias (CompatToolMapping)
+            'install_manager': {'eInstallState': 0, 'currentAppID': 0, 'nDiskSpaceRequired': 0,
+                                'nDiskSpaceAvailable': 0},
+            'download': None,
+            'pages': [],                # extra DevTools targets, e.g. a store page
+        },
+        'devkit_games': {},             # gameid -> what create-shortcut registered
+        'launches': [],                 # every launch Steam was asked for, and what it did
+        'pairing_requests': [],
+        'lepton': {},                   # container name -> {port, pid, package dir}
+    }
+
+
+def _share(fd):
+    # Files are made by root or steamos, whichever comes first; both write them (umask aside).
+    try:
+        os.fchmod(fd, 0o666)
+    except OSError:
+        pass                            # not ours: whoever made it already did this
+
+
+def _ensure_dir():
+    os.makedirs(DIR, exist_ok=True)
+
+
+@contextlib.contextmanager
+def _locked(kind):
+    _ensure_dir()
+    fd = os.open(LOCK, os.O_RDWR | os.O_CREAT, 0o666)
+    _share(fd)
+    try:
+        fcntl.flock(fd, kind)
+        yield
+    finally:
+        os.close(fd)
+
+
+def _load():
+    try:
+        with open(STATE) as f:
+            return json.load(f)
+    except (OSError, ValueError):
+        return default_state()
+
+
+def _save(state):
+    tmp = f'{STATE}.{os.getpid()}.tmp'
+    with open(tmp, 'w') as f:
+        json.dump(state, f, indent=1, sort_keys=True)
+    os.chmod(tmp, 0o666)                # the supervisor (root) and steamos both write it
+    os.replace(tmp, STATE)
+
+
+def read():
+    with _locked(fcntl.LOCK_SH):
+        return _load()
+
+
+@contextlib.contextmanager
+def update():
+    """with update() as s: change s; it's written back when the block ends without an error."""
+    with _locked(fcntl.LOCK_EX):
+        state = _load()
+        yield state
+        _save(state)
+
+
+def reset():
+    with _locked(fcntl.LOCK_EX):
+        _save(default_state())
+        with open(CALLS, 'w'):
+            pass
+        os.chmod(CALLS, 0o666)
+
+
+def log(tool, **fields):
+    """Append one call record to calls.jsonl."""
+    _ensure_dir()
+    line = json.dumps({'time': round(time.time(), 3), 'tool': tool, **fields}) + '\n'
+    fd = os.open(CALLS, os.O_WRONLY | os.O_APPEND | os.O_CREAT, 0o666)
+    _share(fd)
+    try:
+        fcntl.flock(fd, fcntl.LOCK_EX)
+        os.write(fd, line.encode())
+    finally:
+        os.close(fd)
+
+
+def calls(tool=None):
+    try:
+        with open(CALLS) as f:
+            out = [json.loads(line) for line in f if line.strip()]
+    except OSError:
+        return []
+    return [c for c in out if tool is None or c['tool'] == tool]
+
+
+def steam_pid():
+    """The fake Steam client's pid if it's running, as devkit_utils.validate_steam_client checks."""
+    try:
+        with open(HOME + '/.steam/steam.pid') as f:
+            pid = int(f.read())
+        os.kill(pid, 0)
+        return pid
+    except (OSError, ValueError):
+        return None
diff --git a/tests/fakeframe/rootfs/usr/local/lib/fakeframe/fakesteam.py b/tests/fakeframe/rootfs/usr/local/lib/fakeframe/fakesteam.py
new file mode 100755
index 0000000..c76b586
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/local/lib/fakeframe/fakesteam.py
@@ -0,0 +1,490 @@
+#!/usr/bin/env python3
+"""A stand-in for the Frame's Steam client, run as steamos by the supervisor.
+
+What it copies, and from where (BUILD_ID 20260922.6101926 unless noted):
+- The devkit IPC Valve's devkit-utils and the devkit service's hooks use:
+  ~/.steam/steam.pid (validate_steam_client), ~/.steam/steam.token, and
+  "devkit-1 steam://devkit-1/<token>/<command>?<query>" lines on the
+  ~/.steam/steam.pipe FIFO, answered by writing <response> or
+  <response>.error (with <response>.lock while writing), as
+  devkit_utils.wait_on_file_response describes. Commands: approve-ssh-key,
+  create-shortcut, run-game, list-shortcuts and delete-shortcut (all that
+  devkit-utils and the hooks send).
+- steam:// URLs that the `steam` wrapper forwards (rungameid, install, store).
+- The DevTools endpoint on 127.0.0.1:8080 with a SharedJSContext target
+  (docs/steam-games.md, docs/apks.md). Expressions run in node against
+  cef_shim.js.
+
+State lives in fakeframe_state (the "steam", "devkit_games", "launches" and
+"pairing_requests" keys). Anything not seen on a headset is marked "guess".
+"""
+import base64
+import hashlib
+import json
+import os
+import re
+import secrets
+import signal
+import struct
+import subprocess
+import sys
+import threading
+import time
+from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
+from urllib.parse import parse_qs
+
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+import fakeframe_state as fs  # noqa: E402
+
+HOME = fs.HOME
+STEAM_DIR = HOME + '/.steam'
+PID_FILE, TOKEN_FILE, PIPE = (f'{STEAM_DIR}/steam.{n}' for n in ('pid', 'token', 'pipe'))
+CONSOLE_LOG = fs.STEAM_ROOT + '/logs/console_log.txt'  # guess: which file Steam logs devkit launches to
+DEVTOOLS_PORT = 8080
+TARGET_ID = 'F0CA11ED5EA4ED0000000000000000AB'
+GAME_LOGS = '/var/log/fakeframe'
+
+# The 403 text /register returned while Steam wasn't on "Pair new host"
+# (docs/ssh.md, verified 2026-09-26). approve-ssh-key passes the Steam
+# client's error file through as {"error": ...}, so this is what Steam writes.
+PAIRING_MODE_ERROR = 'please put the Steam client in pairing mode: Settings -> Developer -> Pair new host'
+# Guess: what Steam writes when the prompt is declined hasn't been seen.
+PAIRING_DENIED = 'the pairing request was denied on the device'
+# Steam refused create-shortcut for ids like "fc-smoke-exe" with this text, and
+# took the same program as "FCSmokeProbe" (headset smoke test, 2026-09-27,
+# BUILD_ID 20260922.6101926). Valve's client only allows ids matching
+# GAMEID_ALLOWED_PATTERN (devkit_client/gui2/gui2.py), so the fake checks that.
+INVALID_ARGUMENTS = 'missing/invalid arguments\n'
+GAMEID_ALLOWED = re.compile(r'[A-Za-z_][A-Za-z0-9_.]+')
+
+_lock = threading.RLock()   # one state change at a time within this process (the file lock covers others)
+TOKEN = secrets.token_hex(16)
+
+
+def console(line):
+    os.makedirs(os.path.dirname(CONSOLE_LOG), exist_ok=True)
+    with open(CONSOLE_LOG, 'a') as f:
+        f.write(time.strftime('[%Y-%m-%d %H:%M:%S] ') + line + '\n')
+
+
+def respond(path, text=None, error=None):
+    """Answer a devkit request the way devkit_utils.wait_on_file_response expects."""
+    lock = path + '.lock'
+    open(lock, 'w').close()
+    with open(path + '.error' if error is not None else path, 'w') as f:
+        f.write(error if error is not None else text)
+    os.unlink(lock)
+
+
+# ---- the Node side of the DevTools endpoint ----------------------------------
+
+class JS:
+    def __init__(self):
+        self.proc = None
+        self.next = 0
+
+    def _start(self):
+        shim = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'cef_shim.js')
+        self.proc = subprocess.Popen(['node', shim], stdin=subprocess.PIPE, stdout=subprocess.PIPE, text=True)
+
+    def evaluate(self, expression, await_promise):
+        with _lock:
+            if not self.proc or self.proc.poll() is not None:
+                self._start()
+            self.next += 1
+            with fs.update() as state:
+                self.proc.stdin.write(json.dumps({'id': self.next, 'expression': expression,
+                                                  'awaitPromise': await_promise, 'steam': state['steam']}) + '\n')
+                self.proc.stdin.flush()
+                reply = json.loads(self.proc.stdout.readline())
+                state['steam'] = reply['steam']
+            return reply['result']
+
+
+JS_WORKER = JS()
+
+
+# ---- devkit commands ----------------------------------------------------------
+
+def shortcut_for(state, gameid):
+    return next((s for s in state['steam']['shortcuts'] if s.get('devkit_gameid') == gameid), None)
+
+
+def new_shortcut_id(steam):
+    steam['next_shortcut'] = steam.get('next_shortcut', 0) + 1
+    return (0x80000000 + ((steam['next_shortcut'] * 2654435761 & 0xFFFFFFFF) >> 1)) & 0xFFFFFFFF
+
+
+def read_json(path, default=None):
+    try:
+        with open(path) as f:
+            return json.load(f)
+    except (OSError, ValueError):
+        return default
+
+
+def cmd_approve_ssh_key(q):
+    with fs.update() as state:
+        sw = state['switches']
+        answer = sw['pairing_answer'] if sw['pairing_mode'] else 'not in pairing mode'
+        state['pairing_requests'].append({'time': time.time(), 'request': q.get('request', ''), 'answer': answer})
+    if answer == 'not in pairing mode':
+        respond(q['response'], error=PAIRING_MODE_ERROR)
+    elif answer == 'approve':
+        respond(q['response'], text='approved')   # guess: the hook only checks that the file appears
+    elif answer == 'deny':
+        respond(q['response'], error=PAIRING_DENIED)
+    # 'timeout': never answer; the hook gives up after 30 s.
+
+
+def cmd_create_shortcut(q):
+    gameid = q.get('gameid', '')
+    folder = q.get('directory') or fs.DEVKIT_GAMES
+    path = os.path.join(folder, gameid)
+    if not GAMEID_ALLOWED.fullmatch(gameid):
+        respond(q['response'], error=INVALID_ARGUMENTS)
+        return
+    if not os.path.isdir(path):
+        respond(q['response'], error=f'no devkit game folder {path}')   # guess: wording
+        return
+    argv = read_json(f'{folder}/{gameid}-argv.json', [])
+    settings = read_json(f'{folder}/{gameid}-settings.json', {})
+    env = read_json(f'{folder}/{gameid}-env.json', {})
+    with fs.update() as state:
+        steam = state['steam']
+        sc = shortcut_for(state, gameid)
+        if not sc:
+            sc = {'appid': new_shortcut_id(steam), 'name': gameid, 'exe': '', 'start_dir': path, 'icon': '',
+                  'launch_options': '', 'devkit_gameid': gameid}
+            steam['shortcuts'].append(sc)
+        sc['exe'] = argv[0] if argv else ''
+        tool = settings.get('compat_tool')
+        # Steam maps the title to the chosen compat tool (CompatToolMapping and
+        # compat_log.txt on the Frame, docs/sideloading.md, 2026-09-26).
+        if tool:
+            steam['compat_tools'][str(sc['appid'])] = tool
+        else:
+            steam['compat_tools'].pop(str(sc['appid']), None)
+        state['devkit_games'][gameid] = {'appid': sc['appid'], 'directory': path, 'argv': argv,
+                                         'settings': settings, 'env': env, 'registered': time.time()}
+    console(f'devkit create-shortcut: registered devkit game "{gameid}"')
+    respond(q['response'], text='')     # Steam's answer was empty on the Frame (2026-09-27)
+
+
+def cmd_list_shortcuts(q):
+    # The reply format devkit_utils.resolve.resolve_shortcuts asserts.
+    with fs.update() as state:
+        ids = sorted(state['devkit_games'])
+    respond(q['response'], text=json.dumps({'version': 2, 'gameids': ids}))
+
+
+def cmd_delete_shortcut(q):
+    gameid = q.get('gameid', '')
+    with fs.update() as state:
+        sc = shortcut_for(state, gameid)
+        state['devkit_games'].pop(gameid, None)
+        if sc:
+            state['steam']['shortcuts'].remove(sc)
+            state['steam']['compat_tools'].pop(str(sc['appid']), None)
+            # Remove also deleted the title's Proton prefix on the Frame (docs/sideloading.md).
+            subprocess.run(['rm', '-rf', f"{fs.STEAM_ROOT}/steamapps/compatdata/{sc['appid']}"])
+    console(f'devkit delete-shortcut: removed devkit game "{gameid}"')
+    respond(q['response'], text=f'deleted {gameid}\n')
+
+
+def cmd_run_game(q):
+    gameid = q.get('gameid', '')
+    with fs.update() as state:
+        game = state['devkit_games'].get(gameid)
+        tool = game and state['steam']['compat_tools'].get(str(game['appid']))
+        runtimes = state['runtimes']
+    if not game:
+        respond(q['response'], error=f'unknown devkit game "{gameid}"')   # guess: wording
+        return
+    target = game['argv'][0] if game['argv'] else ''
+    full = os.path.join(game['directory'], target.strip('"'))
+    record = {'kind': 'devkit', 'gameid': gameid, 'appid': game['appid'], 'tool': tool, 'time': time.time()}
+    if tool and not runtimes.get(tool, False):
+        # Seen for the x86-64 runtime (docs/sideloading.md, 2026-09-26): Steam
+        # logs this and the game doesn't start.
+        name = fs.RUNTIME_NAMES.get(tool, tool)
+        record.update(started=False, message=f'Tool {fs.RUNTIME_APPIDS.get(tool, 0)} "{name}" is found for '
+                                              f'appID {game["appid"]}, but is not installed')
+    elif tool and tool.startswith('proton'):
+        # How Steam ran a sideloaded .exe on the Frame (docs/sideloading.md).
+        prefix = f"{fs.STEAM_ROOT}/steamapps/compatdata/{game['appid']}/pfx"
+        os.makedirs(prefix, exist_ok=True)
+        record.update(started=True, command=f'proton waitforexitandrun "{full}"', prefix=prefix)
+    else:
+        # An aarch64 title ran natively, without SteamLinuxRuntime_4-arm64's
+        # _v2-entry-point prefix, even though Steam recorded the mapping
+        # (docs/sideloading.md, 2026-09-26). So does the fake, for real.
+        record.update(started=True, command=full)
+        record.update(execute(full, game['directory'], {**game.get('env', {})}, f"devkit-{gameid}"))
+    with fs.update() as state:
+        state['launches'].append(record)
+    console(record['message'] if not record['started'] else f'devkit run-game: started devkit game "{gameid}"')
+    respond(q['response'], text='OK\n')   # guess: steam-devkit-rpc only checks that it arrives
+
+
+DEVKIT = {'approve-ssh-key': cmd_approve_ssh_key, 'create-shortcut': cmd_create_shortcut,
+          'list-shortcuts': cmd_list_shortcuts, 'delete-shortcut': cmd_delete_shortcut,
+          'run-game': cmd_run_game}
+
+
+def execute(path, cwd, env, label):
+    """Start a program the way Steam would, and note its pid and exit status."""
+    os.makedirs(GAME_LOGS, exist_ok=True)
+    log = open(f'{GAME_LOGS}/{label}.log', 'ab')
+    try:
+        proc = subprocess.Popen([path], cwd=cwd if os.path.isdir(cwd) else HOME, env={**os.environ, **env},
+                                stdin=subprocess.DEVNULL, stdout=log, stderr=log, start_new_session=True)
+    except OSError as e:
+        return {'pid': None, 'exec_error': str(e)}
+    finally:
+        log.close()
+
+    def reap():
+        code = proc.wait()
+        with fs.update() as state:
+            for r in state['launches']:
+                if r.get('pid') == proc.pid and 'exit' not in r:
+                    r['exit'] = code
+    threading.Thread(target=reap, daemon=True).start()
+    return {'pid': proc.pid}
+
+
+# ---- steam:// URLs from the `steam` wrapper ----------------------------------
+
+def url_rungameid(gid):
+    gid = int(gid)
+    record = {'kind': 'rungameid', 'gameid': gid, 'time': time.time()}
+    if gid >= 1 << 32:
+        # A non-Steam shortcut: (appid << 32) | 0x02000000 (docs/apks.md).
+        appid = gid >> 32
+        with fs.update() as state:
+            sc = next((s for s in state['steam']['shortcuts'] if s['appid'] == appid), None)
+        if not sc:
+            record.update(started=False, message=f'no shortcut {appid}')
+        else:
+            # Steam sets STEAM_FOSSILIZE_DUMP_PATH for shortcut launches but not
+            # STEAM_COMPAT_SHADER_PATH (docs/apks.md, 2026-09-25).
+            env = {'SteamAppId': str(appid), 'SteamGameId': str(gid),
+                   'STEAM_FOSSILIZE_DUMP_PATH': f'{fs.STEAM_ROOT}/steamapps/shadercache/{appid}/fozpipelinesv6'}
+            record.update(appid=appid, started=True, command=sc['exe'])
+            record.update(execute(sc['exe'], sc.get('start_dir') or HOME, env, f'shortcut-{appid}'))
+    else:
+        with fs.update() as state:
+            app = next((a for a in state['steam']['apps'] if a['appid'] == gid), None)
+        record.update(appid=gid, started=bool(app and app['installed']),
+                      message=None if app and app['installed'] else 'not installed')
+    with fs.update() as state:
+        state['launches'].append(record)
+
+
+def url_install(appid):
+    appid = int(appid)
+    free = os.statvfs(HOME)
+    with fs.update() as state:
+        steam = state['steam']
+        app = next((a for a in steam['apps'] if a['appid'] == appid), None)
+        im = steam['install_manager']
+        if not app:
+            return                      # not owned: Steam shows a store or license dialog, state stays 0
+        im.update(currentAppID=appid, nDiskSpaceRequired=app['size'],
+                  nDiskSpaceAvailable=free.f_bavail * free.f_frsize, eInstallState=app.get('wizard', 14))
+        if im['eInstallState'] == 14:
+            steam['download'] = {'update_appid': appid, 'update_state': 'Downloading', 'paused': False,
+                                 'update_is_install': True, 'overall_percent_complete': 0,
+                                 'overall_estimated_time_remaining_sec': 7,
+                                 'update_network_bytes_per_second': 9500000}
+
+
+def url_store(appid):
+    # A store page showed up in the DevTools page list (docs/steam-games.md).
+    names = {1145360: 'Hades'}
+    with fs.update() as state:
+        state['steam']['pages'].append({'title': f"{names.get(int(appid), 'App ' + appid)} on Steam",
+                                        'url': f'https://store.steampowered.com/app/{appid}/'})
+
+
+URLS = [(re.compile(r'steam://rungameid/(\d+)$'), url_rungameid),
+        (re.compile(r'steam://install/(\d+)$'), url_install),
+        (re.compile(r'steam://store/(\d+)$'), url_store)]
+
+
+def handle_line(line):
+    line = line.strip()
+    if not line:
+        return
+    fs.log('steam.pipe', line=line)
+    try:
+        if line.startswith('devkit-1 '):
+            m = re.fullmatch(r'steam://devkit-1/([^/]*)/([^?]*)\??(.*)', line.split(' ', 1)[1])
+            if not m or m[1] != TOKEN:
+                console('devkit-1: rejected a command with a bad token')
+                return
+            cmd = m[2].rstrip('/')               # steam-devkit-rpc sends "run-game/?..."
+            q = {k: v[0] for k, v in parse_qs(m[3], keep_blank_values=True).items()}
+            handler = DEVKIT.get(cmd)
+            if not handler:
+                console(f'devkit-1: unknown command {cmd}')
+                if 'response' in q:
+                    respond(q['response'], error=f'unknown command {cmd}')
+                return
+            handler(q)
+            return
+        for pat, fn in URLS:
+            m = pat.match(line.split()[-1])
+            if m:
+                fn(*m.groups())
+                return
+        console(f'ignored: {line}')
+    except Exception as e:  # keep reading the pipe whatever one command did
+        console(f'error handling {line!r}: {type(e).__name__}: {e}')
+
+
+def read_pipe():
+    # O_RDWR: there is always a writer, so reads never hit EOF between clients.
+    fd = os.open(PIPE, os.O_RDWR)
+    with os.fdopen(fd, 'rb', buffering=0) as f:
+        buf = b''
+        while True:
+            chunk = f.read(4096)
+            buf += chunk
+            while b'\n' in buf:
+                line, buf = buf.split(b'\n', 1)
+                threading.Thread(target=handle_line, args=(line.decode('utf-8', 'replace'),), daemon=True).start()
+
+
+# ---- DevTools HTTP + WebSocket -------------------------------------------------
+
+def targets():
+    base = {'type': 'page', 'description': '', 'faviconUrl': ''}
+    out = [{**base, 'id': TARGET_ID, 'title': 'SharedJSContext',
+            'url': 'https://steamloopback.host/index.html',
+            'devtoolsFrontendUrl': f'/devtools/inspector.html?ws=127.0.0.1:{DEVTOOLS_PORT}/devtools/page/{TARGET_ID}',
+            'webSocketDebuggerUrl': f'ws://127.0.0.1:{DEVTOOLS_PORT}/devtools/page/{TARGET_ID}'}]
+    for i, p in enumerate(fs.read()['steam'].get('pages', [])):
+        tid = f'{i + 1:032X}'
+        out.append({**base, 'id': tid, 'title': p['title'], 'url': p['url'],
+                    'webSocketDebuggerUrl': f'ws://127.0.0.1:{DEVTOOLS_PORT}/devtools/page/{tid}'})
+    return out
+
+
+class DevTools(BaseHTTPRequestHandler):
+    protocol_version = 'HTTP/1.1'
+
+    def log_message(self, fmt, *args):
+        pass
+
+    def do_GET(self):
+        path = self.path.split('?')[0].rstrip('/')
+        if self.headers.get('Upgrade', '').lower() == 'websocket':
+            if path != f'/devtools/page/{TARGET_ID}':
+                self.send_error(404)
+                return
+            self.websocket()
+            return
+        if path in ('/json', '/json/list'):
+            body = json.dumps(targets(), indent=2).encode()
+        elif path == '/json/version':
+            body = json.dumps({'Browser': 'Chrome/126.0.6478.183', 'Protocol-Version': '1.3',
+                               'User-Agent': 'Valve Steam Client (fakeframe)'}).encode()
+        else:
+            self.send_error(404)
+            return
+        self.send_response(200)
+        self.send_header('Content-Type', 'application/json; charset=UTF-8')
+        self.send_header('Content-Length', str(len(body)))
+        self.end_headers()
+        self.wfile.write(body)
+
+    def websocket(self):
+        key = self.headers.get('Sec-WebSocket-Key', '')
+        accept = base64.b64encode(hashlib.sha1((key + '258EAFA5-E914-47DA-95CA-C5AB0DC85B11').encode()).digest())
+        self.wfile.write(b'HTTP/1.1 101 WebSocket Protocol Handshake\r\nUpgrade: WebSocket\r\n'
+                         b'Connection: Upgrade\r\nSec-WebSocket-Accept: ' + accept + b'\r\n\r\n')
+        self.wfile.flush()
+        self.close_connection = True
+        try:
+            while True:
+                op, data = self.read_frame()
+                if op == 8:
+                    return
+                if op == 9:
+                    self.send_frame(data, 10)
+                    continue
+                if op != 1:
+                    continue
+                msg = json.loads(data)
+                reply = {'id': msg.get('id')}
+                if msg.get('method') == 'Runtime.evaluate':
+                    params = msg.get('params') or {}
+                    reply['result'] = JS_WORKER.evaluate(str(params.get('expression', '')),
+                                                         bool(params.get('awaitPromise')))
+                else:
+                    reply['error'] = {'code': -32601, 'message': f"'{msg.get('method')}' wasn't found"}
+                self.send_frame(json.dumps(reply).encode(), 1)
+        except (EOFError, OSError, ValueError):
+            return
+
+    def read_exact(self, n):
+        data = self.rfile.read(n)
+        if len(data) < n:
+            raise EOFError
+        return data
+
+    def read_frame(self):
+        b0, b1 = self.read_exact(2)
+        n = b1 & 0x7F
+        if n == 126:
+            n = struct.unpack('>H', self.read_exact(2))[0]
+        elif n == 127:
+            n = struct.unpack('>Q', self.read_exact(8))[0]
+        mask = self.read_exact(4) if b1 & 0x80 else None
+        data = self.read_exact(n)
+        if mask:
+            data = bytes(b ^ mask[i % 4] for i, b in enumerate(data))
+        return b0 & 0x0F, data
+
+    def send_frame(self, data, op):
+        n = len(data)
+        head = bytes([0x80 | op]) + (bytes([n]) if n < 126 else
+                                     bytes([126]) + struct.pack('>H', n) if n < 1 << 16 else
+                                     bytes([127]) + struct.pack('>Q', n))
+        self.wfile.write(head + data)
+        self.wfile.flush()
+
+
+def main():
+    os.makedirs(STEAM_DIR, exist_ok=True)
+    if not os.path.exists(PIPE):
+        os.mkfifo(PIPE, 0o600)
+    with open(TOKEN_FILE, 'w') as f:
+        f.write(TOKEN)
+    with open(PID_FILE, 'w') as f:
+        f.write(str(os.getpid()))
+
+    def stop(*_):
+        # Guess: whether Steam removes steam.pid on exit. Either way
+        # validate_steam_client then says Steam isn't running.
+        try:
+            os.unlink(PID_FILE)
+        except OSError:
+            pass
+        if JS_WORKER.proc:
+            JS_WORKER.proc.kill()
+        os._exit(0)
+    signal.signal(signal.SIGTERM, stop)
+    signal.signal(signal.SIGINT, stop)
+
+    httpd = ThreadingHTTPServer(('127.0.0.1', DEVTOOLS_PORT), DevTools)
+    httpd.daemon_threads = True
+    threading.Thread(target=httpd.serve_forever, daemon=True).start()
+    console('fakesteam: started (-cef-enable-debugging on 127.0.0.1:8080)')
+    read_pipe()
+
+
+if __name__ == '__main__':
+    main()
diff --git a/tests/fakeframe/rootfs/usr/local/lib/fakeframe/init.py b/tests/fakeframe/rootfs/usr/local/lib/fakeframe/init.py
new file mode 100755
index 0000000..14593c0
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/local/lib/fakeframe/init.py
@@ -0,0 +1,468 @@
+#!/usr/bin/env python3
+"""The fake Frame's supervisor, run as root under docker's init.
+
+It starts and stops sshd, Valve's steamos-devkit-service (as steamos),
+fakesteam (as steamos) and a few named placeholder processes the status page
+looks for, following the switches in the state file. It also serves the
+control port (9999) that fakeframe-ctl and the e2e tests use, so a test can
+flip a fault switch even while SSH is down.
+
+Control: GET /state, GET /calls, GET /ping, POST /ctl {"args": ["pairing", "on"]}.
+See `fakeframe-ctl help` for the commands.
+"""
+import glob
+import json
+import os
+import pwd
+import shutil
+import socket
+import subprocess
+import sys
+import threading
+import time
+from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
+
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+import fakeframe_state as fs  # noqa: E402
+
+LIB = os.path.dirname(os.path.abspath(__file__))
+USER = 'steamos'
+PW = pwd.getpwnam(USER)
+HOME = fs.HOME
+KEYS = '/keys'                                  # shared with the host container
+HARNESS_KEY = KEYS + '/id_ed25519_frame'
+AUTH_KEYS = HOME + '/.ssh/authorized_keys'
+BALLAST = fs.DEVKIT_GAMES + '/.fakeframe-ballast'
+# Written here; compose mounts the same volumes over /sys/class/power_supply and /sys/class/thermal.
+POWER = '/var/lib/fakeframe/sys/power_supply'
+THERMAL = '/var/lib/fakeframe/sys/thermal'
+CONTROL_PORT = 9999
+LOGS = '/var/log/fakeframe'
+USAGE = """fakeframe-ctl COMMAND
+  pairing on|off              Steam's "Pair new host" screen open or not
+  answer approve|deny|timeout how the pairing prompt is answered
+  steam on|off                Steam client running (steam.pid, pipe, DevTools on 8080)
+  sleep on|off                headset asleep: 22 and 32000 accept but never answer
+  sshd on|off                 sshd running (off: connection refused)
+  devkit-service on|off       steamos-devkit-service on 32000
+  disk-full on|off            fill the small ~/devkit-game filesystem
+  runtime NAME installed|missing   NAME: proton-experimental, proton-stable,
+                              SteamLinuxRuntime_4-arm64, SteamLinuxRuntime_4, lepton
+  battery KEY=VALUE...        e.g. capacity=15 status=Discharging current_now=-900000
+  keys harness|none           authorized_keys: only the harness key, or empty
+  authorized-keys             what ~/.ssh/authorized_keys holds now
+  reset                       default state, nothing installed, harness key only
+  state | calls [TOOL] | ping"""
+
+_lock = threading.RLock()
+_procs = {}
+_blackhole = {'socks': [], 'conns': []}
+
+
+def log(msg):
+    print(time.strftime('%H:%M:%S ') + msg, flush=True)
+
+
+def as_user():
+    env = {'HOME': HOME, 'USER': USER, 'LOGNAME': USER, 'SHELL': '/bin/bash',
+           'PATH': '/usr/local/bin:/usr/bin:/bin', 'XDG_RUNTIME_DIR': f'/run/user/{PW.pw_uid}',
+           'LANG': 'C.UTF-8'}
+    return {'user': PW.pw_uid, 'group': PW.pw_gid, 'extra_groups': [], 'env': env, 'cwd': HOME}
+
+
+def chown(path):
+    os.chown(path, PW.pw_uid, PW.pw_gid)
+
+
+# ---- processes ------------------------------------------------------------------
+
+def spawn(name, argv, user=True, env=None):
+    os.makedirs(LOGS, exist_ok=True)
+    out = open(f'{LOGS}/{name}.log', 'ab')
+    kw = as_user() if user else {'env': dict(os.environ)}
+    kw['env'].update(env or {})
+    _procs[name] = subprocess.Popen(argv, stdin=subprocess.DEVNULL, stdout=out, stderr=out,
+                                    start_new_session=True, **kw)
+    out.close()
+    log(f'started {name} (pid {_procs[name].pid})')
+
+
+def stop(name, sig=15):
+    p = _procs.pop(name, None)
+    if p and p.poll() is None:
+        p.send_signal(sig)
+        try:
+            p.wait(5)
+        except subprocess.TimeoutExpired:
+            p.kill()
+            p.wait()
+        log(f'stopped {name}')
+
+
+def running(name):
+    p = _procs.get(name)
+    return bool(p and p.poll() is None)
+
+
+def kill_ssh_sessions():
+    """Drop every SSH connection, as losing Wi-Fi does."""
+    for comm_file in glob.glob('/proc/[0-9]*/comm'):
+        try:
+            with open(comm_file) as f:
+                comm = f.read().strip()
+            if comm.startswith('sshd'):
+                os.kill(int(comm_file.split('/')[2]), 9)
+        except (OSError, ValueError):
+            pass
+
+
+class Blackhole:
+    """Accept on a port and never answer, so ssh waits and times out. An unreachable
+    Frame times out rather than refusing (seen over Tailscale on 2026-09-27);
+    a closed port would fail at once, which hides timeout bugs."""
+
+    @staticmethod
+    def start(port):
+        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        s.bind(('0.0.0.0', port))
+        s.listen(64)
+        _blackhole['socks'].append(s)
+
+        def accept():
+            while True:
+                try:
+                    c, _ = s.accept()
+                except OSError:
+                    return
+                _blackhole['conns'].append(c)
+        threading.Thread(target=accept, daemon=True).start()
+
+    @staticmethod
+    def stop():
+        for s in _blackhole['socks'] + _blackhole['conns']:
+            try:
+                s.shutdown(socket.SHUT_RDWR)
+            except OSError:
+                pass
+            s.close()
+        _blackhole['socks'].clear()
+        _blackhole['conns'].clear()
+
+
+def reconcile():
+    """Make the running processes match the switches."""
+    with _lock:
+        sw = fs.read()['switches']
+        asleep = sw['asleep']
+        if asleep and not _blackhole['socks']:
+            stop('sshd')
+            stop('devkit-service')
+            kill_ssh_sessions()
+            Blackhole.start(22)
+            Blackhole.start(32000)
+        if not asleep and _blackhole['socks']:
+            Blackhole.stop()
+        want = {'sshd': sw['sshd'] and not asleep, 'devkit-service': sw['devkit_service'] and not asleep,
+                'steam': sw['steam'], 'vrserver': True, 'plasmashell': True}
+        for name, on in want.items():
+            if on and not running(name):
+                start(name)
+            elif not on and running(name):
+                stop(name)
+
+
+def start(name):
+    if name == 'sshd':
+        spawn('sshd', ['/usr/bin/sshd', '-D', '-e'], user=False)
+    elif name == 'devkit-service':
+        # Valve's service, unmodified, with a stand-in dbus module (no systemd-resolved here).
+        spawn('devkit-service', ['python3', '/usr/lib/steamos-devkit/steamos-devkit-service.py'],
+              env={'PYTHONPATH': f'{LIB}/pystubs'})
+    elif name == 'steam':
+        spawn('steam', ['python3', f'{LIB}/fakesteam.py'])
+    else:
+        # frame_status.py looks for these by process name (vrserver: SteamVR,
+        # plasmashell: the headset desktop, which /api/clipboard also needs).
+        spawn(name, [f'{LIB}/bin/{name}', 'infinity'],
+              env={'DBUS_SESSION_BUS_ADDRESS': f'unix:path=/run/user/{PW.pw_uid}/bus'})
+
+
+# ---- the device's files -----------------------------------------------------------
+
+def write(path, text, owner=True):
+    os.makedirs(os.path.dirname(path), exist_ok=True)
+    with open(path, 'w') as f:
+        f.write(text)
+    if owner:
+        chown(path)
+
+
+def sysfs(state):
+    """Battery, charger and thermal zones, in the files frame_status.py reads.
+
+    /sys is read-only in a container, so compose mounts a volume over each of
+    the two folders and again here, where it can be written
+    (tests/fakeframe/compose.yaml); without those this does nothing.
+    """
+    b = state['battery']
+    if not os.path.isdir(POWER) or not os.path.isdir(THERMAL):
+        log('no fake /sys: see the volumes in tests/fakeframe/compose.yaml')
+        return
+    try:
+        for d in glob.glob(POWER + '/*') + glob.glob(THERMAL + '/thermal_zone*'):
+            shutil.rmtree(d, ignore_errors=True)
+        bat = POWER + '/max1720x_battery'   # the fuel gauge frame_status.py was written against
+        for k in ('capacity', 'status', 'voltage_now', 'current_now', 'time_to_full_now', 'temp', 'health'):
+            write(f'{bat}/{k}', f'{b[k]}\n', owner=False)
+        write(f'{bat}/type', 'Battery\n', owner=False)
+        c = b.get('charger') or {}
+        usb = POWER + '/usb'
+        write(f'{usb}/type', 'USB\n', owner=False)
+        write(f'{usb}/online', f"{c.get('online', 0)}\n", owner=False)
+        for k in ('usb_type', 'voltage_now', 'current_now'):
+            if k in c:
+                write(f'{usb}/{k}', f'{c[k]}\n', owner=False)
+        for i, t in enumerate(state['thermal_mc']):
+            write(f'{THERMAL}/thermal_zone{i}/temp', f'{t}\n', owner=False)
+    except OSError as e:
+        log(f'no fake /sys ({e}); see the volumes in tests/fakeframe/compose.yaml')
+
+
+def runtimes(state):
+    """Installed compat tools as Steam app manifests, and the Lepton launcher itself."""
+    apps = fs.STEAM_ROOT + '/steamapps'
+    for alias, installed in state['runtimes'].items():
+        acf = f'{apps}/appmanifest_{fs.RUNTIME_APPIDS[alias]}.acf'
+        if installed:
+            write(acf, '"AppState"\n{\n\t"appid"\t\t"%d"\n\t"name"\t\t"%s"\n\t"SizeOnDisk"\t\t"%d"\n}\n'
+                  % (fs.RUNTIME_APPIDS[alias], fs.RUNTIME_NAMES[alias], 900000000))
+        elif os.path.exists(acf):
+            os.unlink(acf)
+    if state['runtimes'].get('lepton'):
+        os.makedirs(os.path.dirname(fs.LEPTON), exist_ok=True)
+        shutil.copy(f'{LIB}/lepton.py', fs.LEPTON)
+        os.chmod(fs.LEPTON, 0o755)
+    elif os.path.exists(fs.LEPTON):
+        os.unlink(fs.LEPTON)
+    for app in state['steam']['apps']:
+        acf = f"{apps}/appmanifest_{app['appid']}.acf"
+        if app['installed']:
+            write(acf, '"AppState"\n{\n\t"appid"\t\t"%d"\n\t"name"\t\t"%s"\n\t"SizeOnDisk"\t\t"%d"\n}\n'
+                  % (app['appid'], app['display_name'], app['size']))
+    subprocess.run(['chown', '-R', f'{USER}:{USER}', fs.STEAM_ROOT])
+
+
+def disk_full(on):
+    if on:
+        if os.path.ismount(fs.DEVKIT_GAMES) is False:
+            raise ValueError(f'disk-full needs {fs.DEVKIT_GAMES} to be its own small filesystem (compose tmpfs)')
+        st = os.statvfs(fs.DEVKIT_GAMES)
+        size = max(0, st.f_bavail * st.f_frsize - 64 * 1024)
+        fd = os.open(BALLAST, os.O_WRONLY | os.O_CREAT, 0o600)
+        try:
+            os.posix_fallocate(fd, 0, size)
+        finally:
+            os.close(fd)
+    elif os.path.exists(BALLAST):
+        os.unlink(BALLAST)
+
+
+def set_keys(which):
+    os.makedirs(os.path.dirname(AUTH_KEYS), mode=0o700, exist_ok=True)
+    chown(os.path.dirname(AUTH_KEYS))
+    text = ''
+    if which == 'harness':
+        with open(HARNESS_KEY + '.pub') as f:
+            text = f.read()
+    write(AUTH_KEYS, text)
+    os.chmod(AUTH_KEYS, 0o600)
+
+
+def harness_key():
+    """The key the host container logs in with, shared through the /keys volume."""
+    os.makedirs(KEYS, exist_ok=True)
+    if not os.path.exists(HARNESS_KEY):
+        subprocess.run(['ssh-keygen', '-q', '-t', 'ed25519', '-N', '', '-C', 'fakeframe-harness',
+                        '-f', HARNESS_KEY], check=True)
+    os.chmod(HARNESS_KEY, 0o644)        # the host container copies it into its own ~/.ssh with 0600
+
+
+def clean_home():
+    """Everything Frame Control or a test put on the "headset"."""
+    for c in list(fs.read()['lepton'].values()):
+        try:
+            os.kill(c['pid'], 15)
+        except (OSError, KeyError, TypeError):
+            pass
+    for pattern in (fs.DEVKIT_GAMES + '/*', fs.DEVKIT_GAMES + '/.[!.]*', HOME + '/devkit-utils',
+                    HOME + '/.devkit-utils.frame-control', HOME + '/Applications', HOME + '/Downloads/*',
+                    fs.STEAM_ROOT + '/steamapps/compatdata', fs.STEAM_ROOT + '/steamapps/shadercache',
+                    fs.STEAM_ROOT + '/logs', '/var/log/fakeframe/devkit-*', '/var/log/fakeframe/shortcut-*'):
+        for p in glob.glob(pattern):
+            subprocess.run(['rm', '-rf', p])
+    os.makedirs(HOME + '/Downloads', exist_ok=True)
+    chown(HOME + '/Downloads')
+    chown(fs.DEVKIT_GAMES)
+
+
+def apply_files():
+    state = fs.read()
+    sysfs(state)
+    runtimes(state)
+
+
+def reset():
+    with _lock:
+        stop('steam')
+        clean_home()
+        fs.reset()
+        env_switches()
+        set_keys('harness')
+        disk_full(False)
+        apply_files()
+        reconcile()
+
+
+def env_switches():
+    """FAKEFRAME_PAIRING_MODE=1 and the like set a switch's value at start."""
+    with fs.update() as s:
+        for k in s['switches']:
+            v = os.environ.get('FAKEFRAME_' + k.upper())
+            if v is not None:
+                s['switches'][k] = v if k == 'pairing_answer' else v in ('1', 'on', 'true', 'yes')
+
+
+# ---- commands ----------------------------------------------------------------------
+
+ON_OFF = {'on': True, 'off': False}
+SWITCH = {'pairing': 'pairing_mode', 'steam': 'steam', 'sleep': 'asleep', 'sshd': 'sshd',
+          'devkit-service': 'devkit_service'}
+
+
+def command(args):
+    if not args or args[0] == 'help':
+        return {'usage': USAGE}
+    cmd, rest = args[0], args[1:]
+    if cmd == 'state':
+        return fs.read()
+    if cmd == 'calls':
+        return fs.calls(rest[0] if rest else None)
+    if cmd == 'ping':
+        return ping()
+    if cmd == 'reset':
+        reset()
+        return {'ok': True}
+    if cmd in SWITCH and len(rest) == 1 and rest[0] in ON_OFF:
+        with fs.update() as s:
+            s['switches'][SWITCH[cmd]] = ON_OFF[rest[0]]
+        reconcile()
+        return {'ok': True, SWITCH[cmd]: ON_OFF[rest[0]]}
+    if cmd == 'answer' and rest and rest[0] in ('approve', 'deny', 'timeout'):
+        with fs.update() as s:
+            s['switches']['pairing_answer'] = rest[0]
+        return {'ok': True}
+    if cmd == 'disk-full' and len(rest) == 1 and rest[0] in ON_OFF:
+        with _lock:
+            disk_full(ON_OFF[rest[0]])
+            with fs.update() as s:
+                s['switches']['disk_full'] = ON_OFF[rest[0]]
+        return {'ok': True}
+    if cmd == 'runtime' and len(rest) == 2 and rest[1] in ('installed', 'missing'):
+        with fs.update() as s:
+            if rest[0] not in s['runtimes']:
+                raise ValueError(f'unknown runtime {rest[0]}')
+            s['runtimes'][rest[0]] = rest[1] == 'installed'
+        apply_files()
+        return {'ok': True}
+    if cmd == 'battery' and rest:
+        with fs.update() as s:
+            for kv in rest:
+                k, _, v = kv.partition('=')
+                if k not in s['battery'] or k == 'charger':
+                    raise ValueError(f'unknown battery field {k}')
+                s['battery'][k] = int(v) if v.lstrip('-').isdigit() else v
+        apply_files()
+        return {'ok': True}
+    if cmd == 'keys' and rest and rest[0] in ('harness', 'none'):
+        set_keys(rest[0])
+        return {'ok': True}
+    if cmd == 'authorized-keys':
+        with open(AUTH_KEYS) as f:
+            return {'text': f.read()}
+    raise ValueError(f'unknown command {" ".join(args)!r}; try help')
+
+
+def port_open(port):
+    try:
+        with socket.create_connection(('127.0.0.1', port), timeout=1):
+            return True
+    except OSError:
+        return False
+
+
+def ping():
+    sw = fs.read()['switches']
+    checks = {}
+    if sw['sshd'] and not sw['asleep']:
+        checks['sshd'] = port_open(22)
+    if sw['devkit_service'] and not sw['asleep']:
+        checks['devkit_service'] = port_open(32000)
+    if sw['steam']:
+        checks['devtools'] = port_open(8080) and fs.steam_pid() is not None
+    return {'ok': all(checks.values()), 'checks': checks}
+
+
+class Control(BaseHTTPRequestHandler):
+    def log_message(self, fmt, *args):
+        pass
+
+    def reply(self, obj, status=200):
+        body = json.dumps(obj).encode()
+        self.send_response(status)
+        self.send_header('Content-Type', 'application/json')
+        self.send_header('Content-Length', str(len(body)))
+        self.end_headers()
+        self.wfile.write(body)
+
+    def do_GET(self):
+        path, _, query = self.path.partition('?')
+        args = {'/state': ['state'], '/calls': ['calls'] + ([query] if query else []), '/ping': ['ping']}.get(path)
+        if not args:
+            self.reply({'error': 'not found'}, 404)
+            return
+        self.reply(command(args))
+
+    def do_POST(self):
+        if self.path != '/ctl':
+            self.reply({'error': 'not found'}, 404)
+            return
+        try:
+            body = json.loads(self.rfile.read(int(self.headers.get('Content-Length') or 0)) or b'{}')
+            self.reply(command([str(a) for a in body.get('args', [])]))
+        except (ValueError, OSError) as e:
+            self.reply({'error': str(e)}, 400)
+
+
+def main():
+    os.umask(0o022)
+    harness_key()
+    os.makedirs(fs.DIR, mode=0o777, exist_ok=True)
+    os.chmod(fs.DIR, 0o777)
+    os.makedirs(f'/run/user/{PW.pw_uid}', exist_ok=True)
+    chown(f'/run/user/{PW.pw_uid}')
+    reset()
+    httpd = ThreadingHTTPServer(('0.0.0.0', CONTROL_PORT), Control)
+    httpd.daemon_threads = True
+    threading.Thread(target=httpd.serve_forever, daemon=True).start()
+    log(f'fake Frame up; control on :{CONTROL_PORT}')
+    while True:                         # restart anything that died unasked, as systemd would
+        time.sleep(1)
+        try:
+            reconcile()
+        except Exception as e:  # keep supervising
+            log(f'reconcile: {type(e).__name__}: {e}')
+
+
+if __name__ == '__main__':
+    main()
diff --git a/tests/fakeframe/rootfs/usr/local/lib/fakeframe/lepton.py b/tests/fakeframe/rootfs/usr/local/lib/fakeframe/lepton.py
new file mode 100755
index 0000000..ccaa3d5
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/local/lib/fakeframe/lepton.py
@@ -0,0 +1,83 @@
+#!/usr/bin/env python3
+"""Stand-in for Lepton's launcher (~/.local/share/Steam/steamapps/common/Lepton/lepton).
+
+frame/android/lepton-app.sh runs it as `lepton waitforexitandrun -- APK` with
+the Steam compat variables set. Like the real one (docs/apks.md, verified
+2026-09-25, BUILD_ID 20260922.6101926) it:
+- dies with "unbound variable" when STEAM_COMPAT_SHADER_PATH isn't set;
+- needs STEAM_COMPAT_DATA_PATH under ~/.local/share/Steam (only that tree is
+  mounted in the container; elsewhere the app crashes with ENOENT);
+- runs a "steamlaunch" container named lepton-steamlaunch-<SteamAppId> when
+  SteamAppId is set, else Lepton Development (lepton-dev);
+- opens ADB on 0.0.0.0: 5555 for Lepton Development, the next free port for
+  each own instance (README security notes, 2026-09-25);
+- shows a flat window only when lepton-show-flatscreen sits next to the APK.
+There's no Android inside: it records the launch and holds the port until
+`podman stop` (the podman stub) ends it.
+"""
+import json
+import os
+import signal
+import socket
+import sys
+import time
+
+sys.path.insert(0, '/usr/local/lib/fakeframe')
+import fakeframe_state as fs  # noqa: E402
+
+ENV = ('SteamAppId', 'STEAM_COMPAT_INSTALL_PATH', 'STEAM_COMPAT_DATA_PATH', 'STEAM_COMPAT_SHADER_PATH',
+       'STEAM_FOSSILIZE_DUMP_PATH', 'IS_PARENT')
+
+
+def main():
+    args = sys.argv[1:]
+    env = {k: os.environ.get(k) for k in ENV}
+    fs.log('lepton', args=args, env=env)
+    for k in ('STEAM_COMPAT_SHADER_PATH', 'STEAM_COMPAT_DATA_PATH', 'STEAM_COMPAT_INSTALL_PATH'):
+        if not env[k]:
+            sys.exit(f'{sys.argv[0]}: line 1: {k}: unbound variable')
+    if not os.path.realpath(env['STEAM_COMPAT_DATA_PATH']).startswith(fs.STEAM_ROOT + '/'):
+        sys.exit('ENOENT: STEAM_COMPAT_DATA_PATH is outside ~/.local/share/Steam, which is all the container sees')
+    apk = args[-1] if args else ''
+    if not apk.endswith('.apk') or not os.path.isfile(apk):
+        sys.exit(f'lepton: no APK at {apk!r}')
+    steamlaunch = bool(env['SteamAppId'])
+    name = f"lepton-steamlaunch-{env['SteamAppId']}" if steamlaunch else 'lepton-dev'
+
+    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    with fs.update() as state:
+        if name in state['lepton']:
+            sys.exit(f'lepton: {name} is already running')
+        used = {c['port'] for c in state['lepton'].values()}
+        for port in ([5555] if not steamlaunch else range(5556, 5600)):
+            if port in used:
+                continue
+            try:
+                sock.bind(('0.0.0.0', port))
+                break
+            except OSError:
+                continue
+        else:
+            sys.exit('lepton: no free ADB port')
+        sock.listen(8)
+        os.makedirs(os.path.join(env['STEAM_COMPAT_DATA_PATH'], 'internal'), exist_ok=True)
+        state['lepton'][name] = {'port': port, 'pid': os.getpid(), 'apk': apk, 'started': time.time(),
+                                 'flatscreen': os.path.exists(os.path.join(os.path.dirname(apk),
+                                                                           'lepton-show-flatscreen'))}
+
+    def stop(*_):
+        with fs.update() as state:
+            state['lepton'].pop(name, None)
+        fs.log('lepton', stopped=name)
+        os._exit(0)
+    signal.signal(signal.SIGTERM, stop)
+    signal.signal(signal.SIGINT, stop)
+    print(json.dumps({'container': name, 'adb_port': port}), flush=True)
+    while True:
+        conn, _ = sock.accept()     # nothing speaks ADB here; just close
+        conn.close()
+
+
+if __name__ == '__main__':
+    main()
diff --git a/tests/fakeframe/rootfs/usr/local/lib/fakeframe/pystubs/dbus/__init__.py b/tests/fakeframe/rootfs/usr/local/lib/fakeframe/pystubs/dbus/__init__.py
new file mode 100644
index 0000000..050d3b1
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/local/lib/fakeframe/pystubs/dbus/__init__.py
@@ -0,0 +1,50 @@
+"""Stand-in for dbus-python, just enough for Valve's steamos-devkit-service.
+
+The service advertises _steamos-devkit._tcp through systemd-resolved's
+RegisterService over the system bus (on the Frame, `frame` answered mDNS,
+docs/ssh.md, 2026-09-26). A container has no system bus or resolved, so
+this records the call in the fake Frame's log instead.
+"""
+import sys
+
+from . import exceptions  # noqa: F401
+
+sys.path.insert(0, '/usr/local/lib/fakeframe')
+import fakeframe_state as fs  # noqa: E402
+
+
+class Array(list):
+    def __init__(self, items=(), signature=None):
+        super().__init__(items)
+
+
+class Dictionary(dict):
+    def __init__(self, items=(), signature=None):
+        super().__init__(items)
+
+
+def UInt16(v):
+    return int(v)
+
+
+def _plain(v):
+    if isinstance(v, dict):
+        return {k: _plain(x) for k, x in v.items()}
+    if isinstance(v, list):
+        if all(isinstance(x, int) for x in v):
+            return bytes(v).decode('utf-8', 'replace')
+        return [_plain(x) for x in v]
+    return v
+
+
+class _Object:
+    def get_dbus_method(self, name, interface=None):
+        def call(*args):
+            fs.log('resolve1', method=name, args=_plain(list(args)))
+            return f'/org/freedesktop/resolve1/dnssd/{args[0]}' if name == 'RegisterService' else None
+        return call
+
+
+class SystemBus:
+    def get_object(self, bus_name, path):
+        return _Object()
diff --git a/tests/fakeframe/rootfs/usr/local/lib/fakeframe/pystubs/dbus/exceptions.py b/tests/fakeframe/rootfs/usr/local/lib/fakeframe/pystubs/dbus/exceptions.py
new file mode 100644
index 0000000..8e06c27
--- /dev/null
+++ b/tests/fakeframe/rootfs/usr/local/lib/fakeframe/pystubs/dbus/exceptions.py
@@ -0,0 +1,3 @@
+class DBusException(Exception):
+    def get_dbus_name(self):
+        return None
diff --git a/tests/fakeframe/steamos-devkit-service/LICENSE b/tests/fakeframe/steamos-devkit-service/LICENSE
new file mode 100644
index 0000000..63ab7cd
--- /dev/null
+++ b/tests/fakeframe/steamos-devkit-service/LICENSE
@@ -0,0 +1,504 @@
+                  GNU LESSER GENERAL PUBLIC LICENSE
+                       Version 2.1, February 1999
+
+ Copyright (C) 1991, 1999 Free Software Foundation, Inc.
+ 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+[This is the first released version of the Lesser GPL.  It also counts
+ as the successor of the GNU Library Public License, version 2, hence
+ the version number 2.1.]
+
+                            Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+Licenses are intended to guarantee your freedom to share and change
+free software--to make sure the software is free for all its users.
+
+  This license, the Lesser General Public License, applies to some
+specially designated software packages--typically libraries--of the
+Free Software Foundation and other authors who decide to use it.  You
+can use it too, but we suggest you first think carefully about whether
+this license or the ordinary General Public License is the better
+strategy to use in any particular case, based on the explanations below.
+
+  When we speak of free software, we are referring to freedom of use,
+not price.  Our General Public Licenses are designed to make sure that
+you have the freedom to distribute copies of free software (and charge
+for this service if you wish); that you receive source code or can get
+it if you want it; that you can change the software and use pieces of
+it in new free programs; and that you are informed that you can do
+these things.
+
+  To protect your rights, we need to make restrictions that forbid
+distributors to deny you these rights or to ask you to surrender these
+rights.  These restrictions translate to certain responsibilities for
+you if you distribute copies of the library or if you modify it.
+
+  For example, if you distribute copies of the library, whether gratis
+or for a fee, you must give the recipients all the rights that we gave
+you.  You must make sure that they, too, receive or can get the source
+code.  If you link other code with the library, you must provide
+complete object files to the recipients, so that they can relink them
+with the library after making changes to the library and recompiling
+it.  And you must show them these terms so they know their rights.
+
+  We protect your rights with a two-step method: (1) we copyright the
+library, and (2) we offer you this license, which gives you legal
+permission to copy, distribute and/or modify the library.
+
+  To protect each distributor, we want to make it very clear that
+there is no warranty for the free library.  Also, if the library is
+modified by someone else and passed on, the recipients should know
+that what they have is not the original version, so that the original
+author's reputation will not be affected by problems that might be
+introduced by others.
+
+  Finally, software patents pose a constant threat to the existence of
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+
+    SteamOS Devkit Service
+    Copyright (C) 2022 Valve Software inc.
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 2.1 of the License, or (at your option) any later version.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
+    USA
+
+Also add information on how to contact you by electronic and paper mail.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the library, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the
+  library `Frob' (a library for tweaking knobs) written by James Random
+  Hacker.
+
+  <signature of Ty Coon>, 1 April 1990
+  Ty Coon, President of Vice
+
+That's all there is to it!
diff --git a/tests/fakeframe/steamos-devkit-service/README.md b/tests/fakeframe/steamos-devkit-service/README.md
new file mode 100644
index 0000000..a694d7d
--- /dev/null
+++ b/tests/fakeframe/steamos-devkit-service/README.md
@@ -0,0 +1,21 @@
+# Valve's steamos-devkit-service (vendored, for the fake Frame only)
+
+Unmodified copy of [steamos-devkit-service](https://gitlab.steamos.cloud/devkit/steamos-devkit-service):
+the HTTP service on port 32000 (`src/`) and its hooks (`hooks/`), which the
+fake Frame image installs at `/usr/lib/steamos-devkit/` and
+`/usr/share/steamos-devkit/hooks/`, where the service looks for them.
+
+- Source: commit `74cf8fe` (2025-09-16, tag `v0.20250916.0`).
+- Licence: the repository's `LICENSE` is the LGPL 2.1 (copied here).
+  `src/steamos-devkit-service.py` itself carries an MIT header, and
+  `hooks/devkit-1-identify` and `hooks/install-ssh-key` carry LGPL-2.1+
+  headers. Nothing here ships in Frame Control; it's only built into the
+  test image.
+
+The service imports `dbus` to advertise itself over mDNS through
+systemd-resolved, which a container doesn't have. The image puts a small
+stand-in `dbus` module on its `PYTHONPATH` (`rootfs/usr/local/lib/fakeframe/pystubs`)
+that records the registration instead. Everything else runs as Valve wrote it.
+
+To update: copy `src/`, `hooks/` and `LICENSE` from a newer checkout and update
+the commit line above.
diff --git a/tests/fakeframe/steamos-devkit-service/hooks/approve-ssh-key b/tests/fakeframe/steamos-devkit-service/hooks/approve-ssh-key
new file mode 100755
index 0000000..a022ed5
--- /dev/null
+++ b/tests/fakeframe/steamos-devkit-service/hooks/approve-ssh-key
@@ -0,0 +1,71 @@
+#!/usr/bin/env python3
+
+import sys
+import os
+import logging
+import tempfile
+from urllib.parse import quote_plus as urllib_quote_plus
+import subprocess
+import json
+
+ENABLE_SSHD = '/usr/bin/steamos-polkit-helpers/steamos-enable-sshd'
+
+logger = logging.getLogger(os.path.realpath(__file__))
+
+import devkit_utils
+
+if __name__ == '__main__':
+    logger.setLevel(logging.INFO)
+    ch = logging.StreamHandler()
+    ch.setLevel(logging.INFO)
+    ch.setFormatter(logging.Formatter('%(name)s:%(message)s'))
+    logger.addHandler(ch)
+
+    request = open(sys.argv[1], 'rt').read()
+    requestIP = 'Unknown'
+    try:
+        requestIP = sys.argv[2]
+    except NameError:
+        logger.warning('request IP not given as argument to hook')
+        pass
+
+    key_identifier = request.split(' ')[2]
+    request = f'Development host at IP {requestIP} key: {key_identifier!r}'
+
+    ret = {}
+
+    try:
+        devkit_utils.validate_steam_client()
+    except devkit_utils.SteamClientNotRunningException as e:
+        msg = 'Steam is not running'
+        logger.warning(msg)
+        ret['error'] = msg
+    else:
+        with tempfile.TemporaryDirectory(prefix='approve-ssh-key') as tempdir:
+            logger.info('Sending pairing request to Steam')
+            response = os.path.join(tempdir, 'response')
+            cmd = 'approve-ssh-key?response={}&request={}'.format(
+                urllib_quote_plus(response),
+                urllib_quote_plus(request),
+            )
+            devkit_utils.execute_steam_client_command(cmd)
+            try:
+                with devkit_utils.wait_on_file_response(response, timeout=30) as f:
+                    logger.debug('Got response from Steam client')
+                    # Make sure sshd is enabled to support development features
+                    if os.path.exists(ENABLE_SSHD):
+                        subprocess.check_call(ENABLE_SSHD)
+                    else:
+                        subprocess.check_call('sudo systemctl enable --now sshd', shell=True)
+            except devkit_utils.SteamResponse_Timeout:
+                ret['error'] = 'timeout - Steam did not respond to the pairing request'
+            except devkit_utils.SteamResponse_Error as e:
+                ret['error'] = e.error_response
+
+    # json dictionary response gets written to stdout
+    # NOTE: the devkit service unfortunately smashes stdout/stderr all together in a text response, but we can still work with that
+    sys.stdout.flush()
+    sys.stderr.flush()
+    print(json.dumps(ret))
+    retcode = 1 if 'error' in ret else 0
+    sys.exit(retcode)
diff --git a/tests/fakeframe/steamos-devkit-service/hooks/devkit-1-identify b/tests/fakeframe/steamos-devkit-service/hooks/devkit-1-identify
new file mode 100755
index 0000000..301583d
--- /dev/null
+++ b/tests/fakeframe/steamos-devkit-service/hooks/devkit-1-identify
@@ -0,0 +1,151 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+
+# This file is part of steamos-devkit
+# SPDX-License-Identifier: LGPL-2.1+
+#
+# Copyright 2017-2018 Collabora Ltd
+#
+# This package is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This package is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this package.  If not, see
+# <http://www.gnu.org/licenses/>.
+
+# Sample script run to identify the machine we are running on. This
+# is used by the devkit daemon to choose an identity for the machine,
+# and can also be run directly.
+#
+# A script or binary (written in any language) named devkit-1-identify
+# can be placed in the same directory as this sample, and it will be
+# used preferentially.
+#
+# Execution environment:
+# - Runs as root, or as an ordinary user who can run games
+# - Part of a non-interactive secure shell session
+# Input:
+# - None
+# Output:
+# - Exit 0 on success or nonzero on error
+# - On success, must print JSON to stdout containing one object with
+#   the following keys and string values, all of which are optional:
+#   - "machine_id": The hexadecimal systemd/D-Bus machine-id(5)
+#     (in the case of a conflict between systemd's /etc/machine-id and
+#     D-Bus' traditional /var/lib/dbus/machine-id, the systemd version
+#     should be preferred)
+#   - "hostname": The machine-readable hostname as set by sethostname(2)
+#   - "pretty_hostname": A human-friendly version of the hostname as
+#     found in systemd's machine-info(5)
+#   - "product_family", "product_name", "product_serial", "product_uuid",
+#     "sys_vendor": as for /sys/devices/virtual/dmi/id
+#   - "product": The best human-friendly description of the machine
+#     hardware we can devise, for example "Alienware ASM100"
+#   - "serial": The best hardware serial number we can devise
+#   - "machine_name": The best unique name for the machine that we can
+#     devise
+# - Any diagnostic messages must be printed to stderr only
+
+import json
+import os
+import re
+import socket
+import subprocess
+import sys
+
+_MACHINE_ID_RE = re.compile(r'^[0-9A-Fa-f]{32,32}$')
+_USELESS_HOSTNAMES = frozenset((
+    'debian',
+    'host',
+    'localhost',
+    'steamos',
+    'ubuntu',
+))
+# The case combination sometimes varies, so this is lowercased and we
+# use lower() to compare.
+_USELESS_DMI_NAMES = frozenset((
+    'to be filled by o.e.m.',
+))
+
+if __name__ == '__main__':
+
+    info = {}
+    steam_serialnumber = None
+
+    for k in ('product_family', 'product_name', 'product_serial',
+              'product_uuid', 'sys_vendor'):
+        try:
+            with open('/sys/devices/virtual/dmi/id/{}'.format(k)) as reader:
+                v = reader.read().strip()
+
+                if v and v.lower() not in _USELESS_DMI_NAMES:
+                    info[k] = v
+        except (IOError, OSError, UnicodeError):
+            pass
+
+    try:
+        for f in ('/etc/machine-id', '/var/lib/dbus/machine-id'):
+            with open(f) as reader:
+                v = reader.read().strip()
+
+                if _MACHINE_ID_RE.match(v):
+                    info['machine_id'] = v
+    except (IOError, OSError, UnicodeError):
+        pass
+
+    if 'product_family' in info and 'sys_vendor' in info:
+        info['product'] = '{sys_vendor} {product_family}'.format(**info)
+    elif 'product_name' in info and 'sys_vendor' in info:
+        info['product'] = '{sys_vendor} {product_name}'.format(**info)
+    elif 'product_family' in info:
+        info['product'] = info['product_family']
+    elif 'product_name' in info:
+        info['product'] = info['product_name']
+
+    if os.access('/usr/bin/hostnamectl', os.X_OK):
+        try:
+            v = subprocess.check_output([
+                'hostnamectl', '--pretty',
+            ]).decode('utf-8').strip()
+        except (subprocess.CalledProcessError, UnicodeError):
+            pass
+        else:
+            if v:
+                info['pretty_hostname'] = v
+
+            v = subprocess.check_output([
+                'hostnamectl', '--static',
+            ]).decode('utf-8').strip()
+
+            if v:
+                info['hostname'] = v
+
+    if 'hostname' not in info:
+        try:
+            info['hostname'] = socket.gethostname()
+        except (IOError, OSError, UnicodeError):
+            pass
+
+    if steam_serialnumber:
+        info['serial'] = steam_serialnumber
+    elif 'product_serial' in info:
+        info['serial'] = info['product_serial']
+
+    if 'product' in info:
+        info['machine_name'] = info['product']
+
+    if 'hostname' in info and info['hostname'] not in _USELESS_HOSTNAMES:
+        info['machine_name'] = info['hostname']
+
+    if 'pretty_hostname' in info:
+        info['machine_name'] = info['pretty_hostname']
+
+    json.dump(info, sys.stdout, indent=4, sort_keys=True)
+    print()
diff --git a/tests/fakeframe/steamos-devkit-service/hooks/devkit_utils/__init__.py b/tests/fakeframe/steamos-devkit-service/hooks/devkit_utils/__init__.py
new file mode 100644
index 0000000..4d5feba
--- /dev/null
+++ b/tests/fakeframe/steamos-devkit-service/hooks/devkit_utils/__init__.py
@@ -0,0 +1,265 @@
+#!/usr/bin/env python
+# encoding: utf-8
+"""Utility functions for the Steam client hook scripts"""
+
+import sys
+import os
+import traceback
+import tempfile
+import json
+import logging
+import fcntl
+import errno
+import contextlib
+import time
+import fcntl
+
+
+import logging as logging_module
+logger = logging_module.getLogger(__name__)
+
+
+@contextlib.contextmanager
+def wrap_outputs(stderr_prefix):
+    # capture stderr to file to support debugging
+    stderr_fd = sys.stderr.fileno()
+    tf = tempfile.NamedTemporaryFile(
+        mode='w+',
+        prefix=stderr_prefix,
+        delete=True)
+    if sys.version_info >= (3, 4):
+        # this API in the os module is only available for python3
+        # but it does not seem to work with subprocess anyway
+        os.set_inheritable(tf.file.fileno(), True)
+        assert os.get_inheritable(tf.file.fileno())
+    sys.stderr = tf.file
+
+    # we can only write out a json response to stdout,
+    # so redirect stdout to stderr,
+    # and keep a handle on the original stdout for the response
+    stdout_fd = os.dup(sys.stdout.fileno())
+    os.dup2(sys.stderr.fileno(), sys.stdout.fileno())
+
+    ctx = {}
+    try:
+        yield ctx
+    except:
+        logger.error(traceback.format_exc())
+    finally:
+        tf.flush()
+        tf.seek(0)
+        os.write(stderr_fd, tf.read().encode('utf-8'))
+        if 'ret' in ctx:
+            os.write(stdout_fd, json.dumps(ctx['ret']).encode('utf-8'))
+
+
+class SteamClientNotRunningException(Exception):
+    def __init__(self, error_message):
+        self.error_message = error_message
+
+    def __str__(self):
+        return self.error_message
+
+
+def validate_steam_client():
+    """Verify that the steam client is running, and permissions are adequate"""
+    pid_path = os.path.normpath(
+        os.path.realpath(
+            os.path.expanduser('~/.steam/steam.pid')))
+    if not os.path.exists(pid_path):
+        raise SteamClientNotRunningException('{0} does not exist'.format(pid_path))
+    try:
+        pid = int(open(pid_path, 'rt').read())
+    except Exception:
+        raise SteamClientNotRunningException('{0} is invalid'.format(pid_path))
+    try:
+        os.kill(pid, 0)
+    except OSError:
+        raise SteamClientNotRunningException('{0} does not refer to a valid process'.format(pid_path))
+    logger.info('Found steam client pid %s', pid)
+
+
+def execute_steam_client_command(cmd):
+    """Send a command to the steam client over the IPC pipe"""
+    pipe_path = os.path.normpath(
+        os.path.realpath(
+            os.path.expanduser('~/.steam/steam.pipe')))
+    try:
+        pipe = open(pipe_path, 'wb+', 0)
+    except IOError:
+        raise Exception('cannot open steam client pipe')
+    session_token = open(os.path.expanduser('~/.steam/steam.token')).read()
+    pipe_cmd = 'devkit-1 steam://devkit-1/{0}/{1}'.format(
+        session_token,
+        cmd
+    )
+    logger.debug('Sending command line:')
+    logger.debug(pipe_cmd)
+    pipe.write('{0}\n'.format(pipe_cmd).encode('utf-8'))
+    pipe.close()
+
+
+def save_argv(gameid, argv):
+    """Save command line and arguments if provided"""
+
+    if argv is None:
+        return
+
+    argvfile = os.path.join(os.getenv("HOME"), "devkit-game",
+                            gameid + "-argv.json")
+    try:
+        with open(argvfile, "w") as argvf:
+            fcntl.flock(argvf, fcntl.LOCK_EX)
+            json.dump(argv, argvf)
+            fcntl.flock(argvf, fcntl.LOCK_UN)
+    except IOError:
+        raise Exception(
+            "Unable to open argv file for writing: {0}".format(argvfile))
+
+
+def obtain_argv(gameid, argv):
+    """Obtain command line with arguments"""
+
+    # If present and not None or [], just return the local arguments
+    if argv:
+        return argv
+
+    # From here, expect arguments to have been saved previously
+    argvfile = os.path.join(os.getenv("HOME"), "devkit-game",
+                            gameid + "-argv.json")
+    try:
+        with open(argvfile, "r") as argvf:
+            fcntl.flock(argvf, fcntl.LOCK_EX)
+            argv = json.load(argvf)
+            fcntl.flock(argvf, fcntl.LOCK_UN)
+    except IOError:
+        raise Exception(
+            "Unable to open argv file for reading: {0}".format(argvfile))
+    return argv
+
+
+def save_settings(gameid, data):
+    """Save settings"""
+    settingsfile = os.path.join(os.getenv("HOME"), "devkit-game",
+                                gameid + "-settings.json")
+    settings = dict()
+
+    if data.get('clear_settings', False):
+        settings = {}
+    else:
+        try:
+            with open(settingsfile, "r") as f:
+                fcntl.flock(f, fcntl.LOCK_EX)
+                settings = json.load(f)
+                fcntl.flock(f, fcntl.LOCK_UN)
+        except IOError as e:
+            if (e.errno != errno.ENOENT):
+                raise
+
+    # Merge settings from new json
+    if 'settings' in data:
+        settings.update(data['settings'])
+
+    try:
+        with open(settingsfile, "w") as f:
+            fcntl.flock(f, fcntl.LOCK_EX)
+            json.dump(settings, f)
+            fcntl.flock(f, fcntl.LOCK_UN)
+    except (IOError):
+        raise Exception(
+            "Unable to open settings file for writing: {0}".format(
+                settingsfile
+            ))
+
+    return settings
+
+
+def load_settings(gameid):
+    settingsfile = os.path.join(os.getenv("HOME"), "devkit-game", gameid + '-settings.json')
+
+    if not os.path.isfile(settingsfile):
+        return None
+
+    with open(settingsfile, "r") as f:
+        fcntl.flock(f, fcntl.LOCK_EX)
+        settings = json.load(f)
+        fcntl.flock(f, fcntl.LOCK_UN)
+
+    return settings
+
+
+class SteamResponse_Timeout(Exception):
+    pass
+
+
+class SteamResponse_Error(Exception):
+    def __init__(self, error_response):
+        self.error_response = error_response
+
+    def __str__(self):
+        return self.error_response
+
+
+@contextlib.contextmanager
+def wait_on_file_response(path, timeout=5):
+    """
+The pipe to the Steam Client is one way.
+Responses from the Steam Client are written to filesystem.
+Protocol is as follows:
+- Steam Client creates a 'path.lock' file
+- Steam Client writes either 'path' or 'path.error' to indicate a problem
+- Steam Client deletes 'path.lock'
+- Caller (us) can then read the response
+
+NOTE 1: this function is used as a context manager and will block until a response comes in or timeout.
+
+NOTE 2: the files are created by Steam when responding to a command. If the files already exist the response protocol will break.
+    """
+    lock_path = '{0}.lock'.format(path)
+    error_path = '{0}.error'.format(path)
+    max_count = timeout
+    while True:
+        time.sleep(1)
+        if os.path.exists(error_path) or os.path.exists(path) and not os.path.exists(lock_path):
+            if os.path.exists(error_path):
+                with open(error_path, 'r') as f:
+                    fcntl.flock(f, fcntl.LOCK_EX)
+                    error_response = f.read()
+                    fcntl.flock(f, fcntl.LOCK_UN)
+                    raise SteamResponse_Error(error_response)
+            with open(path, 'r') as f:
+                fcntl.flock(f, fcntl.LOCK_EX)
+                success_response = f.read()
+                yield success_response
+                fcntl.flock(f, fcntl.LOCK_UN)
+                return
+        max_count -= 1
+        if max_count > 0:
+            continue
+        raise SteamResponse_Timeout()
+
+
+# Setting up as a context manager so we never miss the deletion
+# Creating a temporary .lock file to guard the create operation
+@contextlib.contextmanager
+def create_pid(pid_path):
+    os.makedirs(os.path.dirname(pid_path), exist_ok=True)
+    lock_path = '{0}.lock'.format(pid_path)
+    try:
+        lock_file = os.open(lock_path, os.O_CREAT | os.O_EXCL)
+    except IOError as e:
+        logger.error('cannot create lock file %s for pid file %s', lock_path, pid_path)
+        logger.error('remove the lock file manually and run again if you are confident no other instance is active')
+        raise
+
+    pid_file = open(pid_path,'w')
+    pid_file.write(str(os.getpid()))
+    pid_file.flush()
+    os.close(lock_file)
+    os.unlink(lock_path)
+    try:
+        yield pid_file
+    finally:
+        pid_file.close()
+        # Assume that's atomic and all is well, no need for another .lock
+        os.unlink(pid_path)
diff --git a/tests/fakeframe/steamos-devkit-service/hooks/install-ssh-key b/tests/fakeframe/steamos-devkit-service/hooks/install-ssh-key
new file mode 100755
index 0000000..e0d9cd1
--- /dev/null
+++ b/tests/fakeframe/steamos-devkit-service/hooks/install-ssh-key
@@ -0,0 +1,74 @@
+#!/bin/sh
+#
+# This file is part of steamos-devkit
+# SPDX-License-Identifier: LGPL-2.1+
+#
+# Copyright © 2017-2018 Collabora Ltd
+#
+# This package is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This package is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this package.  If not, see
+# <http://www.gnu.org/licenses/>.
+
+# Sample script to install ssh keys that were approved by the
+# approve-ssh-key script.
+#
+# A script or binary (written in any language) named install-ssh-key
+# can be placed in the same directory as this sample, and it will be
+# used preferentially.
+#
+# Execution environment:
+# - Runs as root
+# Input:
+# - The public key is in a temporary file accessible via argv[1], in
+#   OpenSSH format
+# - argv[2], ... are the users to which we should grant access
+# Output:
+# - Exit 0 to accept the key, or nonzero to reject or on error
+#
+# This sample implementation should be suitable for any machine that
+# has the specified users. A production implementation would be similar
+# or even identical.
+
+set -e
+
+public_key="$1"
+shift
+
+echo "Installing public key '$public_key' for users: $*"
+
+for user in "$@"
+do
+    if pwent="$(getent passwd "$user")"
+    then
+        home="$(echo "$pwent" | cut -d: -f6)"
+        group="$(id -gn "$user")"
+        install -d -m 0755 -o "$user" -g "$group" "$home/.ssh"
+        if ! [ -e "$home/.ssh/authorized_keys" ]
+        then
+            install -m 0600 -o "$user" -g "$group" "$public_key" "$home/.ssh/authorized_keys"
+        else
+            if ! ( grep -v '^#' "$home/.ssh/authorized_keys" | grep -qF "$(cut -d " " -f2 "$public_key")" )
+            then
+                if [ -n "$(tail -1c "$home/.ssh/authorized_keys")" ]
+                then
+                    echo >> "$home/.ssh/authorized_keys"
+                fi
+                cat "$public_key" >> "$home/.ssh/authorized_keys"
+            fi
+        fi
+    fi
+done
+
+echo "Public key installed"
+
+exit 0
diff --git a/tests/fakeframe/steamos-devkit-service/src/steamos-devkit-service.py b/tests/fakeframe/steamos-devkit-service/src/steamos-devkit-service.py
new file mode 100755
index 0000000..f22f3ac
--- /dev/null
+++ b/tests/fakeframe/steamos-devkit-service/src/steamos-devkit-service.py
@@ -0,0 +1,522 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+# MIT License
+#
+# Copyright (c) 2022 Valve Software inc., Collabora Ltd
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+from http.server import BaseHTTPRequestHandler
+import configparser
+import getpass
+import json
+import os
+import platform
+import socketserver
+import subprocess
+import tempfile
+import urllib.parse
+import argparse
+import threading
+import sys
+import builtins
+import signal
+
+import dbus
+
+# Print to stderr, which is unbuffered and easier to read in journalctl
+STDOUT_PRINT = builtins.print
+def stderr_print(*args, **kwargs):
+    if 'file' not in kwargs:
+        kwargs['file'] = sys.stderr
+    global STDOUT_PRINT
+    return STDOUT_PRINT(*args, **kwargs)
+builtins.print = stderr_print
+
+# Expect a SIGUSR1 signal to exit
+# Could come at any time so we keep a global flag, but also support a callback
+SHOULD_EXIT = False
+EXIT_CALLBACK = None
+def handle_sigusr1(signum, frame):
+    """ Handle SIGUSR1 signal
+    """
+    global SHOULD_EXIT
+    global EXIT_CALLBACK
+    print("Received SIGUSR1, exiting.")
+    SHOULD_EXIT = True
+    if EXIT_CALLBACK:
+        EXIT_CALLBACK()
+def set_exit_callback(callback):
+    """ Set a callback to be called when we receive a SIGUSR1 signal
+    """
+    global SHOULD_EXIT
+    global EXIT_CALLBACK
+    EXIT_CALLBACK = callback
+    #print(f'Exit callback set to {EXIT_CALLBACK}')
+    if SHOULD_EXIT and EXIT_CALLBACK:
+        EXIT_CALLBACK()
+signal.signal(signal.SIGUSR1, handle_sigusr1)
+
+SERVICE_PORT = 32000
+PACKAGE = "steamos-devkit-service"
+DEVKIT_HOOKS_DIR = "/usr/share/steamos-devkit/hooks"
+CURRENT_TXTVERS = '1'
+
+ENTRY_POINT = "devkit-1"
+# root until config is loaded and told otherwise, etc.
+ENTRY_POINT_USER = "root"
+DEVICE_USERS = []
+PROPERTIES = {"txtvers": 1,
+              "login": ENTRY_POINT_USER,
+              "settings": "",
+              "devkit1": [
+                  ENTRY_POINT
+              ]}
+
+# Forced mDNS republish currently disabled, was causing a bad interaction with org.freedesktop.resolve1
+FORCE_PUBLISH_INTERVAL = 0
+
+def write_file(data: bytes) -> str:
+    """ Write given bytes to a temporary file and return the filename
+
+    Return the empty string if unable to open temp file for some reason
+    """
+
+    with tempfile.NamedTemporaryFile(mode='w', prefix='devkit-1', encoding='utf-8',
+        delete=False) as file:
+        file.write(data.decode())
+
+        return file.name
+
+    return ''
+
+
+def write_key(post_body: bytes) -> str:
+    """ Write key to temp file and return filename if valid
+
+    Return the empty string if invalid
+    """
+    length = len(post_body)
+    found_name = False
+
+    if length >= 64 * 1024:
+        print("Key length too long")
+        return ''
+    if not post_body.decode().startswith('ssh-rsa '):
+        print("Key doesn't start with ssh-rsa ")
+        return ''
+
+    # Get to the base64 bits
+    index = 8
+    while index < length and post_body[index] == ' ':
+        index = index + 1
+
+    # Make sure key is base64
+    body_decoded = post_body.decode()
+    while index < length:
+        if ((body_decoded[index] == '+') or (body_decoded[index] == '/') or
+                (body_decoded[index].isdigit()) or
+                (body_decoded[index].isalpha())):
+            index = index + 1
+            continue
+        if body_decoded[index] == '=':
+            index = index + 1
+            if (index < length) and (body_decoded[index] == ' '):
+                break
+            if (index < length) and (body_decoded[index] == '='):
+                index = index + 1
+                if (index < length) and (body_decoded[index] == ' '):
+                    break
+            print("Found = but no space or = next, invalid key")
+            return ''
+        if body_decoded[index] == ' ':
+            break
+
+        print("Found invalid data, invalid key at "
+              f"index: {index} data: {body_decoded[index]}")
+        return ''
+
+    print(f"Key is valid base64, writing to temp file index: {index}")
+    while index < length:
+        if body_decoded[index] == ' ':
+            # it's a space, the rest is name or magic phrase, don't write to disk
+            if found_name:
+                print(f"Found name ending at index {index}")
+                length = index
+            else:
+                print(f"Found name ending index {index}")
+                found_name = True
+        if body_decoded[index] == '\0':
+            print("Found null terminator before expected")
+            return ''
+        if body_decoded[index] == '\n' and index != length - 1:
+            print("Found newline before expected")
+            return ''
+        index = index + 1
+
+    # write data to the file
+    data = body_decoded[:length]
+    filename = write_file(data.encode())
+
+    if filename:
+        print(f"Filename key written to: {filename}")
+
+    return filename
+
+
+def find_hook(name: str) -> str:
+    """ Find a hook with the given name
+
+    Return the path to the hook if found. '' if not found
+    """
+    test_path = f"{DEVKIT_HOOKS_DIR}/{name}"
+    if os.path.exists(test_path) and os.access(test_path, os.X_OK):
+        return test_path
+
+    print(f"Error:: Unable to find hook for {name}")
+    return ''
+
+
+def get_machine_name() -> str:
+    """ Get the machine name and return it in a string
+
+    Use identify hook first, and if that fails just get the hostname.
+    """
+    machine_name = ''
+    # Run devkit-1-identify hook to get hostname, otherwise use default platform.node()
+    identify_hook = find_hook("devkit-1-identify")
+    if identify_hook:
+        # Run hook and parse machine_name out
+        process = subprocess.Popen(identify_hook, shell=False, stdout=subprocess.PIPE)
+        output = ''
+        for line in process.stdout:
+            textline = line.decode(encoding='utf-8', errors="ignore")
+            output += textline
+        process.wait()
+        output_object = json.loads(output)
+        if 'machine_name' in output_object:
+            machine_name = output_object["machine_name"]
+
+    if not machine_name:
+        machine_name = platform.node()
+
+    return machine_name
+
+
+class DevkitHandler(BaseHTTPRequestHandler):
+    """ Class to handle http requests on selected port for registration, getting properties.
+    """
+    def _send_headers(self, code, content_type):
+        self.send_response(code)
+        self.send_header("Content-type", content_type)
+        self.end_headers()
+
+    def do_GET(self):
+        """ Handle GET requests
+        """
+        print(f"GET request to path {self.path} from {self.client_address[0]}")
+
+        if self.path == "/login-name":
+            self._send_headers(200, "text/plain")
+            self.wfile.write(ENTRY_POINT_USER.encode())
+            return
+
+        if self.path == "/properties.json":
+            self._send_headers(200, "application/json")
+            self.wfile.write(json.dumps(PROPERTIES, indent=2).encode())
+            return
+
+        query = urllib.parse.parse_qs(self.path[2:])
+        print(f"query is {query}")
+
+        if len(query) > 0 and query["command"]:
+            command = query["command"][0]
+
+            if command == "ping":
+                self._send_headers(200, "text/plain")
+                self.wfile.write("pong\n".encode())
+                return
+
+            self._send_headers(404, "")
+            return
+
+        self._send_headers(404, "")
+        self.wfile.write("Unknown request\n".encode())
+
+    def do_POST(self):
+        """ Handle POST requests
+        """
+        if self.path == "/register":
+            from_ip = self.client_address[0]
+            content_len = int(self.headers.get('Content-Length'))
+            post_body = self.rfile.read(content_len)
+            print(f"register request from {from_ip}")
+            filename = write_key(post_body)
+
+            if not filename:
+                self._send_headers(403, "text/plain")
+                self.wfile.write(json.dumps({'error':'Failed to write the ssh key'}).encode())
+                return
+
+            # Run approve script
+            approve_hook = find_hook("approve-ssh-key")
+            if not approve_hook:
+                self._send_headers(403, "text/plain")
+                self.wfile.write(json.dumps({'error':'Failed to find approve hook'}).encode())
+                os.unlink(filename)
+                return
+
+            # Run hook and parse output
+            approve_process = subprocess.Popen([approve_hook, filename, from_ip],
+                                               shell=False,
+                                               stdout=subprocess.PIPE)
+            approve_output = ''
+            for approve_line in approve_process.stdout:
+                approve_textline = approve_line.decode(encoding='utf-8', errors="ignore")
+                approve_output += approve_textline
+
+            approve_process.wait()
+            approve_object = json.loads(approve_output)
+            if "error" in approve_object:
+                self._send_headers(403, "text/plain")
+                self.wfile.write(approve_output.encode()) # is already a json {'error':} response
+                os.unlink(filename)
+                return
+
+            # Otherwise, assume it passed
+            install_hook = find_hook("install-ssh-key")
+            if not install_hook:
+                self._send_headers(403, "text-plain")
+                self.wfile.write(json.dumps({'error':'Failed to find install-ssh-key hook'}).encode())
+                os.unlink(filename)
+                return
+
+            command = [install_hook, filename]
+            # Append each user to command as separate arguments
+            for user in DEVICE_USERS:
+                command.append(user)
+
+            install_process = subprocess.Popen(command, shell=False, stdout=subprocess.PIPE)
+            install_output = ''
+            for install_line in install_process.stdout:
+                install_textline = install_line.decode(encoding='utf-8', errors="ignore")
+                install_output += install_textline
+            install_process.wait()
+
+            exit_code = install_process.returncode
+            if exit_code != 0:
+                self._send_headers(500, "text/plain")
+                self.wfile.write("install-ssh-key:\n".encode())
+                self.wfile.write(install_output.encode())
+                os.unlink(filename)
+                return
+
+            self._send_headers(200, "text/plain")
+            self.wfile.write("Registered\n".encode())
+            os.unlink(filename)
+
+
+class DevkitService:
+    """ Class to run as service.
+
+    Parses configuration, creates handler, registers an entry in dynamic DNS, etc.
+    """
+    def __init__(self):
+        global ENTRY_POINT_USER
+        global DEVICE_USERS
+
+        self.port = SERVICE_PORT
+        self.name = get_machine_name()
+        self.stype = "_steamos-devkit._tcp"
+
+        self.service_path = None
+
+        config = configparser.ConfigParser()
+        # Use str form to preserve case
+        config.optionxform = str
+        config.read(["/etc/steamos-devkit/steamos-devkit.conf",
+                     "/usr/share/steamos-devkit/steamos-devkit.conf",
+                     os.path.join(os.path.expanduser('~'), '.config', PACKAGE, PACKAGE + '.conf')])
+
+        self.settings = {}
+        if 'Settings' in config:
+            settings = config["Settings"]
+            self.settings = dict(settings)
+            if 'Port' in settings:
+                self.port = int(settings["Port"])
+
+        PROPERTIES["settings"] = json.dumps(self.settings)
+
+        # Parse users from configs
+        if os.geteuid() == 0:
+            # Running as root, maybe warn?
+            print("Running as root, Probably shouldn't be\n")
+            if 'Users' in config:
+                users = config["Users"]
+                if 'ShellUsers' in users:
+                    DEVICE_USERS = users["ShellUsers"]
+        else:
+            if 'Users' in config:
+                users = config["Users"]
+                if 'ShellUsers' in users:
+                    DEVICE_USERS = users["ShellUsers"]
+            else:
+                username = getpass.getuser()
+                print(f'Username: {username}')
+                DEVICE_USERS = []
+                DEVICE_USERS.append(username)
+
+        # If only one user, that's the entry point user
+        # Otherwise entry_point_user needs to be root to be able to switch between users
+        if len(DEVICE_USERS) == 1:
+            ENTRY_POINT_USER = DEVICE_USERS[0]
+            PROPERTIES["login"] = ENTRY_POINT_USER
+
+        # "an array of dictionaries mapping strings to byte arrays" .. biggest eyeroll
+        py_dict = {}
+        for key, value in [
+            ('txtvers', CURRENT_TXTVERS),
+            ('settings', json.dumps(self.settings)),
+            ('login', ENTRY_POINT_USER),
+            ('devkit1', ENTRY_POINT)
+        ]:
+            py_dict[key] = dbus.Array([ord(c) for c in value], signature='y')
+        self.txt_records = dbus.Array( [dbus.Dictionary(py_dict, signature='say' )], signature='a{say}' )
+
+        self.dbus_bus = dbus.SystemBus()
+        self.resolve1_register = self.dbus_bus.get_object(
+            'org.freedesktop.resolve1',
+            '/org/freedesktop/resolve1'
+        ).get_dbus_method(
+            'RegisterService',
+            'org.freedesktop.resolve1.Manager'
+        )
+        self.resolve1_unregister = self.dbus_bus.get_object(
+            'org.freedesktop.resolve1',
+            '/org/freedesktop/resolve1'
+        ).get_dbus_method(
+            'UnregisterService',
+            'org.freedesktop.resolve1.Manager'
+        )
+
+        self.httpd = socketserver.TCPServer(("", self.port), DevkitHandler, bind_and_activate=False)
+        print(f"serving at port: {self.port}")
+        print(f"machine name: {self.name}")
+        self.httpd.allow_reuse_address = True
+        self.httpd.server_bind()
+        self.httpd.server_activate()
+
+    def publish(self, recursed=False, silent=False):
+        """ Publish ourselves on mdns as an available devkit device.
+        """
+        # https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.resolve1.html
+
+        if not silent:
+            print(f'RegisterService {self.name} {self.stype} {self.port}')
+        self.unpublish(silent)
+
+        try:
+            self.service_path = self.resolve1_register(
+                # Passing '%H' should amount to the same thing
+                # (is expanded based on specifiers, see https://www.man7.org/linux/man-pages/man5/systemd.dnssd.5.html)
+                self.name,
+                # 'name_template' .. what is this?
+                # also referred to as 'service instance name' in the implementation
+                # can't be an empty string, gets expanded with the same specifier rules as name,
+                # gets random numbers appended to it for a new instance name in case of service collisions?
+                self.name,
+                self.stype,
+                dbus.UInt16(int(self.port)),
+                dbus.UInt16(10),    # priority (see https://en.wikipedia.org/wiki/SRV_record)
+                dbus.UInt16(0),     # weight
+                self.txt_records,
+            )
+        except dbus.exceptions.DBusException as e:
+            # services will persist, it's bad if we didn't properly unregister, but we can recover this
+            if not recursed and e.get_dbus_name() == 'org.freedesktop.resolve1.DnssdServiceExists':
+                print('Service is already registered! Trying to recover')
+                self.service_path = f'/org/freedesktop/resolve1/dnssd/{self.name}'
+                self.unpublish()
+                self.publish(True)
+            else:
+                raise e
+
+    def unpublish(self, silent=False):
+        """ Remove publishing of ourselves as devkit device since we are quitting.
+        """
+        if self.service_path:
+            if not silent:
+                print(f'UnregisterService {self.service_path}')
+            self.resolve1_unregister(self.service_path)
+            self.service_path = None
+
+    def force_publish(self, exit_event):
+        while True:
+            exit_event.wait(timeout=FORCE_PUBLISH_INTERVAL)
+            if exit_event.is_set():
+                break
+            self.publish(False, True)
+
+    def on_signal_shutdown(self):
+        print('Shutting down the httpd server')
+        # This is blocking and needs to run in a thread, otherwise we'll deadlock
+        threading.Thread(target=self.httpd.shutdown, daemon=True).start()
+
+    def run_server(self):
+        """ Run server until keyboard interrupt or we are killed
+        """
+
+        thread = None
+        exit_event = None
+        global FORCE_PUBLISH_INTERVAL
+        if 'ForcePublishInterval' in self.settings:
+            FORCE_PUBLISH_INTERVAL = int(self.settings['ForcePublishInterval'])
+        if FORCE_PUBLISH_INTERVAL != 0:
+            exit_event = threading.Event()
+            thread = threading.Thread(target=self.force_publish, args=[exit_event,], daemon=True).start()
+
+        set_exit_callback(self.on_signal_shutdown)
+        try:
+            self.httpd.serve_forever()
+        except KeyboardInterrupt:
+            pass
+        set_exit_callback(None)
+
+        if thread:
+            exit_event.set()
+            thread.join()
+
+        self.httpd.server_close()
+        print(f"done serving at port: {self.port}")
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--hooks', required=False, action='store', help='hooks directory')
+    conf = parser.parse_args()
+
+    if conf.hooks is not None:
+        DEVKIT_HOOKS_DIR = conf.hooks
+
+    service = DevkitService()
+
+    service.publish()
+    service.run_server()
+    service.unpublish()
diff --git a/tests/smoke/frame_smoke.py b/tests/smoke/frame_smoke.py
new file mode 100644
index 0000000..6cad662
--- /dev/null
+++ b/tests/smoke/frame_smoke.py
@@ -0,0 +1,235 @@
+"""Headset smoke test: the fake Frame's core cases against a real Frame.
+
+Runs on your computer through the `frame` SSH alias (or FRAME_ALIAS), with
+Frame Control's own modules, and records what happened with the headset's
+BUILD_ID in tests/smoke/results/<time>-<BUILD_ID>.json (git-ignored):
+
+- properties.json from Valve's devkit service names the login user;
+- status (ui/frame_status.py) reads the build, battery and storage;
+- three tiny titles (tests/smoke/tiny_programs.py: ARM64 and x86-64 static
+  Linux programs, an x86-64 .exe) are installed, launched and removed with
+  ui/frame_titles.py, and Steam's logs about each are kept;
+- with --pair, a throwaway RSA key is paired through the devkit service
+  (someone has to open Settings > Developer > Pair new host and approve it in
+  the headset), checked, and taken out of authorized_keys again.
+
+Everything it installs is removed again, also when a step fails. Titles are
+named fc_smoke_*; leftovers from an interrupted run are removed first.
+
+Usage: python3 tests/smoke/frame_smoke.py [--pair]     (or scripts/frame-smoke.sh)
+Exit status: 0 all passed, 1 a step failed, 2 the headset isn't reachable.
+"""
+import argparse
+import json
+import os
+import platform
+import shlex
+import subprocess
+import sys
+import tempfile
+import time
+import traceback
+import urllib.request
+from pathlib import Path
+
+HERE = Path(__file__).resolve().parent
+ROOT = HERE.parent.parent
+sys.path[:0] = [str(ROOT / 'ui'), str(HERE)]
+ALIAS = os.environ.setdefault('FRAME_ALIAS', 'frame')   # read by frame_android at import
+
+import frame_android  # noqa: E402
+import frame_connect  # noqa: E402
+import frame_titles  # noqa: E402
+import tiny_programs  # noqa: E402
+
+RESULTS = HERE / 'results'
+PREFIX = 'fc_smoke_'
+# Earlier runs named titles fc-smoke*, which Steam refused to register but left on disk.
+OLD_PREFIX = 'fc-smoke'
+
+
+class Smoke:
+    def __init__(self):
+        self.steps = []
+        self.installed = set()
+
+    def step(self, name, fn, *args):
+        """Run one step; record ok/failed, its detail and how long it took."""
+        t0 = time.monotonic()
+        rec = {'step': name}
+        try:
+            detail = fn(*args)
+            rec.update(ok=True, detail=detail)
+        except Exception as e:  # a failed step is a result, not the end of the run
+            rec.update(ok=False, error=f'{type(e).__name__}: {e}', trace=traceback.format_exc(limit=3))
+        rec['seconds'] = round(time.monotonic() - t0, 1)
+        self.steps.append(rec)
+        print(f"  {'ok  ' if rec['ok'] else 'FAIL'} {name} ({rec['seconds']} s)"
+              + ('' if rec['ok'] else f": {rec['error']}"), flush=True)
+        return rec
+
+
+def ssh(cmd, timeout=60):
+    return frame_android.ssh(cmd, timeout=timeout)
+
+
+def ssh_config(key):
+    out = subprocess.run(['ssh', '-G', ALIAS], capture_output=True, text=True, timeout=10).stdout
+    for line in out.splitlines():
+        k, _, v = line.partition(' ')
+        if k == key:
+            return v.strip()
+    return None
+
+
+def os_release():
+    fields = {}
+    for line in ssh('cat /etc/os-release').splitlines():
+        k, _, v = line.partition('=')
+        fields[k] = v.strip('"')
+    return {k: fields.get(k) for k in ('VERSION_ID', 'VARIANT_ID', 'BUILD_ID')}
+
+
+def properties():
+    host = ssh_config('hostname') or ALIAS
+    with urllib.request.urlopen(frame_connect.devkit_url(host, 32000, '/properties.json'), timeout=5) as r:
+        props = json.load(r)
+    user = ssh_config('user')
+    if props.get('login') != user:
+        raise AssertionError(f"properties.json says login {props.get('login')!r}; the alias logs in as {user!r}")
+    return props
+
+
+def status(build):
+    s = json.loads(frame_android.ssh('python3 -', input=(ROOT / 'ui' / 'frame_status.py').read_text(), timeout=30))
+    if s['os']['build'] != build:
+        raise AssertionError(f"status says build {s['os']['build']}, /etc/os-release {build}")
+    for key in ('battery', 'disk', 'memory'):
+        if not s.get(key):
+            raise AssertionError(f'status has no {key}')
+    return {k: s.get(k) for k in ('os', 'battery', 'power', 'temp', 'services', 'volume')}
+
+
+def steam_log_lines(gid):
+    """What Steam logged about a title (log folder layout not verified; best effort)."""
+    out = ssh(f"grep -rsh -- {shlex.quote(gid)} ~/.local/share/Steam/logs/ 2>/dev/null | tail -n 12 || true")
+    return out.strip().splitlines()
+
+
+def title_cycle(smoke, kind, folder):
+    path = tiny_programs.write(folder, kind)
+    gid = PREFIX + kind                 # named outright: the file names would share one id
+
+    def install():
+        smoke.installed.add(gid)
+        meta = frame_titles.install(path, name=gid)
+        listed = {t['id']: t for t in frame_titles.list_titles()}
+        if gid not in listed:
+            raise AssertionError(f'{gid} is not in the title list after installing')
+        return {'id': gid, 'runtime': meta['runtime'], 'steam': meta.get('steam')}
+
+    def launch():
+        frame_titles.launch(gid)       # raises unless Steam confirmed it
+        time.sleep(4)
+        procs = ssh(f"pgrep -af -- {shlex.quote('devkit-game/' + gid)} || true").strip()
+        return {'processes': procs.splitlines(), 'steam_log': steam_log_lines(gid)}
+
+    def remove():
+        frame_titles.remove(gid)
+        left = ssh(f'ls -d ~/devkit-game/{gid} ~/devkit-game/{gid}-*.json 2>/dev/null || true').strip()
+        if left:
+            raise AssertionError(f'left behind: {left}')
+        if gid in {t['id'] for t in frame_titles.list_titles()}:
+            raise AssertionError(f'{gid} is still listed')
+        smoke.installed.discard(gid)
+        return {'removed': gid}
+
+    if smoke.step(f'{kind}: install', install)['ok']:
+        smoke.step(f'{kind}: launch', launch)
+        smoke.step(f'{kind}: remove', remove)
+
+
+def cleanup(smoke):
+    """Remove fc-smoke-* titles: this run's, and any an interrupted run left."""
+    try:
+        ids = {t['id'] for t in frame_titles.list_titles() if t['id'].startswith((PREFIX, OLD_PREFIX))}
+    except frame_android.FrameError:
+        ids = set(smoke.installed)      # can't list: try what this run installed
+    for gid in sorted(ids):
+        try:
+            frame_titles.remove(gid)
+        except frame_android.FrameError as e:
+            print(f'  could not remove {gid}: {e}')
+    return sorted(ids)
+
+
+def pair(folder):
+    """Pair a throwaway RSA key through the devkit service, check it, then remove it."""
+    key = os.path.join(folder, 'id_rsa_smoke')
+    subprocess.run(['ssh-keygen', '-q', '-t', 'rsa', '-b', '3072', '-N', '', '-C', 'frame-control-smoke',
+                    '-f', key], check=True)
+    pub = Path(key + '.pub').read_text()
+    host = ssh_config('hostname') or ALIAS
+    user = ssh_config('user')
+    comment = frame_connect.key_comment(platform.node()).replace('frame-control@', 'frame-control-smoke@')
+    print('    In the headset: Steam Settings > Developer > Pair new host, then approve '
+          f'"{comment}" (waits up to {frame_connect.PAIRING_MODE_WAIT} s)', flush=True)
+    b64 = pub.split()[1]
+    try:
+        reason = frame_connect.devkit_pair(host, pub, comment)
+        if reason:
+            raise AssertionError(reason)
+        r = subprocess.run(['ssh', '-o', 'BatchMode=yes', '-o', 'IdentitiesOnly=yes', '-o', 'ConnectTimeout=8',
+                            '-o', 'ControlPath=none', '-i', key, f'{user}@{host}', 'true'], capture_output=True, text=True)
+        if r.returncode != 0:
+            raise AssertionError(f'paired, but the key does not log in: {r.stderr.strip()}')
+        return {'comment': comment}
+    finally:
+        f = '~/.ssh/authorized_keys'
+        ssh(f'grep -vF {b64} {f} > {f}.smoke; cat {f}.smoke > {f}; rm -f {f}.smoke')
+        if b64 in ssh(f'cat {f}'):
+            raise AssertionError('the smoke key is still in authorized_keys')
+
+
+def main():
+    ap = argparse.ArgumentParser(description=__doc__.splitlines()[0])
+    ap.add_argument('--pair', action='store_true', help='also pair through the devkit service (needs you in the headset)')
+    args = ap.parse_args()
+
+    r = subprocess.run(['ssh', '-o', 'ConnectTimeout=5', '-o', 'BatchMode=yes', ALIAS, 'true'],
+                       capture_output=True, text=True)
+    if r.returncode != 0:
+        print(f'{ALIAS} is not reachable over SSH: {r.stderr.strip()}', file=sys.stderr)
+        return 2
+
+    smoke = Smoke()
+    started = time.strftime('%Y-%m-%dT%H:%M:%SZ', time.gmtime())
+    release = os_release()
+    build = release['BUILD_ID'] or 'unknown'
+    print(f'==> Frame smoke test on {ALIAS}: SteamOS {release["VERSION_ID"]} ({release["VARIANT_ID"]}), build {build}')
+    left = cleanup(smoke)
+    if left:
+        print(f'  removed leftovers from an earlier run: {", ".join(left)}')
+    folder = tempfile.mkdtemp(prefix='frame-smoke-')
+    try:
+        smoke.step('devkit service: properties.json', properties)
+        smoke.step('status', status, build)
+        for kind in ('arm64', 'x86_64', 'exe'):
+            title_cycle(smoke, kind, folder)
+        if args.pair:
+            smoke.step('devkit pairing (throwaway key)', pair, folder)
+    finally:
+        removed = cleanup(smoke)
+        subprocess.run(['rm', '-rf', folder])
+    passed = sum(s['ok'] for s in smoke.steps)
+    RESULTS.mkdir(exist_ok=True)
+    out = RESULTS / f"{started.replace(':', '')}-{build}.json"
+    out.write_text(json.dumps({'started': started, 'alias': ALIAS, 'os_release': release, 'paired': args.pair,
+                               'passed': passed, 'failed': len(smoke.steps) - passed,
+                               'cleanup_removed': removed, 'steps': smoke.steps}, indent=1))
+    print(f'==> {passed}/{len(smoke.steps)} steps passed on build {build}; results in {out.relative_to(ROOT)}')
+    return 0 if passed == len(smoke.steps) else 1
+
+
+if __name__ == '__main__':
+    sys.exit(main())
diff --git a/tests/smoke/tiny_programs.py b/tests/smoke/tiny_programs.py
new file mode 100644
index 0000000..c598b15
--- /dev/null
+++ b/tests/smoke/tiny_programs.py
@@ -0,0 +1,89 @@
+"""Tiny test programs for sideloading, built from bytes: no compiler needed.
+
+- elf_arm64(), elf_x86_64(): static Linux executables that sleep for a few
+  seconds (nanosleep) and exit 0, so a launch can be seen in `ps`.
+- pe_x86_64(): a Windows x86-64 .exe with no imports whose entry point
+  returns 0 straight away, which ends the process (Windows and Wine both
+  exit when the main thread returns).
+
+Each is a single loadable segment or section; they are what the headset
+smoke test and the fake Frame's e2e tests install. Python stdlib only.
+"""
+import struct
+
+SLEEP_SECONDS = 5
+BASE = 0x400000
+
+
+def _elf(machine, code):
+    """ELF64 little-endian ET_EXEC with one PT_LOAD (R+X) covering the whole file."""
+    ehsize, phsize = 64, 56
+    entry = BASE + ehsize + phsize
+    size = ehsize + phsize + len(code)
+    ident = b'\x7fELF' + bytes([2, 1, 1, 0]) + b'\0' * 8
+    header = ident + struct.pack('<HHIQQQIHHHHHH', 2, machine, 1, entry, ehsize, 0, 0,
+                                 ehsize, phsize, 1, 0, 0, 0)
+    phdr = struct.pack('<IIQQQQQQ', 1, 5, 0, BASE, BASE, size, size, 0x1000)
+    return header + phdr + code
+
+
+def elf_arm64(seconds=SLEEP_SECONDS):
+    words = [
+        0x10000100,                 # adr  x0, timespec (32 bytes ahead)
+        0xD2800001,                 # mov  x1, #0
+        0xD2800CA8,                 # mov  x8, #101        (nanosleep)
+        0xD4000001,                 # svc  #0
+        0xD2800000,                 # mov  x0, #0
+        0xD2800BA8,                 # mov  x8, #93         (exit)
+        0xD4000001,                 # svc  #0
+        0xD503201F,                 # nop  (pads the timespec to offset 32)
+    ]
+    return _elf(0xB7, struct.pack('<8I', *words) + struct.pack('<qq', seconds, 0))
+
+
+def elf_x86_64(seconds=SLEEP_SECONDS):
+    code = (b'\x48\x8d\x3d\x12\x00\x00\x00'   # lea  rdi, [rip+18] (the timespec)
+            b'\x31\xf6'                       # xor  esi, esi
+            b'\xb8\x23\x00\x00\x00'           # mov  eax, 35       (nanosleep)
+            b'\x0f\x05'                       # syscall
+            b'\x31\xff'                       # xor  edi, edi
+            b'\xb8\x3c\x00\x00\x00'           # mov  eax, 60       (exit)
+            b'\x0f\x05')                      # syscall
+    assert len(code) == 25
+    return _elf(0x3E, code + struct.pack('<qq', seconds, 0))
+
+
+def pe_x86_64():
+    """PE32+ console program: one .text section holding `xor eax, eax; ret`."""
+    file_align, sect_align, image_base = 0x200, 0x1000, 0x140000000
+    dos = b'MZ' + b'\0' * 0x3A + struct.pack('<I', 0x40)
+    coff = b'PE\0\0' + struct.pack('<HHIIIHH', 0x8664, 1, 0, 0, 0, 240, 0x0022)
+    opt = struct.pack('<HBBIIIII', 0x20B, 14, 0, file_align, 0, 0, 0x1000, 0x1000)
+    opt += struct.pack('<QIIHHHHHHIIIIHHQQQQII', image_base, sect_align, file_align,
+                       6, 0, 0, 0, 6, 0, 0,          # OS, image and subsystem versions, Win32VersionValue
+                       0x2000, file_align, 0,        # SizeOfImage, SizeOfHeaders, CheckSum
+                       3, 0x8100,                    # console subsystem; NX compatible, terminal-server aware
+                       0x100000, 0x1000, 0x100000, 0x1000, 0, 16)
+    opt += b'\0' * (16 * 8)                          # no data directories: no imports, no relocations
+    assert len(opt) == 240
+    text = b'.text\0\0\0' + struct.pack('<IIIIIIHHI', 3, 0x1000, file_align, file_align, 0, 0, 0, 0, 0x60000020)
+    headers = (dos + coff + opt + text).ljust(file_align, b'\0')
+    return headers + b'\x31\xc0\xc3'.ljust(file_align, b'\xcc')
+
+
+PROGRAMS = {                        # kind -> (file name, builder)
+    'arm64': ('fc-smoke-arm64', elf_arm64),
+    'x86_64': ('fc-smoke-x86_64', elf_x86_64),
+    'exe': ('fc-smoke-exe.exe', pe_x86_64),
+}
+
+
+def write(folder, kind):
+    """Write one program into folder; returns its path."""
+    import os
+    name, build = PROGRAMS[kind]
+    path = os.path.join(folder, name)
+    with open(path, 'wb') as f:
+        f.write(build())
+    os.chmod(path, 0o755)
+    return path