From f3c816eea5e2d881884a4bb32b3464311d64395e Mon Sep 17 00:00:00 2001
From: Abdessamad Derraz <3028866+Abdess@users.noreply.github.com>
Date: Mon, 26 Oct 2026 21:01:45 +0100
Subject: [PATCH] feat: put the retrobios app on a handheld card

--add-app, the result screen and a [y/N] question put the launcher of
muOS, KNULLI or ROCKNIX on the card the BIOS folder is on. The files come
from install/launchers/index.json at the same ref, each checked by size
and SHA-256 before the first is written, and the app event reports it.
---
 install.ps1                        |   2 +-
 install.py                         | 526 ++++++++++++++++++++++++++++-
 install.sh                         |   2 +-
 install/launchers/index.json       | 211 ++++++++++++
 schemas/install-events.schema.json |  53 +++
 scripts/generate_event_schema.py   |   2 +-
 scripts/generate_launcher_index.py | 132 ++++++++
 tests/test_install_app.py          | 470 ++++++++++++++++++++++++++
 tests/test_install_tui.py          | 195 ++++++++++-
 tests/test_port.py                 |  41 +++
 10 files changed, 1622 insertions(+), 12 deletions(-)
 create mode 100644 install/launchers/index.json
 create mode 100644 scripts/generate_launcher_index.py
 create mode 100644 tests/test_install_app.py

diff --git a/install.ps1 b/install.ps1
index 24449baef..cbe499f8a 100644
--- a/install.ps1
+++ b/install.ps1
@@ -11,7 +11,7 @@
 
     $ErrorActionPreference = "Stop"
     $defaultInstallUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-    $defaultInstallSha256 = "be9d37048e800072d6d5d2a40afaa5a46d5b062577f83c0fa633fc15159de66a"
+    $defaultInstallSha256 = "cec348d9aa6c9f940a2c9dc9bc6414a923acea8137e4a3624d4710c9d88c38ad"
     $maximumInstallerBytes = 2MB
     $installerExit = 0
     $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }
diff --git a/install.py b/install.py
index 35dc45189..8bb9cbe0a 100644
--- a/install.py
+++ b/install.py
@@ -573,6 +573,12 @@ EVENT_KEYS: dict[str, tuple[str, ...]] = {
     # would move), one per backup folder, empty when none.
     "summary": ("mode", "installed", "up_to_date", "pending", "failed", "skipped",
                 "left_out", "kept", "interrupted"),
+    # --add-app, or yes to its question, after the summary: the RetroBIOS
+    # app put on the handheld card (folder, its root) of system. dests are
+    # the app's files below the root, written those this run wrote (none
+    # when all were in place), kept the backup folders as in summary.
+    # ok false with reason when it was refused or failed.
+    "app": ("system", "folder", "ok", "reason", "dests", "written", "kept"),
     "end": ("code",),
 }
 # Seconds between two progress events while bytes arrive.
@@ -8369,6 +8375,380 @@ def bulk_hint(
     return []
 
 
+# The RetroBIOS app on a handheld's card. A card prepared on a computer can
+# also carry the launcher of ports/ for its system, so the player checks and
+# updates the BIOS files from the console later. The files come from the
+# same ref as the file lists, listed with their hashes in
+# install/launchers/index.json, which scripts/generate_launcher_index.py
+# writes from the members of the launcher archives.
+LAUNCHERS_URL = f"{BASE_URL}/install/launchers/index.json"
+MAX_LAUNCHERS_BYTES = 256 * 1024
+MAX_APP_FILE_SIZE = 8 * 1024 * 1024
+MAX_APP_FILES = 64
+APP_SCHEMA = 1
+
+
+class AppPlace(NamedTuple):
+    """Where a system's launcher goes on its card, and what the player does next.
+
+    key names its entry in the launcher list, folder is below the card's
+    root, executable says whether the menu runs the launcher script itself.
+    """
+
+    key: str
+    folder: str
+    executable: bool
+    then: str
+
+
+APP_PLACES: dict[str, AppPlace] = {
+    # The Archive Manager lists the .muxapp files of ARCHIVE at the root of
+    # SD1, SD2 and a USB drive, and installs one into Applications
+    # (MustardOS/frontend 9c0fb5da, module/muxarchive.c:16,157-164,196-218,
+    # MUOS_ARCH_PATH "ARCHIVE" in common/base/options.h:180). The archive
+    # carries the modes of its members.
+    "muOS": AppPlace("muos", "ARCHIVE", False,
+                     "Then open the Archive Manager on the console, install RetroBIOS, "
+                     "and start it from Applications."),
+    # The card's root is the SHARE partition, /userdata on the console.
+    # Ports runs a .sh with /bin/bash (knulli-cfw distribution ab3a6809,
+    # configgen/generators/sh/shGenerator.py:19-35), and evmapy reads the
+    # .keys file beside it: no mode is needed on the card.
+    "KNULLI": AppPlace("knulli", "roms/ports", False,
+                       "Then update the game list on the console, and start RetroBIOS "
+                       "from Ports."),
+    # The card's root is the STORAGE partition, /storage on the console. Tools
+    # runs each file of /storage/.config/modules in foot or weston-terminal,
+    # which starts it as a program: the build installs them 0755 (ROCKNIX
+    # distribution 8b70f693, projects/ROCKNIX/packages/virtual/emulators/
+    # package.mk:118-122 and 1701-1707).
+    "ROCKNIX": AppPlace("rocknix", ".config/modules", True,
+                        "Then start RetroBIOS from Tools on the console."),
+}
+
+# Card systems with no Python 3 to run the installer: Onion ships Python 2.7
+# alone (OnionUI/Onion 07505ea5, static/build/.tmp_update/bin/parasyte/),
+# MinUI (dbf89435), NextUI (5291344b) and Allium (ee0dda97) none, and
+# MyMinUI is built from MinUI.
+NO_PYTHON_CARDS = frozenset(("Onion", "Allium", "MinUI", "NextUI", "MyMinUI"))
+NO_PYTHON_WORDS = ("This console cannot run RetroBIOS itself: to update its BIOS files "
+                   "later, run this again on the computer.")
+APP_OFFER = "Put RetroBIOS on this card (update from the console later)"
+
+
+class CardApp(NamedTuple):
+    """A card a BIOS folder is on, and whether the RetroBIOS app can go there."""
+
+    root: Path
+    system: str
+    place: AppPlace | None
+    why: str
+
+
+def card_app(bios_dir: Path) -> CardApp | None:
+    """The card bios_dir is the BIOS folder of, None for a folder on no card
+    the installer recognises. why says, when place is None, why the app
+    cannot go on it."""
+    folder = Path(os.path.abspath(bios_dir))
+    for root in [folder, *list(folder.parents)[:3]]:
+        found = card_system(root)
+        if found is None or Path(os.path.abspath(found[1])) != folder:
+            continue
+        system = found[2]
+        place = APP_PLACES.get(system)
+        if place is not None:
+            return CardApp(root, system, place, "")
+        why = (f"{system} has no Python to run RetroBIOS" if system in NO_PYTHON_CARDS
+               else f"there is no RetroBIOS app for {system} yet")
+        return CardApp(root, system, None, why)
+    return None
+
+
+def _app_entry(value: object, field: str, source: bool = True) -> dict:
+    """One file of the launcher list, checked as a manifest entry is."""
+    if not isinstance(value, dict):
+        raise ValueError("an entry is not an object")
+    _safe_relative_path(value.get(field), field)
+    size = value.get("size")
+    if type(size) is not int or not 0 < size <= MAX_APP_FILE_SIZE:
+        raise ValueError(f"{value.get(field)}: invalid size")
+    digest = value.get("sha256")
+    if not isinstance(digest, str) or not re.fullmatch(r"[0-9a-f]{64}", digest):
+        raise ValueError(f"{value.get(field)}: invalid sha256")
+    if not isinstance(value.get("executable", False), bool):
+        raise ValueError(f"{value.get(field)}: invalid executable")
+    if source:
+        repo, content = value.get("repo_path"), value.get("content")
+        if (repo is None) == (content is None):
+            raise ValueError(f"{value.get(field)}: needs repo_path or content")
+        if repo is not None:
+            _safe_relative_path(repo, "repo_path")
+        elif not isinstance(content, str):
+            raise ValueError(f"{value.get(field)}: invalid content")
+    return value
+
+
+def app_targets(data: object, place: AppPlace) -> list[dict]:
+    """The files the launcher list puts on a card for place, each under its
+    folder: an archive carries its members, the others their source.
+
+    The list comes from the same base as the file lists, and is held to
+    the folder its system reads: no entry writes elsewhere on the card.
+    """
+    if not isinstance(data, dict) or data.get("schema") != APP_SCHEMA:
+        raise ValueError(f"not a launcher list of schema {APP_SCHEMA}")
+    launchers = data.get("launchers")
+    launcher = launchers.get(place.key) if isinstance(launchers, dict) else None
+    if not isinstance(launcher, dict):
+        raise ValueError(f"it holds no launcher for {place.key}")
+    if "archive" in launcher:
+        target = dict(_app_entry(launcher["archive"], "dest", source=False))
+        members = launcher.get("members")
+        if not isinstance(members, list) or not 0 < len(members) <= MAX_APP_FILES:
+            raise ValueError("invalid members")
+        target["members"] = [_app_entry(member, "name") for member in members]
+        if len({member["name"] for member in target["members"]}) != len(members):
+            raise ValueError("two members share a name")
+        targets = [target]
+    else:
+        files = launcher.get("files")
+        if not isinstance(files, list) or not 0 < len(files) <= MAX_APP_FILES:
+            raise ValueError("invalid files")
+        targets = [_app_entry(entry, "dest") for entry in files]
+    prefix = PurePosixPath(place.folder).parts
+    for target in targets:
+        parts = PurePosixPath(target["dest"]).parts
+        if len(parts) <= len(prefix) or parts[:len(prefix)] != prefix:
+            raise ValueError(f"{target['dest']} is outside {place.folder}")
+    if len({target["dest"].casefold() for target in targets}) != len(targets):
+        raise ValueError("two files share a destination")
+    return targets
+
+
+def app_archive(members: list[tuple[dict, bytes]]) -> bytes:
+    """A launcher archive from its members: stored, sorted, dated 1980-01-01,
+    only the executable bit kept, so the same members give the same bytes
+    on any machine and the list can record their hash."""
+    buffer = io.BytesIO()
+    with zipfile.ZipFile(buffer, "w", zipfile.ZIP_STORED) as archive:
+        for entry, data in sorted(members, key=lambda member: member[0]["name"]):
+            info = zipfile.ZipInfo(entry["name"], date_time=(1980, 1, 1, 0, 0, 0))
+            info.compress_type = zipfile.ZIP_STORED
+            info.create_system = 3
+            mode = 0o755 if entry.get("executable") else 0o644
+            info.external_attr = (0o100000 | mode) << 16
+            archive.writestr(info, data)
+    return buffer.getvalue()
+
+
+def _app_download(url: str, size: int) -> bytes:
+    """The bytes at url, tried MAX_RETRIES times, never more than size + 1."""
+    _network_allowed("the RetroBIOS app")
+    for attempt in range(1, MAX_RETRIES + 1):
+        try:
+            with urllib.request.urlopen(url, timeout=60) as resp:
+                return resp.read(size + 1)
+        except urllib.error.HTTPError as exc:
+            if exc.code < 500 and exc.code != 429 or attempt == MAX_RETRIES:
+                raise
+        except (urllib.error.URLError, OSError, http.client.HTTPException):
+            if attempt == MAX_RETRIES:
+                raise
+        time.sleep(_retry_delay(attempt, None))
+    raise AssertionError("unreachable")
+
+
+def _app_bytes(entry: dict, name: str) -> bytes:
+    """An entry's bytes, from the list itself or the repository, once they
+    have the size and the SHA-256 the list records."""
+    content = entry.get("content")
+    if content is not None:
+        data = content.encode("utf-8")
+    else:
+        url = RAW_FILE_URL.format(path=urllib.parse.quote(entry["repo_path"], safe="/"))
+        data = _app_download(url, entry["size"])
+    if len(data) != entry["size"]:
+        raise ValueError(f"{name} holds {len(data)} bytes, the list records {entry['size']}")
+    if hashlib.sha256(data).hexdigest() != entry["sha256"]:
+        raise ValueError(f"{name}: SHA-256 mismatch")
+    return data
+
+
+def _target_bytes(target: dict) -> bytes:
+    """What goes at a target's place: its file, or its archive built from
+    its members and checked against the hash the list records for it."""
+    members = target.get("members")
+    if members is None:
+        return _app_bytes(target, target["dest"])
+    data = app_archive([(member, _app_bytes(member, member["name"])) for member in members])
+    if len(data) != target["size"] or hashlib.sha256(data).hexdigest() != target["sha256"]:
+        raise ValueError(f"{target['dest']} built from its members is not the one the "
+                         "list records")
+    return data
+
+
+def _app_in_place(path: Path, target: dict) -> bool:
+    try:
+        return (path.is_file() and path.stat().st_size == target["size"]
+                and _sha256_file(path) == target["sha256"])
+    except OSError:
+        return False
+
+
+def _app_failure(exc: BaseException) -> str:
+    if isinstance(exc, urllib.error.HTTPError):
+        return f"the server answered HTTP {exc.code}"
+    if isinstance(exc, ValueError):
+        return str(exc)
+    if isinstance(exc, _Offline) or _transfer_failure(exc):
+        return network_words(exc)[1]
+    return getattr(exc, "strerror", None) or str(exc)
+
+
+def put_app(card: CardApp) -> dict:
+    """Put the launcher of card's system on it: the fields of the app event.
+
+    Every file is fetched and verified before the first one is written, and
+    written as a BIOS file is, the one in place kept aside when it differs.
+    A file already in place with the recorded hash is left alone, so a
+    second run writes nothing.
+    """
+    fields: dict = {"system": card.system, "folder": str(card.root), "ok": False,
+                    "reason": card.why, "dests": [], "written": [], "kept": []}
+    if card.place is None:
+        return fields
+    try:
+        data = _fetch_json(LAUNCHERS_URL, MAX_LAUNCHERS_BYTES, "list of the app's files")
+        targets = app_targets(data, card.place)
+    except (urllib.error.URLError, OSError, ValueError, http.client.HTTPException) as exc:
+        fields["reason"] = f"its list of files could not be read: {_app_failure(exc)}"
+        return fields
+    fields["dests"] = [target["dest"] for target in targets]
+    places = [(target, _destination_path(card.root, target["dest"])) for target in targets]
+    needed = [(target, path) for target, path in places if not _app_in_place(path, target)]
+    try:
+        payloads = [_target_bytes(target) for target, _path in needed]
+    except (urllib.error.URLError, OSError, ValueError, http.client.HTTPException) as exc:
+        fields["reason"] = f"it could not be downloaded: {_app_failure(exc)}"
+        return fields
+    before = {item["folder"]: (item["files"], item["bytes"]) for item in KEPT.summary()}
+    for (target, path), payload in zip(needed, payloads):
+        try:
+            path.parent.mkdir(parents=True, exist_ok=True)
+        except OSError as exc:
+            fields["reason"] = NOT_WRITABLE if _write_refused(exc) else _app_failure(exc)
+            break
+        _dest, ok, why = _write_verified(
+            target, card.root, path, lambda payload=payload: io.BytesIO(payload), None,
+            "the RetroBIOS app")
+        if not ok:
+            fields["reason"] = f"{target['dest']}: {why}"
+            break
+        fields["written"].append(target["dest"])
+    else:
+        fields["ok"], fields["reason"] = True, ""
+    for item in KEPT.summary():
+        files, size = before.get(item["folder"], (0, 0))
+        if item["files"] > files:
+            fields["kept"].append({"folder": item["folder"], "files": item["files"] - files,
+                                   "bytes": item["bytes"] - size})
+    return fields
+
+
+def app_lines(card: CardApp, fields: dict) -> list[str]:
+    """What putting the app on the card did, in words."""
+    if not fields["ok"]:
+        return [f"RetroBIOS could not be put on the {card.system} card: {fields['reason']}."]
+    if fields["written"]:
+        lines = [f"RetroBIOS is on the {card.system} card: "
+                 f"{_plural(len(fields['written']), 'file')} written in {card.root}."]
+    else:
+        lines = [f"RetroBIOS is already on the {card.system} card: nothing to write."]
+    lines += [f"The files it replaced are kept in {kept['folder']}" for kept in fields["kept"]]
+    if card.place is not None:
+        lines.append(card.place.then)
+    return lines
+
+
+def app_refusal(args: argparse.Namespace, platforms: list[tuple[str, Path]]) -> list[CardApp]:
+    """The cards --add-app puts the app on, one per folder. A folder that is
+    on no card the app can go on is refused with the reason, code 2, before
+    anything is written."""
+    cards: list[CardApp] = []
+    if not args.add_app:
+        return cards
+    for _plat, path in platforms:
+        card = card_app(path)
+        if card is None:
+            why = (f"{path} is not on a card this installer recognises (a muOS, "
+                   "KNULLI or ROCKNIX card)")
+        else:
+            why = card.why
+        if why:
+            EVENTS.emit("app", system=card.system if card else "",
+                        folder=str(card.root if card else path), ok=False, reason=why,
+                        dests=[], written=[], kept=[])
+            print(f"Error: --add-app puts the RetroBIOS app on a handheld's SD card, and "
+                  f"{why}.", file=sys.stderr)
+            if card is not None and card.system in NO_PYTHON_CARDS:
+                print(f"  {NO_PYTHON_WORDS}", file=sys.stderr)
+            else:
+                print("  Name the card's root or its BIOS folder with --dest.",
+                      file=sys.stderr)
+            sys.exit(2)
+        if card not in cards:
+            cards.append(card)
+    _APP_PENDING[:] = cards
+    return cards
+
+
+# The cards --add-app named, until the install finishes and the app is put.
+_APP_PENDING: list[CardApp] = []
+
+
+def app_not_added() -> None:
+    """--add-app in a run that stopped before the app: said, never silent."""
+    cards, _APP_PENDING[:] = list(_APP_PENDING), []
+    for card in cards:
+        EVENTS.emit("app", system=card.system, folder=str(card.root), ok=False,
+                    reason="the install did not finish", dests=[], written=[], kept=[])
+        print(f"  RetroBIOS was not put on the {card.system} card: the install did "
+              "not finish.", file=sys.stderr)
+
+
+def finish_app(
+    args: argparse.Namespace, platforms: list[tuple[str, Path]], cards: list[CardApp],
+    interactive: bool,
+) -> None:
+    """After an install that finished: the app on the cards --add-app named,
+    or on those the person says yes for at a terminal."""
+    _APP_PENDING[:] = []
+    chosen = list(cards)
+    if not args.add_app:
+        for card in dict.fromkeys(filter(None, (card_app(path) for _plat, path in platforms))):
+            if card.place is None:
+                if card.system in NO_PYTHON_CARDS:
+                    print(f"\n{NO_PYTHON_WORDS}")
+                continue
+            if not interactive or args.yes or LOCAL.offline:
+                continue
+            answer = _ask(f"\nPut RetroBIOS on this {card.system} card, to check and update "
+                          "its BIOS files from the console later? [y/N] ")
+            if answer.lower() in ("y", "yes"):
+                chosen.append(card)
+    failed = False
+    for card in chosen:
+        print(f"\nPutting RetroBIOS on the {card.system} card...")
+        fields = put_app(card)
+        EVENTS.emit("app", **fields)
+        stream = sys.stdout if fields["ok"] else sys.stderr
+        for line in app_lines(card, fields):
+            print(f"  {line}", file=stream)
+        failed = failed or not fields["ok"]
+    if failed:
+        sys.exit(1)
+
+
 def _help_epilog() -> str:
     """Examples in the form the run was started with, and where the rest is."""
     run = _INVOCATION.launcher()
@@ -8451,6 +8831,13 @@ def main() -> None:
         action="store_true",
         help="opt in to copies into detected standalone-emulator directories",
     )
+    parser.add_argument(
+        "--add-app",
+        action="store_true",
+        help="after the install, put the RetroBIOS app on the handheld card the BIOS "
+             "folder is on (muOS, KNULLI, ROCKNIX), to check and update the BIOS "
+             "files from the console later",
+    )
     parser.add_argument(
         "--emulator",
         action="append",
@@ -8680,7 +9067,7 @@ def main() -> None:
                  "cores_dir", "save_dir", "system", "core", "region", "no_game_data",
                  "declared_only", "list_systems",
                  "list_cores", "romm_firmware", "list_emulators", "events", "quiet",
-                 "yes", "verbose", "from_pack", "manifest", "from")
+                 "yes", "verbose", "from_pack", "manifest", "from", "add_app")
         given = [name for name in alone if getattr(args, name)]
         if args.jobs != 8:
             given.append("jobs")
@@ -8690,6 +9077,22 @@ def main() -> None:
         sys.exit(restore_kept(args.restore, args.dry_run))
     if args.every_board and args.target:
         parser.error("--every-board installs every board; --target names one")
+    if args.add_app:
+        # Applied or refused, never ignored.
+        for given, reason in (
+            (args.check or args.dry_run,
+             "--add-app writes the RetroBIOS app on the card, which --check and "
+             "--dry-run do not"),
+            (args.list_platforms or args.list_targets or args.list_systems
+             or args.list_cores or args.list_emulators,
+             "--add-app writes the RetroBIOS app on the card, which a listing does not"),
+            (args.from_pack, "--add-app downloads the RetroBIOS app, and --from-pack "
+             "makes no network request"),
+            (args.offline or offline_requested(), "--add-app downloads the RetroBIOS "
+             "app, which --offline does not"),
+        ):
+            if given:
+                parser.error(reason)
     if args.offline:
         # The runs the full-screen interface starts read it from here.
         os.environ[OFFLINE_VARIABLE] = "1"
@@ -8741,6 +9144,13 @@ def _run(args: argparse.Namespace) -> None:
     """The run, its text quiet or not, the archives it read closed after."""
     try:
         _run_text(args)
+    except SystemExit as exc:
+        if exc.code not in (0, None):
+            app_not_added()
+        raise
+    except KeyboardInterrupt:
+        app_not_added()
+        raise
     finally:
         LOCAL.close_indexes()
 
@@ -9318,6 +9728,8 @@ def _install(args: argparse.Namespace, real_stdout: TextIO) -> None:
         # --check installs nothing, and "Install for:" said it would.
         platforms = _prompt_platform_choice(
             platforms, "Check:" if args.check else "Install for:")
+    # --add-app names a card for each folder, or the run stops here.
+    app_cards = app_refusal(args, platforms)
 
     if args.dest is not None and not listing:
         _missing_dest(args.dest, interactive and not (args.check or args.dry_run or args.yes))
@@ -9922,6 +10334,7 @@ def _install(args: argparse.Namespace, real_stdout: TextIO) -> None:
             hints=bulk_lines,
             sources=_run_sources(bios_indexes, total_downloaded, total_errors),
         )
+        finish_app(args, platforms, app_cards, interactive and not total_declined)
 
 
 def _run_sources(bios_indexes: list[FolderIndex], installed: int, failed: int) -> str:
@@ -10340,6 +10753,14 @@ class TuiState:
         self.tail: list = []
         self.log: str = ""
         self.exit_code: int | None = None
+        # The RetroBIOS app on the card the BIOS folder is on: asked for
+        # (--add-app, the options), what putting it did (the app event),
+        # and the card, read once per folder.
+        self.add_app: bool = False
+        self.app: dict | None = None
+        self.app_running: bool = False
+        self.card_for: Path | None = None
+        self.card: CardApp | None = None
 
     @property
     def screen(self) -> str:
@@ -10503,6 +10924,9 @@ def tui_argv(state: TuiState, run: str, python: str, script: str) -> list[str]:
     if state.manifest_path is not None:
         argv.append(f"--manifest={state.manifest_path}")
     argv += [flag if value is None else f"{flag}={value}" for flag, value in tui_flags(state)]
+    if run == "install" and state.add_app and _tui_app_ready(state):
+        # Only the install writes: --check and --dry-run refuse it.
+        argv.append("--add-app")
     return argv + _TUI_MODES[run]
 
 
@@ -10513,8 +10937,40 @@ def tui_command(state: TuiState) -> str:
     hint.options = ([("--manifest", str(state.manifest_path))]
                     if state.manifest_given and state.manifest_path else [])
     hint.options += tui_flags(state)
+    if state.add_app and _tui_app_ready(state):
+        hint.options.append(("--add-app", None))
     return hint.command(state.platform, state.dest)
 
+
+def _tui_card(state: TuiState) -> CardApp | None:
+    """The card the BIOS folder is on, read once for each folder."""
+    if state.dest is None:
+        return None
+    if state.card_for != state.dest:
+        state.card_for, state.card = state.dest, card_app(state.dest)
+    return state.card
+
+
+def _tui_app_ready(state: TuiState) -> bool:
+    """Whether the RetroBIOS app can go on this card: its system has one,
+    and the run may use the network to fetch it."""
+    card = _tui_card(state)
+    return card is not None and card.place is not None and not LOCAL.offline
+
+
+def _tui_installed(state: TuiState) -> bool:
+    """An install that finished with every file in place."""
+    summary = state.summary or {}
+    return bool(summary) and not summary.get("interrupted") and not summary.get("failed") \
+        and state.code == 0
+
+
+def _app_offer(state: TuiState) -> bool:
+    """The result offers the app: the install finished, the card can take
+    it, and it was neither asked for nor put already."""
+    return (state.screen == "result" and state.app is None and not state.app_running
+            and _tui_installed(state) and _tui_app_ready(state))
+
 class TuiRow(NamedTuple):
     """One row a screen lists: what Enter does on it, and what it shows."""
 
@@ -10665,6 +11121,9 @@ def tui_rows(state: TuiState) -> list[TuiRow]:
                        TuiRow("quit", "Quit")]
     if screen == "quit":
         return [TuiRow("quit", "Quit"), TuiRow("stay", "Stay")]
+    if screen == "result" and _app_offer(state):
+        # Exit first: the app is put only when it is chosen.
+        return [TuiRow("exit", "Exit"), TuiRow("addapp", APP_OFFER)]
     return []
 
 
@@ -10794,6 +11253,8 @@ def _option_rows(state: TuiState) -> list[TuiRow]:
         TuiRow("folder", f"BIOS folder: {_short_path(state.dest, state.home)}", "--dest",
                style="path"),
         TuiRow("from", f"Copy from: {copied}", "--from", style="path"),
+        *([TuiRow("addapp", f"Put RetroBIOS on this card: {_yes(state.add_app)}",
+                  "--add-app")] if _tui_app_ready(state) else []),
         TuiRow("preview", "Preview the file list", "--dry-run"),
         TuiRow("command", "Show the command line"),
     ]
@@ -11158,6 +11619,11 @@ def _activate(state: TuiState, row: TuiRow) -> list[tuple]:
         if action == "quit":
             return tui_quit(state)
         return _back(state)
+    if screen == "result":
+        if action == "addapp":
+            state.add_app = state.app_running = True
+            return [("app", _tui_card(state))]
+        return tui_quit(state)
     return []
 
 
@@ -11185,6 +11651,8 @@ def _option(state: TuiState, action: str, step: int) -> list[tuple]:
         state.installed_only = step > 0 if step else not state.installed_only
     elif action == "jobs":
         state.jobs = max(1, min(32, state.jobs + (step or 1)))
+    elif action == "addapp":
+        state.add_app = step > 0 if step else not state.add_app
     elif action == "cores":
         # On the first core: the filter row under A opened a field a
         # controller cannot type into.
@@ -11388,6 +11856,9 @@ def tui_update(state: TuiState, key: TuiKey) -> list[tuple]:
     if state.help:
         state.help = False
         return []
+    if state.app_running:
+        # The app is being written to the card: it finishes first.
+        return []
     state.status = ""
     screen = state.screen
     if screen == "path":
@@ -11411,9 +11882,9 @@ def tui_update(state: TuiState, key: TuiKey) -> list[tuple]:
         return []
     if char == "q":
         return tui_quit(state)
-    if screen in _PAGERS:
-        return _pager_key(state, key)
     rows = tui_rows(state)
+    if screen in _PAGERS and not rows:
+        return _pager_key(state, key)
     if not rows:
         return _back(state) if key.name in ("esc", "backspace") else []
     focus = max(0, min(state.focus.get(screen, 0), len(rows) - 1))
@@ -11441,6 +11912,8 @@ def tui_update(state: TuiState, key: TuiKey) -> list[tuple]:
         rows = tui_rows(state)
         focus = next((i for i, item in enumerate(rows)
                       if item.action == row.action and item.value == row.value), focus)
+    elif name in ("esc", "backspace") and screen == "result":
+        return tui_quit(state)
     elif name in ("esc", "backspace"):
         return _back(state)
     elif (name == "tab" or char == "o") and screen in ("plan", "systems", "confirm"):
@@ -11467,7 +11940,7 @@ def tui_update(state: TuiState, key: TuiKey) -> list[tuple]:
         return _activate(state, rows[0 if char == "a" else 1])
     elif screen == "options" and name in ("left", "right"):
         return _option(state, row.action, 1 if name == "right" else -1) \
-            if row.action in ("game_data", "installed", "jobs") \
+            if row.action in ("game_data", "installed", "jobs", "addapp") \
             or (row.action == "from" and name == "left") else []
     elif char == " ":
         return _space(state, row)
@@ -11502,7 +11975,7 @@ def _miyoo_key(state: TuiState, key: TuiKey) -> TuiKey:
 
 # Rows Space leaves alone: it is X (tick) on PortMaster and Y on muxterm, a
 # key pressed for something else, and these end the run or write.
-_SPACE_INERT = ("install", "close", "quit")
+_SPACE_INERT = ("install", "close", "quit", "exit", "addapp")
 
 
 def _space(state: TuiState, row: TuiRow) -> list[tuple]:
@@ -11522,6 +11995,9 @@ def _space(state: TuiState, row: TuiRow) -> list[tuple]:
 
 def _take_event(state: TuiState, event: dict) -> None:
     kind = event.get("event")
+    if kind == "app" and state.run == "install":
+        state.app = event
+        return
     if kind == "checking" and state.run in ("check", "install"):
         state.reading = (event["files_done"], event["files_total"])
     elif kind == "found" and state.run == "check":
@@ -11578,6 +12054,12 @@ def tui_receive(state: TuiState, message: tuple) -> list[tuple]:
             return []
         state.manifest, state.manifest_for = manifest, plat
         return _start_run(state, "check")
+    if kind == "app":
+        # Put from the result screen, in this process.
+        state.app, state.app_running = message[1], False
+        if not state.app["ok"] and state.code == 0:
+            state.code = 1
+        return []
     if kind == "manifest_failed":
         _kind, plat, title, lines, code = message
         if plat != state.platform or state.screen != "checking":
@@ -11707,7 +12189,7 @@ _ROW_VERBS = {
     "preview": "Open", "folder": "Choose", "game_data": "Change", "installed": "Change",
     "jobs": "Change", "retry": "Try again", "back": "Back", "stay": "Stay",
     "fromcard": "Choose", "from": "Add a folder", "misplaced": "Show", "zip": "Copy from it",
-    "unreadable": "Show",
+    "unreadable": "Show", "exit": "Exit", "addapp": "Put it on the card",
 }
 
 
@@ -12463,12 +12945,27 @@ def tui_outcome(state: TuiState) -> tuple[str, list[str]]:
     for group in summary.get("left_out") or []:
         lines.append(f"Left out as {group['label']}: {_plural(group['files'], 'file')}.")
     lines += _unplaced_lines(summary, state)
+    lines += _tui_app_lines(state)
     lines += ["Same choice without questions:", f"  {tui_command(state)}"]
     if tui_keeps_log(state):
         lines.append(f"Details: {state.log}")
     return title, lines
 
 
+def _tui_app_lines(state: TuiState) -> list[str]:
+    """What became of the RetroBIOS app on the card, once the install finished."""
+    card = _tui_card(state)
+    if card is None:
+        return []
+    if state.app_running:
+        return ["Putting RetroBIOS on the card..."]
+    if state.app is not None:
+        return app_lines(card, state.app)
+    if card.place is None and card.system in NO_PYTHON_CARDS and _tui_installed(state):
+        return [NO_PYTHON_WORDS]
+    return []
+
+
 def tui_keeps_log(state: TuiState) -> bool:
     """Whether the run's log is kept: when a failure names it, and only then.
     57 folders of logs from stopped and finished runs were left in /tmp."""
@@ -12481,6 +12978,12 @@ def tui_keeps_log(state: TuiState) -> bool:
 
 def _view_result(state: TuiState, width: int, height: int) -> tuple:
     title, lines = tui_outcome(state)
+    rows = tui_rows(state)
+    if rows:
+        return (title, _compose(state, width, height, lines, rows),
+                ("A/Enter Choose", "B/Esc Exit"))
+    if state.app_running:
+        return (title, _pager(state, width, height, lines), ("Writing to the card...",))
     return (title, _pager(state, width, height, lines), ("A/Enter Exit", "Up/Down Scroll"))
 
 
@@ -12595,8 +13098,6 @@ def _help_lines(state: TuiState) -> list[tuple[str, str]]:
 
 def _primary(state: TuiState) -> str | None:
     """What A does on the row in focus, for the first entry of the bar."""
-    if state.screen in _PAGERS:
-        return None
     rows = tui_rows(state)
     if not rows:
         return None
@@ -12709,6 +13210,7 @@ def tui_start(
     state.no_game_data = bool(args.no_game_data)
     state.installed_only = bool(args.installed_cores)
     state.jobs = args.jobs
+    state.add_app = bool(getattr(args, "add_app", False))
     state.passthrough = _tui_passthrough(args)
     if args.manifest is not None:
         state.manifest_path = Path(args.manifest).absolute()
@@ -12853,6 +13355,11 @@ TUI_FETCH_TIMEOUT = 15
 TUI_OFFLINE_TITLE = "No internet: offline mode"
 
 
+def _tui_put_app(card: CardApp, inbox: queue.Queue) -> None:
+    """The app put on the card in this process, what it did sent back."""
+    inbox.put(("app", put_app(card)))
+
+
 def _tui_fetch(plat: str, inbox: queue.Queue, log: io.StringIO) -> None:
     """The file list, fetched once in this process, or what went wrong."""
     if LOCAL.manifest is not None or LOCAL.pack is not None:
@@ -13234,6 +13741,9 @@ def run_tui(args: argparse.Namespace) -> int:
             elif kind == "kill":
                 for run in current:
                     run.stop(0)
+            elif kind == "app":
+                threading.Thread(target=_tui_put_app, args=(effect[1], inbox),
+                                 daemon=True).start()
 
     def on_interrupt(_signum: int, _frame: object) -> None:
         flags["interrupt"] = True
diff --git a/install.sh b/install.sh
index 99e21a37b..a3a63ccaa 100755
--- a/install.sh
+++ b/install.sh
@@ -18,7 +18,7 @@ esac
 TEMP_INSTALLER=""
 TEMP_DIRECTORY=""
 DEFAULT_INSTALL_URL="https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-DEFAULT_INSTALL_SHA256="be9d37048e800072d6d5d2a40afaa5a46d5b062577f83c0fa633fc15159de66a"
+DEFAULT_INSTALL_SHA256="cec348d9aa6c9f940a2c9dc9bc6414a923acea8137e4a3624d4710c9d88c38ad"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {
diff --git a/install/launchers/index.json b/install/launchers/index.json
new file mode 100644
index 000000000..968e4f42f
--- /dev/null
+++ b/install/launchers/index.json
@@ -0,0 +1,211 @@
+{
+  "schema": 1,
+  "launchers": {
+    "knulli": {
+      "files": [
+        {
+          "dest": "roms/ports/RetroBIOS.sh",
+          "repo_path": "ports/batocera/RetroBIOS.sh",
+          "size": 1583,
+          "sha256": "7b30f2f5d1c677dc160290562c24779b8e6d79e6db735e343beed7f377f2bbcf",
+          "executable": false
+        },
+        {
+          "dest": "roms/ports/RetroBIOS.sh.keys",
+          "repo_path": "ports/batocera/RetroBIOS.sh.keys",
+          "size": 1157,
+          "sha256": "82014d185bbefb3358e580ae28b77479d0ba60ee9a4158c719e3e46071eea8a9",
+          "executable": false
+        },
+        {
+          "dest": "roms/ports/retrobios/README.md",
+          "repo_path": "ports/batocera/README.md",
+          "size": 1276,
+          "sha256": "b45f6268d6e3e4e0f57337877ff707670325a8b5f8fa77c56668fb30a474ce34",
+          "executable": false
+        },
+        {
+          "dest": "roms/ports/retrobios/install.py",
+          "repo_path": "install.py",
+          "size": 611006,
+          "sha256": "cec348d9aa6c9f940a2c9dc9bc6414a923acea8137e4a3624d4710c9d88c38ad",
+          "executable": false
+        },
+        {
+          "dest": "roms/ports/retrobios/licenses/LICENSE-retrobios.txt",
+          "repo_path": "LICENSE",
+          "size": 1586,
+          "sha256": "4caf349722255530d2aa5ccb98447a8af89454ed5a1f8499faa674de969878f0",
+          "executable": false
+        },
+        {
+          "dest": "roms/ports/retrobios/licenses/NOTICE-retrobios.txt",
+          "repo_path": "NOTICE",
+          "size": 1555,
+          "sha256": "5df6f621cba97bf5ffde17926373c6384a64041d8e820540226f5eb6d6758f19",
+          "executable": false
+        },
+        {
+          "dest": "roms/ports/retrobios/packs.txt",
+          "content": "batocera\tBatocera\nemudeck\tEmuDeck\nmisterfpga\tMiSTer_FPGA\nretroarch\tRetroArch\nretrobat\tRetroBat\nromm\tRomM\n",
+          "size": 105,
+          "sha256": "d9d48576bbfeb4821816a78310019eb4f9913ac45874c29a0118525f2481c8f9",
+          "executable": false
+        },
+        {
+          "dest": "roms/ports/retrobios/rbevents.py",
+          "repo_path": "ports/shared/rbevents.py",
+          "size": 7258,
+          "sha256": "e3c758e73bc2afb2d94714b2a3c9bd20fe0e75af32f2d9ea5634ba5b83a4205b",
+          "executable": false
+        },
+        {
+          "dest": "roms/ports/retrobios/tui.txt",
+          "repo_path": "ports/shared/tui.txt",
+          "size": 34998,
+          "sha256": "6e22292fc3f0688e0509bebd55f242fb3eecf9e149d5dc365ea75447e921bf78",
+          "executable": false
+        }
+      ]
+    },
+    "muos": {
+      "archive": {
+        "dest": "ARCHIVE/RetroBIOS.muxapp",
+        "size": 661660,
+        "sha256": "681ae3d8eb8572640b57dd4ca8699cb2cb8f011d1071ba5ef286c1b2eeb1877d"
+      },
+      "members": [
+        {
+          "name": "RetroBIOS/README.md",
+          "repo_path": "ports/muos/README.md",
+          "size": 1127,
+          "sha256": "c0cfafad5fae8e6764b263b14a06195b267f66c4fe042333941ae6bcc6dab265",
+          "executable": false
+        },
+        {
+          "name": "RetroBIOS/install.py",
+          "repo_path": "install.py",
+          "size": 611006,
+          "sha256": "cec348d9aa6c9f940a2c9dc9bc6414a923acea8137e4a3624d4710c9d88c38ad",
+          "executable": false
+        },
+        {
+          "name": "RetroBIOS/licenses/LICENSE-retrobios.txt",
+          "repo_path": "LICENSE",
+          "size": 1586,
+          "sha256": "4caf349722255530d2aa5ccb98447a8af89454ed5a1f8499faa674de969878f0",
+          "executable": false
+        },
+        {
+          "name": "RetroBIOS/licenses/NOTICE-retrobios.txt",
+          "repo_path": "NOTICE",
+          "size": 1555,
+          "sha256": "5df6f621cba97bf5ffde17926373c6384a64041d8e820540226f5eb6d6758f19",
+          "executable": false
+        },
+        {
+          "name": "RetroBIOS/mux_launch.sh",
+          "repo_path": "ports/muos/mux_launch.sh",
+          "size": 2216,
+          "sha256": "8566922b2ba50e49314f3dab9e3327ff736dd718bb307bb19b39e46e2e8c0f36",
+          "executable": true
+        },
+        {
+          "name": "RetroBIOS/packs.txt",
+          "content": "batocera\tBatocera\nemudeck\tEmuDeck\nmisterfpga\tMiSTer_FPGA\nretroarch\tRetroArch\nretrobat\tRetroBat\nromm\tRomM\n",
+          "size": 105,
+          "sha256": "d9d48576bbfeb4821816a78310019eb4f9913ac45874c29a0118525f2481c8f9",
+          "executable": false
+        },
+        {
+          "name": "RetroBIOS/rbevents.py",
+          "repo_path": "ports/shared/rbevents.py",
+          "size": 7258,
+          "sha256": "e3c758e73bc2afb2d94714b2a3c9bd20fe0e75af32f2d9ea5634ba5b83a4205b",
+          "executable": false
+        },
+        {
+          "name": "RetroBIOS/retrobios.gptk",
+          "repo_path": "ports/shared/retrobios.gptk",
+          "size": 659,
+          "sha256": "fdb30597ec757ff769add5052476ff51e3bc3910022a73ab2a91670a1b65c65a",
+          "executable": false
+        },
+        {
+          "name": "RetroBIOS/tui.txt",
+          "repo_path": "ports/shared/tui.txt",
+          "size": 34998,
+          "sha256": "6e22292fc3f0688e0509bebd55f242fb3eecf9e149d5dc365ea75447e921bf78",
+          "executable": false
+        }
+      ]
+    },
+    "rocknix": {
+      "files": [
+        {
+          "dest": ".config/modules/RetroBIOS.sh",
+          "repo_path": "ports/tools/RetroBIOS.sh",
+          "size": 4732,
+          "sha256": "556c83159111a2071097a38590e3335aea90f76201473e064ba8365882fb2a6f",
+          "executable": true
+        },
+        {
+          "dest": ".config/modules/retrobios/README.md",
+          "repo_path": "ports/tools/README.md",
+          "size": 949,
+          "sha256": "a5dfc71ff2a932a6c102558c0ac49790b112e96914bf29f396d3f90af75d0997",
+          "executable": false
+        },
+        {
+          "dest": ".config/modules/retrobios/install.py",
+          "repo_path": "install.py",
+          "size": 611006,
+          "sha256": "cec348d9aa6c9f940a2c9dc9bc6414a923acea8137e4a3624d4710c9d88c38ad",
+          "executable": false
+        },
+        {
+          "dest": ".config/modules/retrobios/licenses/LICENSE-retrobios.txt",
+          "repo_path": "LICENSE",
+          "size": 1586,
+          "sha256": "4caf349722255530d2aa5ccb98447a8af89454ed5a1f8499faa674de969878f0",
+          "executable": false
+        },
+        {
+          "dest": ".config/modules/retrobios/licenses/NOTICE-retrobios.txt",
+          "repo_path": "NOTICE",
+          "size": 1555,
+          "sha256": "5df6f621cba97bf5ffde17926373c6384a64041d8e820540226f5eb6d6758f19",
+          "executable": false
+        },
+        {
+          "dest": ".config/modules/retrobios/packs.txt",
+          "content": "batocera\tBatocera\nemudeck\tEmuDeck\nmisterfpga\tMiSTer_FPGA\nretroarch\tRetroArch\nretrobat\tRetroBat\nromm\tRomM\n",
+          "size": 105,
+          "sha256": "d9d48576bbfeb4821816a78310019eb4f9913ac45874c29a0118525f2481c8f9",
+          "executable": false
+        },
+        {
+          "dest": ".config/modules/retrobios/rbevents.py",
+          "repo_path": "ports/shared/rbevents.py",
+          "size": 7258,
+          "sha256": "e3c758e73bc2afb2d94714b2a3c9bd20fe0e75af32f2d9ea5634ba5b83a4205b",
+          "executable": false
+        },
+        {
+          "dest": ".config/modules/retrobios/retrobios.gptk",
+          "repo_path": "ports/shared/retrobios.gptk",
+          "size": 659,
+          "sha256": "fdb30597ec757ff769add5052476ff51e3bc3910022a73ab2a91670a1b65c65a",
+          "executable": false
+        },
+        {
+          "dest": ".config/modules/retrobios/tui.txt",
+          "repo_path": "ports/shared/tui.txt",
+          "size": 34998,
+          "sha256": "6e22292fc3f0688e0509bebd55f242fb3eecf9e149d5dc365ea75447e921bf78",
+          "executable": false
+        }
+      ]
+    }
+  }
+}
diff --git a/schemas/install-events.schema.json b/schemas/install-events.schema.json
index 3e437afc0..02bafac05 100644
--- a/schemas/install-events.schema.json
+++ b/schemas/install-events.schema.json
@@ -28,6 +28,7 @@
         "transfer",
         "downloaded",
         "summary",
+        "app",
         "end"
       ]
     }
@@ -87,6 +88,9 @@
     {
       "$ref": "#/$defs/summary"
     },
+    {
+      "$ref": "#/$defs/app"
+    },
     {
       "$ref": "#/$defs/end"
     }
@@ -740,6 +744,55 @@
         }
       }
     },
+    "app": {
+      "type": "object",
+      "additionalProperties": false,
+      "required": [
+        "event",
+        "system",
+        "folder",
+        "ok",
+        "reason",
+        "dests",
+        "written",
+        "kept"
+      ],
+      "properties": {
+        "event": {
+          "const": "app"
+        },
+        "system": {
+          "type": "string"
+        },
+        "folder": {
+          "type": "string"
+        },
+        "ok": {
+          "type": "boolean"
+        },
+        "reason": {
+          "type": "string"
+        },
+        "dests": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        },
+        "written": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        },
+        "kept": {
+          "type": "array",
+          "items": {
+            "type": "object"
+          }
+        }
+      }
+    },
     "end": {
       "type": "object",
       "additionalProperties": false,
diff --git a/scripts/generate_event_schema.py b/scripts/generate_event_schema.py
index e3579c4a6..7fb77bbd1 100644
--- a/scripts/generate_event_schema.py
+++ b/scripts/generate_event_schema.py
@@ -45,7 +45,7 @@ KEY_TYPES: dict[str, dict] = {
         "pending", "code",
     ), _COUNT),
     **dict.fromkeys(("truncated", "ok", "interrupted"), _FLAG),
-    **dict.fromkeys(("systems", "other_drives", "dests"), _NAMES),
+    **dict.fromkeys(("systems", "other_drives", "dests", "written"), _NAMES),
     **dict.fromkeys(("platforms", "failed", "skipped", "left_out", "kept"), _RECORDS),
 }
 
diff --git a/scripts/generate_launcher_index.py b/scripts/generate_launcher_index.py
new file mode 100644
index 000000000..7da8c7103
--- /dev/null
+++ b/scripts/generate_launcher_index.py
@@ -0,0 +1,132 @@
+#!/usr/bin/env python3
+"""Write install/launchers/index.json: the handheld launchers as files for a card.
+
+    python scripts/generate_launcher_index.py           rewrite the list
+    python scripts/generate_launcher_index.py --check   exit 1 when it is stale
+
+install.py --add-app reads this list from the ref its file lists come from,
+and puts on a handheld's card the launcher of its system, each file checked
+against the size and SHA-256 recorded here. The files are the members of the
+archives scripts/build_port.py builds, from the same sources: muOS gets its
+application archive, rebuilt by the installer from the members and checked
+against the hash recorded for it, the others the archive's files at their
+place on the card. Where each system's files go is install.py's APP_PLACES.
+"""
+
+from __future__ import annotations
+
+import argparse
+import hashlib
+import importlib.util
+import json
+import sys
+from pathlib import Path
+
+from build_port import (
+    BATOCERA_ZIP,
+    MUOS_APP,
+    REPO_ROOT,
+    TOOLS_ZIP,
+    _packs_table,
+    archive_members,
+    pinned_installer_sha256,
+)
+
+OUTPUT = REPO_ROOT / "install" / "launchers" / "index.json"
+
+_spec = importlib.util.spec_from_file_location("install", REPO_ROOT / "install.py")
+_install = importlib.util.module_from_spec(_spec)
+_spec.loader.exec_module(_install)
+
+# The archive whose members each system gets, by its key in APP_PLACES.
+LAUNCHER_ARCHIVES = {"muos": MUOS_APP, "knulli": BATOCERA_ZIP, "rocknix": TOOLS_ZIP}
+
+
+def _entry(field: str, name: str, source: Path | None, root: Path) -> dict:
+    """A member as the list records it: where it comes from, its size and
+    hash, and whether it is executable in the repository."""
+    if source is None:
+        data = _packs_table(root)
+        origin: dict = {"content": data.decode("utf-8")}
+        executable = False
+    else:
+        data = source.read_bytes()
+        origin = {"repo_path": source.relative_to(root).as_posix()}
+        executable = bool(source.stat().st_mode & 0o111)
+    return {field: name, **origin, "size": len(data),
+            "sha256": hashlib.sha256(data).hexdigest(), "executable": executable}
+
+
+def _member_bytes(entry: dict, root: Path) -> bytes:
+    if "content" in entry:
+        return entry["content"].encode("utf-8")
+    return (root / entry["repo_path"]).read_bytes()
+
+
+def build_index(root: Path = REPO_ROOT) -> dict:
+    """Every launcher a card can carry, from the archives' members."""
+    actual = hashlib.sha256((root / "install.py").read_bytes()).hexdigest()
+    if actual != pinned_installer_sha256(root):
+        raise ValueError("install.py is not the installer install.sh pins: re-pin the "
+                         "bootstraps before writing the launcher list")
+    places = {place.key: place for place in _install.APP_PLACES.values()}
+    if set(places) != set(LAUNCHER_ARCHIVES):
+        raise ValueError(f"APP_PLACES names {sorted(places)}, the archives "
+                         f"{sorted(LAUNCHER_ARCHIVES)}")
+    launchers: dict[str, dict] = {}
+    for key, archive in sorted(LAUNCHER_ARCHIVES.items()):
+        folder = places[key].folder
+        members = archive_members(archive, root)
+        if archive == MUOS_APP:
+            entries = [_entry("name", name, source, root) for name, source in members]
+            data = _install.app_archive([(entry, _member_bytes(entry, root))
+                                         for entry in entries])
+            launchers[key] = {
+                "archive": {"dest": f"{folder}/{archive}", "size": len(data),
+                            "sha256": hashlib.sha256(data).hexdigest()},
+                "members": entries,
+            }
+        else:
+            # Executable only where the menu starts the script as a program:
+            # a mode a FAT card cannot hold is refused by its driver.
+            files = [_entry("dest", f"{folder}/{name}", source, root)
+                     for name, source in members]
+            for entry in files:
+                entry["executable"] = entry["executable"] and places[key].executable
+            launchers[key] = {"files": files}
+    return {"schema": _install.APP_SCHEMA, "launchers": launchers}
+
+
+def render(index: dict) -> str:
+    return json.dumps(index, indent=2, ensure_ascii=False) + "\n"
+
+
+def main(argv: list[str] | None = None) -> int:
+    parser = argparse.ArgumentParser(allow_abbrev=False, description=__doc__,
+                                     formatter_class=argparse.RawDescriptionHelpFormatter)
+    parser.add_argument("--check", action="store_true",
+                        help="exit 1 when the list differs from the launchers, writing nothing")
+    parser.add_argument("--output", type=Path, default=OUTPUT, help=argparse.SUPPRESS)
+    args = parser.parse_args(argv)
+    try:
+        text = render(build_index())
+    except (OSError, ValueError) as exc:
+        print(f"Error: {exc}", file=sys.stderr)
+        return 1
+    current = args.output.read_text(encoding="utf-8") if args.output.is_file() else None
+    if current == text:
+        return 0
+    if args.check:
+        print(f"{args.output} differs from the launchers in ports/: run "
+              "python scripts/generate_launcher_index.py", file=sys.stderr)
+        return 1
+    args.output.parent.mkdir(parents=True, exist_ok=True)
+    args.output.write_text(text, encoding="utf-8")
+    print(f"Wrote {args.output}")
+    return 0
+
+
+if __name__ == "__main__":
+    from common import run_cli
+
+    run_cli(main)
diff --git a/tests/test_install_app.py b/tests/test_install_app.py
new file mode 100644
index 000000000..5814e7a41
--- /dev/null
+++ b/tests/test_install_app.py
@@ -0,0 +1,470 @@
+"""The RetroBIOS app put on a handheld's card from a computer (--add-app).
+
+Cards are folders holding the files their systems write, the repository a
+loopback copy of the launcher list and the files it names. What a console
+then does with the files (the Archive Manager, the Ports list, the Tools
+menu) is not exercised.
+"""
+
+from __future__ import annotations
+
+import hashlib
+import io
+import json
+import os
+import shutil
+import stat
+import subprocess
+import sys
+import tempfile
+import unittest
+import zipfile
+from pathlib import Path
+from unittest import mock
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+sys.path.insert(0, str(REPO_ROOT))
+sys.path.insert(0, str(REPO_ROOT / "tests"))
+sys.path.insert(0, str(REPO_ROOT / "scripts"))
+
+import install  # noqa: E402
+from test_install_selection import FakeRepository  # noqa: E402
+
+INDEX = REPO_ROOT / "install" / "launchers" / "index.json"
+
+
+def make_card(root: Path, system: str) -> Path:
+    """A card as each system leaves it, and the BIOS folder on it."""
+    bios = _card_files(root, system)
+    bios.mkdir(parents=True, exist_ok=True)
+    return bios
+
+
+def _card_files(root: Path, system: str) -> Path:
+    root.mkdir(parents=True, exist_ok=True)
+    if system == "muOS":
+        (root / "MUOS" / "bios").mkdir(parents=True)
+        return root / "MUOS" / "bios"
+    if system == "KNULLI":
+        (root / "system").mkdir()
+        (root / "system" / "batocera.conf").write_text("system.hostname=KNULLI\n")
+        return root / "bios"
+    if system == "ROCKNIX":
+        (root / ".config" / "system" / "configs").mkdir(parents=True)
+        (root / ".config" / "system" / "configs" / "system.cfg").write_text(
+            "root.password=rocknix\n")
+        return root / "roms" / "bios"
+    if system == "Onion":
+        (root / ".tmp_update" / "onionVersion").mkdir(parents=True)
+        (root / ".tmp_update" / "onionVersion" / "version.txt").write_text("4.3.1\n")
+        return root / "BIOS"
+    if system == "spruceOS":
+        (root / "spruce").mkdir()
+        return root / "BIOS"
+    if system == "MinUI":
+        (root / ".system").mkdir()
+        (root / ".system" / "version.txt").write_text("MinUI-20250101\n")
+        return root
+    raise ValueError(system)
+
+
+# The file list each card's system gets.
+CARD_PLATFORMS = {"muOS": "retroarch", "KNULLI": "knulli", "ROCKNIX": "rocknix",
+                  "Onion": "retroarch", "spruceOS": "retroarch", "MinUI": "minui"}
+
+
+class AppRepository(FakeRepository):
+    """The fake repository with the launcher list and every file it names,
+    and the BIOS lists of the systems whose cards are tried."""
+
+    def __enter__(self) -> AppRepository:
+        super().__enter__()
+        index = json.loads(INDEX.read_text(encoding="utf-8"))
+        (self.root / "install" / "launchers").mkdir()
+        (self.root / "install" / "launchers" / "index.json").write_text(json.dumps(index))
+        for launcher in index["launchers"].values():
+            for entry in launcher.get("files", launcher.get("members", [])):
+                if "repo_path" in entry:
+                    target = self.root / entry["repo_path"]
+                    target.parent.mkdir(parents=True, exist_ok=True)
+                    shutil.copyfile(REPO_ROOT / entry["repo_path"], target)
+        base = json.loads((self.root / "install" / "retroarch.json").read_text())
+        for plat in ("knulli", "rocknix", "minui"):
+            (self.root / "install" / f"{plat}.json").write_text(
+                json.dumps({**base, "platform": plat}))
+        return self
+
+    def card(self, system: str) -> tuple[Path, Path]:
+        root = self.root / "cards" / system
+        return root, make_card(root, system)
+
+    def tamper(self, repo_path: str) -> None:
+        """One byte changed, the size kept: only the hash tells."""
+        path = self.root / repo_path
+        data = bytearray(path.read_bytes())
+        data[-1] ^= 0x20
+        path.write_bytes(bytes(data))
+
+    def cli(self, *options: str, env: dict | None = None) -> subprocess.CompletedProcess:
+        return subprocess.run(
+            [sys.executable, str(REPO_ROOT / "install.py"), *options],
+            env={**self.env(), **(env or {})}, capture_output=True, text=True,
+            timeout=120, check=False, stdin=subprocess.DEVNULL)
+
+
+def _tempdir(test: unittest.TestCase) -> Path:
+    (REPO_ROOT / "tmp").mkdir(exist_ok=True)
+    path = Path(tempfile.mkdtemp(dir=REPO_ROOT / "tmp"))
+    test.addCleanup(shutil.rmtree, path, True)
+    return path
+
+
+class Placement(unittest.TestCase):
+    def test_each_card_and_where_its_app_goes(self):
+        root = _tempdir(self)
+        expected = {"muOS": "ARCHIVE", "KNULLI": "roms/ports", "ROCKNIX": ".config/modules"}
+        for system, folder in expected.items():
+            with self.subTest(system=system):
+                card = install.card_app(make_card(root / system, system))
+                self.assertIsNotNone(card)
+                self.assertEqual(card.system, system)
+                self.assertEqual(card.root, root / system)
+                self.assertEqual(card.place.folder, folder)
+                self.assertEqual(card.why, "")
+
+    def test_a_bios_folder_inside_the_card_finds_its_root(self):
+        root = _tempdir(self)
+        bios = make_card(root / "sd1", "muOS")
+        bios.mkdir(parents=True, exist_ok=True)
+        self.assertEqual(install.card_app(bios).root, root / "sd1")
+        # The card's root itself is not its BIOS folder.
+        self.assertIsNone(install.card_app(root / "sd1"))
+
+    def test_cards_without_a_launcher_say_why(self):
+        root = _tempdir(self)
+        for system, words in (("Onion", "has no Python"), ("MinUI", "has no Python"),
+                              ("spruceOS", "no RetroBIOS app for spruceOS")):
+            with self.subTest(system=system):
+                card = install.card_app(make_card(root / system, system))
+                self.assertIsNone(card.place)
+                self.assertIn(words, card.why)
+
+    def test_a_folder_on_no_card(self):
+        self.assertIsNone(install.card_app(_tempdir(self) / "bios"))
+
+    def test_the_table_names_systems_detection_names(self):
+        names = {rule.name for rule in install._card_rules()}
+        names |= {install.display_name(name) for name, _f, _p in install._CARD_RULES}
+        self.assertLessEqual(set(install.APP_PLACES), names)
+        self.assertLessEqual(install.NO_PYTHON_CARDS, names)
+        self.assertFalse(set(install.APP_PLACES) & install.NO_PYTHON_CARDS)
+
+    def test_the_list_follows_the_table(self):
+        index = json.loads(INDEX.read_text(encoding="utf-8"))
+        for place in install.APP_PLACES.values():
+            with self.subTest(key=place.key):
+                targets = install.app_targets(index, place)
+                for target in targets:
+                    self.assertTrue(target["dest"].startswith(place.folder + "/"))
+                    self.assertEqual(target.get("executable", False) and not place.executable,
+                                     False, target["dest"])
+
+
+class TheList(unittest.TestCase):
+    def setUp(self):
+        self.index = json.loads(INDEX.read_text(encoding="utf-8"))
+        self.place = install.APP_PLACES["KNULLI"]
+
+    def refused(self, change) -> str:
+        data = json.loads(json.dumps(self.index))
+        change(data["launchers"]["knulli"]["files"][0], data)
+        with self.assertRaises(ValueError) as caught:
+            install.app_targets(data, self.place)
+        return str(caught.exception)
+
+    def test_entries_are_held_to_their_folder(self):
+        self.assertIn("outside", self.refused(
+            lambda entry, _d: entry.update(dest="roms/RetroBIOS.sh")))
+        self.assertIn("unsafe", self.refused(
+            lambda entry, _d: entry.update(dest="roms/ports/../../bios/x")))
+        self.assertIn("unsafe", self.refused(
+            lambda entry, _d: entry.update(repo_path="/etc/passwd")))
+
+    def test_hash_size_and_source_are_checked(self):
+        self.assertIn("sha256", self.refused(lambda entry, _d: entry.update(sha256="ab")))
+        self.assertIn("size", self.refused(lambda entry, _d: entry.update(size=0)))
+        self.assertIn("repo_path or content", self.refused(
+            lambda entry, _d: entry.update(content="x")))
+        self.assertIn("schema", self.refused(lambda _e, data: data.update(schema=2)))
+        self.assertIn("no launcher", self.refused(
+            lambda _e, data: data["launchers"].pop("knulli")))
+
+    def test_the_archive_rebuilds_to_its_recorded_hash(self):
+        launcher = self.index["launchers"]["muos"]
+        members = [(entry, (REPO_ROOT / entry["repo_path"]).read_bytes()
+                    if "repo_path" in entry else entry["content"].encode())
+                   for entry in launcher["members"]]
+        data = install.app_archive(list(reversed(members)))
+        # Under every Python the installer runs on: CI runs this under 3.8 too.
+        self.assertEqual(hashlib.sha256(data).hexdigest(), launcher["archive"]["sha256"])
+        self.assertEqual(len(data), launcher["archive"]["size"])
+
+    @unittest.skipIf(sys.version_info < (3, 9), "the build scripts need Python 3.9")
+    def test_the_archive_holds_what_the_release_archive_holds(self):
+        launcher = self.index["launchers"]["muos"]
+        members = [(entry, (REPO_ROOT / entry["repo_path"]).read_bytes()
+                    if "repo_path" in entry else entry["content"].encode())
+                   for entry in launcher["members"]]
+        data = install.app_archive(members)
+        import build_port  # noqa: PLC0415
+        built = _tempdir(self) / build_port.MUOS_APP
+        build_port.build_archive(build_port.MUOS_APP, built)
+        with zipfile.ZipFile(built) as release, zipfile.ZipFile(io.BytesIO(data)) as ours:
+            self.assertEqual(release.namelist(), ours.namelist())
+            for name in release.namelist():
+                self.assertEqual(release.read(name), ours.read(name), name)
+                self.assertEqual(release.getinfo(name).external_attr,
+                                 ours.getinfo(name).external_attr, name)
+
+
+class PutTheApp(unittest.TestCase):
+    def setUp(self):
+        self.repo = AppRepository()
+        self.repo.__enter__()
+        self.addCleanup(self.repo.__exit__, None, None, None)
+        install.KEPT.reset()
+        patcher = mock.patch.multiple(
+            install, LAUNCHERS_URL=f"{self.repo.env()['RETROBIOS_BASE_URL']}"
+            "/install/launchers/index.json",
+            RAW_FILE_URL=f"{self.repo.env()['RETROBIOS_BASE_URL']}/{{path}}")
+        patcher.start()
+        self.addCleanup(patcher.stop)
+        self.index = json.loads(INDEX.read_text(encoding="utf-8"))
+        self.bios: dict[str, Path] = {}
+
+    def put(self, system: str) -> tuple[install.CardApp, dict]:
+        if system not in self.bios:
+            self.bios[system] = self.repo.card(system)[1]
+        card = install.card_app(self.bios[system])
+        return card, install.put_app(card)
+
+    def assertMatchesTheList(self, card: install.CardApp) -> None:
+        for target in install.app_targets(self.index, card.place):
+            path = card.root / target["dest"]
+            self.assertEqual(hashlib.sha256(path.read_bytes()).hexdigest(), target["sha256"])
+
+    def test_muos_gets_its_archive(self):
+        card, fields = self.put("muOS")
+        self.assertTrue(fields["ok"], fields)
+        self.assertEqual(fields["written"], ["ARCHIVE/RetroBIOS.muxapp"])
+        self.assertMatchesTheList(card)
+        with zipfile.ZipFile(card.root / "ARCHIVE" / "RetroBIOS.muxapp") as archive:
+            self.assertEqual(archive.read("RetroBIOS/install.py"),
+                             (REPO_ROOT / "install.py").read_bytes())
+            mode = archive.getinfo("RetroBIOS/mux_launch.sh").external_attr >> 16
+            self.assertEqual(mode & 0o777, 0o755)
+
+    def test_knulli_and_rocknix_get_the_files(self):
+        for system, script, executable in (("KNULLI", "roms/ports/RetroBIOS.sh", False),
+                                           ("ROCKNIX", ".config/modules/RetroBIOS.sh", True)):
+            with self.subTest(system=system):
+                card, fields = self.put(system)
+                self.assertTrue(fields["ok"], fields)
+                self.assertEqual(sorted(fields["written"]), sorted(fields["dests"]))
+                self.assertMatchesTheList(card)
+                mode = (card.root / script).stat().st_mode
+                self.assertEqual(bool(mode & stat.S_IXUSR), executable)
+
+    def test_a_second_run_writes_nothing(self):
+        card, first = self.put("KNULLI")
+        stamps = {path: path.stat().st_mtime_ns for path in card.root.rglob("*")}
+        _card, second = self.put("KNULLI")
+        self.assertTrue(second["ok"])
+        self.assertEqual(second["written"], [])
+        self.assertEqual(second["dests"], first["dests"])
+        self.assertEqual({path: path.stat().st_mtime_ns for path in card.root.rglob("*")},
+                         stamps)
+        self.assertIn("already on the KNULLI card", install.app_lines(card, second)[0])
+
+    def test_a_different_file_in_place_is_kept_aside(self):
+        root, bios = self.repo.card("KNULLI")
+        self.bios["KNULLI"] = bios
+        mine = root / "roms" / "ports" / "RetroBIOS.sh"
+        mine.parent.mkdir(parents=True)
+        mine.write_text("my own script\n")
+        card, fields = self.put("KNULLI")
+        self.assertTrue(fields["ok"], fields)
+        self.assertEqual(len(fields["kept"]), 1)
+        self.assertEqual(fields["kept"][0]["files"], 1)
+        kept = list(Path(fields["kept"][0]["folder"]).rglob("RetroBIOS.sh"))
+        self.assertEqual([path.read_text() for path in kept], ["my own script\n"])
+        self.assertMatchesTheList(card)
+        self.assertTrue(any("kept in" in line for line in install.app_lines(card, fields)))
+
+    def test_a_tampered_file_is_refused_and_nothing_written(self):
+        self.repo.tamper("ports/shared/tui.txt")
+        root, bios = self.repo.card("ROCKNIX")
+        self.bios["ROCKNIX"] = bios
+        before = sorted(root.rglob("*"))
+        card, fields = self.put("ROCKNIX")
+        self.assertFalse(fields["ok"])
+        self.assertIn("SHA-256 mismatch", fields["reason"])
+        self.assertEqual(fields["written"], [])
+        self.assertEqual(sorted(root.rglob("*")), before)
+        self.assertIn("could not be put", install.app_lines(card, fields)[0])
+
+    def test_a_tampered_member_never_reaches_the_archive(self):
+        self.repo.tamper("ports/muos/mux_launch.sh")
+        root, bios = self.repo.card("muOS")
+        self.bios["muOS"] = bios
+        _card, fields = self.put("muOS")
+        self.assertFalse(fields["ok"])
+        self.assertFalse((root / "ARCHIVE").exists())
+
+    def test_a_card_without_a_launcher_is_not_written(self):
+        root, bios = self.repo.card("Onion")
+        self.bios["Onion"] = bios
+        _card, fields = self.put("Onion")
+        self.assertFalse(fields["ok"])
+        self.assertIn("has no Python", fields["reason"])
+        self.assertEqual(sorted(p.name for p in root.iterdir()), [".tmp_update", "BIOS"])
+
+
+class TheQuestion(unittest.TestCase):
+    """Line mode at a terminal asks once, and only yes puts the app."""
+
+    def run_finish(self, answer: str, system: str = "muOS", **given) -> list:
+        root = _tempdir(self)
+        bios = make_card(root / "card", system)
+        args = mock.Mock(add_app=False, yes=False)
+        for key, value in given.items():
+            setattr(args, key, value)
+        put = mock.Mock(return_value={"system": system, "folder": str(root / "card"),
+                                      "ok": True, "reason": "", "dests": ["x"],
+                                      "written": ["x"], "kept": []})
+        out = io.StringIO()
+        with mock.patch.object(install, "_ask", return_value=answer) as ask, \
+                mock.patch.object(install, "put_app", put), \
+                mock.patch("sys.stdout", out):
+            install.finish_app(args, [("retroarch", bios)], [], interactive=True)
+        self.output = out.getvalue()
+        return [ask.call_args_list, put.call_args_list]
+
+    def test_yes_puts_it(self):
+        asked, put = self.run_finish("y")
+        self.assertEqual(len(asked), 1)
+        self.assertIn("[y/N]", asked[0][0][0])
+        self.assertEqual(len(put), 1)
+        self.assertIn("Archive Manager", self.output)
+
+    def test_enter_or_no_leaves_the_card_alone(self):
+        for answer in ("", "n", "no", "q"):
+            with self.subTest(answer=answer):
+                _asked, put = self.run_finish(answer)
+                self.assertEqual(put, [])
+
+    def test_yes_flag_asks_nothing(self):
+        asked, put = self.run_finish("y", yes=True)
+        self.assertEqual((asked, put), ([], []))
+
+    def test_a_console_without_python_says_so_once(self):
+        asked, put = self.run_finish("y", system="Onion")
+        self.assertEqual((asked, put), ([], []))
+        self.assertIn(install.NO_PYTHON_WORDS, self.output)
+
+
+class TheOption(unittest.TestCase):
+    """--add-app is applied or refused, never ignored."""
+
+    @classmethod
+    def setUpClass(cls):
+        cls.repo = AppRepository()
+        cls.repo.__enter__()
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.repo.__exit__(None, None, None)
+
+    def test_refused_where_it_cannot_apply(self):
+        root = _tempdir(self)
+        pack = root / "RetroArch_BIOS_Pack.zip"
+        zipfile.ZipFile(pack, "w").close()
+        for options, words in (
+            (["--check"], "--check and --dry-run do not"),
+            (["--dry-run"], "--check and --dry-run do not"),
+            (["--list-systems"], "a listing does not"),
+            (["--from-pack", str(pack)], "--from-pack makes no network request"),
+            (["--offline"], "which --offline does not"),
+            (["--restore", str(root)], "takes no --add-app"),
+        ):
+            with self.subTest(options=options):
+                where = [] if "--restore" in options else ["--platform", "retroarch",
+                                                            "--dest", str(root)]
+                proc = self.repo.cli(*where, "--add-app", *options)
+                self.assertEqual(proc.returncode, 2, proc.stderr)
+                self.assertIn("error:", proc.stderr)
+                self.assertIn(words, proc.stderr)
+
+    def test_refused_for_a_folder_on_no_card_or_no_launcher(self):
+        root = _tempdir(self)
+        for system, words in ((None, "is not on a card this installer recognises"),
+                              ("Onion", "Onion has no Python"),
+                              ("spruceOS", "no RetroBIOS app for spruceOS yet")):
+            with self.subTest(system=system):
+                bios = make_card(root / str(system), system) if system else root / "bios"
+                proc = self.repo.cli("--platform", "retroarch", "--dest", str(bios),
+                                     "--add-app", "--events")
+                self.assertEqual(proc.returncode, 2, proc.stderr)
+                self.assertIn(words, proc.stderr)
+                events = [json.loads(line) for line in proc.stdout.splitlines()]
+                app = [event for event in events if event["event"] == "app"]
+                self.assertEqual(len(app), 1)
+                self.assertFalse(app[0]["ok"])
+                self.assertIn(words, app[0]["reason"])
+                self.assertEqual(events[-1], {"event": "end", "code": 2})
+                self.assertFalse([e for e in events if e["event"] == "download"])
+
+    def test_applied_after_the_install_and_reported(self):
+        root = _tempdir(self)
+        for system in ("muOS", "KNULLI"):
+            with self.subTest(system=system):
+                bios = make_card(root / system, system)
+                plat = CARD_PLATFORMS[system]
+                command = ("--platform", plat, "--dest", str(root / system), "--add-app",
+                           "--events")
+                proc = self.repo.cli(*command)
+                self.assertEqual(proc.returncode, 0, proc.stderr)
+                events = [json.loads(line) for line in proc.stdout.splitlines()]
+                kinds = [event["event"] for event in events]
+                self.assertEqual(kinds[-3:], ["summary", "app", "end"])
+                app = events[-2]
+                self.assertTrue(app["ok"], app)
+                self.assertEqual(app["system"], system)
+                self.assertEqual(app["folder"], str(root / system))
+                self.assertEqual(sorted(app["written"]), sorted(app["dests"]))
+                self.assertEqual(list(app), ["event", *install.EVENT_KEYS["app"]])
+                self.assertEqual(len(list(bios.iterdir())), 5)
+                self.assertIn("RetroBIOS is on the", proc.stderr)
+                again = self.repo.cli(*command)
+                app = [json.loads(line) for line in again.stdout.splitlines()][-2]
+                self.assertEqual((again.returncode, app["ok"], app["written"]), (0, True, []))
+
+    def test_not_added_when_the_install_does_not_finish(self):
+        root = _tempdir(self)
+        make_card(root / "card", "muOS")
+        # A BIOS folder that is a file: every download fails.
+        (root / "card" / "MUOS" / "bios").rmdir()
+        (root / "card" / "MUOS" / "bios").write_text("in the way")
+        proc = self.repo.cli("--platform", "retroarch", "--dest", str(root / "card"),
+                             "--add-app", "--events")
+        self.assertNotEqual(proc.returncode, 0)
+        events = [json.loads(line) for line in proc.stdout.splitlines()]
+        app = [event for event in events if event["event"] == "app"]
+        self.assertEqual(len(app), 1, proc.stderr)
+        self.assertEqual((app[0]["ok"], app[0]["reason"]),
+                         (False, "the install did not finish"))
+        self.assertFalse((root / "card" / "ARCHIVE").exists())
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/test_install_tui.py b/tests/test_install_tui.py
index aa81f1b87..c34c290f0 100644
--- a/tests/test_install_tui.py
+++ b/tests/test_install_tui.py
@@ -79,7 +79,7 @@ def _args(**given) -> argparse.Namespace:
         cores_dir=None, system=None, core=None, region=None, no_game_data=False,
         list_systems=False, list_cores=False, romm_firmware=None, list_emulators=False,
         no_input=False, dry_run=False, yes=False, quiet=False, events=False,
-        restore=None, from_pack=None, manifest=None, tui=False, plain=False,
+        restore=None, from_pack=None, manifest=None, tui=False, plain=False, add_app=False,
     )
     values["from"] = None
     values.update(given)
@@ -3380,6 +3380,144 @@ class SaveDirectoryRepository(FakeRepository):
         return self
 
 
+def _app_card(test: unittest.TestCase, system: str) -> tuple[Path, Path]:
+    """A card of system in the repository's tmp/, its root and BIOS folder."""
+    from test_install_app import make_card  # noqa: PLC0415
+
+    (REPO_ROOT / "tmp").mkdir(exist_ok=True)
+    root = Path(tempfile.mkdtemp(dir=REPO_ROOT / "tmp"))
+    test.addCleanup(shutil.rmtree, root, True)
+    return root / "card", make_card(root / "card", system)
+
+
+def _installed_state(dest: Path, code: int = 0, failed: list | None = None) -> install.TuiState:
+    """The result screen of an install into dest."""
+    state = fresh_state()
+    state.platform, state.dest, state.manifest = "retroarch", dest, MANIFEST
+    state.stack, state.run, state.code = ["result"], "install", code
+    state.summary = {"event": "summary", "mode": "install", "installed": 5, "up_to_date": 0,
+                     "pending": 0, "failed": failed or [], "skipped": [], "left_out": [],
+                     "kept": [], "interrupted": False}
+    return state
+
+
+class AppOnTheCard(unittest.TestCase):
+    """The RetroBIOS app offered on the result screen and in the options."""
+
+    def setUp(self):
+        patcher = mock.patch.dict(os.environ)
+        patcher.start()
+        self.addCleanup(patcher.stop)
+        os.environ.pop(install.OFFLINE_VARIABLE, None)
+
+    def fields(self, card_root: Path, ok: bool = True) -> dict:
+        return {"event": "app", "system": "muOS", "folder": str(card_root), "ok": ok,
+                "reason": "" if ok else "it could not be downloaded: no connection",
+                "dests": ["ARCHIVE/RetroBIOS.muxapp"],
+                "written": ["ARCHIVE/RetroBIOS.muxapp"] if ok else [], "kept": []}
+
+    def test_the_result_offers_it_and_exit_stays_the_default(self):
+        root, bios = _app_card(self, "muOS")
+        state = _installed_state(bios)
+        rows = install.tui_rows(state)
+        self.assertEqual([row.action for row in rows], ["exit", "addapp"])
+        self.assertEqual(rows[1].label, install.APP_OFFER)
+        screen = "\n".join(install.tui_view(state, 80, 24))
+        self.assertIn(install.APP_OFFER, screen)
+        self.assertIn("A/Enter Exit", screen)
+        self.assertEqual(press(state, "enter"), [])
+        self.assertEqual(state.exit_code, 0)
+
+    def test_choosing_it_puts_it_then_says_what_it_did(self):
+        root, bios = _app_card(self, "muOS")
+        state = _installed_state(bios)
+        effects = press(state, "down", "enter")
+        self.assertEqual(effects, [("app", install.card_app(bios))])
+        self.assertTrue(state.app_running)
+        screen = "\n".join(install.tui_view(state, 80, 24))
+        self.assertIn("Putting RetroBIOS on the card...", screen)
+        # Nothing ends the screen while the card is written.
+        self.assertEqual(press(state, "enter", "esc"), [])
+        self.assertIsNone(state.exit_code)
+        install.tui_receive(state, ("app", self.fields(root)))
+        self.assertEqual(install.tui_rows(state), [])
+        screen = "\n".join(install.tui_view(state, 80, 24))
+        self.assertIn("RetroBIOS is on the muOS card: 1 file written", screen)
+        self.assertIn("Archive Manager", screen)
+        self.assertIn("--add-app", install.tui_command(state))
+        press(state, "enter")
+        self.assertEqual(state.exit_code, 0)
+
+    def test_a_failure_is_said_and_ends_on_1(self):
+        root, bios = _app_card(self, "KNULLI")
+        state = _installed_state(bios)
+        press(state, "down", "enter")
+        install.tui_receive(state, ("app", {**self.fields(root, ok=False), "system": "KNULLI"}))
+        _title, lines = install.tui_outcome(state)
+        self.assertTrue(any("could not be put on the KNULLI card" in line for line in lines))
+        press(state, "enter")
+        self.assertEqual(state.exit_code, 1)
+
+    def test_space_and_b_never_put_it(self):
+        _root, bios = _app_card(self, "muOS")
+        state = _installed_state(bios)
+        self.assertEqual(press(state, "down", " "), [])
+        self.assertFalse(state.app_running)
+        press(state, "esc")
+        self.assertEqual(state.exit_code, 0)
+
+    def test_no_offer_where_it_cannot_go(self):
+        _root, muos = _app_card(self, "muOS")
+        _root, onion = _app_card(self, "Onion")
+        cases = {
+            "failed install": _installed_state(muos, 1, [{"dest": "a", "reason": "x"}]),
+            "plain folder": _installed_state(SYSTEM_DIR),
+            "no launcher": _installed_state(onion),
+        }
+        offline = _installed_state(muos)
+        for name, state in cases.items():
+            with self.subTest(case=name):
+                self.assertEqual(install.tui_rows(state), [])
+        os.environ[install.OFFLINE_VARIABLE] = "1"
+        self.assertEqual(install.tui_rows(offline), [])
+        os.environ.pop(install.OFFLINE_VARIABLE)
+        _title, lines = install.tui_outcome(cases["no launcher"])
+        self.assertIn(install.NO_PYTHON_WORDS, lines)
+
+    def test_put_by_the_install_itself_no_second_offer(self):
+        root, bios = _app_card(self, "muOS")
+        state = _installed_state(bios)
+        install._take_event(state, self.fields(root))
+        self.assertEqual(install.tui_rows(state), [])
+        self.assertIn("RetroBIOS is on the muOS card", "\n".join(install.tui_outcome(state)[1]))
+
+    def test_the_options_row_sets_the_flag_of_the_install_only(self):
+        _root, bios = _app_card(self, "muOS")
+        state = _installed_state(bios)
+        state.stack = ["plan", "options"]
+        rows = install.tui_rows(state)
+        row = next(row for row in rows if row.action == "addapp")
+        self.assertEqual((row.label, row.right), ("Put RetroBIOS on this card: no", "--add-app"))
+        state.focus["options"] = rows.index(row)
+        press(state, "enter")
+        self.assertTrue(state.add_app)
+        self.assertIn("--add-app", install.tui_argv(state, "install", "py", "install.py"))
+        for run in ("check", "confirm", "preview"):
+            self.assertNotIn("--add-app", install.tui_argv(state, run, "py", "install.py"))
+        self.assertIn("--add-app", install.tui_command(state))
+        press(state, "left")
+        self.assertFalse(state.add_app)
+        plain = _installed_state(SYSTEM_DIR)
+        plain.stack = ["plan", "options"]
+        self.assertFalse(any(row.action == "addapp" for row in install.tui_rows(plain)))
+
+    def test_the_command_line_flag_ticks_the_row(self):
+        _root, bios = _app_card(self, "ROCKNIX")
+        state, _effects = install.tui_start(_args(add_app=True, platform="rocknix",
+                                                  dest=bios), "linux", detect=False)
+        self.assertTrue(state.add_app)
+
+
 @unittest.skipUnless(pyte and pty and hasattr(pty, "fork"),
                      "screen tests need pyte (pip install pyte==0.8.2) and a pty")
 class EndToEnd(unittest.TestCase):
@@ -3410,6 +3548,61 @@ class EndToEnd(unittest.TestCase):
         self.addCleanup(lambda: term.status is None and os.kill(term.pid, 9))
         return term
 
+
+    def card_repo(self, system: str) -> tuple[Path, Path]:
+        from test_install_app import AppRepository, make_card  # noqa: PLC0415
+
+        repo = self.repo(AppRepository)
+        root = repo.root / "card"
+        return root, make_card(root, system)
+
+    def assertAppOnCard(self, root: Path, system: str) -> None:
+        index = json.loads((REPO_ROOT / "install" / "launchers" / "index.json").read_text())
+        targets = install.app_targets(index, install.APP_PLACES[system])
+        for target in targets:
+            data = (root / target["dest"]).read_bytes()
+            self.assertEqual(hashlib.sha256(data).hexdigest(), target["sha256"],
+                             target["dest"])
+
+    def test_put_the_app_on_a_muos_card_from_the_result(self):
+        root, bios = self.card_repo("muOS")
+        term = self.start("--platform", "retroarch", "--dest", str(root))
+        term.wait("files to download")
+        term.send("\r")
+        screen = term.wait(install.APP_OFFER)
+        self.assertIn("> Exit", screen)
+        term.send(DOWN, "\r")
+        screen = term.wait("RetroBIOS is on the muOS card")
+        self.assertIn("Archive Manager", screen)
+        term.send("\r")
+        self.assertEqual(term.close(), 0)
+        self.assertAppOnCard(root, "muOS")
+        self.assertEqual(len(list(bios.iterdir())), 5)
+        self.assertIn("RetroBIOS is on the muOS card", term.after())
+
+    def test_put_the_app_on_a_knulli_card_from_the_options(self):
+        root, _bios = self.card_repo("KNULLI")
+        term = self.start("--platform", "knulli", "--dest", str(root))
+        term.wait("files to download")
+        term.send("o")
+        term.wait("Each row is an option")
+        for _step in range(20):
+            if "> Put RetroBIOS on this card: no" in term.settle():
+                break
+            term.send(DOWN)
+        term.send("\r")
+        term.wait("> Put RetroBIOS on this card: yes")
+        term.send("\x1b")
+        term.wait("files to download")
+        term.send("\r")
+        screen = term.wait("RetroBIOS is on the KNULLI card")
+        self.assertIn("start RetroBIOS from Ports", screen)
+        self.assertNotIn(install.APP_OFFER, screen)
+        term.send("\r")
+        self.assertEqual(term.close(), 0)
+        self.assertAppOnCard(root, "KNULLI")
+        self.assertIn("--add-app", term.after())
+
     def test_three_presses_install_everything(self):
         repo = self.repo()
         term = self.start()
diff --git a/tests/test_port.py b/tests/test_port.py
index 82f797441..269d4023e 100644
--- a/tests/test_port.py
+++ b/tests/test_port.py
@@ -111,6 +111,47 @@ class ThePortArchive(unittest.TestCase):
         self.assertIn(f'DEFAULT_INSTALL_SHA256="{bundled}"', install_sh)
 
 
+class LauncherIndex(unittest.TestCase):
+    """install/launchers/index.json, which --add-app reads, lists the members of
+    the archives built from the same tree, each with its size and hash."""
+
+    def test_the_committed_list_is_current(self):
+        import generate_launcher_index  # noqa: PLC0415
+
+        text = generate_launcher_index.render(generate_launcher_index.build_index())
+        self.assertEqual(
+            generate_launcher_index.OUTPUT.read_text(encoding="utf-8"), text,
+            "install/launchers/index.json is stale: run "
+            "python scripts/generate_launcher_index.py")
+
+    def test_every_member_of_the_archives_is_listed(self):
+        import generate_launcher_index  # noqa: PLC0415
+
+        index = json.loads(generate_launcher_index.OUTPUT.read_text(encoding="utf-8"))
+        places = {place.key: place for place in install.APP_PLACES.values()}
+        for key, archive in generate_launcher_index.LAUNCHER_ARCHIVES.items():
+            with self.subTest(key=key):
+                launcher = index["launchers"][key]
+                listed = launcher.get("members") or launcher["files"]
+                names = [entry.get("name") or entry["dest"] for entry in listed]
+                prefix = "" if "members" in launcher else places[key].folder + "/"
+                self.assertEqual(sorted(names), sorted(
+                    prefix + name for name, _path in build_port.archive_members(archive)))
+                for entry in listed:
+                    if "repo_path" in entry:
+                        data = (REPO_ROOT / entry["repo_path"]).read_bytes()
+                        self.assertEqual(hashlib.sha256(data).hexdigest(), entry["sha256"])
+
+    def test_the_list_refuses_an_installer_the_bootstraps_do_not_pin(self):
+        import generate_launcher_index  # noqa: PLC0415
+
+        root = _tempdir(self)
+        shutil.copyfile(REPO_ROOT / "install.py", root / "install.py")
+        (root / "install.sh").write_text('DEFAULT_INSTALL_SHA256="' + "0" * 64 + '"\n')
+        with self.assertRaises(ValueError):
+            generate_launcher_index.build_index(root)
+
+
 class EventRecords(unittest.TestCase):
     """rbevents turns --events into fields the FIFO carries intact."""