Add IR remote control (LIRC) with a number-key content mapping

Adds a TCP client for lircd's classic protocol: play/pause/next/prev/
volume/mute map to the same intents every other front-end already
emits, and number keys 0-9 play an assigned album/audiobook from the
start or a podcast show's newest episode, resolved fresh on every
press. The mapping is configured in config.yml and editable from the
frontend: a small "Taste zuweisen" button on the play screen (or the
A+digit keyboard shortcut) opens a 10-key picker to assign whatever is
currently playing.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

python-backend/config.yml.example

@@ -66,6 +66,18 @@ general:
     # Built frontend to serve at /. Omit to expose only the JSON API.
     static_dir: ../web/dist
 
+  # IR remote control, over lircd's TCP socket (see ansible/roles/pi_lirc for how
+  # lircd itself is set up on the Pi). Omit the whole section to run without a remote.
+  # Play/pause/stop/previous/forward/rewind/volume/mute map to normal music control;
+  # number keys 0-9 play whatever the "remote:" section below assigns them.
+  lirc:
+    host: "musicmouse-pi.local"
+    port: 2222                 # this deployment's lircd listens on 2222, not its own
+                                # default of 8765 - see the ansible role
+    remote_name: "Hauppauge"   # other remotes registered with the same lircd (an LED
+                                # remote, say) are ignored
+    reconnect_interval: 5.0
+
   # Home Assistant integration. Omit the whole section to run without MQTT.
   # The backend exposes three lights, a player sensor, a volume slider, transport
   # buttons, device triggers for every button/touch area, and a tag scanner.
@@ -124,3 +136,20 @@ figures:
     id: "04b2c3d4e5"
     colors: ["#3355ff", "#66aaff", "#001133", "#ffffff"]
     kind: book
+
+# Number keys 0-9 on the IR remote, mapped to what they play. Omit the whole section,
+# or any digit within it, for "unassigned" - a fresh install boots with none of this
+# and that is not an error. Editable from the web front-end, which writes back here.
+#
+#   target_kind: album   -> always starts from the first track (music, audiobooks).
+#                            target is an album id, as shown at GET /api/library.
+#   target_kind: series  -> always plays the newest episode of a podcast show, resolved
+#                            fresh on every press - never a fixed episode. target is the
+#                            show's folder name under Kinderpodcasts, e.g. "Wissen macht Ah".
+remote:
+  "1":
+    target_kind: album
+    target: "3f9a0c12ab44"
+  "2":
+    target_kind: series
+    target: "Wissen macht Ah"

python-backend/musicmouse/__main__.py

@@ -36,6 +36,7 @@ from musicmouse.library import MusicLibrary
 from musicmouse.library.analysis import build_analyzer
 from musicmouse.reactions import register_all
 from musicmouse.services.base import Service
+from musicmouse.services.lirc import LircService
 from musicmouse.services.mqtt import MqttService, build_entities
 from musicmouse.services.podcasts import PodcastFeedService
 from musicmouse.services.web import WebService
@@ -330,6 +331,12 @@ def _build_services(
     else:
         services.append(WebService(app, web_config, config_path))
 
+    lirc_config = app.config.general.lirc
+    if lirc_config is None:
+        _log.info("No lirc section in the config: the IR remote is off")
+    else:
+        services.append(LircService(app, lirc_config, clock=clock))
+
     # Unconditional: a show only starts downloading once someone drops a `feed.txt`
     # into its folder, so there is nothing to gate here with its own config section.
     web_service = next((s for s in services if isinstance(s, WebService)), None)

python-backend/musicmouse/app.py

@@ -31,6 +31,9 @@ class AppState:
     #: readable off the transport; a broker's is not, so it is remembered here.
     mqtt_connected: bool = False
 
+    #: Whether the lircd TCP link for the IR remote is currently reachable.
+    lirc_connected: bool = False
+
 
 @dataclass
 class App:

python-backend/musicmouse/config.py

@@ -33,18 +33,24 @@ __all__ = [
     "SIMULATE",
     "Config",
     "ConfigError",
+    "Digit",
     "FigureColors",
     "FigureConfig",
     "GeneralConfig",
     "HaConfig",
     "HaDeviceConfig",
     "LibraryConfig",
+    "LircConfig",
     "MqttConfig",
+    "RemoteSlotConfig",
     "WebConfig",
     "format_validation_error",
     "load_config",
 ]
 
+#: Number keys on the IR remote, as lircd's ``BTN_0``..``BTN_9`` map to them.
+type Digit = Literal["0", "1", "2", "3", "4", "5", "6", "7", "8", "9"]
+
 DEFAULT_AUDIO_EXTENSIONS = (".mp3", ".ogg", ".oga", ".opus", ".flac", ".wav", ".m4a", ".aac")
 
 #: Stand-in value for ``serial_port`` and ``alsa_device``. Running without the mouse or
@@ -133,6 +139,22 @@ class MqttConfig(_Strict):
     reconnect_interval: float = Field(default=10.0, gt=0)
 
 
+class LircConfig(_Strict):
+    """TCP client for lircd's classic network protocol - see ``ansible/roles/pi_lirc``.
+
+    Omit the whole section to run without an IR remote.
+    """
+
+    host: str
+    #: This deployment's lircd listens on 2222 (see the ansible role); lircd's own
+    #: default is 8765, so this is worth overriding rather than assuming.
+    port: int = Field(default=2222, ge=1, le=65535)
+    #: Only button events from this remote are acted on - other remotes registered
+    #: with the same lircd (an LED remote, say) are ignored.
+    remote_name: str = "Hauppauge"
+    reconnect_interval: float = Field(default=5.0, gt=0)
+
+
 class LibraryConfig(_Strict):
     """Where the music lives.
 
@@ -221,6 +243,7 @@ class GeneralConfig(_Strict):
     mqtt: MqttConfig | None = None
     web: WebConfig | None = None
     ha: HaConfig | None = None
+    lirc: LircConfig | None = None
 
     min_volume: int = Field(default=0, ge=0, le=200)
     max_volume: int = Field(default=100, ge=0, le=200)
@@ -262,9 +285,26 @@ class FigureConfig(_Strict):
     kind: Literal["music", "book"] = "music"
 
 
+class RemoteSlotConfig(_Strict):
+    """What a number key on the IR remote plays.
+
+    ``"album"``: ``target`` is an ``Album.id``, always started from track 0 - a music
+    album or an audiobook. ``"series"``: ``target`` is a podcast show name (an
+    ``Album.series``); resolved to that show's newest episode fresh on every press,
+    since a podcast show is not itself one playable thing in this library - each
+    episode is its own album.
+    """
+
+    target_kind: Literal["album", "series"]
+    target: str
+
+
 class Config(_Strict):
     general: GeneralConfig
     figures: dict[str, FigureConfig] = Field(min_length=1)
+    #: Number key (0-9) -> what it plays. Empty by default: a fresh install has no
+    #: assignments, and that is not an error.
+    remote: dict[Digit, RemoteSlotConfig] = Field(default_factory=dict)
 
     @model_validator(mode="after")
     def _check_unique_tag_ids(self) -> Self:

python-backend/musicmouse/events.py

@@ -35,8 +35,10 @@ __all__ = [
     "LedEffectRequested",
     "NextTrackRequested",
     "PauseRequested",
+    "PlayAlbumRequested",
     "PlayFigureRequested",
     "PlayRequested",
+    "PlaySeriesLatestRequested",
     "PlaybackChanged",
     "PlaylistFinished",
     "PrevTrackRequested",
@@ -51,7 +53,7 @@ __all__ = [
     "VolumeChanged",
 ]
 
-type EventSource = Literal["device", "player", "mqtt", "web", "simulator", "system"]
+type EventSource = Literal["device", "player", "mqtt", "web", "lirc", "simulator", "system"]
 
 
 @dataclass(frozen=True, slots=True, kw_only=True)
@@ -186,6 +188,17 @@ class PlayAlbumRequested(IntentEvent):
     track_index: int = 0
 
 
+@dataclass(frozen=True, slots=True, kw_only=True)
+class PlaySeriesLatestRequested(IntentEvent):
+    """Start the newest episode of a podcast show.
+
+    The IR remote's number-key mapping assigns a whole show rather than one fixed
+    episode, so this is resolved to an actual album fresh on every press.
+    """
+
+    series: str
+
+
 @dataclass(frozen=True, slots=True, kw_only=True)
 class SeekRequested(IntentEvent):
     #: Seconds from the start of the current track.
@@ -257,5 +270,5 @@ class LedEffectChanged(StateEvent):
 
 @dataclass(frozen=True, slots=True, kw_only=True)
 class ConnectionChanged(StateEvent):
-    target: Literal["firmware", "mqtt"]
+    target: Literal["firmware", "mqtt", "lirc"]
     connected: bool

python-backend/musicmouse/library/__init__.py

@@ -124,6 +124,26 @@ class MusicLibrary:
             if album.figure is not None
         }
 
+    def latest_episode(self, series: str) -> Album | None:
+        """The newest episode-unit album of a podcast show, by filename.
+
+        Episode files are named ``YYYYMMDD - Title``, so filename order is
+        chronological - the same fact ``Kinderpodcasts``' ``order="newest_first"``
+        already relies on at scan time. ``None`` if the show is unknown or empty.
+        """
+        candidates = [
+            album
+            for album in self.albums
+            if album.series == series
+            and (section := SECTIONS.get(album.section)) is not None
+            and section.album_unit == "episode"
+        ]
+        if not candidates:
+            return None
+        return max(
+            candidates, key=lambda album: album.tracks[0].path.name if album.tracks else ""
+        )
+
     def beats(self, identifier: str, index: int) -> BeatGrid | None:
         album = self.get(identifier)
         if album is None or not 0 <= index < len(album.tracks):

python-backend/musicmouse/reactions/playback.py

@@ -19,6 +19,7 @@ from musicmouse.events import (
     PlayFigureRequested,
     PlaylistFinished,
     PlayRequested,
+    PlaySeriesLatestRequested,
     PrevTrackRequested,
     RotaryTurned,
     SeekRequested,
@@ -26,6 +27,7 @@ from musicmouse.events import (
     VolumeChangeRequested,
 )
 from musicmouse.hardware import Button, ButtonAction, RotaryDirection
+from musicmouse.library.models import Album
 from musicmouse.reactions.registry import on
 
 _log = logging.getLogger(__name__)
@@ -74,6 +76,14 @@ def play_figure(event: PlayFigureRequested, app: App) -> None:
     app.player.play_from_start()
 
 
+def _start_album(app: App, album: Album, track_index: int) -> None:
+    # A figure album keeps the figure's own resume bookkeeping honest: it is the same
+    # Playlist object either way, because both come from the library index.
+    playlist = app.playlists.get(album.figure) if album.figure else album.to_playlist()
+    app.player.set_playlist(playlist or album.to_playlist())
+    app.player.play_track(track_index)
+
+
 @on(PlayAlbumRequested)
 def play_album(event: PlayAlbumRequested, app: App) -> None:
     """Play any album in the library. This is the web front-end's way in."""
@@ -81,12 +91,17 @@ def play_album(event: PlayAlbumRequested, app: App) -> None:
     if album is None:
         _log.warning("No album %r in the library", event.album_id)
         return
+    _start_album(app, album, event.track_index)
 
-    # A figure album keeps the figure's own resume bookkeeping honest: it is the same
+
-    # Playlist object either way, because both come from the library index.
+@on(PlaySeriesLatestRequested)
-    playlist = app.playlists.get(album.figure) if album.figure else album.to_playlist()
+def play_series_latest(event: PlaySeriesLatestRequested, app: App) -> None:
-    app.player.set_playlist(playlist or album.to_playlist())
+    """Play the newest episode of a podcast show - the IR remote's number-key way in."""
-    app.player.play_track(event.track_index)
+    album = app.library.latest_episode(event.series)
+    if album is None:
+        _log.warning("No episodes for series %r", event.series)
+        return
+    _start_album(app, album, 0)
 
 
 @on(PlaylistFinished)

python-backend/musicmouse/reactions/status.py

@@ -16,3 +16,5 @@ from musicmouse.reactions.registry import on
 def connection_changed(event: ConnectionChanged, app: App) -> None:
     if event.target == "mqtt":
         app.state.mqtt_connected = event.connected
+    elif event.target == "lirc":
+        app.state.lirc_connected = event.connected

python-backend/musicmouse/services/lirc/__init__.py

@@ -0,0 +1,6 @@
+"""IR remote control, via lircd's TCP socket."""
+
+from musicmouse.services.lirc.protocol import LircButtonEvent, parse_line
+from musicmouse.services.lirc.service import LircService
+
+__all__ = ["LircButtonEvent", "LircService", "parse_line"]

python-backend/musicmouse/services/lirc/protocol.py

@@ -0,0 +1,37 @@
+"""lircd's classic network protocol: one line per button press or repeat.
+
+A line looks like::
+
+    0000000000001781 00 BTN_1 Hauppauge
+
+that is ``<code> <repeat, hex> <button name> <remote name>``. ``repeat`` is ``00`` for
+the first press and increments while the button is held - lircd has no separate
+key-up event, just repeats stopping.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+__all__ = ["LircButtonEvent", "parse_line"]
+
+
+@dataclass(frozen=True, slots=True)
+class LircButtonEvent:
+    code: str
+    repeat: int
+    button: str
+    remote: str
+
+
+def parse_line(line: str) -> LircButtonEvent | None:
+    """One broadcast line, or ``None`` if it does not look like one."""
+    parts = line.strip().split()
+    if len(parts) != 4:
+        return None
+    code, repeat_hex, button, remote = parts
+    try:
+        repeat = int(repeat_hex, 16)
+    except ValueError:
+        return None
+    return LircButtonEvent(code=code, repeat=repeat, button=button, remote=remote)

python-backend/musicmouse/services/lirc/service.py

@@ -0,0 +1,140 @@
+"""The IR remote: a TCP client for lircd, translated into the same intents every other
+front-end emits.
+
+Connect, read lines until the link drops, wait, repeat - the same reconnect shape as
+:class:`~musicmouse.devices.serial_link.SerialLink`, over a plain socket instead of a
+serial port because lircd speaks its classic protocol on a bare TCP connection.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import logging
+from collections.abc import Callable
+
+from musicmouse.app import App
+from musicmouse.clock import Clock, RealClock
+from musicmouse.config import Digit, LircConfig
+from musicmouse.events import (
+    ConnectionChanged,
+    IntentEvent,
+    NextTrackRequested,
+    PauseRequested,
+    PlayAlbumRequested,
+    PlayRequested,
+    PlaySeriesLatestRequested,
+    PrevTrackRequested,
+    SetVolumeRequested,
+    VolumeChangeRequested,
+)
+from musicmouse.services.lirc.protocol import LircButtonEvent, parse_line
+
+_log = logging.getLogger(__name__)
+
+__all__ = ["LircService"]
+
+#: Acted on only at repeat 0 (the first press) - holding the button must not replay it.
+_TRANSPORT: dict[str, Callable[[], IntentEvent]] = {
+    "KEY_PLAY": lambda: PlayRequested(source="lirc"),
+    # No separate "stop" concept exists in this player; the remote's stop button just
+    # pauses, like its pause button.
+    "KEY_PAUSE": lambda: PauseRequested(source="lirc"),
+    "KEY_STOP": lambda: PauseRequested(source="lirc"),
+    "KEY_PREVIOUS": lambda: PrevTrackRequested(source="lirc"),
+    "KEY_REWIND": lambda: PrevTrackRequested(source="lirc"),
+    "KEY_FORWARD": lambda: NextTrackRequested(source="lirc"),
+}
+
+#: Acted on every repeat, for a continuous ramp while held - same feel as the rotary
+#: encoder (see ``reactions.playback.rotary_turned``).
+_VOLUME: dict[str, int] = {"KEY_VOLUMEUP": 1, "KEY_VOLUMEDOWN": -1}
+
+_DIGITS: dict[str, Digit] = {
+    "BTN_0": "0",
+    "BTN_1": "1",
+    "BTN_2": "2",
+    "BTN_3": "3",
+    "BTN_4": "4",
+    "BTN_5": "5",
+    "BTN_6": "6",
+    "BTN_7": "7",
+    "BTN_8": "8",
+    "BTN_9": "9",
+}
+
+
+class LircService:
+    name = "lirc"
+
+    def __init__(self, app: App, config: LircConfig, *, clock: Clock | None = None) -> None:
+        self.app = app
+        self.config = config
+        self._clock = clock or RealClock()
+        #: Volume to restore on the next mute press, remembered the way the frontend's
+        #: own mute toggle does (App.tsx) rather than via any new Player API.
+        self._pre_mute_volume: int | None = None
+
+    async def run(self) -> None:
+        """Connect, read lines until the link drops, wait, repeat. Runs until cancelled."""
+        while True:
+            try:
+                await self._session()
+            except OSError as exc:
+                _log.warning(
+                    "lircd link to %s:%d lost (%s); retrying in %gs",
+                    self.config.host,
+                    self.config.port,
+                    exc,
+                    self.config.reconnect_interval,
+                )
+            await self._clock.sleep(self.config.reconnect_interval)
+
+    async def _session(self) -> None:
+        reader, writer = await asyncio.open_connection(self.config.host, self.config.port)
+        _log.info("Connected to lircd at %s:%d", self.config.host, self.config.port)
+        self.app.bus.emit(ConnectionChanged(target="lirc", connected=True, source="lirc"))
+        try:
+            while True:
+                raw = await reader.readline()
+                if not raw:
+                    return
+                event = parse_line(raw.decode(errors="replace"))
+                if event is None or event.remote != self.config.remote_name:
+                    continue
+                self._handle(event)
+        finally:
+            writer.close()
+            self.app.bus.emit(ConnectionChanged(target="lirc", connected=False, source="lirc"))
+
+    def _handle(self, event: LircButtonEvent) -> None:
+        if event.button in _TRANSPORT:
+            if event.repeat == 0:
+                self.app.bus.emit(_TRANSPORT[event.button]())
+        elif event.button in _VOLUME:
+            step = self.app.config.general.volume_increment * _VOLUME[event.button]
+            self.app.bus.emit(VolumeChangeRequested(delta=step, source="lirc"))
+        elif event.button == "KEY_MUTE":
+            if event.repeat == 0:
+                self._toggle_mute()
+        elif (digit := _DIGITS.get(event.button)) is not None and event.repeat == 0:
+            self._play_digit(digit)
+
+    def _toggle_mute(self) -> None:
+        player = self.app.player
+        if player.volume > 0:
+            self._pre_mute_volume = player.volume
+            self.app.bus.emit(SetVolumeRequested(volume=0, source="lirc"))
+        else:
+            restore = self._pre_mute_volume or self.app.config.general.initial_volume
+            self.app.bus.emit(SetVolumeRequested(volume=restore, source="lirc"))
+
+    def _play_digit(self, digit: Digit) -> None:
+        slot = self.app.config.remote.get(digit)
+        if slot is None:
+            return
+        if slot.target_kind == "album":
+            self.app.bus.emit(
+                PlayAlbumRequested(album_id=slot.target, track_index=0, source="lirc")
+            )
+        else:
+            self.app.bus.emit(PlaySeriesLatestRequested(series=slot.target, source="lirc"))

python-backend/musicmouse/services/web/api.py

@@ -20,7 +20,7 @@ from fastapi import APIRouter, HTTPException, Response, WebSocket, WebSocketDisc
 from fastapi.responses import FileResponse
 
 from musicmouse.app import App
-from musicmouse.config import HaConfig
+from musicmouse.config import Digit, HaConfig, RemoteSlotConfig
 from musicmouse.events import (
     IntentEvent,
     NextTrackRequested,
@@ -32,13 +32,17 @@ from musicmouse.events import (
     SetVolumeRequested,
 )
 from musicmouse.services.web.hub import StateHub
+from musicmouse.services.web.remote_settings import read_mapping, write_mapping
 from musicmouse.services.web.schemas import (
     AlbumOut,
     HaConfigOut,
     HaDeviceOut,
     LibraryOut,
+    LircConfigOut,
     PlayerStateOut,
     PlayIn,
+    RemoteMappingIn,
+    RemoteMappingOut,
     SeekIn,
     SettingsIn,
     SettingsOut,
@@ -196,6 +200,38 @@ def build_router(
         await hub.broadcast_state()
         return read_settings(general)
 
+    # -------------------------------------------------------------- IR remote
+
+    @router.get("/lirc")
+    def get_lirc_config() -> LircConfigOut:
+        if app.config.general.lirc is None:
+            raise HTTPException(status_code=404, detail="lirc not configured")
+        return LircConfigOut(connected=app.state.lirc_connected)
+
+    @router.get("/remote/mapping")
+    def get_remote_mapping() -> RemoteMappingOut:
+        return read_mapping(app.config.remote, app.library)
+
+    @router.put("/remote/mapping")
+    async def put_remote_mapping(body: RemoteMappingIn) -> RemoteMappingOut:
+        resolved: dict[Digit, RemoteSlotConfig] = {}
+        for digit, slot in body.slots.items():
+            found = (
+                app.library.get(slot.target)
+                if slot.target_kind == "album"
+                else app.library.latest_episode(slot.target)
+            )
+            if found is None:
+                raise HTTPException(
+                    status_code=422,
+                    detail=f"key {digit}: no such {slot.target_kind} {slot.target!r}",
+                )
+            resolved[digit] = RemoteSlotConfig(target_kind=slot.target_kind, target=slot.target)
+
+        app.config.remote = resolved
+        await asyncio.to_thread(write_mapping, config_path, resolved)
+        return read_mapping(app.config.remote, app.library)
+
     # --------------------------------------------------------------- room control
     #
     # The browser never sees the Home Assistant token: it stays server-side, attached

python-backend/musicmouse/services/web/remote_settings.py

@@ -0,0 +1,48 @@
+"""Reading and writing the IR remote's number-key mapping.
+
+Same job as :mod:`musicmouse.services.web.settings`, for a dict-shaped config section
+rather than flat scalars: the ``remote:`` top-level key, not something under
+``general``.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from musicmouse.config import Digit, RemoteSlotConfig
+from musicmouse.library import MusicLibrary
+from musicmouse.services.web.schemas import RemoteMappingOut, RemoteSlotOut
+from musicmouse.services.web.settings import atomic_write, load_document
+
+__all__ = ["read_mapping", "write_mapping"]
+
+
+def _resolve(slot: RemoteSlotConfig, library: MusicLibrary) -> str | None:
+    if slot.target_kind == "album":
+        album = library.get(slot.target)
+    else:
+        album = library.latest_episode(slot.target)
+    return album.id if album else None
+
+
+def read_mapping(remote: dict[Digit, RemoteSlotConfig], library: MusicLibrary) -> RemoteMappingOut:
+    slots = [
+        RemoteSlotOut(
+            digit=digit,
+            target_kind=slot.target_kind,
+            target=slot.target,
+            resolved_album_id=_resolve(slot, library),
+        )
+        for digit, slot in sorted(remote.items())
+    ]
+    return RemoteMappingOut(slots=slots)
+
+
+def write_mapping(path: Path, mapping: dict[Digit, RemoteSlotConfig]) -> None:
+    document = load_document(path)
+    remote = {
+        digit: {"target_kind": slot.target_kind, "target": slot.target}
+        for digit, slot in mapping.items()
+    }
+    document["remote"] = remote
+    atomic_write(path, document)

python-backend/musicmouse/services/web/schemas.py

@@ -8,8 +8,11 @@ configured ceiling is a parent's business, not a child's, so it never crosses th
 
 from __future__ import annotations
 
+from typing import Literal
+
 from pydantic import BaseModel, Field
 
+from musicmouse.config import Digit
 from musicmouse.library import Album
 from musicmouse.library.analysis import TrackAnalysis
 
@@ -18,8 +21,13 @@ __all__ = [
     "HaConfigOut",
     "HaDeviceOut",
     "LibraryOut",
+    "LircConfigOut",
     "PlayIn",
     "PlayerStateOut",
+    "RemoteMappingIn",
+    "RemoteMappingOut",
+    "RemoteSlotIn",
+    "RemoteSlotOut",
     "SeekIn",
     "SettingsIn",
     "SettingsOut",
@@ -125,6 +133,7 @@ class TrackDetailOut(BaseModel):
 class ConnectionOut(BaseModel):
     firmware: bool
     mqtt: bool
+    lirc: bool
 
 
 class PlayerStateOut(BaseModel):
@@ -188,3 +197,36 @@ class HaConfigOut(BaseModel):
 
     devices: list[HaDeviceOut]
     scenes: list[HaDeviceOut]
+
+
+class LircConfigOut(BaseModel):
+    """Presence-only, like ``HaConfigOut``: there is nothing secret in a host/port,
+    but the frontend only needs to know whether the remote is set up and connected."""
+
+    connected: bool
+
+
+class RemoteSlotOut(BaseModel):
+    digit: str
+    target_kind: Literal["album", "series"]
+    target: str
+    #: The album this slot resolves to *right now* - the fixed album for "album" slots,
+    #: or today's newest episode for "series" slots. `None` when the target no longer
+    #: resolves (a moved/deleted album, an unknown show), so the frontend can show a
+    #: broken-assignment state instead of silently dropping it.
+    resolved_album_id: str | None
+
+
+class RemoteMappingOut(BaseModel):
+    slots: list[RemoteSlotOut]
+
+
+class RemoteSlotIn(BaseModel):
+    target_kind: Literal["album", "series"]
+    target: str
+
+
+class RemoteMappingIn(BaseModel):
+    """Full replacement, like ``SettingsIn``: a digit absent here becomes unassigned."""
+
+    slots: dict[Digit, RemoteSlotIn]

python-backend/musicmouse/services/web/settings.py

@@ -12,6 +12,7 @@ from __future__ import annotations
 import logging
 import os
 from pathlib import Path
+from typing import Any
 
 from ruamel.yaml import YAML
 
@@ -20,7 +21,14 @@ from musicmouse.services.web.schemas import SettingsIn, SettingsOut
 
 _log = logging.getLogger(__name__)
 
-__all__ = ["read_settings", "to_device_volume", "to_percent", "write_settings"]
+__all__ = [
+    "atomic_write",
+    "load_document",
+    "read_settings",
+    "to_device_volume",
+    "to_percent",
+    "write_settings",
+]
 
 
 def to_device_volume(percent: int, general: GeneralConfig) -> int:
@@ -47,30 +55,40 @@ def read_settings(general: GeneralConfig) -> SettingsOut:
     )
 
 
-def write_settings(path: Path, settings: SettingsIn) -> None:
+def _yaml() -> YAML:
-    """Patch the settings into ``config.yml`` in place.
-
-    Loaded round-trip rather than with the safe loader :mod:`musicmouse.config` uses,
-    so the file keeps its comments, ordering and formatting - a config that explains
-    itself is worth more than one this could rewrite from scratch. Written through a
-    sibling temp file so an interrupted save cannot truncate the real one.
-    """
     yaml = YAML(typ="rt")
     yaml.preserve_quotes = True
+    return yaml
 
+
+def load_document(path: Path) -> Any:
+    """The config file, round-trip parsed so it keeps its comments and formatting.
+
+    Shared by every writer that patches ``config.yml`` in place - a config that
+    explains itself is worth more than one a save could rewrite from scratch.
+    """
     with path.open(encoding="utf-8") as handle:
-        document = yaml.load(handle)
+        return _yaml().load(handle)
 
-    general = document["general"]
-    for key, value in settings.model_dump().items():
-        general[key] = value
 
+def atomic_write(path: Path, document: Any) -> None:
+    """Write a round-trip-loaded document back, through a sibling temp file so an
+    interrupted save cannot truncate the real one."""
     temp = path.with_name(f"{path.name}.tmp{os.getpid()}")
     try:
         with temp.open("w", encoding="utf-8") as handle:
-            yaml.dump(document, handle)
+            _yaml().dump(document, handle)
         temp.replace(path)
     except BaseException:
         temp.unlink(missing_ok=True)
         raise
     _log.info("Wrote settings to %s", path)
+
+
+def write_settings(path: Path, settings: SettingsIn) -> None:
+    """Patch the settings into ``config.yml`` in place."""
+    document = load_document(path)
+    general = document["general"]
+    for key, value in settings.model_dump().items():
+        general[key] = value
+    atomic_write(path, document)

python-backend/musicmouse/services/web/state.py

@@ -43,5 +43,6 @@ def snapshot(app: App) -> PlayerStateOut:
         connected=ConnectionOut(
             firmware=app.mouse.connected,
             mqtt=app.state.mqtt_connected,
+            lirc=app.state.lirc_connected,
         ),
     )

python-backend/tests/test_config.py

@@ -56,6 +56,46 @@ def test_ha_section_is_optional(config_dir: Path) -> None:
     assert load_config(write_config(config_dir, VALID_CONFIG)).general.ha is None
 
 
+def test_lirc_section_is_optional(config_dir: Path) -> None:
+    assert load_config(write_config(config_dir, VALID_CONFIG)).general.lirc is None
+
+    data = _config(lirc={"host": "musicmouse-pi.local"})
+    config = load_config(write_config(config_dir, data))
+    assert config.general.lirc is not None
+    assert config.general.lirc.port == 2222
+    assert config.general.lirc.remote_name == "Hauppauge"
+
+
+def test_remote_mapping_is_optional_and_empty_by_default(config_dir: Path) -> None:
+    assert load_config(write_config(config_dir, VALID_CONFIG)).remote == {}
+
+
+def test_remote_mapping_loads_album_and_series_slots(config_dir: Path) -> None:
+    data = copy.deepcopy(VALID_CONFIG)
+    data["remote"] = {
+        "1": {"target_kind": "album", "target": "abc123"},
+        "7": {"target_kind": "series", "target": "Wissen macht Ah"},
+    }
+    config = load_config(write_config(config_dir, data))
+    assert config.remote["1"].target_kind == "album"
+    assert config.remote["1"].target == "abc123"
+    assert config.remote["7"].target_kind == "series"
+
+
+def test_remote_mapping_rejects_an_out_of_range_digit(config_dir: Path) -> None:
+    data = copy.deepcopy(VALID_CONFIG)
+    data["remote"] = {"10": {"target_kind": "album", "target": "abc123"}}
+    message = _error(config_dir, data)
+    assert "remote" in message
+
+
+def test_remote_mapping_rejects_an_unknown_target_kind(config_dir: Path) -> None:
+    data = copy.deepcopy(VALID_CONFIG)
+    data["remote"] = {"1": {"target_kind": "playlist", "target": "abc123"}}
+    message = _error(config_dir, data)
+    assert "remote" in message
+
+
 def test_ha_device_and_scene_name_is_optional(config_dir: Path) -> None:
     data = _config(
         ha={

python-backend/tests/test_library.py

@@ -128,6 +128,28 @@ async def test_podcast_episodes_are_newest_first(config_dir: Path) -> None:
     assert [a.title for a in episodes] == ["Neu", "Alt"]
 
 
+async def test_latest_episode_finds_the_newest_episode_of_a_show(config_dir: Path) -> None:
+    library = await build(config_dir)
+    latest = library.latest_episode("Wissen macht Ah")
+    assert latest is not None
+    assert latest.title == "Neu"
+
+
+async def test_latest_episode_is_none_for_an_unknown_show(config_dir: Path) -> None:
+    library = await build(config_dir)
+    assert library.latest_episode("no such show") is None
+
+
+async def test_latest_episode_ignores_series_that_are_not_episode_unit(config_dir: Path) -> None:
+    """A music/book section groups by `series` too (an audiobook's character), but it
+    is a folder-unit shelf, not an episode-unit one - `latest_episode` must not treat
+    an audiobook as if it had "episodes"."""
+    library = await build(config_dir)
+    audiobook = album_named(library, "Conni in den Bergen")
+    assert audiobook.series is not None
+    assert library.latest_episode(audiobook.series) is None
+
+
 async def test_other_sections_keep_filename_order(config_dir: Path) -> None:
     album = album_named(await build(config_dir), "Kinderparty Lieder")
     assert [track.path.name for track in album.tracks] == [

python-backend/tests/test_lirc.py

@@ -0,0 +1,342 @@
+"""The IR remote: line parsing, and the service against a scripted lircd."""
+
+from __future__ import annotations
+
+import asyncio
+import contextlib
+from collections.abc import AsyncIterator
+from pathlib import Path
+
+import pytest
+
+from musicmouse.clock import FakeClock
+from musicmouse.config import LircConfig, RemoteSlotConfig, load_config
+from musicmouse.events import (
+    ConnectionChanged,
+    Event,
+    IntentEvent,
+    NextTrackRequested,
+    PauseRequested,
+    PlayAlbumRequested,
+    PlayRequested,
+    PlaySeriesLatestRequested,
+    PrevTrackRequested,
+    VolumeChangeRequested,
+)
+from musicmouse.services.lirc import LircService
+from musicmouse.services.lirc.protocol import LircButtonEvent, parse_line
+from musicmouse.simulator.harness import Simulation, build_simulation
+from tests.conftest import VALID_CONFIG, write_config
+
+# ---------------------------------------------------------------------- parse_line
+
+
+def test_a_valid_line_is_parsed() -> None:
+    assert parse_line("0000000000001781 00 BTN_1 Hauppauge") == LircButtonEvent(
+        code="0000000000001781", repeat=0, button="BTN_1", remote="Hauppauge"
+    )
+
+
+def test_a_repeat_field_is_hexadecimal() -> None:
+    event = parse_line("0000000000001781 0a BTN_1 Hauppauge")
+    assert event is not None
+    assert event.repeat == 10
+
+
+@pytest.mark.parametrize(
+    "line",
+    [
+        "",
+        "0000000000001781 00 BTN_1",  # missing remote
+        "0000000000001781 00 BTN_1 Hauppauge extra",  # extra token
+        "0000000000001781 zz BTN_1 Hauppauge",  # non-hex repeat
+    ],
+)
+def test_malformed_lines_are_rejected(line: str) -> None:
+    assert parse_line(line) is None
+
+
+def test_surrounding_whitespace_is_ignored() -> None:
+    assert parse_line("  0000000000001781 00 BTN_1 Hauppauge  \n") is not None
+
+
+# --------------------------------------------------------------------------- service
+
+
+class ScriptedLircd:
+    """A tiny stand-in for lircd: accepts one connection at a time and lets the test
+    push lines to whoever is currently connected."""
+
+    def __init__(self) -> None:
+        self._writer: asyncio.StreamWriter | None = None
+        self._connected = asyncio.Event()
+        self.connection_count = 0
+
+    async def _handle(self, _reader: asyncio.StreamReader, writer: asyncio.StreamWriter) -> None:
+        self._writer = writer
+        self.connection_count += 1
+        self._connected.set()
+        with contextlib.suppress(asyncio.CancelledError):
+            await asyncio.Event().wait()  # held open until the test drops it
+
+    async def wait_connected(self) -> None:
+        await self._connected.wait()
+
+    async def send(self, line: str) -> None:
+        await self._connected.wait()
+        assert self._writer is not None
+        self._writer.write(f"{line}\n".encode())
+        await self._writer.drain()
+        # Real socket I/O, not the fake clock: give the reader a moment to actually
+        # see the bytes before the caller checks what happened.
+        await asyncio.sleep(0.02)
+
+    def drop(self) -> None:
+        """Simulate the link dying: close the socket, and wait for a new connect."""
+        assert self._writer is not None
+        self._writer.close()
+        self._writer = None
+        self._connected = asyncio.Event()
+
+
+@pytest.fixture
+async def lircd() -> AsyncIterator[tuple[ScriptedLircd, asyncio.base_events.Server]]:
+    station = ScriptedLircd()
+    server = await asyncio.start_server(station._handle, "127.0.0.1", 0)
+    try:
+        yield station, server
+    finally:
+        server.close()
+        # The scripted connection handler holds its connection open forever (it does
+        # not know the test is done), so `wait_closed()` alone would hang here.
+        server.close_clients()
+        await server.wait_closed()
+
+
+@pytest.fixture
+async def sim(config_dir: Path) -> AsyncIterator[Simulation]:
+    config = load_config(write_config(config_dir, VALID_CONFIG))
+    # Real time for the socket I/O itself, virtual time for the reconnect sleep - tests
+    # drive that explicitly via `sim.clock.advance()` and drain the bus after.
+    simulation = await build_simulation(config, clock=FakeClock())
+    try:
+        yield simulation
+    finally:
+        await simulation.aclose()
+
+
+def _lirc_config(port: int, *, reconnect_interval: float = 5.0) -> LircConfig:
+    return LircConfig(host="127.0.0.1", port=port, reconnect_interval=reconnect_interval)
+
+
+async def _run_service(sim: Simulation, config: LircConfig) -> asyncio.Task[None]:
+    service = LircService(sim.app, config, clock=sim.clock)
+    return asyncio.create_task(service.run())
+
+
+async def test_transport_and_volume_buttons_emit_intents(
+    lircd: tuple[ScriptedLircd, asyncio.base_events.Server], sim: Simulation
+) -> None:
+    station, server = lircd
+    port = server.sockets[0].getsockname()[1]
+    seen: list[Event] = []
+    sim.bus.subscribe_all(seen.append)
+
+    task = await _run_service(sim, _lirc_config(port))
+    try:
+        await station.wait_connected()
+        await station.send("0 00 KEY_PLAY Hauppauge")
+        await station.send("0 00 KEY_PAUSE Hauppauge")
+        await station.send("0 00 KEY_STOP Hauppauge")
+        await station.send("0 00 KEY_PREVIOUS Hauppauge")
+        await station.send("0 00 KEY_FORWARD Hauppauge")
+        await station.send("0 00 KEY_VOLUMEUP Hauppauge")
+        await sim.bus.drain()
+    finally:
+        task.cancel()
+
+    kinds = [type(event) for event in seen if isinstance(event, IntentEvent)]
+    assert kinds == [
+        PlayRequested,
+        PauseRequested,
+        PauseRequested,
+        PrevTrackRequested,
+        NextTrackRequested,
+        VolumeChangeRequested,
+    ]
+
+
+async def test_events_from_another_remote_are_ignored(
+    lircd: tuple[ScriptedLircd, asyncio.base_events.Server], sim: Simulation
+) -> None:
+    station, server = lircd
+    port = server.sockets[0].getsockname()[1]
+    seen: list[Event] = []
+    sim.bus.subscribe_all(seen.append)
+
+    task = await _run_service(sim, _lirc_config(port))
+    try:
+        await station.wait_connected()
+        await station.send("0 00 KEY_PLAY small_led_remote")
+        await sim.bus.drain()
+    finally:
+        task.cancel()
+
+    assert not any(isinstance(event, IntentEvent) for event in seen)
+
+
+async def test_transport_buttons_only_act_on_the_first_press(
+    lircd: tuple[ScriptedLircd, asyncio.base_events.Server], sim: Simulation
+) -> None:
+    station, server = lircd
+    port = server.sockets[0].getsockname()[1]
+    seen: list[Event] = []
+    sim.bus.subscribe(NextTrackRequested, seen.append)
+
+    task = await _run_service(sim, _lirc_config(port))
+    try:
+        await station.wait_connected()
+        await station.send("0 00 KEY_FORWARD Hauppauge")
+        await station.send("0 01 KEY_FORWARD Hauppauge")
+        await station.send("0 02 KEY_FORWARD Hauppauge")
+        await sim.bus.drain()
+    finally:
+        task.cancel()
+
+    assert len(seen) == 1
+
+
+async def test_volume_buttons_act_on_every_repeat(
+    lircd: tuple[ScriptedLircd, asyncio.base_events.Server], sim: Simulation
+) -> None:
+    station, server = lircd
+    port = server.sockets[0].getsockname()[1]
+    seen: list[VolumeChangeRequested] = []
+    sim.bus.subscribe(VolumeChangeRequested, seen.append)
+
+    task = await _run_service(sim, _lirc_config(port))
+    try:
+        await station.wait_connected()
+        await station.send("0 00 KEY_VOLUMEDOWN Hauppauge")
+        await station.send("0 01 KEY_VOLUMEDOWN Hauppauge")
+        await station.send("0 02 KEY_VOLUMEDOWN Hauppauge")
+        await sim.bus.drain()
+    finally:
+        task.cancel()
+
+    assert len(seen) == 3
+    assert all(event.delta < 0 for event in seen)
+
+
+async def test_mute_toggles_and_restores(
+    lircd: tuple[ScriptedLircd, asyncio.base_events.Server], sim: Simulation
+) -> None:
+    station, server = lircd
+    port = server.sockets[0].getsockname()[1]
+
+    task = await _run_service(sim, _lirc_config(port))
+    try:
+        await station.wait_connected()
+        sim.player.set_volume(37)
+        await sim.bus.drain()
+
+        await station.send("0 00 KEY_MUTE Hauppauge")
+        await sim.bus.drain()
+        assert sim.player.volume == 0
+
+        await station.send("0 00 KEY_MUTE Hauppauge")
+        await sim.bus.drain()
+        assert sim.player.volume == 37
+    finally:
+        task.cancel()
+
+
+async def test_a_digit_with_no_assignment_does_nothing(
+    lircd: tuple[ScriptedLircd, asyncio.base_events.Server], sim: Simulation
+) -> None:
+    station, server = lircd
+    port = server.sockets[0].getsockname()[1]
+    seen: list[Event] = []
+    sim.bus.subscribe(PlayAlbumRequested, seen.append)
+    sim.bus.subscribe(PlaySeriesLatestRequested, seen.append)
+
+    task = await _run_service(sim, _lirc_config(port))
+    try:
+        await station.wait_connected()
+        await station.send("0 00 BTN_5 Hauppauge")
+        await sim.bus.drain()
+    finally:
+        task.cancel()
+
+    assert seen == []
+
+
+async def test_an_album_digit_plays_from_the_beginning(
+    lircd: tuple[ScriptedLircd, asyncio.base_events.Server], sim: Simulation
+) -> None:
+    station, server = lircd
+    port = server.sockets[0].getsockname()[1]
+    album = next(a for a in sim.app.library.albums if a.title == "Kinderparty Lieder")
+    sim.app.config.remote = {"3": RemoteSlotConfig(target_kind="album", target=album.id)}
+
+    task = await _run_service(sim, _lirc_config(port))
+    try:
+        await station.wait_connected()
+        await station.send("0 00 BTN_3 Hauppauge")
+        await sim.bus.drain()
+    finally:
+        task.cancel()
+
+    assert sim.player.playlist is not None
+    assert sim.player.playlist.album_id == album.id
+    assert sim.player.track_index == 0
+
+
+async def test_a_series_digit_plays_the_latest_episode(
+    lircd: tuple[ScriptedLircd, asyncio.base_events.Server], sim: Simulation
+) -> None:
+    station, server = lircd
+    port = server.sockets[0].getsockname()[1]
+    sim.app.config.remote = {"7": RemoteSlotConfig(target_kind="series", target="Wissen macht Ah")}
+
+    task = await _run_service(sim, _lirc_config(port))
+    try:
+        await station.wait_connected()
+        await station.send("0 00 BTN_7 Hauppauge")
+        await sim.bus.drain()
+    finally:
+        task.cancel()
+
+    assert sim.player.playlist is not None
+    played = sim.app.library.get(sim.player.playlist.album_id)
+    assert played is not None
+    assert played.title == "Neu"
+
+
+async def test_a_dropped_link_reconnects(
+    lircd: tuple[ScriptedLircd, asyncio.base_events.Server], sim: Simulation
+) -> None:
+    station, server = lircd
+    port = server.sockets[0].getsockname()[1]
+    seen: list[ConnectionChanged] = []
+    sim.bus.subscribe(ConnectionChanged, seen.append)
+
+    task = await _run_service(sim, _lirc_config(port, reconnect_interval=10.0))
+    try:
+        await station.wait_connected()
+        await sim.bus.drain()
+        assert station.connection_count == 1
+
+        station.drop()
+        await asyncio.sleep(0.05)  # let the client notice EOF
+        await sim.bus.drain()
+
+        assert isinstance(sim.clock, FakeClock)
+        await sim.clock.advance(10.0)
+        await station.wait_connected()
+        await sim.bus.drain()
+
+        assert station.connection_count == 2
+        assert [event.connected for event in seen] == [True, False, True]
+    finally:
+        task.cancel()

python-backend/tests/test_reactions.py

@@ -18,7 +18,7 @@ from musicmouse.effects import (
     EffectStaticConfig,
     EffectSwipeAndChange,
 )
-from musicmouse.events import Event, LedEffectChanged, VolumeChanged
+from musicmouse.events import Event, LedEffectChanged, PlaySeriesLatestRequested, VolumeChanged
 from musicmouse.hardware import MOUSE_LED_RANGES, LedZone, TouchButton
 from musicmouse.simulator.driver import SimulatorDriver
 from musicmouse.simulator.harness import Simulation, build_simulation
@@ -367,3 +367,24 @@ async def test_reconnecting_restores_the_leds(
     # equivalent-but-not-equal colours.
     assert restored.as_bytes() == before.as_bytes()
     assert sim.transport.brightness() == pytest.approx(0.5)
+
+
+# --------------------------------------------------------------------- podcast shows
+
+
+async def test_playing_a_series_starts_its_newest_episode(sim: Simulation) -> None:
+    await sim.bus.emit_and_wait(PlaySeriesLatestRequested(series="Wissen macht Ah", source="web"))
+
+    playlist = sim.player.playlist
+    assert playlist is not None
+    played = sim.app.library.get(playlist.album_id)
+    assert played is not None
+    assert played.title == "Neu"
+    assert sim.player.is_playing
+
+
+async def test_playing_an_unknown_series_does_nothing(sim: Simulation) -> None:
+    await sim.bus.emit_and_wait(PlaySeriesLatestRequested(series="no such show", source="web"))
+
+    assert sim.player.playlist is None
+    assert not sim.player.is_playing

python-backend/tests/test_remote_api.py

@@ -0,0 +1,155 @@
+"""The IR remote's number-key mapping, over the REST API."""
+
+from __future__ import annotations
+
+from collections.abc import AsyncIterator
+from pathlib import Path
+
+import httpx2
+import pytest
+
+from musicmouse.config import WebConfig, load_config
+from musicmouse.services.web.service import build_app
+from musicmouse.simulator.harness import Simulation, build_simulation
+from tests.conftest import VALID_CONFIG, write_config
+
+#: A config file with comments, to prove saving does not flatten them.
+COMMENTED = """\
+# The MusicMouse config.
+general:
+  library:
+    root: music
+    cache: .cache
+  serial_port: "/dev/ttyUSB0"
+  alsa_device: simulate
+  min_volume: 0
+  max_volume: 60
+  initial_volume: 40
+
+figures:
+  fuchs:
+    id: "04a1b2c3d4"
+    colors: ["#ff6600", "#ffcc00", "#331100", "wff"]
+  eule:
+    id: "04b2c3d4e5"
+    colors: ["#3355ff", "#66aaff", "#001133", "#ffffff"]
+"""
+
+
+@pytest.fixture
+async def sim(config_dir: Path) -> AsyncIterator[Simulation]:
+    config = load_config(write_config(config_dir, VALID_CONFIG))
+    simulation = await build_simulation(config)
+    try:
+        yield simulation
+    finally:
+        await simulation.aclose()
+
+
+@pytest.fixture
+async def client(sim: Simulation, config_dir: Path) -> AsyncIterator[httpx2.AsyncClient]:
+    path = config_dir / "config.yml"
+    path.write_text(COMMENTED, encoding="utf-8")
+    api, hub = build_app(sim.app, WebConfig(), path)
+    hub.start()
+    transport = httpx2.ASGITransport(app=api)
+    try:
+        async with httpx2.AsyncClient(transport=transport, base_url="http://mouse") as http:
+            yield http
+    finally:
+        hub.stop()
+        await api.state.ha_client.aclose()
+
+
+async def album_id(sim: Simulation, title: str) -> str:
+    return next(a.id for a in sim.app.library.albums if a.title == title)
+
+
+# ------------------------------------------------------------------------------ lirc
+
+
+async def test_lirc_is_a_404_when_unconfigured(client: httpx2.AsyncClient) -> None:
+    assert (await client.get("/api/lirc")).status_code == 404
+
+
+# --------------------------------------------------------------------------- reading
+
+
+async def test_the_mapping_is_empty_by_default(client: httpx2.AsyncClient) -> None:
+    body = (await client.get("/api/remote/mapping")).json()
+    assert body["slots"] == []
+
+
+# --------------------------------------------------------------------------- writing
+
+
+async def test_saving_an_album_slot_round_trips(
+    client: httpx2.AsyncClient, sim: Simulation, config_dir: Path
+) -> None:
+    target = await album_id(sim, "Kinderparty Lieder")
+    response = await client.put(
+        "/api/remote/mapping", json={"slots": {"3": {"target_kind": "album", "target": target}}}
+    )
+    assert response.status_code == 200
+    slots = response.json()["slots"]
+    assert slots == [
+        {"digit": "3", "target_kind": "album", "target": target, "resolved_album_id": target}
+    ]
+
+    text = (config_dir / "config.yml").read_text(encoding="utf-8")
+    assert "# The MusicMouse config." in text  # comments survive
+    reloaded = load_config(config_dir / "config.yml")
+    assert reloaded.remote["3"].target == target
+
+
+async def test_saving_a_series_slot_resolves_to_the_latest_episode(
+    client: httpx2.AsyncClient,
+) -> None:
+    response = await client.put(
+        "/api/remote/mapping",
+        json={"slots": {"7": {"target_kind": "series", "target": "Wissen macht Ah"}}},
+    )
+    assert response.status_code == 200
+    slot = response.json()["slots"][0]
+    assert slot["target_kind"] == "series"
+    assert slot["target"] == "Wissen macht Ah"
+    assert slot["resolved_album_id"] is not None
+
+
+async def test_saving_clears_digits_left_out(
+    client: httpx2.AsyncClient, sim: Simulation
+) -> None:
+    target = await album_id(sim, "Kinderparty Lieder")
+    await client.put(
+        "/api/remote/mapping", json={"slots": {"1": {"target_kind": "album", "target": target}}}
+    )
+    response = await client.put("/api/remote/mapping", json={"slots": {}})
+    assert response.json()["slots"] == []
+
+
+async def test_an_unresolvable_album_target_is_rejected(client: httpx2.AsyncClient) -> None:
+    response = await client.put(
+        "/api/remote/mapping",
+        json={"slots": {"1": {"target_kind": "album", "target": "no-such-album"}}},
+    )
+    assert response.status_code == 422
+    assert "1" in response.json()["detail"]
+
+
+async def test_an_unresolvable_series_target_is_rejected(client: httpx2.AsyncClient) -> None:
+    response = await client.put(
+        "/api/remote/mapping",
+        json={"slots": {"2": {"target_kind": "series", "target": "no such show"}}},
+    )
+    assert response.status_code == 422
+
+
+async def test_a_rejected_save_leaves_the_file_alone(
+    client: httpx2.AsyncClient, config_dir: Path
+) -> None:
+    before = (config_dir / "config.yml").read_text(encoding="utf-8")
+    await client.put(
+        "/api/remote/mapping",
+        json={"slots": {"1": {"target_kind": "album", "target": "no-such-album"}}},
+    )
+    assert (config_dir / "config.yml").read_text(encoding="utf-8") == before

python-backend/tests/test_web.py

@@ -150,7 +150,7 @@ async def test_state_starts_idle(client: Client) -> None:
     assert state["playing"] is False
     assert state["album_id"] is None
     assert state["active_figure"] is None
-    assert state["connected"] == {"firmware": True, "mqtt": False}
+    assert state["connected"] == {"firmware": True, "mqtt": False, "lirc": False}
 
 
 async def test_play_loads_the_album_and_starts_it(client: Client, sim: Simulation) -> None:

web/src/App.tsx

@@ -9,7 +9,7 @@
 import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 
 import { api } from "./api/client";
-import type { Album, HaConfig } from "./api/types";
+import type { Album, HaConfig, RemoteMapping, RemoteSlotInput } from "./api/types";
 import { AlbumModal } from "./components/AlbumModal";
 import { Ambience, type AmbienceDebugSnapshot } from "./components/Ambience";
 import { AmbienceDebugOverlay } from "./components/AmbienceDebugOverlay";
@@ -19,6 +19,7 @@ import { HelpOverlay } from "./components/HelpOverlay";
 import { ParentPanel } from "./components/ParentPanel";
 import { PlayerBar } from "./components/PlayerBar";
 import { PlayView } from "./components/PlayView";
+import { RemoteAssignPopup } from "./components/RemoteAssignPopup";
 import { RoomView } from "./components/RoomView";
 import { useGridColumns } from "./hooks/useGridColumns";
 import { useLibrary } from "./hooks/useLibrary";
@@ -28,9 +29,16 @@ import type { AmbienceTunables, ManualControl } from "./lib/ambienceTunables";
 import type { Action, UiState } from "./lib/keyboard";
 import { handleKey, initialUiState } from "./lib/keyboard";
 import { playPop } from "./lib/pop";
+import { targetForAlbum } from "./lib/remote";
 import type { Group, Results, SongHit } from "./lib/search";
 import { groupOf, results as computeResults } from "./lib/search";
 
+/** How long an armed "A" waits for the digit that completes the shortcut. */
+const ASSIGN_PENDING_TIMEOUT_MS = 4000;
+
+/** How long a "taste zugewiesen" confirmation stays on screen. */
+const ASSIGN_STATUS_TIMEOUT_MS = 2500;
+
 /** Volume when un-muting, matching the mockup. */
 const UNMUTE_PERCENT = 60;
 
@@ -63,6 +71,17 @@ export function App() {
     void api.haConfig().then(setHaConfig);
   }, []);
 
+  // The remote key -> album/show mapping. Always fetched (unlike haConfig, this
+  // endpoint has no "not configured" state - it's just empty on a fresh install) so
+  // the assign popup and the keyboard shortcut always have something to read/merge.
+  const [remoteMapping, setRemoteMapping] = useState<RemoteMapping | null>(null);
+  const [assignPopupOpen, setAssignPopupOpen] = useState(false);
+  const [assignStatus, setAssignStatus] = useState<string | null>(null);
+
+  useEffect(() => {
+    void api.remoteMapping().then(setRemoteMapping);
+  }, []);
+
   const state = connection.state;
 
   useEffect(() => {
@@ -117,6 +136,50 @@ export function App() {
   }, [connection, library.albums, play, results.albums, state]);
 
   /** The one place a keyboard action, a click or a tap all end up. */
+  // Read-modify-write the whole mapping, like ParentPanel does for settings: the
+  // backend takes a full replacement, not a per-slot patch.
+  const saveMapping = useCallback(
+    async (mutate: (slots: Record<string, RemoteSlotInput>) => void) => {
+      const slots: Record<string, RemoteSlotInput> = Object.fromEntries(
+        (remoteMapping?.slots ?? []).map((slot) => [
+          slot.digit,
+          { target_kind: slot.target_kind, target: slot.target },
+        ]),
+      );
+      mutate(slots);
+      const updated = await api.saveRemoteMapping(slots);
+      setRemoteMapping(updated);
+      return updated;
+    },
+    [remoteMapping],
+  );
+
+  const assignCurrentTo = useCallback(
+    async (digit: string) => {
+      if (!currentAlbum) return;
+      const target = targetForAlbum(currentAlbum);
+      try {
+        await saveMapping((slots) => {
+          slots[digit] = target;
+        });
+        setAssignStatus(`Taste ${digit}: „${currentAlbum.title}"`);
+      } catch {
+        setAssignStatus("Konnte nicht zugewiesen werden.");
+      }
+      setAssignPopupOpen(false);
+    },
+    [currentAlbum, saveMapping],
+  );
+
+  const clearSlot = useCallback(
+    (digit: string) => {
+      void saveMapping((slots) => {
+        delete slots[digit];
+      });
+    },
+    [saveMapping],
+  );
+
   const run = useCallback(
     (actions: Action[]) => {
       for (const action of actions) {
@@ -130,6 +193,9 @@ export function App() {
           case "toggle":
             toggle();
             break;
+          case "assign":
+            void assignCurrentTo(action.digit);
+            break;
           case "next":
             playPop(260);
             if (currentAlbum && groupOf(currentAlbum) === "podcasts") {
@@ -175,7 +241,7 @@ export function App() {
         }
       }
     },
-    [connection, currentAlbum, play, setVolume, state, toggle],
+    [assignCurrentTo, connection, currentAlbum, play, setVolume, state, toggle],
   );
 
   // Held in a ref so the listener is installed once rather than on every state change.
@@ -198,6 +264,22 @@ export function App() {
     return () => window.removeEventListener("keydown", onKeyDown);
   }, []);
 
+  // An abandoned "A" press disarms itself rather than leaving the app half-primed.
+  useEffect(() => {
+    if (!ui.assignPending) return;
+    const timer = setTimeout(
+      () => setUi((previous) => ({ ...previous, assignPending: false })),
+      ASSIGN_PENDING_TIMEOUT_MS,
+    );
+    return () => clearTimeout(timer);
+  }, [ui.assignPending]);
+
+  useEffect(() => {
+    if (!assignStatus) return;
+    const timer = setTimeout(() => setAssignStatus(null), ASSIGN_STATUS_TIMEOUT_MS);
+    return () => clearTimeout(timer);
+  }, [assignStatus]);
+
   const onEnterGroup = (group: Group, category: string | null) => {
     playPop(category ? 440 : 380);
     setUi((previous) => ({ ...previous, group, category, search: "", selIndex: 0 }));
@@ -302,9 +384,43 @@ export function App() {
           onMute={onMute}
           onBrowse={() => setUi((previous) => ({ ...previous, view: "browse" }))}
           onOpenAlbum={onOpenCurrentAlbum}
+          onOpenAssign={() => setAssignPopupOpen(true)}
+          assignPending={ui.assignPending}
         />
       )}
 
+      {assignPopupOpen && currentAlbum && (
+        <RemoteAssignPopup
+          album={currentAlbum}
+          mapping={remoteMapping}
+          albums={library.albums}
+          onAssign={(digit) => void assignCurrentTo(digit)}
+          onClear={clearSlot}
+          onClose={() => setAssignPopupOpen(false)}
+        />
+      )}
+
+      {assignStatus && (
+        <div
+          style={{
+            position: "absolute",
+            bottom: 24,
+            left: "50%",
+            transform: "translateX(-50%)",
+            zIndex: 7,
+            background: "var(--ink)",
+            color: "#fff",
+            fontSize: 14,
+            fontWeight: 800,
+            padding: "10px 20px",
+            borderRadius: 999,
+            boxShadow: "0 8px 24px oklch(15% 0.05 210 / .4)",
+          }}
+        >
+          {assignStatus}
+        </div>
+      )}
+
       {ui.view === "room" && haConfig && (
         <RoomView
           config={haConfig}

web/src/api/client.ts

@@ -1,6 +1,16 @@
 /** Every call the UI makes. Commands are fire-and-forget: the websocket reports back. */
 
-import type { Album, HaConfig, HaEntityState, PlayerState, Settings, TrackDetail } from "./types";
+import type {
+  Album,
+  HaConfig,
+  HaEntityState,
+  LircConfig,
+  PlayerState,
+  RemoteMapping,
+  RemoteSlotInput,
+  Settings,
+  TrackDetail,
+} from "./types";
 
 async function request<T>(path: string, init?: RequestInit): Promise<T> {
   const response = await fetch(`/api${path}`, {
@@ -29,6 +39,15 @@ async function fetchHaConfig(): Promise<HaConfig | null> {
   return (await response.json()) as HaConfig;
 }
 
+/** `null` means the IR remote isn't configured, not an error - same convention as
+ * `fetchHaConfig`. */
+async function fetchLircConfig(): Promise<LircConfig | null> {
+  const response = await fetch("/api/lirc");
+  if (response.status === 404) return null;
+  if (!response.ok) throw new Error(`GET /lirc failed: ${response.status}`);
+  return (await response.json()) as LircConfig;
+}
+
 /** `null` covers both "unknown to Home Assistant" and "Home Assistant unreachable
  * right now" (the backend answers the latter with a 502) - the room page treats a
  * device with no state the same way either way, rather than crashing on a poll. */
@@ -80,6 +99,11 @@ export const api = {
     post(`/ha/services/${domain}/${service}`, body),
 
   trackDetail: fetchTrackDetail,
+
+  lircConfig: fetchLircConfig,
+  remoteMapping: () => request<RemoteMapping>("/remote/mapping"),
+  saveRemoteMapping: (slots: Record<string, RemoteSlotInput>) =>
+    request<RemoteMapping>("/remote/mapping", { method: "PUT", body: JSON.stringify({ slots }) }),
 };
 
 export const coverUrl = (albumId: string) => `/api/albums/${albumId}/cover`;

web/src/api/types.ts

@@ -72,7 +72,7 @@ export interface PlayerState {
   /** Percent, 0..100. The device's configured range never leaves the backend. */
   volume: number;
   active_figure: string | null;
-  connected: { firmware: boolean; mqtt: boolean };
+  connected: { firmware: boolean; mqtt: boolean; lirc: boolean };
 }
 
 export interface Settings {
@@ -107,3 +107,31 @@ export interface HaEntityState {
   state: string;
   attributes: Record<string, unknown>;
 }
+
+export type RemoteTargetKind = "album" | "series";
+
+/** One number key (0-9) on the IR remote. "album": `target` is an `Album.id`, always
+ * started from track 0. "series": `target` is a podcast show name (`Album.series`),
+ * resolved to that show's newest episode fresh on every press. `resolved_album_id` is
+ * what it plays *right now* - `null` when the target no longer resolves (a moved
+ * album, an unknown show). Mirrors `RemoteSlotOut`. */
+export interface RemoteSlot {
+  digit: string;
+  target_kind: RemoteTargetKind;
+  target: string;
+  resolved_album_id: string | null;
+}
+
+export interface RemoteMapping {
+  slots: RemoteSlot[];
+}
+
+export interface RemoteSlotInput {
+  target_kind: RemoteTargetKind;
+  target: string;
+}
+
+/** Presence-only, like `HaConfig` - there is nothing secret in a host/port. */
+export interface LircConfig {
+  connected: boolean;
+}

web/src/components/HelpOverlay.tsx

@@ -10,6 +10,7 @@ const KEYS: Array<[caps: string[], label: string]> = [
   [["?"], "Einzelne Titel suchen"],
   [["F1"], "Diese Hilfe"],
   [["TAB"], "Musik / Hörbücher / Podcasts"],
+  [["A", "0-9"], "Aktuellen Titel einer Fernbedienungs-Taste zuweisen"],
   [["← ↑ ↓ →"], "Auswahl bewegen"],
   [["ENTER"], "Auswahl abspielen"],
   [["ESC"], "Schließen / Suche löschen"],

web/src/components/PlayView.tsx

@@ -21,6 +21,10 @@ interface Props {
   onMute: () => void;
   onBrowse: () => void;
   onOpenAlbum: () => void;
+  /** Assigning the current album/show to a remote key. `assignPending` is true right
+   * after "A" is pressed, waiting for the digit that completes the shortcut. */
+  onOpenAssign: () => void;
+  assignPending: boolean;
 }
 
 export function PlayView({
@@ -34,6 +38,8 @@ export function PlayView({
   onMute,
   onBrowse,
   onOpenAlbum,
+  onOpenAssign,
+  assignPending,
 }: Props) {
   const position = usePlaybackClock(state.position, state.playing);
   const book = album ? isBook(album) : false;
@@ -245,6 +251,32 @@ export function PlayView({
           </span>
           Zurück zur Suche
         </button>
+
+        {album && (
+          <button
+            onClick={onOpenAssign}
+            title="Einer Fernbedienungs-Taste zuweisen (oder: A und dann eine Zahl)"
+            style={{
+              position: "absolute",
+              top: 28,
+              right: 84,
+              border: "none",
+              cursor: "pointer",
+              background: assignPending ? "var(--accent)" : "oklch(97% 0.01 210 / .95)",
+              borderRadius: 999,
+              padding: "11px 20px",
+              fontSize: 14,
+              fontWeight: 800,
+              color: assignPending ? "#fff" : "var(--ink)",
+              display: "flex",
+              alignItems: "center",
+              gap: 8,
+              boxShadow: "0 8px 24px oklch(15% 0.05 210 / .4)",
+            }}
+          >
+            🎛️ {assignPending ? "Zahl drücken …" : "Taste zuweisen"}
+          </button>
+        )}
       </div>
     </div>
   );

web/src/components/RemoteAssignPopup.tsx

@@ -0,0 +1,141 @@
+/** "Which remote key?" - a simple 0-9 grid for assigning the currently playing album
+ * or podcast show to a number key on the IR remote. Same job as pressing "A" then a
+ * digit; this is the tap-only way in, for a viewer with no keyboard. */
+
+import type { Album, RemoteMapping } from "../api/types";
+import { remoteSlotView } from "../lib/remote";
+import { Cover } from "./Cover";
+
+const DIGITS = ["1", "2", "3", "4", "5", "6", "7", "8", "9", "0"];
+
+interface Props {
+  album: Album;
+  mapping: RemoteMapping | null;
+  albums: Album[];
+  onAssign: (digit: string) => void;
+  onClear: (digit: string) => void;
+  onClose: () => void;
+}
+
+export function RemoteAssignPopup({ album, mapping, albums, onAssign, onClear, onClose }: Props) {
+  const byDigit = new Map(mapping?.slots.map((slot) => [slot.digit, slot]));
+
+  return (
+    <div className="overlay" style={{ zIndex: 6 }} onClick={onClose}>
+      <div
+        className="sheet"
+        style={{ padding: "26px 30px", width: 420 }}
+        onClick={(event) => event.stopPropagation()}
+      >
+        <div style={{ fontSize: 17, fontWeight: 800, color: "var(--ink)", marginBottom: 4 }}>
+          🎛️ Taste zuweisen
+        </div>
+        <div
+          style={{
+            fontSize: 13,
+            fontWeight: 700,
+            color: "oklch(45% 0.03 210)",
+            marginBottom: 16,
+          }}
+        >
+          „{album.title}" antippen, welche Taste?
+        </div>
+
+        <div
+          style={{
+            display: "grid",
+            gridTemplateColumns: "repeat(5, 1fr)",
+            gap: 10,
+          }}
+        >
+          {DIGITS.map((digit) => {
+            const view = remoteSlotView(byDigit.get(digit), albums);
+            return (
+              <div key={digit} style={{ position: "relative" }}>
+                <button
+                  onClick={() => onAssign(digit)}
+                  title={
+                    view.state === "ok"
+                      ? `Taste ${digit}: ${view.album.title} → überschreiben`
+                      : `Taste ${digit} zuweisen`
+                  }
+                  style={{
+                    width: "100%",
+                    aspectRatio: 1,
+                    border: "none",
+                    borderRadius: 14,
+                    cursor: "pointer",
+                    padding: 6,
+                    display: "flex",
+                    flexDirection: "column",
+                    alignItems: "center",
+                    justifyContent: "center",
+                    gap: 4,
+                    background: view.state === "ok" ? "oklch(90% 0.04 210)" : "oklch(94% 0.01 210)",
+                    overflow: "hidden",
+                  }}
+                >
+                  {view.state === "ok" ? (
+                    <Cover album={view.album} size={40} radius="6px" />
+                  ) : (
+                    <span
+                      style={{
+                        fontSize: 20,
+                        fontWeight: 900,
+                        color:
+                          view.state === "missing" ? "oklch(55% 0.15 30)" : "oklch(60% 0.02 210)",
+                      }}
+                    >
+                      {view.state === "missing" ? "⚠️" : "+"}
+                    </span>
+                  )}
+                  <span style={{ fontSize: 13, fontWeight: 900, color: "var(--ink)" }}>
+                    {digit}
+                  </span>
+                </button>
+                {view.state !== "empty" && (
+                  <button
+                    onClick={(event) => {
+                      event.stopPropagation();
+                      onClear(digit);
+                    }}
+                    aria-label={`Taste ${digit} freigeben`}
+                    style={{
+                      position: "absolute",
+                      top: -6,
+                      right: -6,
+                      width: 22,
+                      height: 22,
+                      borderRadius: 999,
+                      border: "none",
+                      cursor: "pointer",
+                      background: "var(--ink)",
+                      color: "#fff",
+                      fontSize: 12,
+                      fontWeight: 900,
+                      lineHeight: 1,
+                    }}
+                  >
+                    ×
+                  </button>
+                )}
+              </div>
+            );
+          })}
+        </div>
+
+        <div
+          style={{
+            marginTop: 16,
+            fontSize: 12,
+            fontWeight: 600,
+            color: "oklch(50% 0.03 210 / .8)",
+            textAlign: "center",
+          }}
+        >
+          Tippe daneben, um zu schließen
+        </div>
+      </div>
+    </div>
+  );
+}

web/src/lib/__tests__/keyboard.test.ts

@@ -231,6 +231,43 @@ describe("keyboard", () => {
   });
 });
 
+describe("remote key assignment", () => {
+  const playing: UiState = { ...initialUiState, view: "play" };
+
+  it("A arms assignment while something is playing", () => {
+    expect(press("a", playing)).toEqual([{ type: "ui", patch: { assignPending: true } }]);
+    expect(press("A", playing)).toEqual([{ type: "ui", patch: { assignPending: true } }]);
+  });
+
+  it("a plain a still types into search everywhere else", () => {
+    expect(press("a", initialUiState)).toEqual([
+      { type: "ui", patch: { search: "a", view: "browse", selIndex: 0 } },
+    ]);
+    expect(
+      press("a", { ...initialUiState, view: "play", openAlbumId: "b" }),
+    ).toEqual([{ type: "ui", patch: { search: "a", view: "browse", selIndex: 0 } }]);
+  });
+
+  it("a following digit assigns and disarms", () => {
+    const armed: UiState = { ...playing, assignPending: true };
+    expect(press("5", armed)).toEqual([
+      { type: "assign", digit: "5" },
+      { type: "ui", patch: { assignPending: false } },
+    ]);
+  });
+
+  it("a digit does the normal thing when nothing is armed", () => {
+    expect(press("5", initialUiState)).toEqual([
+      { type: "ui", patch: { search: "5", view: "browse", selIndex: 0 } },
+    ]);
+  });
+
+  it("ESC disarms before doing anything else", () => {
+    const armed: UiState = { ...playing, assignPending: true };
+    expect(press("Escape", armed)).toEqual([{ type: "ui", patch: { assignPending: false } }]);
+  });
+});
+
 describe("selectionAt", () => {
   it("walks songs, then categories, then albums in one flat index space", () => {
     const ui: UiState = { ...initialUiState, mode: "tracks", search: "zweites" };

web/src/lib/__tests__/remote.test.ts

@@ -0,0 +1,86 @@
+import { describe, expect, it } from "vitest";
+
+import type { Album, RemoteSlot } from "../../api/types";
+import { remoteSlotView, targetForAlbum } from "../remote";
+
+function album(id: string, over: Partial<Album> = {}): Album {
+  return {
+    id,
+    section: "Musik",
+    kind: "music",
+    title: `Album ${id}`,
+    artist: "Kinderparty",
+    series: null,
+    figure: null,
+    category: "Kinderparty",
+    colors: ["#111111", "#222222", "#333333"],
+    has_cover: false,
+    duration: 120,
+    tracks: [],
+    ...over,
+  };
+}
+
+describe("targetForAlbum", () => {
+  it("targets the album itself for music and audiobooks", () => {
+    expect(targetForAlbum(album("a"))).toEqual({ target_kind: "album", target: "a" });
+    expect(targetForAlbum(album("b", { kind: "book", series: "Conni" }))).toEqual({
+      target_kind: "album",
+      target: "b",
+    });
+  });
+
+  it("targets the show, not the episode, for a podcast", () => {
+    const episode = album("ep1", {
+      kind: "book",
+      section: "Kinderpodcasts",
+      series: "Wissen macht Ah",
+    });
+    expect(targetForAlbum(episode)).toEqual({
+      target_kind: "series",
+      target: "Wissen macht Ah",
+    });
+  });
+});
+
+describe("remoteSlotView", () => {
+  const albums = [album("resolved-id")];
+
+  it("is empty when nothing is assigned", () => {
+    expect(remoteSlotView(undefined, albums)).toEqual({ state: "empty" });
+  });
+
+  it("is ok when the slot resolves to a known album", () => {
+    const slot: RemoteSlot = {
+      digit: "3",
+      target_kind: "album",
+      target: "resolved-id",
+      resolved_album_id: "resolved-id",
+    };
+    expect(remoteSlotView(slot, albums)).toEqual({
+      state: "ok",
+      slot,
+      album: albums[0],
+    });
+  });
+
+  it("is missing when the backend could not resolve the target", () => {
+    const slot: RemoteSlot = {
+      digit: "4",
+      target_kind: "series",
+      target: "no such show",
+      resolved_album_id: null,
+    };
+    expect(remoteSlotView(slot, albums)).toEqual({ state: "missing", slot });
+  });
+
+  it("is missing when the resolved album has since left the library", () => {
+    const slot: RemoteSlot = {
+      digit: "5",
+      target_kind: "album",
+      target: "gone",
+      resolved_album_id: "gone",
+    };
+    expect(remoteSlotView(slot, albums)).toEqual({ state: "missing", slot });
+  });
+});

web/src/lib/keyboard.ts

@@ -23,6 +23,9 @@ export interface UiState {
   openAlbumId: string | null;
   showHelp: boolean;
   cols: number;
+  /** Armed by `A` on the play screen: the next digit assigns what's playing to that
+   * remote key instead of doing whatever it would normally do. */
+  assignPending: boolean;
 }
 
 export const initialUiState: UiState = {
@@ -35,6 +38,7 @@ export const initialUiState: UiState = {
   openAlbumId: null,
   showHelp: false,
   cols: 4,
+  assignPending: false,
 };
 
 export type Action =
@@ -45,11 +49,20 @@ export type Action =
   | { type: "previous" }
   | { type: "volume"; delta: number }
   | { type: "seek"; delta: number }
-  | { type: "pop"; freq: number };
+  | { type: "pop"; freq: number }
+  | { type: "assign"; digit: string };
 
 /** Matches the mockup's `/^[a-zA-Z0-9]$/`, widened to the umlauts a German title needs. */
 const SEARCHABLE = /^[\p{L}\p{N}]$/u;
 
+/** The default behaviour for a plain character key: type it into search. Shared by
+ * `default` and by `a`/`A`, which only sometimes means something else. */
+function typeIntoSearch(state: UiState, key: string): Action[] {
+  return SEARCHABLE.test(key)
+    ? [{ type: "ui", patch: { search: state.search + key, view: "browse", selIndex: 0 } }]
+    : [];
+}
+
 const GROUP_ORDER: Group[] = ["music", "audiobooks", "podcasts"];
 
 export const VOLUME_STEP = 10;
@@ -89,6 +102,9 @@ function moveSelection(state: UiState, results: Results, dx: number, dy: number)
 
 /** ESC peels one layer off at a time rather than dumping you back at the top. */
 function escape(state: UiState): Action[] {
+  if (state.assignPending) {
+    return [{ type: "ui", patch: { assignPending: false } }];
+  }
   if (state.showHelp || state.openAlbumId !== null) {
     return [{ type: "ui", patch: { showHelp: false, openAlbumId: null } }];
   }
@@ -135,6 +151,12 @@ export function handleKey(event: KeyEvent, state: UiState, results: Results): Ac
     }
   }
 
+  // Armed by "A" below; the next digit assigns what's playing to that remote key
+  // instead of whatever it would normally do (typing into search, seeking, ...).
+  if (state.assignPending && /^[0-9]$/.test(key)) {
+    return [{ type: "assign", digit: key }, { type: "ui", patch: { assignPending: false } }];
+  }
+
   const browsing = state.view === "browse" && state.openAlbumId === null && !state.showHelp;
 
   switch (key) {
@@ -201,10 +223,15 @@ export function handleKey(event: KeyEvent, state: UiState, results: Results): Ac
       const chosen = selectionAt(results, state.selIndex);
       return chosen ? [chosen] : [];
     }
-    default:
+    case "a":
-      if (SEARCHABLE.test(key)) {
+    case "A":
-        return [{ type: "ui", patch: { search: state.search + key, view: "browse", selIndex: 0 } }];
+      // Only while something is loaded on the play screen - everywhere else "a" is
+      // just the first letter of a search, like any other key.
+      if (state.view === "play" && !state.showHelp && state.openAlbumId === null) {
+        return [{ type: "ui", patch: { assignPending: true } }];
       }
-      return [];
+      return typeIntoSearch(state, key);
+    default:
+      return typeIntoSearch(state, key);
   }
 }

web/src/lib/remote.ts

@@ -0,0 +1,41 @@
+/** Assigning the currently playing album to a number key on the IR remote.
+
+Kept pure so the popup and the `A` + digit keyboard shortcut can share one place that
+decides what a press actually assigns, and so a slot's display state - "nothing here",
+"here's what plays", "this used to point somewhere real" - needs no branching logic
+inside the component that renders it.
+*/
+
+import type { Album, RemoteSlot, RemoteSlotInput } from "../api/types";
+import { groupOf } from "./search";
+
+/** What pressing "assign" on `album` actually stores.
+ *
+ * A podcast is not itself one playable thing in this library - each episode is its
+ * own album - so a podcast assignment targets the *show* (its series name), resolved
+ * to whatever is newest on every press. Everything else targets the album itself,
+ * always started from track 0.
+ */
+export function targetForAlbum(album: Album): RemoteSlotInput {
+  if (groupOf(album) === "podcasts" && album.series) {
+    return { target_kind: "series", target: album.series };
+  }
+  return { target_kind: "album", target: album.id };
+}
+
+export type RemoteSlotView =
+  | { state: "empty" }
+  | { state: "ok"; slot: RemoteSlot; album: Album }
+  | { state: "missing"; slot: RemoteSlot };
+
+/** How one digit's card should render, given the current mapping and the library. */
+export function remoteSlotView(
+  slot: RemoteSlot | undefined,
+  albums: Album[],
+): RemoteSlotView {
+  if (!slot) return { state: "empty" };
+  const album = slot.resolved_album_id
+    ? albums.find((candidate) => candidate.id === slot.resolved_album_id)
+    : undefined;
+  return album ? { state: "ok", slot, album } : { state: "missing", slot };
+}