# Task: make "podcast" a kind of album

## Why

`AlbumKind` is `Literal["music", "book"]` (`python-backend/musicmouse/library/sections.py`),
and the `Kinderpodcasts` shelf is declared `kind="book"`. So "is this a podcast?" is
answered differently in each layer:

- web: `album.section === "Kinderpodcasts"` (`web/src/lib/search.ts`, `groupOf`), and
  everything else goes through `groupOf(album) === "podcasts"` (App, PlayView,
  BrowseView, MobileBrowse, keyboard.ts, remote.ts, ambience.ts, useTrackDetail);
- backend: `SECTIONS[album.section].album_unit == "episode"` (`MusicLibrary.latest_episode`,
  `tippen/rewards.py`);
- typing game: reward kinds `"episode"` and `"podcast_episode"`
  (`services/web/tippen_api.py`).

The shelf's folder name is therefore a de-facto API string the front-end depends on.
`todo.md` already asks for a cleaner podcast data model.

## What the owner decided

Add `"podcast"` to the album kind. Podcast-ness is then a property of the album, carried
in the index and the API, and nobody compares section names.

## Design

### Backend

- `AlbumKind = Literal["music", "book", "podcast"]`. `SECTIONS["Kinderpodcasts"]` gets
  `kind="podcast"`.
- `Section.album_unit` stays. It is the scanner's structural fact (one album per file),
  not a classification. Keep using it in the scanner (`scan_library`) and in
  `podcast_feeds.find_feed_shows`. Every place that asks "is this album a podcast?"
  switches to `album.kind == "podcast"`:
  - `MusicLibrary.latest_episode`;
  - `tippen/rewards.py` (`_chronological_episodes`, and the `album_unit == "folder"`
    branches that really mean "not a podcast");
  - `tippen_api._animation_kind`;
  - the `is_podcast` helper, if task 04 added one: change its body, keep its callers.
- `scanner.scan_album` derives `series` only for `kind == "book"`. Check that episode
  albums still get `series = folder.name` (they do, in `scan_episodes`) and that
  nothing else branches on `"book"` meaning "book or podcast".
  `grep -rn '"book"' python-backend/musicmouse` and decide per hit.
- `FigureConfig.kind` stays `Literal["music", "book"]`. A figurine holding a podcast is
  not a thing. Type `Config.figure_kinds` accordingly.
- `cache._album_from_json` validates the kind: accept `"podcast"`. Bump
  `_INDEX_VERSION` (with a comment line, like the existing ones), so every cached
  podcast album is re-scanned with the new kind instead of being read back as
  `"book"`.
- `_ANALYZED_KINDS` stays `("music",)`.
- `services/web/schemas.py`: `AlbumOut.kind` and `PlayerStateOut.kind` become the
  `AlbumKind` literal instead of `str`, so the OpenAPI schema says what the values are.

### Web

- `src/api/types.ts`: `AlbumKind = "music" | "book" | "podcast"`.
- `src/lib/search.ts`, `groupOf`: map from `kind` alone (`podcast` → `"podcasts"`,
  `book` → `"audiobooks"`, else `"music"`). No `section` comparison may remain
  anywhere in `web/src`.
- `src/lib/covers.ts`: `isBook` and `aspectOfKind` treat `"book"` specially. Podcasts
  are drawn like books today *because* they were `kind: "book"`. Keep them looking
  exactly as they do now: decide explicitly whether `isBook` / `aspectOfKind` include
  `"podcast"`, and check BrowseView's `mostlyBooks` / `allPodcasts` tiles and the play
  view. The result must be visually unchanged; compare screenshots of the podcast
  shelf, a podcast category and the podcast play view before and after.
- Anything else that reads `state.kind` or `album.kind`: grep and decide per hit.

### Leave alone

The `section` field stays in the API; it is still useful for display and debugging.
Don't rename the shelves, the folders or the `Group` names.

## Tests

- `tests/test_library.py`: a `Kinderpodcasts` episode scans as `kind == "podcast"`; a
  cache written at the previous `_INDEX_VERSION` is discarded; `latest_episode` still
  works.
- `tests/test_tippen_rewards.py` / `test_tippen_api.py`: episode rewards still resolve
  and still animate as `podcast_episode`.
- `tests/test_web.py`: `/api/library` reports `"podcast"`.
- `web/src/lib/__tests__/search.test.ts`: `groupOf` uses `kind`; an album whose section
  says `Kinderpodcasts` but whose kind is `music` is music. That proves nothing compares
  the section any more.

## Done when

`scripts/check.sh` passes, `grep -rn "Kinderpodcasts" web/src` finds nothing, the
backend's "is it a podcast" checks all read `album.kind`, and the podcast UI looks the
same as before.