The driving case. playlist exercises by: row selection, per-type children: mappings and inline property stamps at once, and fixes BUG-013 in the process.
It also carries the one design question SPEC-130 said it must answer and did not.
Tracking started Sep 14 — check back for trends.
type: { matches: ['album', 'podcast', 'audiobook', 'series', 'mix'] } // line 28 … schemaOrgType: 'MusicPlaylist' // line 237, unconditional const trackAttrs = { typeof: 'MusicRecording' }; // line 153, unconditional
So {% playlist type="podcast" %} publishes a podcast as a music playlist whose episodes are music recordings. The rune already declares what its content is and emits the wrong schema anyway.
type | schema.org | Items | Track property | Relation to MusicPlaylist |
|---|---|---|---|---|
album | MusicAlbum | MusicRecording | track | subtype — safe narrowing |
mix | MusicPlaylist | MusicRecording | track | today's emitted type, for every row |
podcast | PodcastSeries | PodcastEpisode | hasPart | branch switch |
audiobook | Audiobook | Chapter | hasPart | branch switch |
series | CreativeWorkSeries | CreativeWork | hasPart | branch switch |
Even the default is imprecise: the attribute defaults to album (attrs.type ?? 'album', line 98), and MusicAlbum — a subtype of MusicPlaylist — has been available and unused the whole time.
children: { track: 'PodcastEpisode' } changes the item's @type and nothing else, and the item's properties are stamped inline as MusicRecording properties. Today's output for type="podcast":
{ "@type": "MusicPlaylist", "name": "The Sunday Show", "byArtist": "Acme", "track": [ { "@type": "MusicRecording", "name": "Episode One", "byArtist": "Acme", "duration": "PT1800S" } ] }
Retyping the item alone leaves byArtist on a PodcastEpisode, which does not have that property — worse than MusicRecording, which at least was coherently wrong. So:
podcast: { type: 'PodcastSeries', properties: { track: 'hasPart' }, children: { track: { type: 'PodcastEpisode', properties: { 'track-name': 'name', 'track-duration': 'duration' }, // `track-artist` is dropped: PodcastSeries carries the publisher, not the item }, }, }
SPEC-130 left this open, calling it a question it "must answer, not gloss", and none of D1–D8 resolved it: MusicRecording is stamped both by playlist's own <li> items and by the standalone track rune, so does a per-type child mapping have to reach both?
Settled in D9, measured against the built packages. The premise was false. The two emitters never populate the same collection — playlist builds its items exclusively from markdown-list itemModel data, and a {% track %} inside a {% playlist %} is not one of its tracks at all (BUG-016). So there is nothing to keep in step, and contextProperties is not needed.
Each rune keys off the attribute its author already set:
| Rune | by: | Rows |
|---|---|---|
playlist | its type | album, mix, podcast, audiobook, series — plus the child mapping for its transform-built items |
track | its type | song, episode, chapter, talk, video |
So track is in scope here too. It carries its own five-value enum (track.ts:15) and emits MusicRecording for all five — the same defect as playlist, in a second rune, and part of BUG-013. Converting it here rather than leaving it in Group B keeps the pair coherent and the review in one place.
BUG-016 is not this item's to fix — it is a content-model defect, and WORK-572 lands it first. What that costs this item is one widening: playlist's children: mapping must match tag-built children as well as transform-built ones, so the table covers the whole track population rather than half of it. Still nothing declared on the child.
That ordering is deliberate. A children: mapping written while {% track %} children are not yet children would be revised the moment WORK-572 ships.
playlist declares a by: 'type' table with rows for all five values, and an explicit fallback row for the absent case matching the attribute's own album default{% playlist type="podcast" %} publishes PodcastSeries / hasPart / PodcastEpisode, resolving BUG-013byArtist does not survive onto a PodcastEpisode — properties that do not belong to the child's type are dropped, not carriedalbum narrows to MusicAlbum, so the default stops being imprecisetrack rune gains its own by: 'type' table over song | episode | chapter | talk | video, so {% track type="episode" %} stops emitting MusicRecordingchildren: mapping reaches tag-built children as well as transform-built ones, so a {% track %} child and a list item get the same rowtype still matches its list-item equivalent after the table replaces the imperative formdata-names (track-name, track-artist, track-duration) — playlist needs no new namesplaylist's image source resolves through the name WORK-561 gave itrefrakt inspect's resolved-table view, per WORK-566type value — mix unchanged, the other four changedDo playlist first among Group C. It is the rune that needs the least prep — its inline spans are already addressable — and it exercises by:, children: and inline stamps together, so a shape problem in the mechanism surfaces here rather than after four more runes have been converted against it.
The curation is a human judgement recorded in config, and nothing checks it: refrakt ships no schema.org ontology (D5). Chapter for an Audiobook and CreativeWork for a CreativeWorkSeries are the two rows worth a second opinion before they ship — review them in inspect's resolved view, which is what that view is for. track's talk row needs the same attention: there is no obvious schema.org type for it, and CreativeWork may be the honest answer.
Check the pair's output on one page. With two independent tables, the failure mode D9 rules out by construction is still worth asserting once: a page carrying both a {% playlist type="podcast" %} and a standalone {% track type="episode" %} should emit a PodcastSeries with PodcastEpisode parts and a separate PodcastEpisode, each correct on its own terms.
children: matcher has to be widerposition — WORK-572 notes nested tracks could take position: 'index', which list items lack entirely. Decide here, where the one generator livesplugins/media/src/tags/playlist.ts:28,98,153,237 — the enum, the default, the item type, the unconditional parent typeplugins/media/src/tags/track.ts:15,96 — track's own enum and its unconditional MusicRecording