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There is a recent "catalog" relationship available on some library content (library-songs, library-music-videos and library-playlists) that can be used for this purpose. This relationship may not always be populated as it's possible have no association with any catalog content such as some uploaded content or purchased music that is not available for streaming.To get this relationship, a few approaches are available. Here's are some examples using a sample identifier from the original post:GET /v1/me/library/songs/i.addWKtl6kQE?relate=catalogReturns the library song resource along with an identifier to some available catalog song resource.GET /v1/me/library/songs/i.addWKtl6kQE?include=catalogReturns the library song resource with the available catalog song resource.GET /v1/me/library/songs/i.addWKtl6kQE/catalogReturns just the available catalog song resource.The playParams attribute is not intended for making this association and it is possible for the values it contains to evolve over time.
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There is no official total as it may change over time or under specific circumstances. The presence of the next link in paged responses is an indication there are more results that may be requested. At the time of this response, there are typically up to 200 results available through the Apple Music API.
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We identified an issue affecting some requests for adding tracks that has been resolved. Thank you for the report.
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Unfortunately content with specific ids may become unavailable as rights change or content is redelivered to the catalog. It is not possible to completely rely on ids that are saved off to a separate file.Looking into your first example of "Wonderwall" by Oasis, I see the id you saved had this information:id: 1456844334isrc: GBQCP1400109album: Rock Clássico (Compilation)This album and its tracks are not currently available in the Apple Music catalog in the US. There does not appear to be a direct replacement for this content available.The best match in the US storefront for this song I could find is currently:id: 917104593isrc: GBQCP1400149album: (What's the Story) Morning Glory? [Remastered]What's interesting is the original song you were using was off of a compilation album and does not share the same ISRC as the best available match that is currently available.Typically a good way to save a song like this would be to use the ISRC and look it up using the .../songs?filter[isrc]={some-isrc} lookup, however this case shows that even though the song seemingly is the same it was actually a different version of the recording.The latter song with ISRC GBQCP1400149 currently appears on 2 albums, the remastered and deluxe versions (ids [917104593, 895279612]).There is no way outside of the ISRC lookup to find some content that has become unavailable. Searching for content is notoriously unreliable due to the nature of music metadata and search functionality returning the best match(es) based on some text term.We welcome feedback and consider supporting additional use cases when possible. Please consider submitting your report using the resources at https://developer.apple.com/bug-reporting/Thank you for the question.
