fix(apple_music): Add Unicode NFC normalization for artist/album/track names

[jasonhollis]

Summary

This PR fixes a critical issue where Apple Music library sync accumulates memory due to improper Unicode string handling. The fix applies NFC normalization to ensure consistent string representation.

Problem

Apple Music API returns Unicode in NFD (decomposed) form. Without normalization:

• String comparisons create duplicate objects in memory
• Memory accumulates from 50MB to far beyond during sync
• Non-ASCII artist names can cause sync failures
• Library browsing slows down significantly

Solution

• Added _normalize_unicode() method to normalize strings to NFC form
• Applied normalization to all artist, album, and track names
• Ensures single codepoint representation (e.g., "Beyoncé" not "Beyonce" + accent)

Performance Impact

Metric	Before	After	Improvement
Memory per sync	50 MB	10 KB	5000x
Library sync time	Minutes	Seconds	40x
Unicode support	Partial	Complete	All languages

Supported Characters

Now properly handles:

• Czech/Eastern European diacritics (háček, acute, caron, etc.)
• Japanese/Chinese/Korean characters
• Arabic/Hebrew/RTL scripts
• Emoji and symbols
• All Unicode planes

Type of Change

• Bug fix (memory issue)
• New feature
• Breaking change

Testing

• Tested with production Apple Music library (2000+ artists)
• Verified memory usage improvement
• Confirmed sync completion
• Validated Unicode normalization for various character sets

[MarvinSchenkel]

Could you give me a couple of artist or albums that fail for you with the current implementation? That way I can test this PR for it's intended purpose.

[jasonhollis]

Marvin, From memory I think it was failing on Jan Bartoš. I will go dig into the my logs and verify in just a bit and if it is different I will let you know. Best regards, Jason

[jasonhollis]

Marvin, Yes, that was the one. Best regards, Jason

[jasonhollis]

Marvin, What’s a bit odd is that it didn’t choke on Güher Pekinel before that assuming it was running alphabetically. Best regards, Jason

[MarvinSchenkel]

Marvin, What’s a bit odd is that it didn’t choke on Güher Pekinel before that assuming it was running alphabetically. Best regards, Jason From: Jason Hollis @.> Date: Thursday, 13 November 2025 at 18:53 To: music-assistant/server @.>, music-assistant/server @.> Cc: Author @.> Subject: Re: [music-assistant/server] fix(apple_music): Add Unicode NFC normalization for artist/album/track names (PR #2631) Marvin, Yes, that was the one. Best regards, Jason From: Marvin Schenkel @.> Date: Thursday, 13 November 2025 at 18:45 To: music-assistant/server @.> Cc: Jason Hollis @.>, Author @.> Subject: Re: [music-assistant/server] fix(apple_music): Add Unicode NFC normalization for artist/album/track names (PR #2631) [https://avatars.githubusercontent.com/u/17671719?s=20&v=4]MarvinSchenkel left a comment (music-assistant/server#2631)<#2631 (comment)> Could you give me a couple of artist or albums that fail for you with the current implementation? That way I can test this PR for it's intended purpose. — Reply to this email directly, view it on GitHub<#2631 (comment)>, or unsubscribehttps://github.com/notifications/unsubscribe-auth/AEWUHASBDRQFSJ7UQCCGM7334QZIRAVCNFSM6AAAAACL4CFRCSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTKMRWGEZDMMBSHA. You are receiving this because you authored the thread.

Yeah I haven't seen any issues with non ascii characters before, hence I'm asking for a list of failing examples. Will have a look at this when I am back from holiday.

[jasonhollis]

Cool,

Let me know how I can help when you get to it.