docs(remote): a null in a track correction is a removal, never an omission

[InstaZDLL]

Summary

• The server's PATCH /tracks/{id} becomes a partial patch in three states (fix(api): a track correction leaves alone what it does not mention waveflow-server#184, fixing bug: a track PATCH drops every correction it does not mention waveflow-server#177): a field absent leaves its correction alone, null removes it, a value sets it.
• This client's behaviour does not change. remote/drain.rs already spells every field out, null included, so an emptied field still reaches the server as a removal — against the new server and an older one alike. The server PR replays this client's request exactly as drain.rs sends it.
• What changes is what the comments tell the next reader. They justified the explicit nulls by wholesale semantics, and read that way they invite skipping None fields — which against the new server would silently keep a correction the user had just emptied. They now say the nulls are load-bearing, and that the three fields the editor has no input for (sort_title, comment, musicbrainz_recording_id) are left alone rather than erased.

How I tested

• The diff touches comment lines only: filtering every // line out of git diff leaves nothing.
• rustfmt --edition 2021 --check on both files, with the repository's rustfmt.toml: exit 0, so the doc-comment syntax is valid and the formatting unchanged.
• The behaviour the comments describe is tested on the server side in fix(api): a track correction leaves alone what it does not mention waveflow-server#184, proven by inverting each half of the change.

Checklist

• Title uses Conventional Commits (type(scope): subject, kebab-case scope)
• bun run lint + bun run typecheck — not run: no TypeScript touched
• cargo check --manifest-path src-tauri/Cargo.toml --all-targets — not run locally: comment-only change, syntax checked with rustfmt --check instead; CI runs the full check
• UI strings / locales — not applicable, none changed
• CLAUDE.md and docs/ — not applicable, no cross-cutting pattern changed
• Breaking change — none, comment-only

Linked issues

Refs InstaZDLL/waveflow-server#177
Refs InstaZDLL/waveflow-server#184

Best merged after InstaZDLL/waveflow-server#184: until then the comments describe server semantics that are not deployed yet. The rule they state — never omit a None field — is safe against either.

Summary by CodeRabbit

• Correctifs
  • Les mises à jour des métadonnées des pistes appliquent désormais correctement les modifications partielles.
  • L’envoi explicite d’une valeur vide supprime la correction correspondante.
  • Les champs omis restent inchangés, évitant la suppression involontaire de métadonnées existantes.
  • Les champs non pris en charge ne modifient pas les corrections ajoutées par d’autres clients.

[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between 287db97 and a5d8fe0.

📒 Files selected for processing (2)

• src-tauri/crates/app/src/remote/drain.rs
• src-tauri/crates/app/src/remote/mutation.rs

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📝 Walkthrough

Walkthrough

La documentation de UpdateTrackMetadata décrit maintenant un comportement PATCH incrémental. Les champs absents restent inchangés. Les valeurs None sont envoyées comme null pour supprimer une correction.

Changes

Métadonnées de piste

Layer / File(s)	Summary
Contrat PATCH et documentation du flux src-tauri/crates/app/src/remote/mutation.rs, src-tauri/crates/app/src/remote/drain.rs	La documentation précise les trois états d’un champ : absent, null ou valeur définie. Les champs non pris en charge restent inchangés lorsqu’ils sont omis.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Other

Merge Risk: ⚪ Minimal · up to a5d8f

This documentation update does not change runtime behavior and accurately describes the existing metadata patch contract.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 2 files.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	Le titre décrit précisément la modification principale : la distinction entre une valeur null qui supprime une correction et un champ omis. Il suit aussi le format Conventional Commits avec le scope…
Description check	✅ Passed	La description respecte la structure attendue. Elle explique le changement, le comportement client, les tests réalisés, les éléments non applicables et les issues liées. Les commandes non exécutées so…

✨ Finishing Touches

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• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch docs/track-patch-null-is-a-removal

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