[botandbang]

What and why

Fixes LOC-100. Replaces the plan in #227.

Adds two plugins on the providers hook, modelled on coverart:

• plugins/discogs: discogs.covers (artwork) and discogs.tags (metadata), for locallibrary art fetch --from discogs.covers and locallibrary track fetch --from discogs.tags.
  • An album is searched by artist, album title and label when one of its tracks has a label, then by artist and album title if that finds nothing. A track without an album is searched by artist and track title.
  • Only releases titled as the album count, and a master's editions count once.
  • Each candidate is labelled like Bicep, Ninja Tune ZEN242, 2016, so the catalogue number shows (neither a track nor its tags have a field for it).
  • Tags offered: the album, its earliest year, the first label (Warp (2) read as Warp, "Not On Label" skipped) and the first style, else genre.
  • Scores: 0.95 found by label, 0.9 by name, 0.6 for the one release found by a track's title, 0.5 when there are several.
  • Covers are saved into the request's scratch folder and checked to be an image at least 16px wide, else a warning.
  • Discogs allows 60 authenticated requests a minute. On a 429 it waits as long as Retry-After says (a minute without one) and tries up to three times; a wait over two minutes leaves the album out with a warning. X-Discogs-Ratelimit-Remaining: 0 holds the next search for the rest of the minute.
  • Without an account, or with a token Discogs refuses, the lookup stops with one note saying how to sign in.
  • Capabilities: library:read (for a track's label), net:api.discogs.com (one request a second at most) and net:i.discogs.com. Requests carry locallibrary/<version> (+https://github.com/cutenode/localnetwork) as their contact.
• plugins/accounts/discogs-account: a keys account type for a personal access token from discogs.com/settings/developers, sent as Discogs token={token}, whoami at /oauth/identity, with one scope covering only GET https://api.discogs.com/database/search*. Images are fetched without the account.

Also: both plugins are in apps/locallibrary/docs/plugins.md, how-it-works.md, editing.md and the plugin diagram, each crate has a README, and the CLI and player tests that list providers now list Discogs's too.

How it was tested

• Plugin tests on FakeHost, with Discogs scripted from trimmed API shapes (no network): lookup order, scores, master grouping, no account, a refused token, 429 waits and retries, the per-minute hold, covers that can't be had, cancelling mid-wait, Discogs out of reach; Hegel properties for candidates only for what was asked, lookup order, and retries. 20 tests pass. Mutations checked: not holding after the last request of the minute, one try too many, splitting a title at the wrong dash, keeping a bad cover, scoring a title match as a name match.
• cargo nextest run -p locallibrary-cli: 1278 passed, including the shipped-manifest checks that validate both new manifests.
• cargo clippy --all-targets -- -D warnings on both crates and the CLI, cargo fmt --check.
• Coverage of the new crate: 97.86% regions, 96.30% functions, 98.32% lines.

Not checked against the live API: Discogs' developer pages refused automated reads, so the response shapes follow the go-discogs client's types. Discogs' terms on downloading and keeping images (support.discogs.com/hc/en-us/articles/360009334593), which #227 asked about, need reading before merge.

New app or plugin

• I went through Adding an app or plugin and did every step for this kind of project
• The steps no check sees are done too: a changelog line, and READMEs that say what it does

Diagrams

diagrams-checked: apps/locallibrary/README.md: discogs links only crates the diagram already draws.
diagrams-checked: apps/locallibrary/docs/diagrams/accounts.md: a keys account behaves as the diagram's note says.

Checklist

• Tests cover the change
• For locallibrary: apps/locallibrary/changes/discogs-plugin.md has a changelog line
• The READMEs, docs/ and --help still say what the code does

Budgets

budget-raise: deps/locallibrary-cli: the discogs plugin crate is the one package the CLI links that main does not (581 to 582)

[linear-code]

LOC-100

[github-actions]

Size

Compared with main. KiB are 1,024 bytes.

	This pull request	main	Change
Client JavaScript	858.9 KiB	858.9 KiB	0 B (0%)
Client JavaScript, brotli	294.7 KiB	294.7 KiB	0 B (0%)
Client CSS	97.6 KiB	97.6 KiB	0 B (0%)
Client CSS, brotli	14.4 KiB	14.4 KiB	0 B (0%)

[github-actions]

Rust coverage

From run 840. Both are held to the thresholds in .cargo/config.toml.

Tests	Lines	Functions	Regions
All	98.14% (92937/94702)	97.66% (15243/15608)	96.81% (206308/213104)
Hegel property tests alone	97.22% (92070/94702)	96.7% (15093/15608)	95.73% (204008/213104)