feat(search-artist-links): implement Spotify adapter

[chiptus]

Adds a complete Spotify artist search implementation with Client Credentials auth, API search, and normalization.
Search failures for individual artists don't affect results for other artists.

Verification

Preconditions: Set Supabase secrets SPOTIFY_CLIENT_ID and SPOTIFY_CLIENT_SECRET in the edge function environment.

• Call /search-artist-links with provider: "spotify" and multiple artist names; verify all artists return up to 3 candidates each.
• Call with one artist that has no results; verify other artists' results are returned.
• Verify normalized candidates have correct shape: { name, url, imageUrl, followers, genres }.
• Verify a Spotify artist with 0 followers preserves the count as 0, not null.
• Verify missing images return imageUrl: null.
• Verify missing genres return empty array.

Stacked on #337.

Closes #336

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Project	Deployment	Actions	Updated (UTC)
upline	Ready	Preview	Aug 21, 2026 3:57pm

[github-actions]

Deploy → staging — workflow run
Last updated: 2026-08-21 15:58:08 UTC

• ⏭️ DB migrations skipped (no changes)
• ✅ Edge functions succeeded

[Copilot]

Pull request overview

Implements the Spotify provider for the search-artist-links Supabase Edge Function by adding Spotify Client Credentials auth, Spotify search response validation, and normalization into the shared Candidate shape used by the link wizard flow.

Changes:

• Add a Spotify Client Credentials token helper with in-memory caching.
• Implement searchSpotify to query Spotify’s artist search API and return up to 3 normalized candidates per artist (per-artist failures are isolated).
• Add Spotify Zod schemas plus unit tests for normalizeSpotifySearchResult.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
supabase/functions/search-artist-links/spotify-adapter.ts	Implements the Spotify provider search flow (token fetch + per-artist search + normalization).
supabase/functions/search-artist-links/normalize.ts	Adds normalizeSpotifySearchResult to map Spotify artists into the shared Candidate shape.
supabase/functions/search-artist-links/normalize.test.ts	Adds unit tests covering Spotify normalization edge cases (missing images/genres/followers, followers=0).
supabase/functions/_shared/spotify-api/schemas.ts	Introduces Zod schemas/types for Spotify artists and search responses.
supabase/functions/_shared/spotify-api/auth.ts	Adds Spotify Client Credentials token acquisition with caching.

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Playwright test results

 50 passed

Details

 50 tests across 14 suites
 1 minute, 9 seconds
 281423b

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated no new comments.

Suppressed comments (1)

Previously missed (1) — in code that hasn't changed since the last review.

supabase/functions/_shared/spotify-api/schemas.ts:30

• This schema accepts {} or { artists: {} } as a valid Spotify response, so an incomplete/malformed 200 response is silently reported as a legitimate zero-result search instead of the per-artist error handled by the adapter. Spotify search responses require both artists and items; keep those containers required while leaving genuinely nullable artist fields optional.

export const SpotifySearchResponseSchema = z.object({
  artists: z
    .object({
      items: z.array(SpotifyArtistSchema).optional(),
    })
    .optional(),