feat: Export & Backup — collection data portability

[SimplicityGuy]

Summary

Enable users to export their collection, wantlist, and gap analysis results in portable formats (CSV, JSON, PDF) for offline use, sharing, and backup. Optionally support importing collections from other platforms.

Motivation

Currently all user data lives inside the platform with no way to extract it. Data portability is both a user trust feature and a practical need — users may want to:

• Share gap analysis results with friends or record stores
• Back up their collection data
• Migrate from other platforms (MusicBrainz, Rate Your Music, Discogs CSV exports)
• Use collection data in spreadsheets or other tools

Proposed Endpoints

GET /api/export/collection?format=csv|json
GET /api/export/wantlist?format=csv|json
GET /api/export/gaps/{type}/{id}?format=csv|json
POST /api/import/collection  (multipart file upload)

Export Formats

Format	Use Case
CSV	Spreadsheets, record store shopping lists
JSON	Developer integrations, backup/restore
PDF	Printable gap analysis reports (stretch goal)

Implementation Notes

• Leverage existing /api/user/collection, /api/user/wantlist, and /api/collection/gaps/* query infrastructure
• Stream large exports to avoid memory pressure
• Rate limit exports (e.g., 5/hour) to prevent abuse
• For imports: parse Discogs CSV export format, match release IDs, create COLLECTED relationships

Complements

• feat: Complete My Collection — gap analysis for labels, artists, and pressings #87 — Gap analysis results become exportable
• feat: Recommender Service — graph-powered music discovery #82 — Recommendation results could also be exported
• feat: Notifier Service — watchlists and alerts for new music data #86 — Notifier could alert when an import completes

Acceptance Criteria

• Collection and wantlist exportable as CSV and JSON
• Gap analysis results exportable as CSV and JSON
• Exports include release metadata (title, artist, year, formats, label)
• Streaming response for large collections
• Rate limiting on export endpoints
• Import endpoint accepts Discogs CSV export format (stretch)

[SimplicityGuy]

Update: The recommender (#82) is now merged — recommendation results could be added to the export scope.

[SimplicityGuy]

Status Update — 2026-03-25

Not started. No implementation or design work has been merged to main for this feature.