User story: Play music from any source

**As a** listener, **I want** to play any audio content regardless of which plugin produced it, **so that** I don't need to think about where my music comes from.

User story: Play music from any source

As a listener,
I want to play any audio content regardless of which plugin produced it,
so that I don’t need to think about where my music comes from.

Priority

Must

Acceptance criteria

1. Given a content item is visible in search results or library, when I click play, then audio starts within 2 seconds (stream URL) or 500ms (local file).
2. Given I play a track from Plugin A, when the track ends and the next track in the queue came from Plugin B, then playback transitions seamlessly.
3. Given I am playing content from any plugin, when I press pause, seek, or adjust volume, then the playback engine responds immediately.
4. Given I save a track to my library, when I play it later, then I don’t need to remember which plugin it came from.

Notes / constraints

• The playback engine does not know which plugin produced the content (FR-CORE-1).

Traceability

• Requirement IDs: FR-CORE-1, FR-CORE-2
• NFRs: NFR-PERF-1, NFR-PERF-2
• Feature docs: docs/user/features/ (playback)