# Riff Player requirements

> Owner: Player process (`:app` default process). Indexing, source discovery and immutable
> generation are out of scope.

This page is a registry, not a second requirements authority. Each child owns the named scope.

The active library/catalog consumer is [Cuetree integration](/Riff/LATEST/cuetree-integration); FILF
transport is owned by [Playback transport](/Riff/LATEST/player-transport).

## Library and state

- [Content mode](/Riff/LATEST/player-content-mode)
- [Catalog membership](/Riff/LATEST/player-catalog-membership)
- [Progressive A-Z navigation](/Riff/LATEST/player-az-navigation)
- [Search and ordering](/Riff/LATEST/player-search-ordering)
- [Application-data storage](/Riff/LATEST/player-storage)
- [State and profiles](/Riff/LATEST/player-state)
- [Queues and playlists](/Riff/LATEST/player-queues)
- [Listening history](/Riff/LATEST/player-listening-history)
- [Audio focus and restoration](/Riff/LATEST/player-audio-focus)
- [Audiobook bookmarks](/Riff/LATEST/player-bookmarks)
- [Automatic selection](/Riff/LATEST/player-automatic-selection)

## Playback and UI

- [Inactivity and Dim Backlight](/Riff/LATEST/player-inactivity)
- [Audiobook speed](/Riff/LATEST/player-audiobook-speed)
- [Playback transport](/Riff/LATEST/player-transport)
- [ReplayGain playback](/Riff/LATEST/replaygain-playback) — active with Cuetree MDRG
- [Chapters and checkpoints](/Riff/LATEST/player-chapters)
- [Saved contexts](/Riff/LATEST/player-contexts)
- [UI foundation](/Riff/LATEST/ui-foundation)
- Screen contracts: [Main](/Riff/LATEST/main-screen), [Hierarchy](/Riff/LATEST/hierarchy-screen),
  [AI](/Riff/LATEST/ai-screen), [Settings](/Riff/LATEST/settings-screen),
  [Calibration](/Riff/LATEST/calibration-screen)
- [Application modes](/Riff/LATEST/application-modes) and [icon system](/Riff/LATEST/icon-system)