# Delta for android-auto-media

## MODIFIED Requirements

### Requirement: Browsable Media Tree

`getChildren` MUST return a browsable tree rooted at `AudioService.browsableRootId`, organized into non-playable folders (Favoritos, Todas las emisoras, Mis emisoras, Ecualizador) containing playable items. Playable station items SHOULD carry an audio-quality subtitle when known. The `Favoritos` folder additionally MAY contain non-playable favorite-group sub-folders; `Todas las emisoras` and `Mis emisoras` remain flat. The `Ecualizador` folder is flat, non-playable, and contains only the 6 fixed EQ preset items (see "EQ Preset Browsable Folder").
(Previously: root contained exactly 3 folders — Favoritos, Todas las emisoras, Mis emisoras — with no EQ folder.)

#### Scenario: Car requests the root

- GIVEN the car head unit connects and requests the root (`AudioService.browsableRootId`)
- WHEN `getChildren` is called with the root id
- THEN it returns four folder `MediaItem`s (Favoritos, Todas las emisoras, Mis emisoras, Ecualizador), each with `playable: false`

#### Scenario: Car requests a folder with no stations

- GIVEN the user has zero favorite stations
- WHEN `getChildren` is called with the Favoritos folder id
- THEN it returns an empty list, not an error

#### Scenario: Browse requested before app state is loaded

- GIVEN the audio handler starts cold and station/favorites Provider state has not finished loading
- WHEN `getChildren` is called (root or any folder)
- THEN it returns a valid, possibly empty, list without throwing and without blocking or crashing the service

#### Scenario: Station has known codec and bitrate

- GIVEN a station's `Emisora.codec` and `Emisora.bitrate` are both known
- WHEN it is mapped to a playable `MediaItem`
- THEN `displaySubtitle` SHALL contain a human-readable quality hint (e.g. "128 kbps · MP3")

#### Scenario: Station has unknown codec or bitrate

- GIVEN a station's `Emisora.codec` or `Emisora.bitrate` is null/unknown
- WHEN it is mapped to a playable `MediaItem`
- THEN `displaySubtitle` SHALL omit the quality hint gracefully, never rendering literal placeholder text

#### Scenario: Ungrouped station appears exactly as before (regression guard)

- GIVEN a station's `Emisora.grupoFavoritosId` equals `GrupoFavoritos.sinAsignarId`
- WHEN the `Favoritos`, `Todas las emisoras`, or `Mis emisoras` folders are browsed
- THEN that station appears as a playable `emisora:<uuid>` item in the same folder(s), position, title, art, and subtitle as before this change
- AND its presence and shape are unaffected by the new `Ecualizador` folder

## ADDED Requirements

### Requirement: EQ Preset Browsable Folder

The Android Auto browse tree MUST expose the 6 fixed EQ presets (`PresetEcualizador.presets`) as playable items inside the `Ecualizador` root folder, each using a distinct `eq_preset:<nombre>` media-id scheme, separate from `emisora:<uuid>` and `grupo:<id>`.

#### Scenario: Car requests the Ecualizador folder

- GIVEN the `Ecualizador` folder id was returned under the root
- WHEN `getChildren` is called with the `Ecualizador` folder id
- THEN it returns exactly 6 playable `MediaItem`s, one per `PresetEcualizador.presets` entry, titled with the preset's name
- AND each item's id is `eq_preset:<nombre>`, where `<nombre>` is that preset's unique name

### Requirement: EQ Preset Selection Applies Without Disturbing Playback

Selecting an `eq_preset:<nombre>` item MUST apply that preset immediately through the headless-safe EQ seam (e.g. `PluriWaveAudioHandler.aplicarPreset`), via a branch in `playFromMediaId` intercepted BEFORE the `emisora:`/`grupo:` routing. It MUST NOT call `playMediaItem`, MUST NOT mutate the now-playing `mediaItem`, and MUST NOT start, stop, restart, or otherwise alter current playback or playback position.

#### Scenario: User selects a preset while a station is playing

- GIVEN a station is currently playing and projected to the car
- WHEN the user taps an `eq_preset:<nombre>` item, resolved via `playFromMediaId`
- THEN the matching preset is applied via the headless-safe apply seam
- AND the currently playing station continues uninterrupted, with no change to playback position or now-playing metadata

#### Scenario: User selects a preset while nothing is playing

- GIVEN no station is currently playing
- WHEN the user taps an `eq_preset:<nombre>` item
- THEN the matching preset is applied via the headless-safe apply seam
- AND no playback starts as a result of the selection

#### Scenario: Unknown or stale preset id

- GIVEN `playFromMediaId` receives an `eq_preset:<nombre>` id whose `<nombre>` matches no entry in the current `PresetEcualizador.presets`
- WHEN resolution fails to find a matching preset
- THEN the selection is a no-op: no preset is applied, no playback state changes, and no unhandled exception propagates from the handler

### Requirement: EQ Preset Persistence and Phone/Car Parity

An EQ preset applied from the car MUST persist as the principal preset, with the same observable outcome as the phone's existing `ServicioEcualizador.guardarPrincipal`/`cambiarPresetPrincipal` path, and MUST be reflected on the phone. A principal preset changed on the phone MUST be observable from the car. The exact code path used to reach the headless-safe persistence seam from an Android Auto bind is deferred to `sdd-design`.

#### Scenario: Preset applied from the car persists for the phone

- GIVEN the user selects `eq_preset:<nombre>` from the car head unit
- WHEN the selection is processed
- THEN the preset is persisted as the principal preset
- AND opening the phone's EQ UI afterward shows that preset as the active/principal preset

#### Scenario: Preset applied from the phone is reflected for the car

- GIVEN the user changes the principal preset from the phone UI
- WHEN the car head unit subsequently observes EQ-related state through the browse/selection surface
- THEN the car-observable state reflects the phone's most recently applied principal preset

### Requirement: Active Preset Indication (Optional)

The system MAY indicate the active/principal preset within the `Ecualizador` folder's rows. Because the legacy `MediaBrowserService` browsable-item model has no native "selected item" affordance, any indication, if implemented, MUST be conveyed via a row `title` text convention (e.g. a marker prefix/suffix) rather than assuming a checkmark or selection icon exists. If a reliable title-text convention is too costly to maintain, this requirement MAY instead be satisfied by explicitly not implementing active-preset indication.

#### Scenario: Active preset is indicated via title convention (if implemented)

- GIVEN the currently applied principal preset is known when `Ecualizador`'s children are built
- WHEN the design's chosen title-text convention is applied
- THEN exactly one of the 6 preset rows' `title` carries the active-preset marker, uniquely identifying that preset among the 6

#### Scenario: Active preset indication is out of scope (if not implemented)

- GIVEN the design opts not to implement an active-preset marker
- WHEN the `Ecualizador` folder's children are built
- THEN all 6 preset rows are returned with their plain preset names, with no partial or inconsistent marking applied