pluriwave/openspec/changes/rediseno-funcional/specs/eq-custom-presets/spec.md

EQ Custom Presets Specification

Purpose

User-defined preset save/name/list on top of the existing 6 fixed presets, a per-station EQ entry point from the player's tool tray, and a "stations with their own EQ" drill-down. Band count stays 5 — resolved by spike (Engram id 2498), not a pending decision. Traceable to WU13 (Settings screen) and WU14 (player tool tray, shares WU13's editor component).

Requirements

Requirement: Five-Band Equalizer (Regression Guard, First-Class)

The equalizer screen MUST render exactly 5 vertical sliders. assert(bandas.length == 5) in preset_ecualizador.dart MUST remain unchanged. Band count is device-reported via just_audio's AndroidEqualizer (params.bands), not app-chosen; any requirement or implementation asserting 7 bands is rejected on sight.

Scenario: Ecualizador screen renders 5 sliders

• GIVEN the user opens the Ecualizador settings screen
• WHEN it renders
• THEN exactly 5 vertical sliders are shown, one per band

Scenario: Band-count regression is rejected (edge case)

• GIVEN a future change proposes 7 sliders or a modified bandas.length assert
• WHEN that change is reviewed against this requirement
• THEN it fails: 5 is the resolved, binding band count for this change

Requirement: Custom Preset Save

The user MUST be able to save the current 5-band configuration as a new, named custom preset, which then appears alongside the 6 fixed presets in the preset chip row.

Scenario: Saving a custom preset

• GIVEN the user has adjusted the 5 sliders from a fixed preset
• WHEN they choose "Guardar como preset" and enter the name "Mi preset"
• THEN a new preset named "Mi preset" is persisted
• AND it appears in the preset chip row on next render

Requirement: Custom Preset Naming Validates Non-Empty Input

The system MUST reject an empty or whitespace-only preset name without crashing, and MUST NOT persist a preset in that case.

Scenario: Empty name is rejected

• GIVEN the "Guardar como preset" flow is open
• WHEN the user submits an empty name
• THEN a validation message is shown and no preset is saved

Requirement: Per-Station EQ Entry Point From the Player

The player's tool tray MUST expose an "EQ propio" tile that opens a per-station EQ bottom sheet. That sheet MUST reuse the same 5-band editor component used by the Settings Ecualizador screen (not a separate implementation).

Scenario: Opening per-station EQ from the player

• GIVEN a station is currently playing
• WHEN the user taps "EQ propio" in the tool tray
• THEN a bottom sheet opens with 5 sliders bound to that station's resolved preset
• AND changes made there apply through the existing per-station EQ persistence path

Requirement: Stations-With-Own-EQ Drill-Down

The Settings Ecualizador screen MUST expose a row that navigates to a list of stations that currently have a station-specific preset override, sourced from the existing presetsPorEmisora map.

Scenario: Drill-down lists exactly the overridden stations

• GIVEN 2 stations have entries in presetsPorEmisora and N others do not
• WHEN the user opens the drill-down
• THEN exactly those 2 stations are listed

Requirement: Base-vs-Per-Station Explainer Preserved

An info banner distinguishing the base (global/device) EQ from per-station overrides MUST remain visible on the Ecualizador screen.

Scenario: Banner is visible on screen open

• GIVEN the user opens the Ecualizador screen
• WHEN it renders
• THEN the base-vs-per-station explainer banner is visible

Requirement: Active Output Surfaced on the Main Screen

The "Salida activa" (active output device) row MUST be visible on the main Ecualizador screen, not only in the Advanced sub-section.

Scenario: Output row updates on device change

• GIVEN the Ecualizador screen is open
• WHEN the active audio output device changes (e.g. Bluetooth connects)
• THEN the "Salida activa" row updates to reflect the new device