Initial TrueGrowth source import

openspec/changes/add-music-brief-controls/specs/audio-generation/spec.md

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+## ADDED Requirements
+
+### Requirement: Music Analyzer Song Positioning Brief
+The system SHALL let the music analyzer collect a lightweight song positioning brief before lyric generation or rewrite, without creating a new workflow entity or audio generation modality.
+
+#### Scenario: Create lyrics from a song brief
+- **GIVEN** the user is creating a song from scratch in the music analyzer
+- **WHEN** the user provides song positioning fields such as purpose, genre style, vocal style, energy mood, or lyric goal
+- **THEN** the lyric generation prompt SHALL include those fields as upstream creative context
+- **AND** the generated result SHALL still populate the existing title, style tags, and lyric draft fields
+
+#### Scenario: Rewrite lyrics with a song brief
+- **GIVEN** the user is rewriting an existing lyric draft in the music analyzer
+- **WHEN** song positioning fields are present
+- **THEN** the lyric rewrite prompt SHALL include those fields alongside the current lyrics and existing analysis
+- **AND** the rewrite SHALL preserve the existing versioning behavior
+
+#### Scenario: Restore legacy music records
+- **GIVEN** a stored music analyzer record does not contain a song positioning brief
+- **WHEN** the record is loaded
+- **THEN** the system SHALL treat the missing brief as empty
+- **AND** the record SHALL remain usable without migration errors
+
+#### Scenario: Generate music from prepared lyrics
+- **GIVEN** the user proceeds from lyrics to Suno music generation
+- **WHEN** the record contains a song positioning brief
+- **THEN** the system SHALL continue submitting only the existing Suno title, tags, lyric prompt, model version, and edit-action fields
+- **AND** the brief SHALL not introduce new Suno submit fields