Fix lyrics bracket rules: cues in [brackets], parentheses for backing vocals only (v1.3.1)

Suno was occasionally singing parenthesized performance cues as literal lyrics.
Changed all cues from (whispered) to [whispered] format. Added explicit rule
that all instructions/cues/directives must be in [ ] brackets — anything not
bracketed is treated as singable lyrics. Parentheses now reserved for backing
vocals only.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## [1.3.1] - 2026-02-20
+
+### Fixed
+- **Performance cues changed from parentheses to brackets** — `(whispered)`, `(belted)`, etc. are now `[whispered]`, `[belted]`, etc. Suno was occasionally singing parenthesized cues as literal lyrics instead of treating them as directives.
+- **Parentheses now reserved for backing vocals only** — `( )` wrapped text like `(ooh, ooh)` is treated by Suno as a background vocal layer. They should never be used for instructions or performance cues.
+- **Added explicit bracket rule** — All instructions, cues, and directives in the lyrics field must be in `[ ]` brackets. Anything not bracketed is treated as singable lyrics by Suno. Rule added to both the Structure Tags section and the Output Architecture section.
+
 ## [1.3.0] - 2026-02-18
 
 ### Added

knowledge_base.py

@@ -101,11 +101,13 @@ Persona tags: [Persona: raspy-female], [Vocal: breathy, intimate] (place near to
 Section tags (each on its own line): [Intro], [Verse], [Verse 1], [Verse 2], [Pre-Chorus], [Chorus], [Bridge], [Breakdown], [Drop], [Outro]
 Use unique labels to force different content: [Verse A], [Verse B]
 Bar counts: [Intro: 8 bars], [Verse: 16 bars], [Chorus: 8 bars]
-Performance cues inline in parentheses: (whispered), (belted), (rap), (spoken), (growl)
+Performance/delivery cues in brackets: [whispered], [belted], [rap], [spoken], [growl]
+Parentheses ( ) are ONLY for backing vocals: (ooh, ooh), (yeah yeah). Suno treats ( ) wrapped text as a background vocal layer — never use them for instructions or cues.
 Energy/mood tags: [Energy: High], [Energy: Low], [Mood: Dark], [Mood: Bright]
 Harmony tags: [Harmony: 3-part], [Harmony: stacked]
 Lyric tone tags: [LyricTone: blunt], [LyricTone: intimate]
 Chord progressions: [Chords: C G Am F] (above or inline with lyric lines)
+All instructions, cues, and directives in the lyrics field MUST be in [ ] brackets. Anything not in brackets is treated as singable lyrics by Suno. Never use bare text or ( ) parentheses for instructions — Suno will try to sing them.
 
 === HARMONY, TEMPO & GROOVE ===
 
@@ -313,7 +315,9 @@ You MUST generate ALL of the following:
    Keep under 400 chars. Put most important element in Position 1.
 
 3. LYRICS WITH TAGS — section-by-section structure (goes in Suno's Lyrics field):
-   Each section tag on its own line. Below each: performance/arrangement cues in brackets, then lyrics.
+   Each section tag on its own line. Below each: performance/arrangement cues in [brackets], then lyrics.
+   All instructions, cues, and directives MUST be in [ ] brackets — Suno will sing anything not bracketed.
+   Use ( ) parentheses ONLY for backing vocals, never for instructions or performance cues.
    Include performance energy, arrangement density, and vocal delivery cues per section.
    NEVER use em dashes in lyrics. Use commas, periods, or ellipses instead.