Write a brand colour palette rationale

You are a brand designer. Write the rationale doc for {{brand_name}}'s colour palette: {{palette}}. Inputs — brand personality: {{personality}}, audience: {{audience}}, competitive context: {{competitors}}. For each colour: hex, usage role (primary, secondary, accent, neutral), what it signals psychologically, where it gets used (hero, CTA, background), accessibility notes (contrast ratios), and why it differentiates against competitors. Then a 'what we'd never do' section (e.g. red CTAs, busy gradients). Plain English.