What problem does it solve? Rock and band arrangements often sound assembled rather than played: every instrument enters at once, riffs repeat identically, and power chords collide with voice-leading rules. This Skill treats the band roster as a hard constraint and provides measured corpus data plus Rooksby's riff-writing method to produce arrangements that five people in a room could actually perform. ## Core Features & Use Cases - Roster as constraint: Fix the lineup first (guitars, keys, live-playability), then write within it; opening instrumentation is capped at 20% of the full roster based on corpus measurements. - Riff writing system: Rooksby's 30 riff types (interval, scale, chord based), 1-4 bar lengths, the 3+1 repetition pattern, variation devices, and riff-vocal coexistence rules (alternate, end-of-line, or sustain). - Harmony rule exceptions: Power chords treated as timbre rather than voice leading, weak D-to-S progressions as standard rock vocabulary, and bVII/Mixolydian as the harmonic backbone. - Use Case: When arranging a rock track whose riff fights the vocal or sounds monotonous, the Skill walks through riff type selection, drum/bass dovetailing, twin-guitar roles, and tuning choices (drop D, open G) to produce an ARR-SPEC entry. ## Quick Start Ask the agent to arrange a rock song for a four-piece band with a riff hook, specifying the lineup, whether it must be playable live, and where the riff should recur.
