Voice Leading

README.md

@@ -107,15 +107,15 @@ Identical notation bodies share layout and body rasterization even when titles o
 
 The build-time pipeline is Soundslice/MuseScore -> `.xml` -> musical model and rhythm plans -> part generation -> JSON, engraved PNG pages, generated-tone audio, Pico title artwork, and a read-only catalog database. Sources in `data/songs/` retain the seven-section performance form. Songs generate Acoustic, Electric, and Vocal parts in their authored key, without key variants or a key-selection menu.
 
-Accompaniment uses deterministic four-bar phrase cycles: a two-bar motif repeats with a one-beat variation in the fourth bar when a suitable candidate exists. Acoustic has independently planned bass and upper-chord rhythms, including simultaneous attacks, sharing one fixed playable grip until the harmony changes. Its bass pitch, upper voicing, and TAB positions stay constant across rests, barlines, repeated chord symbols, and section labels while accompaniment continues. Any defined chord tone can be the bass, including thirds, sevenths, and extensions; explicit slash basses and inversions remain authoritative. The rhythms combine into one notated voice with no ties: each attack releases by the next attack or barline, simultaneous tones share a stem and duration, and rests appear only when the entire part is silent. Held notes are not reattacked. Electric accompaniment targets about two attacks per 4/4 bar, scaled for other meters, favoring gaps around the melody and acoustic rhythms. Its notes retain the selected rhythm's duration without a one-beat cap, stopping at chord changes or barlines and reusing the corresponding melody passage's chord shape when available. Both parts remain tie-free; clipped binary durations that need ties shorten to one conventional note followed by silence. Rhythm snippets supply attacks and rests; tied continuations do not create accompaniment attacks. Structured harmony supplies chord tones. N.C. and absent harmony remain silent. Solo slashes and the seven-section form retain their roles. Unsupported accompaniment meters and mid-measure meter changes fail explicitly.
+Accompaniment uses deterministic four-bar phrase cycles: a two-bar motif repeats with a one-beat variation in the fourth bar when a suitable candidate exists. Acoustic has independently planned bass and upper-chord rhythms, including simultaneous attacks, sharing one fixed playable voicing until the harmony changes within an arrangement iteration. Bass, upper voices, and TAB positions stay constant across rests, barlines, and repeated chord symbols. Any defined chord tone can serve as the bass; explicit slash basses and inversions remain authoritative. The rhythms combine into one notated voice with no ties: each attack releases by the next attack or barline, simultaneous tones share a stem and duration, and rests appear only when the entire part is silent. Held notes are not reattacked. Electric accompaniment targets about two attacks per 4/4 bar, scaled for other meters, favoring gaps around the melody and acoustic rhythms. Its notes retain the selected rhythm's duration without a one-beat cap, stopping at chord changes or barlines and reusing the corresponding melody passage's chord shape when available. Both parts remain tie-free; clipped binary durations that need ties shorten to one conventional note followed by silence. Rhythm snippets supply attacks and rests; tied continuations do not create accompaniment attacks. Structured harmony supplies chord tones. N.C. and absent harmony remain silent. Solo slashes and the seven-section form retain their roles. Unsupported accompaniment meters and mid-measure meter changes fail explicitly.
 
 There are no musical genre presets, genre defaults, or genre metadata. Obsolete `vamp:style` hints are rejected; visual styles, fonts, colors, and barline notation remain supported. Phrase cycles are written into the generated score and played once in reading order.
 
-Guitar parts share a theory-based voicing and proximity search over standard tuning, frets 1-20, and a maximum four-fret span. Open strings are excluded from chords and single-note melodies. Acoustic uses a bass on string 5 or 6 and two or three consecutive upper strings within 2-4, with zero or one unused string between them. Electric chords use strings 1-3 or 1-4 and may omit the root. Electric melody notes longer than a quarter note, including full tied runs, receive chords when playable; chord changes create fresh attacks even for short remaining fragments. Electric melodies are raised one octave; vocal registers stay unchanged. All parts still sound one octave below their generated notation, and explicit MusicXML transposition is honored once. Unplayable melody harmonizations remain single notes with a diagnostic; unplayable accompaniment or exact melody pitches fail generation.
+Guitar parts share standard tuning and chord-tone helpers but use separate acoustic and electric placement systems. Both use frets 1-20, exclude open strings, and require a maximum fret difference of three. Frets 7-10 qualify; frets 7-11 do not. Acoustic requires a bass on string 5 or 6 plus all three upper strings 4, 3, and 2, with at least one occupied string at fret 12 or below. Electric uses chords on strings 1-3 or 1-4. Electric melody notes longer than a quarter note, including full tied runs, receive chords when playable; chord changes create fresh attacks even for short remaining fragments. Electric melodies are raised one octave; vocal registers stay unchanged. All parts still sound one octave below their generated notation, and explicit MusicXML transposition is honored once. Unplayable melody harmonizations remain single notes with a diagnostic; unplayable accompaniment or exact melody pitches fail generation.
 
 All parts use two music systems per page, with a single system only when the score ends on an odd system. Lines break only between measures and share consistent staff/TAB widths. A measure that cannot fit at readable spacing fails with a diagnostic instead of being split. Tall notation is scaled uniformly to fit the two rows; guitar notation and TAB stay together and aligned. TAB displays frets and ties without duplicate rests; standard notation retains the complete rhythm. The generated `.pages/*.png` files are the same page images displayed by the product.
 
-Electric melody prioritizes four-string chords, then melody on top. Every generated guitar grip requires the root, the fifth, or both somewhere in the grip, not necessarily in the bass. Defining chord tones remain mandatory. Acoustic first prefers physical reach no wider than frets 7-10, accounting for narrower fret spacing higher on the neck. Wider grips are considered only if none meet that limit, using the least-reaching valid options with a diagnostic. Within that pool, complete major, minor, diminished, and augmented triads take priority when available; authored omissions and extended-chord omission rules remain intact. Movement, fret height, and distinct-fret count then choose the sequence, with no further reward for compressing an already comfortable grip. Acoustic per-string movement still has weight two, and both chord profiles retain the lower-fret preference and additional penalty above fret 12. Electric keeps its existing span and doubled-center movement costs. This is a geometric playability approximation, not a finger-assignment model. Exact melody pitches and rhythms remain unchanged.
+Electric melody prioritizes four-string chords, then melody on top. Every generated guitar voicing requires the root, the actual fifth, or both somewhere in the voicing, not necessarily in the bass. Defining chord tones remain mandatory. Acoustic chooses four connected string-voice journeys independently for each arrangement iteration, minimizing total fret travel across harmonic spans. Upper strings stay fixed; bass movement counts both fret distance and one step for switching between strings 5 and 6. All bass inversions are eligible. There is no acoustic register, physical-reach, or shape-effort penalty beyond its hard fret constraints. Complete triads are preferred when feasible; doubling is allowed, authored omissions are never restored, and missing optional tones break equal-movement ties. Electric retains its existing register, span, shape, and position-center movement costs. This is a fretboard-feasibility approximation, not a finger-assignment model. Exact melody pitches and rhythms remain unchanged.
 
 Write all music in reading order: repeat bars, numbered endings, navigation jumps, and pass-specific ties are rejected. The seven-section performance arrangements remain fully written out. Chord labels use `M`, `m`, `aug`, `dim`, `sus`, and `mM7`, including explicit major triads such as `CM`. Recognized Soundslice text-only harmonies are normalized into structured chords; parenthesized chords mark optional turnarounds omitted from the final arrangement ending.