Acoustic Comping

TECHNICAL_GUIDE.md

@@ -127,7 +127,7 @@ Electric accompaniment shares the electric melody's `guitar.chord_positions(...,
 
 Acoustic families are transposable degree orders for triads, tetrads and extended chords, with root/fifth alternatives on both bass strings. Slots resolve to the written third/suspension, sixth/seventh, fifth and extension, including alterations and omissions. They are not per-song grip tables. Only harmonically and physically valid realizations enter selection; unavailable bass/inversion variants are discarded. Coverage checks exercise 35 common qualities in all 12 keys. Four-fret fallbacks support previously unavailable acoustic Bb9, BbM9, Bb7#9 and Bb6add9; for example, Bb9 uses fifth-bass frets 8/10/7/9 on strings 5/4/3/2. Acoustic Bbm9 and Bm9 still have no grip meeting all constraints. Unsupported chords fail with source measure, beat and chord rather than silently omitting defining tones.
 
-The active voicing selector compares complete paths with dynamic programming over concrete grips. The leading cost minimizes four-fret grip selections: every span of one, two or three positions has zero cost in this tier. Existing criteria then apply within the tier. Electric accompaniment prioritizes chord size and shared family rank, then grip effort plus hand-center travel, missing optional tones and register preference. Acoustic prefers declared degree-order families on either bass string, then travel of the bass and all three upper voices, optional-tone coverage and register preference. Stable role-specific keys resolve equal costs. Since accompaniment transitions have travel costs but no hard travel cutoff, four-fret candidates are safely removed from a span when any primary grip exists; this exact dominance reduction keeps the repeat search small. Electric placement retains distinct alternatives where future held/tied notes can constrain feasibility, and does not charge tied continuations as fresh grip choices. The remaining acoustic placement helper uses the same leading fallback tier.
+The active voicing selector compares complete paths with dynamic programming over concrete grips. The leading cost minimizes four-fret grip selections: every span of one, two or three positions has zero cost in this tier. Existing criteria then apply within the tier. Electric accompaniment prioritizes chord size and shared family rank, then grip effort plus hand-center travel, missing optional tones and register preference. Acoustic prefers declared degree-order families on either bass string, then a combined travel/register/position cost, optional-tone coverage and register tie-breaking. Stable role-specific keys resolve equal costs. Since accompaniment transitions have travel costs but no hard travel cutoff, four-fret candidates are safely removed from a span when any primary grip exists; this exact dominance reduction keeps the repeat search small. Electric placement retains distinct alternatives where future held/tied notes can constrain feasibility, and does not charge tied continuations as fresh grip choices. The remaining acoustic placement helper uses the same leading fallback tier.
 
 Silent spans retain the preceding hand position. A continuous accompaniment repeat includes the last-to-first transition. Source-harmony variants, such as relocated pickup harmony, are solved between fixed canonical neighbors without mutating a shared previous-grip state; request order cannot change them. Per-span composition reports include candidate counts, selected family, bass/string family availability, selected positions, bass degree and movement, plus `fret_span`, `span_group` and `span_candidates` (primary/fallback counts before dominance reduction). These are diagnostic sidecar fields; the score/runtime format is unchanged.
 
@@ -143,6 +143,14 @@ Acoustic events use temporary bass/upper notation lanes for projection; then `ac
 
 Monophonic solos use strings 1–6 and frets 1–12, with no open strings or acoustic/electric string restrictions. Placement compares complete paths through legal positions, accounting for hand-region changes, travel time and string crossings. Ties retain their position. Chord placement retains its separate policy: frets 1–20, a sounding anchor on frets 1–12, primary spans of up to three consecutive positions and fallback spans of exactly four. The span is inclusive: 7–9 is three positions, 7–10 is four. Five positions are always invalid. The anchor must remain sounding, including after shorter notes release. Acoustic accompaniment additionally keeps its bass within frets 1–12 and requires an independent anchor in its upper three-note cluster, preserving the option of separate bass/upper attacks. These costs approximate physical feasibility; they do not assign fingers or guarantee comfortable playing.
 
+Acoustic voicing selection retains the lexicographic compact-span and preferred-family tiers. Within those tiers, the whole-form cost is finger travel plus `register_weight * abs(mean sounding MIDI - center)` plus `high_position_weight * max(0, mean fret - comfortable_max_fret)`, summed once per active harmonic span. The acoustic role's `voicing` policy defaults to weights 1 and 1, threshold 9, and the existing register center 53. All arithmetic is rational. Missing allowed tones and the original register distance remain later tie-breakers. Existing finger-travel costs include bass-string changes, source-form repeat joins and neighboring grips; high positions can still win when avoiding a costly shift. No preferred bass string or song-specific grip list is added. The ending uses the same local cost and its incoming grip.
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+Each selected acoustic span reports `voicing_cost` contributions for movement, weighted register, weighted position and their combined effort. These contributions describe the balanced tier, not the higher span/family priorities; repeat-join travel is assigned to the first canonical span. New acoustic `voicing` settings remain in concrete cache dependencies but are excluded from rhythmic choice seeds, including settings overrides, preserving the pre-policy rhythm choices. Other role policies and electric selection are unchanged.
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+Lower-position verification on October 6, 2026: all 400 Python tests and 124 native test cases passed. Native and ARM builds passed asset checks; all 139 score/page files matched byte for byte. Against the saved production output, acoustic rhythms and all other five role documents were identical for both songs. Mean fret across canonical active acoustic grips changed from 8.90 to 4.50 in Autumn Leaves and 5.19 to 4.29 in All of Me; movement costs rose from 144 to 190 and 128 to 140 respectively. In the requested six-chord passage, five suggested grips won; Em7b5 instead chose its valid fifth-bass shape on strings 6/4/3/2 at frets 6/5/7/5. Tests also verify that the complete suggested sequence beats the previous higher sequence with fixed neighbors, and that sufficiently costly travel can still retain a higher grip. These are score/selection facts, not an ear-based audition.
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+Isolated uncached acoustic role generation took 0.61–0.62 seconds per song, versus 0.56–0.58 seconds before this change; cache hits took about 0.048 seconds and matched clean output. With two composition and engraving workers, the native asset rebuild took approximately 11 seconds (4 composing, 6 engraving, 1 other); ARM reused caches and took approximately 6 seconds. These are individual local measurements, not a statistical benchmark. Supplied recordings remain byte-identical.
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 ### Recording Playback and Page Timing
 
 Vamp uses only supplied PCM16 WAVs. `package/assets/sounds/beat1.wav` and `beat2.wav` provide measure accents and ordinary beats. Backing files are `package/assets/backing/<normalized_source_id>_<bpm>.wav`. `generator/performance.py` checks containment, format, decoded length and checksums, then copies the recordings byte for byte into the staged output. A catalog `resources` row stores their paths, checksums, sample rates, channels, frame counts, song IDs and tempos. No note-event audio compiler, pitch synthesizer, release envelope or generated audition audio remains. Pitch mathematics remains for notation, TAB, composition and exact MusicXML comparisons.