feat(core): per-note bend shape (bt + bnv) — wire + GP import (PR-A) - #531
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Implements feedpak spec §6.2.1 (feedpak 1.4.0) per-note bend shape on the
core side:
- `bn` stays the bend's peak magnitude in semitones (unchanged).
- `bt` — bend intent (0 up, 1 release, 2 pre-bend, 3 pre-bend-release,
4 round-trip), default 0, default-omitted on the wire.
- `bnv` — time-stamped bend curve [{t: seconds-from-onset, v: semitones}],
authoritative when present; default-omitted. Older readers ignore both.
Wire (lib/song.py): Note.bend_intent/bend_values; note_to_wire emits bt/bnv
only when set; note_from_wire reads them via _sanitize_bend_curve (drops
malformed entries, empty -> None never []). _parse_note reads them from the
GP-import XML (bendIntent attr + bendValues JSON) so GP curves survive
import -> XML -> wire -> highway.
GP5 (lib/gp2rs.py): _gp_bend_shape maps pyguitarpro BendPoints to a bnv
curve — semitones = value/2.0 (consistent with the existing scalar bn),
t = position/12 * duration — and _bend_intent_from_values derives bt from
the shape. Emitted for <note> and <chordNote> via the shared _build_xml.
GP8 (lib/gp2rs_gpx.py): _gpx_bend_shape builds a 3-point curve from the
GPIF origin/middle/destination value+offset Properties (value/divisor
semitones, offset/100 * sustain seconds), reusing the shared _build_xml.
GPIF offset Property names should be confirmed against a real GP8 export.
Tests cover wire round-trip + default-omit + sanitization, GP5 unit/time
mapping + intent classification end-to-end through the XML, and the GP8
curve builder.
Part of #334
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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#535) Post-merge Codex review of the bend-curve PRs (#531/#532) surfaced edge cases: - GP8 (#531 P2): bnv timing used rn.sustain, which is zeroed for notes <= 0.2s, so short GP8 bends kept the scalar bn but lost bt/bnv. Use the beat duration `dur` (matching the GP5 path) so the curve survives. - 2D highway (#532 P2): bnvNormalizedPoints mapped x over the curve's own t-range [first,last] instead of the note span, so curves not starting at 0 / ending at sus were time-distorted. Now maps over [0, sus] (clamped), with a curve-span fallback when sus<=0 (existing no-sus callers unaffected). - 3D highway (#532 P3): the sustain ribbon + bend chevron were gated on bn>0, so a note carrying an authoritative bnv with bn==0 drew no ribbon/marker. Both now also fire on bnv presence; chevron steps derived from max(bn, bnv peak). Codex-reviewed: clean (no findings). +1 JS test (sus-relative mapping + fallback). JS 8/8, 250 core GP/song tests pass. NB: GP8's short-bend path still lacks a dedicated synthetic-GPIF fixture (same gap as the GP8 offset-prop-names P3) — _gpx_bend_shape units cover the function; the fix is the one-line caller change. Part of #334. Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Jun 21, 2026
…n (§6.2.2) (#536) Add the three OPTIONAL per-note feedpak 1.5.0 teaching marks — fg (fret-hand finger), ch (strum-group key), sd (scale degree) — to the Note model and wire format, mirroring the bend-shape work (#531). These are DISPLAY/TEACHING ONLY: nothing in the scoring / note-verification path reads them. - lib/song.py: Note.fret_finger / strum_group / scale_degree, default-omitted on the wire (fg/ch/sd) and decoded via _wire_int_optional; _parse_note reads the GP-written fretFinger XML attr. Pure helpers key_to_tonic_pc (§7.7 key name -> tonic pitch class) + scale_degree_for_pitch, plus base_open_string_midis / pitch_from_base / note_pitch_midi (tuning offsets + capo + fret -> MIDI, mirroring app.js _TUNING_BASE_MIDI). - lib/gp2rs.py: GP5 note.effect.leftHandFinger -> fg (RsNote field + fretFinger XML attr), reusing the chord Fingering value convention. - lib/gp2rs_gpx.py: GP8/GPIF per-note <LeftFingering> (p-i-m-a-c letter codes, verified against real GP8 exports) -> fg. - server.py highway_ws: derive sd for notes + chord notes from the active keys.json key + sounding pitch when the author didn't author one (author value wins); base hoisted out of the per-note loop. Tests: round-trip + omit-when-default + malformed-tolerance for fg/ch/sd; key_to_tonic_pc + scale_degree_for_pitch + note_pitch_midi (standard/drop-D/ capo/bass) units; GP5 leftHandFinger and GP8 <LeftFingering> import. Part of #334 Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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What
Implements the core half of per-note bend shape per feedpak spec §6.2.1 (feedpak 1.4.0). This is PR-A of three (PR-A core wire + GP import → PR-B highway render → PR-C editor authoring).
bn(existing) — bend peak magnitude in semitones, unchanged.bt— bend intent (int, default0):0up,1release,2pre-bend,3pre-bend-and-release,4round-trip. Default-omitted on the wire.bnv— time-stamped bend curve:[{ "t": seconds-from-onset, "v": semitones }], non-descendingt, authoritative when present. Default-omitted. Both additive — older readers ignore them.Changes
Wire —
lib/song.pyNote.bend_intent/Note.bend_valuesfields.note_to_wireemitsbtonly when non-zero andbnvonly when present (mirrors the existingln/fhm/… default-omit style).note_from_wirereads them;_sanitize_bend_curvedrops malformed entries (non-finite/non-numeric/non-dict) and collapses empty →None(never[]).chord_note_to_wire/chord_from_wire._parse_notereadsbendIntent+bendValues(JSON) from the GP-import XML, so a GP-imported curve survives import → XML → wire → highway.GP5 —
lib/gp2rs.py_gp_bend_shapemaps pyguitarproBendPoints to abnvcurve:semitones = value / 2.0(consistent with the existing scalarbn),t = position / 12 × duration(BendEffect.maxPosition == 12)._bend_intent_from_valuesderivesbtfrom the curve shape.<note>and<chordNote>via the shared_build_xml.GP8 —
lib/gp2rs_gpx.py_gpx_bend_shapebuilds a 3-point curve from the GPIF origin/middle/destination value+offset Properties (value / divisorsemitones,offset / 100 × sustainseconds), reusing the shared_build_xml.Testing
PYTHONPATH=lib python -m pytest tests/test_song.py tests/test_gp2rs.py tests/test_gp2rs_gpx.py -q→ 250 passed. Full suite green except the 2 pre-existingtest_diagnostics_bundlefailures (username-path redaction; fail on cleanmaintoo)._parse_note→note_to_wire.Codex preflight (read-only): no P1/P2 findings.
Notes / follow-ups
BendOriginOffset/BendMiddleOffset1/BendDestinationOffset) should be confirmed against a real GP8 export — there are no.gpxfixtures in-repo; the value path matches the existing scalar-bend extraction regardless, and missing offsets fall back to even spacing.Part of #334
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