fix(editor): normalize chord-template frets, wire-coerce arp, clear solo provenance

[byrongamatos]

Closes #152. Three pre-existing data-integrity bugs in the chord save path, surfaced by CodeRabbit on #151 and each verified by running the real module, not inferred from the diff.

1. relinkChordTemplate stored an un-normalized fret row

relinkChordTemplate([3,2,0,-1,-1,-1], {}, 8).frets.length   → 6   (expected 8)

It did frets: frets.slice() on whatever it was handed. A preserved template can arrive narrower than the chart — buildHandshapeChordIdMap's preserve-append passes one straight off the wire — and a non-finite slot (undefined / NaN / a hand-edited string) rode through untouched.

The fold _fretKeyForL already applied for the lookup key is now a shared _normFretsToL, used by both. Key, preserved-lookup, and stored row can no longer disagree — the same class of bug as the raw-join dedupe key fixed in #151. fingers has always been padded to L this way; frets now matches. Padding only ever appends -1 (unfretted), so no fret data is lost.

2. arp: !!(old && old.arp) turned the string "false" into true

relinkChordTemplate([3,-1,…], { '3,-1,…': { arp: 'false' } }, 6).arp   → true

_safeWireBool lives in that same module for exactly this — its own comment names the case — and simply wasn't used. A hand-edited or legacy sloppak carrying arp: "false" no longer switches arpeggio on across a load→save. Every input the old code accepted as true (true, 'true', '1', 1) still reads true.

3. Solo notes kept _fromChord / _chordId

A chord reduced to one note pushed the survivor by reference with its chord provenance intact. Now cleared alongside _fn.

But not for the reason CodeRabbit gave. None of the three can reach disk — the backend's _note() whitelists the keys it writes. The reason _fn must go is that _groupFn reads it back: a stale _fn would be adopted by majority vote if that note were later dragged into a chord. The comment there claimed the delete was about the wire; corrected. Also fixed the stale claim above flattenChords that reconstructChords groups by time+_fromChord — it groups by rounded time alone.

Not a bug — checked and closed out

CodeRabbit's fourth finding, that time: cn.time || ch.time drops first-beat notes. It doesn't: chord-member time is absolute, so a chord on beat one has cn.time === ch.time === 0. Verified on Arcturus - The Sham Mirrors - Kinetic.feedpak: 66 chords, every member's time equal to its chord's, none zero.

Verification

• node --test 86/86, pytest 248/248.

• Eight new cases in tests/chords.test.mjs — and each was re-run against the un-fixed code to confirm it fails there. A guard that passes both ways guards nothing.

• Real save → reload round-trip through the running server, on the chord-heavy Arcturus pack (8 templates, 66 chords). I intercepted the actual POST body rather than trusting the UI:

  templates with frets width ≠ 6	0
  templates with a non-finite fret	0
  templates with a non-boolean arp	0
  posted notes carrying _fromChord/_chordId/_fn	0
  status	Saved successfully
  templates + chords after reload	8 / 66, unchanged

  To be precise about what that proves: the round-trip shows the new shape is accepted and preserved by routes.py. The discriminating evidence for the bugs themselves is the unit suite above.

• Headless draw / hit-test / resize harnesses green. Codex preflight: NO ISSUES.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Preserved chord shapes now keep their expected width when reloaded, preventing templates from shifting across different string counts.
  • Chord data now handles invalid fret values more safely, avoiding stray placeholder notes in saved handshapes.
  • Arpeggio settings now respect saved false values correctly, so disabled arpeggios stay disabled.
  • Single-note chords no longer inherit stale chord metadata during rebuilds, reducing unexpected chord carryover.

[Copilot]

Pull request overview

This PR fixes three data-integrity bugs in the chord-template save/relink path by ensuring fret rows are width-normalized, arp is wire-coerced correctly (avoiding the "false" → true trap), and chord-provenance internal fields are cleared when a chord collapses to a solo note.

Changes:

• Introduces a shared fret-row normalization fold (_normFretsToL) and uses it for both template keying and stored frets rows.
• Switches relinkChordTemplate’s arp coercion to _safeWireBool to correctly handle "false" and other wire spellings.
• Clears _fn, _fromChord, and _chordId on lone notes during reconstructChords, and adds targeted regression tests covering all three fixes.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/chords.js	Normalizes stored template frets, wire-coerces arp, and clears chord provenance on solo survivors to prevent stale internal state from persisting.
tests/chords.test.mjs	Adds regression tests for fret-row widening/sanitization, arp coercion, and removal of chord-provenance fields on solo notes.
CHANGELOG.md	Documents the three fixed chord-template save-path issues and clarifies the rationale for clearing _fn.

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📒 Files selected for processing (3)

• CHANGELOG.md
• src/chords.js
• tests/chords.test.mjs

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📝 Walkthrough

Walkthrough

Updates chord-template persistence in src/chords.js: fret rows are normalized to chart string width with non-finite slots folded to -1 via a new _normFretsToL helper used by relinkChordTemplate and _fretKeyForL; arp coercion switches to _safeWireBool; solo notes have _fromChord/_chordId cleared alongside _fn. Adds regression tests and changelog entries.

Changes

Chord template and provenance fixes

Layer / File(s)	Summary
Fret-row normalization helper src/chords.js	Adds _normFretsToL to fold non-finite fret slots to -1 and pad/widen rows to chart width L; _fretKeyForL now derives its key from this normalized row.
relinkChordTemplate width and arp fixes src/chords.js, tests/chords.test.mjs	relinkChordTemplate stores normalized fret rows for lookup and output instead of raw frets.slice(), and switches arp handling from !!old.arp to _safeWireBool so string "false" stays falsy; tests cover widening, non-finite folding, narrowed-input lookup, and arp coercion cases.
Solo note provenance cleanup src/chords.js, tests/chords.test.mjs	reconstructChords deletes _fromChord and _chordId alongside _fn when a chord reduces to a single note; comment updated to describe time-only grouping; regression test confirms no provenance tags survive flattenChords/reconstructChords.
Changelog CHANGELOG.md	Documents the fret normalization, arp coercion, and provenance cleanup fixes, plus a note clarifying the time fallback is not a first-beat bug.

Estimated code review effort: 3 (Moderate) | ~25 minutes

Possibly related PRs

• got-feedBack/feedBack-plugin-editor#143: Also modifies the relinkChordTemplate/reconstructChords chord-saving flow and adds a related wire-purity regression test affected by these template/provenance changes.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title concisely names the three main chord-save fixes and matches the PR scope.
Linked Issues check	✅ Passed	The changes implement all three linked chord-save data-integrity fixes and the noted non-bug clarification.
Out of Scope Changes check	✅ Passed	The extra doc/comment updates and tests stay aligned with the linked chord-save fixes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

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• Commit unit tests in branch fix/chord-save-path-152

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