feat(editor): scale-degree overlay on fretted notes (in-key highlight)

[ChrisBeWithYou]

DAW roadmap 4.16a — the guitar-lane scale-degree tint. Its prerequisite (the D4 tuning→pitch resolver, _soundingPitchPure) shipped in #115. Editor-only.

What

With the in-key highlight active, each note in String view now shows a small scale-degree label in its top-right corner — 1, ♭3, 5, ♭7, … relative to the current key — coloured by role so the 1/3/5/7 harmonic skeleton pops:

• root → gold · thirds (min/maj) → sky · fifth → green · sevenths (♭7/maj7) → violet · everything else → neutral tint.

Out-of-key notes still show their chromatic degree, dimmed, so a fretted line reads as scale degrees at a glance. Capo- and tuning-aware (it reuses the exact sounding pitch the in-key shading already computes). Shown only while the highlight is on; skipped for any note whose pitch can't be resolved. Display-only — it never edits the chart or the authored sd teaching mark, and the keys view / piano roll are untouched.

Implementation

• @pure:scale-degree: _scaleDegreeSemisPure / _scaleDegreeLabelPure (degree relative to the tonic, flats for the chromatics) + _scaleDegreeColorPure (the role palette).
• _drawNote: hoists the sounding pitch (degMidi) it already resolves for the in-key shading, then draws the degree label top-right when ghl is present. Zero extra per-note arrangement work.

Tests — tests/scale_degree.test.js (6, all fail on main)

Degree wrap in both directions, the full chromatic label row, a real A-major key (A=1, E=5, C#=3, G#=7), the non-finite guard, and the role palette (distinct 1/3/5/7, shared min/maj 3rd and 7th colours, neutral passing tones). Full JS suite green.

Scope / fresh region

New @pure:scale-degree block by @pure:scale, plus the overlay in _drawNote (the String-view note render) — a region no open PR touches (#126's roll work was in _drawPianoNote). No core, no spec.

Summary by CodeRabbit

• New Features

  • Added scale-degree labels for fretted notes in String view when key highlighting is active.
  • Labels are key-relative and role-colored; in-key notes display accents by chord-tone role, while out-of-key notes are dimmed using chromatic degrees.
  • Overlay is display-only and won’t alter your chart or any authored note data.

• Tests

  • Added automated coverage for chromatic spelling, degree wrapping, color roles, and edge cases (including non-finite inputs).

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: e1b68828-9891-4d8c-9ce1-4094e9a7fe35

📥 Commits

Reviewing files that changed from the base of the PR and between c88b58a and 243b924.

📒 Files selected for processing (2)

• CHANGELOG.md
• screen.js

📝 Walkthrough

Walkthrough

This PR adds a scale-degree overlay for fretted notes in screen.js, using sounding-pitch-based degree resolution to color and label notes when key highlighting is active. It also adds standalone tests and a changelog entry.

Changes

Scale-degree overlay feature

Layer / File(s)	Summary
Scale-degree helpers and rendering integration screen.js	Adds pure label/color helpers, computes degMidi per note, uses it for outOfKey evaluation, and draws the conditional degree overlay when key highlighting is active.
Scale-degree test coverage tests/scale_degree.test.js	Adds a Node.js script that extracts the pure helper block from screen.js and validates semitone wrapping, label output, input handling, and role/color mapping, with pass/fail reporting.
Changelog documentation CHANGELOG.md	Adds an Unreleased changelog entry describing the overlay behavior and its display-only scope.

Estimated code review effort: 2 (Simple) | ~15 minutes

Possibly related PRs

• got-feedBack/feedBack-plugin-editor#108: Both changes touch the key/scale in-key rendering path and out-of-key note styling in screen.js.
• got-feedBack/feedBack-plugin-editor#115: Both changes rely on capo-aware sounding-pitch resolution used for fretted-note highlighting.

🚥 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 clearly and concisely describes the main editor change: a scale-degree overlay on fretted notes when in-key highlighting is active.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/editor-scale-degree-tint

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