Build cohesive MIDI Studio V2 visual music studio prototype - PR_26146_020-midi-studio-v2-visual-studio-prototype

Author: ToolboxAid

docs/dev/reports/PR_26146_020-midi-studio-v2-signal-style-note-table_validation.md

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+# PR_26146_020 MIDI Studio V2 Signal-Style Note Table Validation
+
+## Scope
+- Replaced the dense MIDI Studio V2 multi-instrument grid body with a Signal-style note table.
+- Kept the first column as `Instrument`, followed by timing/note columns aligned by bar and beat.
+- Moved section labels and normalized stats/warnings outside the note table body while preserving diagnostics outside the table.
+- Updated the explicit example/test song to Twinkle Twinkle Little Star with Chords, Bass, Pad, Lead, and Drums rows.
+- Preserved Load Example And Play, Stop All Audio, Preview Synth playback, playhead alignment, mute/solo row controls, note editing, generated lanes, MIDI inspection, and honest export status behavior.
+- No SoundFont playback, rendered export implementation, MIDI input/recording, inline script/style blocks, or inline event handlers were added.
+
+## Changed Files
+- `tools/midi-studio-v2/js/MidiStudioV2App.js`
+- `tools/midi-studio-v2/js/controls/InstrumentGridControl.js`
+- `tools/midi-studio-v2/index.html`
+- `tools/midi-studio-v2/styles/midiStudioV2.css`
+- `tests/playwright/tools/MidiStudioV2.spec.mjs`
+- `docs/dev/reports/PR_26146_020-midi-studio-v2-signal-style-note-table_validation.md`
+- `docs/dev/reports/codex_review.diff`
+- `docs/dev/reports/codex_changed_files.txt`
+- `docs/dev/reports/playwright_v8_coverage_report.txt`
+- `docs/dev/reports/coverage_changed_js_guardrail.txt`
+- `docs/dev/codex_commands.md`
+- `docs/dev/commit_comment.txt`
+
+## Validation
+- PASS: `node --check tools/midi-studio-v2/js/controls/InstrumentGridControl.js`
+- PASS: `node --check tools/midi-studio-v2/js/MidiStudioV2App.js`
+- PASS: `node --check tests/playwright/tools/MidiStudioV2.spec.mjs`
+- PASS: external HTML guard checked `tools/midi-studio-v2/index.html`; only external script references were found and no inline style/event handlers were added.
+- PASS: `npx.cmd playwright test tests/playwright/tools/MidiStudioV2.spec.mjs --grep "Twinkle|loads example and starts audible|edits spreadsheet|applies Preview Synth"`
+  - Result: 4 passed.
+- PASS: `npx.cmd playwright test tests/playwright/tools/MidiStudioV2.spec.mjs --grep "renders an aligned|reports grid note"`
+  - Result: 2 passed after replacing stale old-grid section-label assertions with summary-area checks.
+- PASS: `npx.cmd playwright test tests/playwright/tools/MidiStudioV2.spec.mjs`
+  - Result: 37 passed.
+- PASS: `git diff --check`
+- PASS: `git diff --check HEAD~1 HEAD`
+
+## Coverage Reports
+- Updated `docs/dev/reports/playwright_v8_coverage_report.txt`.
+- Updated `docs/dev/reports/coverage_changed_js_guardrail.txt`.
+- Guardrail status: advisory PASS, no changed runtime JS coverage warnings.
+
+## Environment Notes
+- Chromium was missing from the repo-local Playwright browser cache, so Chromium was installed under `node_modules/.cache/ms-playwright` for validation.
+- The repo-local Playwright browser cache was removed after validation.
+
+## Skips
+- Full samples smoke test: SKIPPED per request.
+- Workspace Manager V2 registration/handoff: SKIPPED because this PR did not touch Workspace V2 registration or handoff.
+
+## ZIP
+- Repo-structured delta ZIP: `tmp/PR_26146_020-midi-studio-v2-signal-style-note-table_delta.zip`