feat(editor): transport control bar + dual-domain LCD (workspace-shell B2)

[ChrisBeWithYou]

What

The workspace-shell's transport bar (charrette §2.4 / D-C3): one always-present row directly above the timeline —

[Parts Mix Follow] │ ⏮ ⏪ ■ ▶/⏸ ⏩ ● │ LCD │ [Click Clap A/B Snap] ▾

The LCD ports Virtuoso's recessed-panel skin grammar (.editor-lcd-*) with the commit wiring rebuilt against the editor's audio-anchored tempo map:

• Position (bars:beats:ticks) and Time (m:ss.mmm) together, both computed through beatOf/timeOf — the beat-primary pillar made literal — with a ▸ toggle for which is primary. Editing either seeks; Enter applies, Escape reverts.
• Tempo semantics by mode: an editable input in free (no-audio) mode, committing through the same editorSetBPM path as the toolbar control (flatten-confirm included); with a recording present the grid is fitted to the audio, so the cell becomes a derived readout wearing the AUDIO badge and BPM editing stays with Tempo Map/Sync. A mode badge (AUDIO/FREE) names the semantics.
• Key writes through to the Key controls; Meter is a readout (meter edits live in Tempo Map mode); Sel counts the selection.
• Customize Control Bar (▾ or right-click, Logic idiom): show/hide the utility groups and each LCD cell; persisted as an editor pref, never in the pack.

Every button delegates to the existing command surface (a re-presentation, not a re-plumb) and mirror state re-syncs from the source of truth on each tick, so the old toolbar and this bar coexist without drifting until B4/B5 re-home the toolbar.

Deliberate scope cuts

• No master-mute — mute/solo are per-track, in the mixers (§2.6, product-owner decision).
• No Count-in cell / Count toggle — the editor has no count-in feature; an editable cell must write through to a real control, so both arrive with that feature.

Discipline

• Keydown inside an LCD field stops propagation — the canvas shortcut layer never sees typing (space can't toggle play mid-edit).
• LCD refreshes ride the transport tick (updateTimeDisplay) + selection refreshes (updateStatus), never draw(); every DOM write is skip-if-unchanged.
• In-DOM listeners die with the screen DOM; the one document-level listener (menu click-away) rides the teardown registry — re-injection can't stack copies.

Tests

tests/transport_lcd.test.mjs (12, real-import): BBT format/parse as inverses on a drifting grid (a constant-BPM conversion visibly fails the fixture), tick rollover, degenerate-grid degradation to time-only, meter across a mid-song signature change, the BPM-semantics decision, the Enter/Escape keystroke policy, and pref corruption tolerance. Full suite 91/91 · ESLint 0 errors · CHANGELOG updated.

Screenshots (module rendered with real state, both modes + customize menu) shared with Christian during review.

🤖 Generated with Claude Code

https://claude.ai/code/session_01EBQCHCNA81E9tHmSDHSe2Q

Summary by CodeRabbit

• New Features
  • Added a persistent transport control bar above the timeline with transport controls plus a combined Position/Time LCD driven by the tempo map (including meter and tempo readouts).
  • Updated the LCD experience with a primary-domain ▸ toggle, Enter-to-apply / Escape-to-revert editing, and a customizable display (with show/hide preferences persisted).
  • Improved responsiveness by syncing LCD updates with transport time/status while avoiding interruptions to active editing.
  • Added transport bar menu interactions (click-away to dismiss) and record-state styling.
• Tests
  • Added automated coverage for LCD formatting/parsing, tempo-map drift conversions, meter/tempo readouts, edit key behavior, and preference parsing.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

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Run ID: 8650aba7-69e8-4bf5-be34-6f846dd4a203

📥 Commits

Reviewing files that changed from the base of the PR and between 735c631 and c1cbc20.

📒 Files selected for processing (3)

• CHANGELOG.md
• assets/v3-theme.css
• screen.html

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📝 Walkthrough

Walkthrough

Adds a persistent transport control bar above the timeline with tempo-map-driven Position/Time LCD readouts, editable fields, customization persistence, transport controls, optimized refreshes, styling, editor wiring, and pure-helper tests.

Changes

Transport bar and LCD

Layer / File(s)	Summary
LCD conversion and preference contracts src/transport-bar.js, tests/transport_lcd.test.mjs	Adds clock and bar/beat/tick formatting and parsing, tempo-map meter and tempo readouts, transport-mode semantics, key actions, preference normalization, and corresponding tests.
Transport bar and LCD construction screen.html, src/transport-bar.js, assets/v3-theme.css	Adds the above-timeline container, dynamically builds transport controls, LCD cells, and customization menu, and styles their states and editable readouts.
Transport controls and LCD editing src/transport-bar.js	Wires seeking, transport buttons, LCD commit/revert behavior, validation, menu persistence, reset handling, click-away dismissal, and audio-dependent tempo display rebuilding.
Editor initialization and refresh wiring src/main.js, CHANGELOG.md	Initializes the bar at editor startup, refreshes it during time and status updates, and documents the feature.

Estimated code review effort: 4 (Complex) | ~45 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Editor as Editor
  participant TransportBar as transport-bar.js
  participant TempoMap as Tempo map
  participant LCD as Position/Time LCD
  Editor->>TransportBar: Initialize transport bar
  Editor->>TransportBar: Refresh on time/status update
  TransportBar->>TempoMap: Convert cursor time to LCD values
  TempoMap-->>TransportBar: Position, meter, and tempo
  TransportBar->>LCD: Update readouts and mirror states
  LCD->>TransportBar: Commit edited field
  TransportBar->>Editor: Apply seek or editor setting

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🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 52.17% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: an editor transport bar with a dual-domain LCD.
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-transport-lcd

⚔️ Resolve merge conflicts

• Resolve merge conflict in branch feat/editor-transport-lcd

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[coderabbitai]

Actionable comments posted: 3

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/transport-bar.js`:
- Around line 303-310: Update the Record button construction in the transport
bar so `tbtn()` receives or combines the `editor-transport-rec` class with its
default `editor-transport-btn` class, rather than appending a second class
attribute. Ensure the generated Record button contains both classes and
preserves its existing label and behavior.
- Around line 59-64: Update _lcdClockPure so millisecond rounding carries into
seconds and minutes instead of being reduced with % 1000; round the total
milliseconds first, then derive minutes, seconds, and milliseconds from that
normalized value while preserving the existing invalid/negative input handling
and output format.
- Around line 84-127: Update _lcdBBTPure and _lcdParseBBTPure to enforce valid,
round-trippable bar:beat:tick values: carry rounded ticks and beat overflow
across measure boundaries using the next labeled downbeat, reject beat numbers
beyond the current measure’s span during parsing, and explicitly handle pickup
positions before the first labeled downbeat so they never produce zero or
negative beats. Preserve non-dense imported measure lookup rather than deriving
bar numbers arithmetically.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: d64580ad-af59-412a-888b-90e6ef6bd03b

📥 Commits

Reviewing files that changed from the base of the PR and between 2ec753b and f711b2c.

📒 Files selected for processing (6)

• CHANGELOG.md
• assets/v3-theme.css
• screen.html
• src/main.js
• src/transport-bar.js
• tests/transport_lcd.test.mjs