refactor(editor): remove the transport seek bar

[EtienneLescot]

Summary

• The timeline already seeks. Clicking or dragging the ruler right below moves the playhead, and ←/→ step a frame. The header bar was a second control for the same thing.
• The header row is now tools, ▶ and the timecode, then the Pan/Zoom hints. The freed width makes the controls easier to read.
• Cleanup that follows: the bar's rAF coalescing and its tests, its CSS, the transport.seekVideo key in all 15 locales, the probe's bar scrub source, and the checklist item that dragged the bar. The ruler items of the checklist already cover seeking.
• Only loss: Home/End jumped to the start or end, but only while the bar had focus. No global shortcut replaces them yet.

Related issue

Part of #814, the audit integration.

Type of change

• Bug fix
• Feature
• Enhancement
• Documentation
• Refactor / maintenance
• Performance
• Security

Release impact

• Patch
• Minor
• Major / breaking change
• No release note needed

Desktop impact

• Windows
• macOS
• Linux
• Installer / packaging
• Not platform-specific

Screenshots / video

Before: the violet seek bar filled the header between the timecode and the Pan/Zoom hints. After: nothing between them. Checked in the browser-only v4 preview, dark theme.

Testing

• npm run test: 274 files, 3566 tests passed, 5 skipped. CI does not run on this base branch.
  28 files dropped out of the first run on worker start timeouts; they pass on a rerun with --maxWorkers=4.
• Both tsc configs, Biome, npm run i18n:check.
• Browser-only v4 preview (vite.v4preview.config.ts): the "Playback controls" toolbar holds only Play/Pause and the timecode, and no seek control is left on the page.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Interface Changes
  • The transport bar displays playback controls and timecode without a seek bar. Seeking from the transport bar is no longer available; timeline seeking remains available while paused or playing.
  • The displayed timecode continues to reflect playback updates and active scrub positions.
  • Transport labels have changed across supported languages.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: 4f15f40a-bb1b-49b6-bba7-b4cf38fa9c81

📥 Commits

Reviewing files that changed from the base of the PR and between 3d25465 and d726af1.

📒 Files selected for processing (21)

• src/components/ai-edition/NewEditorShell.module.css
• src/components/ai-edition/TransportBar.test.tsx
• src/components/ai-edition/TransportBar.tsx
• src/components/ai-edition/v4/V4Timeline.tsx
• src/i18n/locales/ar/editor.json
• src/i18n/locales/cs/editor.json
• src/i18n/locales/de/editor.json
• src/i18n/locales/en/editor.json
• src/i18n/locales/es/editor.json
• src/i18n/locales/fr/editor.json
• src/i18n/locales/it/editor.json
• src/i18n/locales/ja-JP/editor.json
• src/i18n/locales/ko-KR/editor.json
• src/i18n/locales/pt-BR/editor.json
• src/i18n/locales/ru/editor.json
• src/i18n/locales/tr/editor.json
• src/i18n/locales/vi/editor.json
• src/i18n/locales/zh-CN/editor.json
• src/i18n/locales/zh-TW/editor.json
• src/lib/ai-edition/perf/uiFrameProbe.ts
• technical-documentation/testing/manual-e2e-checklist.md

💤 Files with no reviewable changes (3)

• src/components/ai-edition/v4/V4Timeline.tsx
• src/components/ai-edition/NewEditorShell.module.css
• technical-documentation/testing/manual-e2e-checklist.md

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📝 Walkthrough

Walkthrough

The transport bar now shows playback controls and timecode without a seek bar. Related scrub styles, seek translations, tests, and checklist coverage were removed. UI frame probe measurements now combine timeline and bar scrubbing states.

Changes

Transport scrubbing

Layer / File(s)	Summary
Combine scrub probe states src/lib/ai-edition/perf/uiFrameProbe.ts	The probe records scrubbing as a boolean. It reports a combined scrub state, with or without preview activity, instead of separate timeline and bar states.
Remove transport seeking src/components/ai-edition/TransportBar.tsx, src/components/ai-edition/TransportBar.test.tsx, src/components/ai-edition/v4/V4Timeline.tsx, src/components/ai-edition/NewEditorShell.module.css, src/i18n/locales/*/editor.json, technical-documentation/testing/manual-e2e-checklist.md	TransportBar no longer accepts onSeek or renders a scrub bar. The timeline call no longer passes onSeek. Tests, scrub styles, transport.seekVideo translations, and the seek-control checklist item were removed.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Other

Suggested reviewers: my-denia

Merge Risk: ⚪ Minimal · up to d726a

The ruler remains available for seeking, and no actionable regression from removing the header seek bar was identified. The PR is mergeable after normal checks.

Security Architecture Review

Security architecture risk: 🔵 Low · up to d726a

The remaining seek control uses the existing timeline path, and no new security exposure was identified. Diagnostic report labels have changed; whether anything outside the editor relies on the old labels is unknown.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — Removing the header input reduces the available UI routes to the existing project-playhead update; the reviewed change does not add a new caller or privilege to that path.

Trust Boundaries and Controls

• observed — Timeline pointer coordinates are clamped to the canvas before seeking. The changed transport component no longer handles pointer-derived seek values.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 40.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 5 functions across 3 files. (15 skipped: …	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: removing the editor transport seek bar.
Description check	✅ Passed	The description includes all required template sections. It explains the change, related issue, change types, release impact, platform impact, visual result, testing, and the known Home/End behavior l…
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.

Full details: Docstring Coverage

Explanation

Docstring coverage is 40.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 5 functions across 3 files. (15 skipped: 15 unsupported.)

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[EtienneLescot]

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