[Dong1017]

First-time previews fail after TTS because the browser timeline has not been exported. Music also stops early when the final scene outlasts its narration. This follow-up to #388 addresses both review findings.

• Document python render.py . count immediately after TTS and before preview. It exports the current timeline and configured FPS, including after updates, without duplicating the renderer's export logic.
• Pad mixed narration to the complete timeline before splitting the voice and sidechain inputs, so music continues through the scene tail and fades out.
• Add real-browser checks for first and updated previews, plus a six-second FFmpeg regression with short narration, late music samples, and a fade-out assertion.

Validation:

• The audio regression fails on the previous renderer with zero RMS at 2 seconds; it passes after this fix, with nonzero RMS at 2, 3.5, 4.5 and 5.5 seconds and decreasing final fade level.
• All 6 video tests pass with Chromium and FFmpeg installed.
• Focused video, installer and packaged-runtime pytest suite: 21 passed, 2 optional browser skips in the default Python environment. The browser checks pass in the video environment above.
• Skill validation, test-file Ruff and git diff --check pass. The renderer retains four pre-existing E741 variable-name findings; this change does not expand into their cleanup.
• No online TTS requests are required for these checks.

Original review threads:

• feat(skills): add explainer-video workflow and templates #388 (comment)
• feat(skills): add explainer-video workflow and templates #388 (comment)

[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	⚠️ Failed 2026-10-28T09:57:07.322806Z We couldn’t complete this review. Comment @codex review to try again.	b1cdced	PR opened

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