/create-lesson-from-source

Create a series of lesson videos based on content from: $ARGUMENTS

This command extracts content from an external source and breaks it into a multi-part lesson series — connected videos that teach the topic step by step.

Step 0: Extract Content from Source (with Caching)

1. Read the extract-content skill carefully — it contains the ONLY working method for YouTube transcripts AND the source caching system
2. Check source cache first:
   • Determine the cache key (e.g., yt-{VIDEO_ID}, article-{slug}, pdf-{slug})
   • Check if outputs/_sources/{cache-key}/ exists
   • If cached: Read transcript.txt/raw-content.txt and content-brief.md from cache — skip extraction entirely
   • If not cached: Extract content (see below), then save to outputs/_sources/{cache-key}/
3. If extraction is needed, identify the source type:
   • YouTube URL → MUST use youtubetotranscript.com. Extract video ID from URL, navigate Chrome to https://youtubetotranscript.com/transcript?v={VIDEO_ID}, extract text from #transcript element via javascript_tool (chunk in 12K pieces for large transcripts). Do NOT try to extract transcript directly from youtube.com — it will fail.
   • PDF file → Read tool or pdf skill
   • Article URL → WebFetch
4. Save to source cache (if newly extracted):
   • mkdir -p outputs/_sources/{cache-key}/
   • Save raw content as transcript.txt (YouTube) or raw-content.txt (article/PDF)
   • Save content-brief.md and metadata.json
5. Create a Content Brief with the full Series Breakdown (see extract-content skill) — or load existing from cache
6. The extraction should be thorough — we need enough material for multiple lessons

Extraction Depth by Source Length

Source Length	Recommended Lessons	Notes
Short article / 5-10min video	3 lessons	Focus on depth, not breadth
Medium article / 10-30min video	4-5 lessons	Natural chapter breaks
Long PDF / 30min+ video	5-8 lessons	Group related topics
Book / course material	8-12 lessons	One lesson per chapter/module

Step 1: Plan the Series

1. Based on the Content Brief, break the source into lesson-sized chunks
2. Each lesson should cover one clear concept (not too much, not too little)
3. Plan the series arc:
   • Lesson 1: Hook + Why this matters — set the stage, create urgency
   • Middle lessons: Core teaching — one concept per lesson, building complexity
   • Final lesson: Recap + actionable CTA — bring it all together
4. Write a Series Outline (see format below)
5. Show the outline to the user and get approval before creating any videos

Series Outline Format

# Series: {Series Title}
## Source: {source type} — {source title/URL}
## Lessons: {count}
## Duration per lesson: {duration}s

---

### Lesson 1: {Title}
- **Source section**: [which part of the source this covers]
- **Key points**: [point 1], [point 2], [point 3]
- **Hook**: "[opening line]"
- **Connects to next**: "[teaser for lesson 2]"

### Lesson 2: {Title}
- **Source section**: [which part of the source this covers]
- **Key points**: [point 1], [point 2], [point 3]
- **Recap from previous**: "[brief callback]"
- **Connects to next**: "[teaser for lesson 3]"

[... etc]

### Lesson {N}: {Title} (Finale)
- **Source section**: [final section / summary]
- **Key points**: [key takeaway 1], [key takeaway 2]
- **Series recap**: "[what we learned]"
- **CTA**: "[call to action]"

Step 2: Set Up Series Folder

1. Choose a descriptive kebab-case slug (e.g., hormozi-offers-lekce, seo-zaklady-serie)
2. Create series root: mkdir -p outputs/{series-slug}/
3. Each lesson subfolder: outputs/{series-slug}/lesson-01-{lesson-slug}/
4. Save the series outline + Content Brief in the root folder

Step 3: Design Series Visual Style

Define consistent visual identity BEFORE creating individual lessons:

1. Color palette — derived from the source topic, consistent across all lessons
2. HTML template — shared layout structure for all lessons
3. Lesson number badge — "Lekce X/Y" visible in every video (top-right corner)
4. Series title — shown at start of each video
5. Source attribution — subtle "Zdroj: {source}" in the last scene of each video
6. Branding — "@michalvarys.eu" + "Start a Business" in every video
7. End teaser — last scene of each lesson (except final) teases the next topic

Lesson Badge CSS

.lesson-badge {
  position: fixed;
  top: 3vh;
  right: 4vw;
  background: linear-gradient(135deg, rgba(255,255,255,0.15), rgba(255,255,255,0.05));
  border: 1px solid rgba(255,255,255,0.2);
  border-radius: 12px;
  padding: 0.8vh 2vw;
  font-size: clamp(0.9rem, 2.2vh, 2.5rem);
  font-weight: 700;
  color: rgba(255,255,255,0.9);
  z-index: 100;
}

Step 4: Create Each Lesson Video

For EACH lesson, follow the full video pipeline:

Design HTML

• Use the series template, customize for this lesson's content
• Include lesson number badge ("Lekce X/Y")
• Map source content to visual scenes (key quotes, data, examples from the source)
• Follow all typography rules (body: clamp(1.2rem, 3.2vh, 3.5rem)+)
• First animation at 0.3–0.5s, no dead gaps
• NEVER use emoji — always inline SVG icons

Render Video

• Playwright + ffmpeg, 1080x1920 (9:16)

Validate Rendered Video (MANDATORY)

1. Read the validate-video skill
2. Run validation on the HTML + silent video:

   node validate-video.mjs outputs/{series-slug}/lesson-{NN}-{slug}/lesson-{NN}-video.html {duration} 1080 1920
   

3. If any check FAILs — STOP, fix HTML, re-render, re-validate
4. Do NOT proceed to voiceover until validation passes

Generate Voiceover

• Read generate-voiceover skill
• Write script targeting ~2s shorter than video (~2.5 words/sec)
• Content derived from the source material for this lesson
• Reference the series: "V této lekci se podíváme na...", "V minulé lekci jsme zjistili..."
• First sentence = immediate hook, no filler

Verify Voiceover Duration & Adjust Video (MANDATORY)

TTS output duration is unpredictable — you MUST verify and adjust.

ffprobe -v error -show_entries format=duration -of csv=p=0 voiceover.mp3

• If voiceover > (video - 2s): EXTEND THE VIDEO
  • New duration = ceil(voiceover_duration) + 2
  • Rescale ALL animation-delay and sceneVis durations by new_duration / old_duration
  • Update DURATION in render script, re-render
  • Do NOT regenerate TTS — extend the video instead
• If voiceover < (video - 5s): Regenerate with longer script or shorten video
• Proceed only when gap is 1.5–5s

Generate Background Music

• Read generate-background-music skill
• Use the SAME music prompt for all lessons (consistent feel across the series)
• Upbeat, energetic style
• Duration matches the (possibly extended) video

Mix Audio

ffmpeg -y -i voiceover.mp3 -i bg_music.mp3 \
  -filter_complex "[0:a]volume=1.0[vo];[1:a]volume=0.015[bg];[vo][bg]amix=inputs=2:duration=first:dropout_transition=3:normalize=0[out]" \
  -map "[out]" -c:a aac -b:a 192k mixed_audio.m4a

Voiceover at 100%, bg at 1.5%, normalize=0 mandatory.

Merge with Video

ffmpeg -y -i video.mp4 -i mixed_audio.m4a \
  -c:v copy -c:a aac -b:a 192k -shortest \
  -map 0:v:0 -map 1:a:0 {slug}-final.mp4

Validate Final Video (MANDATORY)

1. Run full validation:

   node validate-video.mjs outputs/{series-slug}/lesson-{NN}-{slug}/lesson-{NN}-video.html {duration} 1080 1920 outputs/{series-slug}/lesson-{NN}-{slug}/lesson-{NN}-voiceover.mp3 outputs/{series-slug}/lesson-{NN}-{slug}/lesson-{NN}-final.mp4
   

2. If any check FAILs — fix and re-validate
3. Do NOT start the next lesson until this one passes all checks

Generate Thumbnail (MANDATORY)

Every lesson MUST have a thumbnail — without it, videos appear as blank/black in platform grids.

1. Use Puppeteer to screenshot the HTML at 3 seconds (when Scene 1 hook text + subtitle are fully visible)
2. Save as thumbnail.png (1080×1920 PNG) in the lesson folder
3. For batch generation across all lessons, create a simple script:

const page = await browser.newPage();
await page.setViewport({ width: 1080, height: 1920 });
await page.goto(`file://${htmlPath}`, { waitUntil: "networkidle0" });
await new Promise(r => setTimeout(r, 3000)); // Wait for hook animations
await page.screenshot({ path: "thumbnail.png", type: "png" });

4. The thumbnail will be included when publishing (see publish-post skill — thumbnail field)

Generate Captions

• Platform-specific text with series context
• Include "Lekce X/Y" in every caption
• Reference the source: "Inspirováno: {source title}"
• Consistent series hashtag across all lessons

Step 5: Deliver

1. Show ALL lesson videos to the user
2. Display the full folder structure
3. Ask the user:
   • Publish all at once or schedule?
   • Suggested cadence: one lesson per day or Mon/Wed/Fri
   • Any adjustments to specific lessons?
4. If scheduling, use the schedule-post skill