atomize-course-chapter

---

name: atomize-course-chapter description: Convert a long, flat course chapter (a single wall-of-text .mdx) into a nested hub + a stream of bite-size interactive "atoms" in apps/course (Next.js + Fumadocs). Use this when someone wants to atomize a chapter — or a whole course — of growth-with-posthog: it walks the proven "atom factory" pipeline end to end (pull transcripts → snapshot the block inventory → split into hub + atoms per the authoring contract → delete the flat file → regenerate + verify the manifest hasn't drifted → run gates → one commit per chapter). Reproduces chapters 0 and 1, which already ship in this shape.

Atomize a course chapter (the atom factory)

Turn one flat chapter (content/courses/growth-with-posthog/NN-slug.mdx, a long wall of text) into a nested folder: a short hub page + 6–12 bite-size atoms. The pattern already ships for chapters 00-product-led-growth and 01-what-is-posthog — your output must be indistinguishable in shape from those. Read them before you start.

Factory-shaped, not book-shaped. You are not chopping a book into smaller book-chunks — you're running a production line. Raw material = the existing long MDX + its embedded YouTube videos. Output = many small atoms, each a satisfying 1–3 minute loop: read one idea → one interaction → done-tick → next. Atoms are also the substrate for the planned in-course agent and certification, which need atoms not walls. You do not write new content and you do not build machinery — the workbook/quiz/video/progress platform already ships.

Preconditions & where things live

• Work from apps/course (all commands below assume cd apps/course). App = Next.js + Fumadocs; dev server runs on port 3006.
• Course content: content/courses/growth-with-posthog/. A flat chapter is NN-slug.mdx; an atomized chapter is a folder NN-slug/ with index.mdx (hub) + meta.json + NN-atom.mdx.
• Reference chapters to imitate: 00-product-led-growth/ and 01-what-is-posthog/.
• The authoring contract this skill enforces (verbatim source): read 01-what-is-posthog/{index.mdx,meta.json,01-why-measure.mdx,04-two-demos.mdx,10-set-up-account.mdx} as the canonical examples of a hub, a CheckIn atom, a two-video atom, and the final atom.
• yt-dlp must be on PATH for transcript pulls.
• Lesson identity in the app is slugs.slice(1).join("/") — so atom NN-slug/MM-atom.mdx is the lesson NN-slug/MM-atom, and index.mdx collapses to the chapter slug NN-slug (Fumadocs strips index). The numeric NN-/MM- prefixes make sidebar order == reading order == manifest DFS order.

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The pipeline — per chapter, in order

1. Pull transcripts

cd apps/course
node scripts/pull-transcripts.mjs        # scans ALL course MDX, pulls MISSING transcripts
node scripts/generate-transcripts.mjs    # bundles content/transcripts/*.md -> lib/transcripts.generated.json

pull-transcripts.mjs needs yt-dlp on PATH and hits YouTube, which rate-limits (HTTP 429) — a per-video failure is logged and skipped, never fatal. Re-run to fill gaps. To force specific ids: node scripts/pull-transcripts.mjs <id> <id>. You need a transcript for every <VideoEmbed id="…"> in the chapter before you write its "watch & digest" digests.

2. Snapshot the block inventory (your verification baseline)

Before touching anything, record the chapter's current interactive-block keys. This is the safety net for step 6 — atomizing relocates blocks across files but must not change their ids/counts.

# Sorted list of every interactive-block key for the chapter (save it as the baseline).
node -e 'const m=require("./lib/workbook-manifest.generated.json");const ch=process.argv[1];const c=m["growth-with-posthog"]||{};const keys=Object.entries(c).filter(([k])=>k===ch||k.startsWith(ch+"/")).flatMap(([,items])=>items.map(i=>i.key)).sort();console.log(keys.join("\n"))' 02-aarrr-and-the-leaky-bucket > /tmp/atoms-baseline.txt
cat /tmp/atoms-baseline.txt

(Swap 02-aarrr-and-the-leaky-bucket for your chapter slug.) Keys look like profile:teamSize, media:WPjJLpNxI6s, checklist:…, note:…, flashcards:cards-posthog, quiz:growth-with-posthog/NN-slug. Note the quiz key is path-derived — it will legitimately change when the flat file becomes a nested folder (see step 6). Every id-keyed block (profile/media/checklist/note/flashcards) must survive the move unchanged.

3. Split the flat chapter into hub + atoms (the authoring contract)

Create content/courses/growth-with-posthog/NN-slug/ and write meta.json, index.mdx, and one NN-atom.mdx per atom. Rules (summarized from the atom contract — the reference chapters are the ground truth):

• Seams = ## (h2) sections. One atom per ## by default. Merge two tiny adjacent sections (each a single paragraph) into one atom; split one overlong section that clearly holds two separable ideas. Target 6–12 atoms. ### subsections stay INSIDE their parent atom. Preserve original order.
• Atom slugs are short, kebab-case, describe the idea (not "section-2-3"): ## 2.3 Activation and the aha moment → 03-activation-aha.mdx.
• Prose: keep the author's voice and facts — trim each section to its single point, lightly tighten transitions that referenced neighbouring sections, but do NOT rewrite or summarise the substance. Keep tables, code blocks, lists intact.
• Interactive blocks — COPY VERBATIM (highest-risk rule). <CheckIn>, <Flashcards>, <Quiz>, <WorkbookPrompt>, <Checklist>, <VideoEmbed>, <PodcastLink> are persistence-keyed by their id (Quiz by lesson path). Copy each block character-for-character from the source — every id, every entry in a cards={[…]}/questions={[…]}/options={[…]}/items={[…]} array, every attribute. Never rename an id, reword a card, add/remove/reorder an array entry, or reformat props. Changing anything silently orphans a reader's saved answer or changes the counts the app displays. When in doubt, extract the exact source substring and paste it. Place each block in the atom carrying its idea. The <Quiz> goes on the final atom.
• Video treatment ("watch & digest"). For every <VideoEmbed id="XXXXXXXXXXX" …/>:
  1. Keep the <VideoEmbed> exactly as-is.
  2. On the very next line add <VideoTranscript id="XXXXXXXXXXX" /> (same id) — the server component that renders the on-page collapsible transcript + Copy/Claude/ChatGPT/Perplexity buttons. You do NOT author those buttons.
  3. Then a short distilled digest (read content/transcripts/XXXXXXXXXXX.md for real, specific takeaways — match the tone in 04-two-demos.mdx):

     **What to take from it:**
     
     - <takeaway 1 — a genuine point from the video>
     - <takeaway 2>
     - <takeaway 3 (optional)>
     

  <PodcastLink> gets NO <VideoTranscript> and NO digest — copy it verbatim, leave it.
• Final atom = the chapter's concluding section (its "Before you move on" / summary). It carries the <Quiz> and the ## Go deeper list — move both there verbatim.
• Do NOT author <LlmActions> / "Copy for LLM" / <ChapterWorkbook> — the lesson page (app/learn/[[...slug]]/page.tsx) injects those automatically per lesson.
• Do NOT edit the top-level content/courses/growth-with-posthog/meta.json.

Atom anatomy — each NN-atom.mdx:

---
title: "Short human title for THIS idea (not the chapter title)"
description: "One or two sentences: what this is and why it matters. Used as meta description + sub-header."
workbook: "Only if this atom carries a CheckIn/WorkbookPrompt/Quiz/Flashcards/Checklist/VideoEmbed/PodcastLink. One line on what the reader captures/does here."
---

<prose: the section body, trimmed to its single point — author's voice and facts intact>

<interactive block(s) that belonged to this section — COPIED VERBATIM>

Include workbook: only when the atom has an interactive block (01-why-measure.mdx omits it; 04-two-demos.mdx and 10-set-up-account.mdx include it).

Hub index.mdx — model on 01-what-is-posthog/index.mdx:

---
title: "Chapter N — <original chapter title>"
description: "<reuse/lightly-adapt the original chapter description; end with '… in <count> short pieces.'>"
workbook: "<reuse the original chapter's workbook: frontmatter verbatim if it had one>"
---

> **In this chapter:** <reuse the original chapter's opening '> **In this chapter:**' blockquote — it already exists at the top of the flat file>

**How this chapter works.** It's broken into <count> short pieces — most are a one- to
three-minute read. <one sentence on the video treatment if the chapter has videos>. Work
through them in order, or jump to what you need:

1. [<atom 1 title>](./01-kebab) — <half-line hook>.
2. [<atom 2 title>](./02-kebab) — <half-line hook>.
…

Reuse the original chapter's title/description/workbook frontmatter and the existing top-of-file blockquote — invent no new claims. Link every atom in order with a half-line hook.

meta.json — model on 01-what-is-posthog/meta.json:

{
  "title": "Chapter N · <2–4 word short name>",
  "pages": ["01-kebab", "02-kebab", "…", "NN-final"]
}

List every atom slug in order. Do NOT list index (Fumadocs shows the folder as the hub).

4. Delete the flat file

git rm content/courses/growth-with-posthog/NN-slug.mdx

5. (Only for give-away chapters) make the whole chapter free

If the entire chapter is a top-of-funnel magnet, add its course/chapter key to FREE_CHAPTERS in lib/gating.ts (default is only the course's first lesson is free):

const FREE_CHAPTERS = new Set<string>([
  "growth-with-posthog/00-product-led-growth",
  "growth-with-posthog/01-what-is-posthog",
  "growth-with-posthog/NN-slug",   // ← add
]);

Skip this for paid chapters.

6. Regenerate + VERIFY (the manifest is your net)

node scripts/generate-workbook-manifest.mjs \
  && node scripts/generate-transcripts.mjs \
  && node scripts/generate-lesson-text.mjs

generate-workbook-manifest.mjs THROWS on any interactive block it can't parse (missing required attr, non-array cards/items, etc.) — a throw here is the net catching a malformed copy-paste, not a nuisance. Fix the block and re-run.

Then diff the chapter's block keys against the step-2 baseline:

node -e 'const m=require("./lib/workbook-manifest.generated.json");const ch=process.argv[1];const c=m["growth-with-posthog"]||{};const keys=Object.entries(c).filter(([k])=>k===ch||k.startsWith(ch+"/")).flatMap(([,items])=>items.map(i=>i.key)).sort();console.log(keys.join("\n"))' NN-slug > /tmp/atoms-after.txt
diff /tmp/atoms-baseline.txt /tmp/atoms-after.txt

Expected diff: only the quiz: line changes — its path suffix moves from quiz:…/NN-slug to quiz:…/NN-slug/MM-final (the quiz is path-keyed and now lives in the final atom). Every id-keyed block (profile/media/checklist/note/flashcards) must be byte-identical — any add/drop/rename there means you changed a block; go fix it.

If you deliberately ADDED blocks (rare — this is a repurpose, not a rewrite), bump the hard-coded counts in FLAGSHIP_CONTENT_FACTS in lib/courses.ts (quizQuestions, workbookItems) to match the new totals. If you added nothing, leave them.

7. Gates

pnpm --filter @hogsend/course check-types    # runs all 3 generators + fumadocs typegen + tsc

Then a render check — start the dev server and fetch the hub + a few atoms for HTTP 200:

pnpm --filter @hogsend/course dev            # serves on :3006 (predev re-runs the generators)
# in another shell:
curl -so /dev/null -w "%{http_code}\n" http://localhost:3006/learn/growth-with-posthog/NN-slug
curl -so /dev/null -w "%{http_code}\n" http://localhost:3006/learn/growth-with-posthog/NN-slug/01-kebab
curl -so /dev/null -w "%{http_code}\n" http://localhost:3006/learn/growth-with-posthog/NN-slug/MM-final

Assert CONTENT, not just 200. The overview (/growth-with-posthog) and /workbook aggregate every lesson and return 200 even when empty — so also count what rendered, not just the status. After converting the LAST flat chapter (every chapter now a folder), fetch the overview and assert it lists many lessons:

curl -s http://localhost:3006/growth-with-posthog | grep -oE '/learn/growth-with-posthog/[0-9][^" ]*' | sort -u | wc -l
# expect the full lesson count (~230), NOT 0

(An earlier regression: lib/course-ui.tsx findCourseFolder matched the course by a direct-child page, which broke — silently, still 200 — once no flat lessons remained. It now recurses; a content-count assertion is what catches this class.)

build (pnpm --filter @hogsend/course build) is the fuller gate if you want it — prebuild re-runs the three generators too.

8. Commit (one commit per chapter)

Conventional commit, e.g.:

git add -A
git commit -m "feat(course): atomize chapter N into bite-size lessons"

Do NOT push. No co-author. No tool/marketing mentions in the message.

---

Parallelize across chapters

Chapters are independent — each is a disjoint folder, and atomizing one never touches another's files. So you can fan out one subagent per chapter, each handed this skill + the atom contract, all splitting in parallel (step 3 is the bulk of the work and is embarrassingly parallel). Keep the regenerate + verify + commit steps (6–8) central/serial so the generated manifests (lib/*.generated.json) don't race, and so each chapter lands as its own clean commit. Steps 1–2 (transcript pull + baseline snapshot) can run once up front for the whole course.

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Gotchas

• Interactive block ids are persistence keys. Never rename, reword, reorder, or drop an array entry in a <CheckIn>/<Flashcards>/<Quiz>/<WorkbookPrompt>/<Checklist> — you silently orphan a reader's saved answer or change the item counts the app renders. Copy the exact source substring.
• The manifest generator THROWS on bad blocks — that's the safety net, not an obstacle. A throw means a malformed/incomplete block copy; the parse error names the file + attr.
• The quiz key is path-derived (quiz:<course>/<lesson>), so moving the quiz into the nested final atom changes its key — expected and fine for a not-yet-nested chapter. Only the quiz: line should differ in the step-6 diff.
• <PodcastLink> gets no transcript and no digest — it's not a video; copy it verbatim.
• The lesson page auto-injects the LLM buttons ("Copy for LLM" <LlmActions>) and <ChapterWorkbook> per lesson — atoms must NOT author them.
• <VideoTranscript id> must use the same 11-char YouTube id as its <VideoEmbed>; it renders nothing if no transcript exists for that id (so step 1 must succeed first).
• Lesson identity is slugs.slice(1).join("/") and the manifest key mirrors it (numeric prefixes retained; index collapses to the folder). Don't rename atom files after readers have progress — the slug is the progress key.
• Don't edit the top-level course meta.json or write summary markdown / leave TODOs.