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codebase-explainer

Turn a codebase into an onboarding playlist — Claude-authored analysis docs plus NotebookLM explainer videos (one overview + one per subsystem).

Skill by TheophilusChinomona

IndexedMIT
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Works with Claude Code, Claude apps, Codex, Cursor, Gemini CLI, GitHub Copilot, VS Code, OpenCode, Goose, Windsurf. Read the repository before you give any tool access to your data.

npx agentmarket install skill/theophiluschinomona-codebase-explainer

Asks which of your tools to add it to (Claude Code, Codex, Cursor, VS Code, Windsurf, Gemini CLI, Claude Desktop) and shows the change first. See https://agentmart.dev/cli.

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About

Turn a codebase into an onboarding playlist — Claude-authored analysis docs plus NotebookLM explainer videos (one overview + one per subsystem). Use when asked to explain a codebase, onboard onto a repo, make explainer/walkthrough videos of the code, or 'help me understand how this whole thing works'.

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What this skill can do and what it asks for, from its SKILL.md. Checked Oct 25, 2026.

Tools
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Install scripts
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Runs as
Python package

Network hosts it talks to 1

  • codeload.github.com · found in install command

Files it touches

  • ~/.claude/skills/codebase-explainer

What's inside

Skill name
codebase-explainer
Description
Turn a codebase into an onboarding playlist — Claude-authored analysis docs plus NotebookLM explainer videos (one overview + one per subsystem). Use when asked to explain a codebase, onboard onto a repo, make explainer/walkthrough videos of the code, or 'help me understand how this whole thing works'.
License
MIT
Instructions
81 lines in SKILL.md · view on GitHub

Before installing

  • Ships executable scripts

Files (5)

  • SKILL.md
  • build_videos.py
  • notebooklm_runner.py
  • plan_state.py
  • preflight.py

SKILL.md (first lines)

# Codebase Explainer

Produces an onboarding playlist for a repository: narration-friendly Markdown
docs plus NotebookLM **explainer videos** (one overview + one per subsystem).
Claude does the judgement stages (map, author docs); Python scripts do the
mechanical stages (preflight, build). Built on `notebooklm-py` via its CLI.

## Outputs (in the target repo)
- `docs/onboarding/00-overview.md`, `NN-<subsystem>.md` — analysis docs
- `docs/onboarding/videos/*.mp4` — generated videos
- `docs/onboarding/index.md` — playlist linking each doc → its video
- `.claude/idev/codebase-explainer/plan.json` — build plan (you author this)
- `.claude/idev/codebase-explainer/state.json` — resumable progress

## Stage 1 — Preflight
Run and read the JSON:
```bash
python3 "${CLAUDE_PLUGIN_ROOT}/skills/codebase-explainer/preflight.py"
```
If `ready` is false, surface each `messages` line to the user (install /
`notebooklm login`) and STOP until resolved. Auth is an interactive Google
login the user performs once.

## Stage 2 — Map the codebase
Read existing idev caches first when present (they are a head start):
`.claude/idev/smart-context/index.json`, `.claude/idev/project-map/project.map.md`,
`.claude/idev/architecture-scanner/cache.json`. Then dispatch the
`onboarding-guide` agent to identify: tech stack, entry points, and the major
**subsystems** (name, purpose, boundary paths, key files, dependencies, primary
data flow). If few/no subsystems are detected (tiny repo), plan an overview
video only.

## Stage 3 — Author docs + build plan
Write to `docs/onboarding/`:
- `00-overview.md` — architecture, how the pieces fit, main end-to-end flows.
- `NN-<subsystem>.md` — one per subsystem: purpose, how it works, key files,
  dependencies, data flow. Write **prose that explains concepts**, not code dumps.

Then write `.claude/idev/codebase-explainer/plan.json`:
```json
{
  "style": "whiteboard",
  "videos": [
    {"key": "overview", "title": "Overview",
     "notebook_name": "<repo> — Overview",
     "sources": ["docs/onboarding/00-overview.md", "<1-2 key entry files>"],
     "instructions": "Explain how this system works for a new developer: architecture and main flows.",
     "output": "docs/onboarding/videos/00-overview.mp4",
     "doc": "docs/onboarding/00-overview.md"},
    {"key": "<subsystem-key>", "title": "<Subsystem>",
     "notebook_name": "<repo> — <Subsystem>",
     "sources": ["docs/onboarding/01-<subsystem>.md", "docs/onboarding/00-overview.md", "<key raw file>"],
     "instructions": "Explain the <subsystem> for a new developer: responsibilities, key files, main data flow.",
     "output": "docs/onboarding/videos/01-<subsystem>.mp4",
     "doc": "docs/onboarding/01-<subsystem>.md"}
  ]
}
```
- `sources` are file paths (docs + a few key raw files for grounding — hybrid).
- `style` applies to every video for a consistent look; set it to the `--style <visual-style>` value from `$ARGUMENTS` (default `whiteboard` if omitted).
- If a `subsystem` positional argument was given in `$ARGUMENTS`, limit `videos` to the overview entry plus that one subsystem's entry only (still write the overview doc for context, but omit all other subsystem docs from plan.json).
- If few/no subsystems were detected (tiny repo, same as Stage 2), omit the per-subsystem `NN-<subsystem>.md` docs and include only the overview video in plan.json.

## Stage 4 — CHECKPOINT (mandatory)
STOP. Tell the user the docs are in `docs/onboarding/` and ask them to review/edit
before any videos are generated. Nothing has been sent to NotebookLM yet. Only
continue on explicit approval.

## Stage 5 — Build & generate
```bash
python3 "${CLAUDE_PLUGIN_ROOT}/skills/codebase-explainer/build_videos.py" \
  --plan .claude/idev/codebase-explainer/plan.json \
  --state .claude/idev/codebase-explainer/state.json \
  --index docs/onboarding/index.md
```
Generates sequentially (overview first), polling and downloading each video.
On a failure (e.g. NotebookLM daily limit) it records progress and stops — tell
the user which videos remain and that **re-running the same command resumes**,
skipping completed videos. Report the final playlist at `docs/onboarding/index.md`.

From TheophilusChinomona/idev, MIT.

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Last commit (this folder)
Jun 25, 2026 (4 months ago)
Last release
Jun 25, 2026 (4 months ago)

From GitHub (fetched Oct 24, 2026).

Details

License
MIT
First seen
Oct 24, 2026
Last checked
Oct 24, 2026

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Cite this page

codebase-explainer skill. Agent Mart. https://agentmart.dev/skills/theophiluschinomona-codebase-explainer (last updated 2026-10-24)