Lathe is a tool that uses language models to create hands-on, multi-part technical tutorials and lets people study them in a local interface. It is intended for learners who want to follow tutorials themselves, while coding agents can generate, verify, extend, and manage those tutorials through its skills and command-line tool.
Borrowing it
Nothing to install: this file belongs to devenjarvis/lathe. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/devenjarvis/lathe/main/.claude/skills/lathe-extend/SKILL.mdgit clone --depth 1 https://github.com/devenjarvis/latheWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/devenjarvis/lathe/lathe-extend)<a href="https://agentmods.dev/skills/devenjarvis/lathe/lathe-extend"><img src="https://agentmods.dev/badge/skills/devenjarvis/lathe/lathe-extend/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/devenjarvis/lathe/lathe-extend"><img src="https://agentmods.dev/badge/skills/devenjarvis/lathe/lathe-extend.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Rogue Agent · line 3 Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00075 | $0.01367 |
| Opus 5.5 | $0.00030 | $0.00547 |
| Sonnet 5.5 | $0.00015 | $0.00273 |
| Haiku 4.5 | $0.00007 | $0.00137 |
Grade A, and why
lathe-extend scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 19d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 55 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Lathe — Extend a Tutorial
Add the next part to a stored tutorial. Triggered by /lathe-extend <slug> [guidance…]. The new part must continue that tutorial — its example, its numbers, its voice — not a fresh generic one. Everything about shape, research discipline, and callouts comes from the lathe skill; read it and apply it. The voice is whatever the tutorial was generated in — fetch it from the CLI (see step 1), don't guess or re-pick. This skill only adds what's different about extending: continuity and the extend-start → write → extend-commit handshake.
Protocol
- Absorb the existing tutorial. Read every part in
~/.lathe/tutorials/<slug>/(part-NN.md). You need the load-bearing context before you write a word:- The controlling example and the fixed numbers (sample rate, page size, buffer size) — reuse them exactly; don't invent new ones.
- The controlling metaphor, if any, and whether a prior part already retired it (if retired, don't resurrect it).
- The voice. Fetch the tutorial's recorded voice and apply it for all tonal choices:
This prints the wrapped voice spec (guardrail preamble + tone guidance). It resolves the voice recorded on the tutorial's metadata, falling back to the configured default for tutorials stored before voices existed. Don't re-pick or drift the voice; structure and substance still defer to thelathe voice show --tutorial <slug>latheskill, which wins on any conflict with the voice. - The level of the reader.
- The repo and pinned tool versions in
metadata.json(repo,repo_branch,tools) — the new part inherits them. Write against the same versions; don't silently bump to a newer toolchain. (If the reader explicitly wants to move the tutorial to a new version, that's a heads-up that it may be time for a fresh tutorial, not a quiet drift — flag it rather than re-pinning here.) - Where the previous part's "What's next" pointed — that's your mandate for this part unless the user's guidance redirects it.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 19d ago Changed 386e39a0106b
- 2mo ago First seen · 55 lines · 75 tokens per session scan A fb629df274ca
lathe-extend is a skill published in the GitHub repository devenjarvis/lathe (1,714 stars, last pushed 19d ago), licensed MIT. It adds 75 tokens to every session and 1,367 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
lathe-extend compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| lathe-extenddevenjarvis/lathe | Skill | 1.7k | 19d ago | MIT | A | 75 | Claude Code |
| imagegenopenai/codex | Skill | 133k | yesterday | Apache-2.0 | A | 113 | Codex |
| playwright-climicrosoft/playwright | Skill | 99k | yesterday | Apache-2.0 | A | 19 | Claude Code |
| local-ai-agentsmicrosoft/ai-agents-for-beginners | Skill | 79k | 4d ago | MIT | A | 200 | Claude Code, Codex |
| systematic-debuggingobra/superpowers | Skill | 313k | 3d ago | MIT | A | 21 | Claude Code |
| next-cache-components-adoptionvercel/next.js | Skill | 143k | today | MIT | A | 95 | Claude Code |
| next-partial-prefetching-adoptionvercel/next.js | Skill | 143k | today | MIT | A | 103 | Claude Code |