jacobian-math

jacobian-math is a skill for Codex from morluto/jacobian. It costs 24 tokens per session (166 once invoked), scanned A, original, MIT.

A tool for playing asciinema .cast files, which store recordings of terminal sessions, in a dedicated iTerm2 window on macOS. It provides controls for how the recording is displayed and played.

In plain words
What is it for?
Use it to review, demonstrate, or inspect terminal recordings, including large files.
Why use it?
It gives large recordings a local terminal-based player instead of relying on a browser that may load slowly or run out of memory.

Skill for Codex

Written for Codex: agents/openai.yaml present. Also seen: installed under .agents/ (shared by several agents).

Good fit Use it to review, demonstrate, or inspect terminal recordings, including large files.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/morluto/jacobian/jacobian-math
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add morluto/jacobian --skill jacobian-math
Clone the repo
git clone --depth 1 https://github.com/morluto/jacobian

Made for: Codex.

Wrote 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.

agentmods badge for jacobian-math

README.md
[![agentmods](https://agentmods.dev/badge/skills/morluto/jacobian/jacobian-math.svg)](https://agentmods.dev/skills/morluto/jacobian/jacobian-math)
Your own site
<a href="https://agentmods.dev/skills/morluto/jacobian/jacobian-math"><img src="https://agentmods.dev/badge/skills/morluto/jacobian/jacobian-math.svg" alt="Measured on agentmods" height="20"></a>
Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 166 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00024 $0.00166
Opus 5 $0.00012 $0.00083
Sonnet 5 $0.00005 $0.00033
Haiku 4.5 $0.00002 $0.00017

Measured 3d ago against content hash b0b99c6eb71d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

jacobian-math 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 3d 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.

.agents/skills/jacobian-math/SKILL.md · 21 lines

What it actually says

Jacobian Math Tools

Jacobian is a local library of typed mathematical operations for computation and structural analysis.

Use math.find as the library-navigation tool: search for a desired outcome, browse an unfamiliar domain, or inspect an operation's schema and examples. Use math.run to execute a selected operation and obtain its typed result. Feed results into later reasoning, further Jacobian operations, or Python scratch work as useful.

The operations are composable. Choose the representation, decomposition, order of operations, and stopping point that fit the problem. Reach for the library proactively when exact computation, finite search, or structural analysis may help.

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

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.

  1. 3d ago Changed · -23 tokens per session b0b99c6eb71d
  2. 8d ago First seen · 21 lines · 47 tokens per session scan A 6f16f4668464

Subscribe to this mod's changes

jacobian-math is a skill published in the GitHub repository morluto/jacobian (178 stars, last pushed yesterday), licensed MIT. It adds 24 tokens to every session and 166 once invoked, about $0.0001 per session on Opus 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.

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