jacobian: Skill for Codex

.agents/skills/audit-public-operation-contracts/SKILL.md

audit-public-operation-contracts is a skill for Codex from morluto/jacobian. It costs 24 tokens per session (623 once invoked), scanned A, original, MIT.

A review method for checking whether a mathematical operation has a clear, truthful, and compatible public interface. It compares the request, computation, result, documentation, examples, and users of the result as one contract.

In plain words
What is it for?
Use it to review new or existing Jacobian operations, investigate mathematical performance, and check whether a backend implementation and its public documentation agree.
Why use it?
It helps find hidden extra work, inaccurate claims, lossy exact results, unsupported conclusions, and mismatches between an operation and the code that consumes it.

Skill for Codex

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

This is morluto/jacobian's own configuration. It tells Codex how to work on jacobian itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything jacobian configures →

Reuse

Borrowing it

Nothing to install: this file belongs to morluto/jacobian. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/morluto/jacobian/main/.agents/skills/audit-public-operation-contracts/SKILL.md
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 audit-public-operation-contracts

README.md
[![agentmods](https://agentmods.dev/badge/skills/morluto/jacobian/audit-public-operation-contracts/github.svg)](https://agentmods.dev/skills/morluto/jacobian/audit-public-operation-contracts)
Your own site
<a href="https://agentmods.dev/skills/morluto/jacobian/audit-public-operation-contracts"><img src="https://agentmods.dev/badge/skills/morluto/jacobian/audit-public-operation-contracts/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.

agentmods 80×15 button for audit-public-operation-contracts

Your own site · 80×15
<a href="https://agentmods.dev/skills/morluto/jacobian/audit-public-operation-contracts"><img src="https://agentmods.dev/badge/skills/morluto/jacobian/audit-public-operation-contracts.svg" alt="Reviewed on agentmods" width="80" 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 623 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 $0.00623
Opus 5 $0.00012 $0.00311
Sonnet 5 $0.00005 $0.00125
Haiku 4.5 $0.00002 $0.00062

Measured 6d ago against content hash 5c39fb1ffce5, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

audit-public-operation-contracts 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 6d 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/audit-public-operation-contracts/SKILL.md · 67 lines

How it starts

The opening of the file, as written. The whole thing — 67 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Audit Public Operation Contracts

Determine whether an operation is a bounded, truthful, composable mathematical instrument. Record the revision, operation IDs, inspected scope, and whether the request includes implementation. Audit-only work does not authorize repository or external mutations.

Trace the contract

Treat request representation, canonical values, semantic admission, kernel, trusted result construction, and downstream consumers as one execution path. Inspect schemas, declarations, examples, and MCP errors when public projection is in scope. The implementation alone does not define the advertised contract.

Use the applicable sections of the operation library. For public admission, consult the admission contract; for a backend boundary, consult the backend contract. Record applicable evidence in the requested audit or existing issue/PR description; do not create a universal review form.

Probe the plausible failures

Use small deterministic reproductions to test the suspected mechanism:

  • accepted requests beyond the backend domain or admitted work/growth bounds;
  • useful structured requests rejected by an ambient-size or expansion-based limit;
  • repeated admission or computation during validation and result construction;
  • lost units, multiplicities, axes, parents, witnesses, or reconstruction data;
  • independently supplied claims accepted without establishing the needed property;
  • incompatible producer/consumer values, including empty or singular cases;
  • implicit changes of ring, field, parent, or axes; and
  • advertised semantics that disagree with the typed result or kernel.

Check serialized producer-consumer composition when relevant. Defining-invariant proof belongs in tests or an admitted caller-claim operation, not replay during ordinary result construction. Use current official backend documentation and the pinned implementation for consequential backend claims.

Read the full file on GitHub · 67 lines

Files

What ships with it

2 files 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. 6d ago Changed · +3 lines 5c39fb1ffce5
  2. 7d ago Changed · -154 lines · -56 tokens per session 48ac46476730
  3. 12d ago First seen · 218 lines · 80 tokens per session scan A e360baa38b6a

Subscribe to this mod's changes

audit-public-operation-contracts is a skill published in the GitHub repository morluto/jacobian (191 stars, last pushed 2d ago), licensed MIT. It adds 24 tokens to every session and 623 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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