opentax-engine: Instructions file for Codex

AGENTS.md

opentax-engine AGENTS.md is an instructions file for Codex, OpenCode from Invaro/opentax-engine. It costs 2,067 tokens per session, scanned A, original, no licence file.

Project instructions for working on Invaro's opentax-engine, including its agent guide, workflow, and tax-formatting rules. It provides project-specific guidance rather than a general programming tutorial.

In plain words
What is it for?
Use it while modifying or reviewing opentax-engine, especially when following its agent workflow or formatting tax amounts and tax-year rules.
Why use it?
It gives coding agents the local rules and expected work process for this repository. This reduces mistakes caused by applying generic assumptions to the project.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md.

This is Invaro/opentax-engine's own configuration. It tells Codex and OpenCode how to work on opentax-engine 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 opentax-engine configures →

Reuse

Borrowing it

Nothing to install: this file belongs to Invaro/opentax-engine. 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/Invaro/opentax-engine/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/Invaro/opentax-engine

Made for: Codex, OpenCode.

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 opentax-engine AGENTS.md

README.md
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Your own site
<a href="https://agentmods.dev/instructions/invaro/opentax-engine/agents-md"><img src="https://agentmods.dev/badge/instructions/invaro/opentax-engine/agents-md/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 opentax-engine AGENTS.md

Your own site · 80×15
<a href="https://agentmods.dev/instructions/invaro/opentax-engine/agents-md"><img src="https://agentmods.dev/badge/instructions/invaro/opentax-engine/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 2,067 This file is loaded in full into every session.
When invoked 2,067 The same file — it is already loaded in full.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown 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 $0.02067 $0.02067
Opus 5.5 $0.00827 $0.00827
Sonnet 5.5 $0.00413 $0.00413
Haiku 4.5 $0.00207 $0.00207

Measured 2d ago against content hash 734d27c9c9b0, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

opentax-engine AGENTS.md 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 2d 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.md · 98 lines

The source is not reproduced here

A licence we could not identify

The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.

Read it on GitHub

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. 2d ago Changed · +108 tokens per session 734d27c9c9b0
  2. 12d ago Changed · +5 lines · +151 tokens per session 4ab2ccaad92e
  3. 2mo ago First seen · 93 lines · 1,808 tokens per session scan A 9e8083317cfe

Subscribe to this mod's changes

opentax-engine AGENTS.md is an instructions file published in the GitHub repository Invaro/opentax-engine (166 stars, last pushed 2d ago), with no licence file. It adds 2,067 tokens to every session, about $0.0083 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.

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