What is prb-math AGENTS.md?

Developer instructions for PRBMath, a Solidity library for signed and unsigned fixed-point arithmetic with 18 decimal places. They describe its math types, source layout, tests, and build tools.

Use them when modifying PRBMath code, adding tests, running Foundry builds and tests, checking formatting, or validating Solidity changes.

They give contributors the commands and structure needed to change the library without overlooking formatting, linting, tests, or both supported modes.

How PaulRBerg/prb-math configures Codex and OpenCode

About the project

PRBMath is a Solidity library for calculations with signed and unsigned fixed-point numbers using 18 decimal places. It provides functions for operations such as logarithms, exponentials, powers, square roots, and overflow-safe multiplication and division. The catalogue instructions help agents work with this library in smart-contract projects.

PaulRBerg/prb-math · 1,008 stars · on GitHub

Reuse

Borrowing it

Nothing to install: this file belongs to PaulRBerg/prb-math. 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/PaulRBerg/prb-math/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/PaulRBerg/prb-math

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.

$agentmods badge for prb-math AGENTS.md$

README.md

[![agentmods](https://agentmods.dev/badge/instructions/paulrberg/prb-math/agents-md/github.svg)](https://agentmods.dev/instructions/paulrberg/prb-math/agents-md)

Your own site

<a href="https://agentmods.dev/instructions/paulrberg/prb-math/agents-md"><img src="https://agentmods.dev/badge/instructions/paulrberg/prb-math/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.

$agentmods 80×15 button for prb-math AGENTS.md$

Your own site · 80×15

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Per session 847 This file is loaded in full into every session.

When invoked 847 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 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.

Model	Per session	Once invoked
Fable 5.1	$0.00847	$0.00847
Opus 5.5	$0.00339	$0.00339
Sonnet 5.5	$0.00169	$0.00169
Haiku 4.5	$0.00085	$0.00085

Measured 1mo ago against content hash 15e4aa8cb362, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

prb-math 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 1mo 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 · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

PRBMath

Solidity library for advanced fixed-point math with signed (SD59x18) and unsigned (UD60x18) 18-decimal types.

Stack

Solidity 0.8.30
Foundry (forge build, forge test, forge fmt)
Bun for package management
Prettier, Solhint for formatting/linting

Structure

src/
  Common.sol          # Shared utilities (mulDiv, exp2, log2, pow, sqrt)
  SD59x18.sol         # Signed 59.18 fixed-point type (entry point)
  UD60x18.sol         # Unsigned 60.18 fixed-point type (entry point)
  SD1x18.sol, UD2x18.sol, SD21x18.sol, UD21x18.sol   # Compact/medium types
  sd59x18/, ud60x18/  # Core type ops (Casting, Constants, Helpers, Math, ValueType)
  sd1x18/, ud2x18/, sd21x18/, ud21x18/               # Compact/medium type dirs
  casting/            # Casting from uint40/uint128/uint256
test/
  unit/               # Unit tests
  fuzz/               # Fuzz tests
  utils/              # Assertions and test utilities

Commands

just build - Build with Forge
just test - Run tests (forge test)
just full-check - Prettier + Solhint + Forge format check
just full-write - Auto-fix all formatting issues

Releases

npm publishing runs only in .github/workflows/release.yml through npm trusted publishing in staged mode. Never run npm publish, npm stage approve, or npm stage reject locally.
To ship: bump the version and changelog, commit, create the annotated tag vX.Y.Z (prerelease: vX.Y.Z-beta.N), push the commit, then run git push origin <tag>.
CI stages the version. It stays unpublished until the maintainer approves it with 2FA on npmjs.com (Staged Packages) or npm stage approve <stage-id>. Prereleases use their identifier as the dist-tag.
Setup, once: npm trust github @prb/math --repo PaulRBerg/prb-math --file release.yml --allow-stage-publish -y

Development

After generating or updating code:

Run just full-check to verify
If errors, run just full-write to auto-fix
Fix remaining issues manually

Read the full file on GitHub · 85 lines

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.

1mo ago Changed · +10 lines · +183 tokens per session 15e4aa8cb362
2mo ago First seen · 75 lines · 664 tokens per session scan A 27145416dc38

Subscribe to this mod's changes

prb-math AGENTS.md is an instructions file published in the GitHub repository PaulRBerg/prb-math (1,008 stars, last pushed 13d ago), licensed MIT. It adds 847 tokens to every session, about $0.0034 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.

ethereum evm library math smart-contracts solidity

prb-math AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
prb-math AGENTS.mdPaulRBerg/prb-math	Instructions file	1.0k	13d ago	MIT	A	847	Codex, OpenCode
vscode buildNext.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	9,719	GitHub Copilot
next.js AGENTS.mdvercel/next.js	Instructions file	143k	yesterday	MIT	A	7,461	Codex, OpenCode
langchain AGENTS.mdlangchain-ai/langchain	Instructions file	149k	yesterday	MIT	A	4,680	Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	5,516	GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	3,093	GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness	Instructions file	274k	2d ago	MIT	A	4,313	Codex, OpenCode

prb-math: Instructions file for Codex