fixmath AGENTS.md

Repository guidance for fixmath, a C++20 library that performs fixed-point arithmetic using header files rather than a compiled library.

In plain words
What is it for?
Use it when changing the arithmetic headers, fixed-point math, CMake test setup, or unit tests, and when verifying those changes.
Why use it?
It documents the project layout and the commands for configuring, compiling, and running its GoogleTest test suite.

Instructions file for CodexOpenCode

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.

agentmods
npx agentmods add instructions/michaelsuen-thepointer/fixmath/agents-md
Clone the repo
git clone --depth 1 https://github.com/MichaelSuen-thePointer/fixmath

Made for: Codex, OpenCode.

Per session 957 This file is loaded in full into every session.
When invoked 957 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
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 $0.00957 $0.00957
Opus 5 $0.00478 $0.00478
Sonnet 5 $0.00191 $0.00191
Haiku 4.5 $0.00096 $0.00096

Measured 2d ago against content hash 2ca4f360bcb8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

fixmath 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 · 62 lines

How it starts

The opening of the file, as written. The whole thing — 62 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Repository Guidelines

Project Structure & Module Organization

Fixmath is a header-only C++20 fixed-point arithmetic library. Public headers live in include/fixmath/; fixed.hpp is the main entry point, fixed_impl.inl and fixed_math.inl contain core operations, and the remaining .inl files provide traits, bit utilities, and platform-independent 128-bit helpers. Tests are consolidated in tests/unit_tests.cpp. The tests/CMakeLists.txt project downloads GoogleTest during configuration and builds the FIXMATH_unittests executable. GitHub Actions configuration is under .github/workflows/.

Build, Test, and Development Commands

Run commands from the repository root:

cmake -S tests -B build -DCMAKE_BUILD_TYPE=Debug
cmake --build build --config Debug
ctest --test-dir build -C Debug --output-on-failure

The first command configures the test project and fetches GoogleTest, so network access is required on a clean build. The second compiles the C++20 tests. The final command runs all discovered GoogleTest cases and prints failure details. Use a separate build directory (for example, build-release) rather than adding generated files to the source tree.

Format all C++ sources and verify that no formatting changes remain before committing. In PowerShell:

$files = rg --files -g '*.hpp' -g '*.h' -g '*.inl' -g '*.cpp' -g '*.cc' -g '*.cxx'
clang-format -i $files
clang-format --dry-run --Werror $files

The repository .clang-format file is the source of truth. It targets clang-format 19 or a compatible newer version. Keep C and C++ source files encoded as UTF-8 with BOM. Whenever .clang-format changes, first ensure that C and C++ files contain no uncommitted behavioral changes, restore those files to HEAD, and then format the repository again. Do not layer a new formatting configuration over output produced by the previous configuration.

Coding Style & Naming Conventions

Match the surrounding C++ style: tabs for indentation, a maximum line length of 300 characters, braces on the same line as declarations, and snake_case for functions, variables, and implementation headers. Types use descriptive names such as fixed_policy; compile-time constants use UPPER_SNAKE_CASE. Internal helpers currently use the _fm_ prefix. Keep public declarations in .hpp files and template implementations in .inl files. Preserve the MPL 2.0 notice at the top of source files. Use .clang-format for automatic formatting and minimize unrelated changes.

Read the full file on GitHub · 62 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.

  1. 2d ago First seen · 62 lines · 957 tokens per session scan A 2ca4f360bcb8

Subscribe to this mod's changes

fixmath AGENTS.md is an instructions file published in the GitHub repository MichaelSuen-thePointer/fixmath (22 stars, last pushed 9d ago), licensed MPL-2.0. It adds 957 tokens to every session, about $0.0048 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.