platform-nordicnrf54: Instructions file for Codex

AGENTS.md

platform-nordicnrf54 AGENTS.md is an instructions file for Codex, OpenCode from caveman99/platform-nordicnrf54. It costs 1,812 tokens per session, scanned A, original, Apache-2.0.

A PlatformIO development platform for Nordic nRF54L microcontrollers, which are small chips used in embedded devices. It defines boards and controls how Arduino sketches are built and uploaded, but does not contain the firmware itself.

In plain words
What is it for?
Use it when changing PlatformIO package definitions, build and upload behavior, board variants, examples, or links to the Arduino core and bootloader.
Why use it?
It clarifies that this repository coordinates board support and related packages rather than being the device application code.

Instructions file for CodexOpenCode

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

This is caveman99/platform-nordicnrf54's own configuration. It tells Codex and OpenCode how to work on platform-nordicnrf54 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 platform-nordicnrf54 configures →

Reuse

Borrowing it

Nothing to install: this file belongs to caveman99/platform-nordicnrf54. 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/caveman99/platform-nordicnrf54/master/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/caveman99/platform-nordicnrf54

Made for: Codex, OpenCode.

Wrote this? Show the measurements

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Per session 1,812 This file is loaded in full into every session.
When invoked 1,812 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.01812 $0.01812
Opus 5 $0.00906 $0.00906
Sonnet 5 $0.00362 $0.00362
Haiku 4.5 $0.00181 $0.00181

Measured 8d ago against content hash 70b28056c311, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

platform-nordicnrf54 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 8d 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 · 146 lines

How it starts

The opening of the file, as written. The whole thing — 146 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent guide for this repo

What this repo is

The PlatformIO development platform for the Nordic nRF54L series (nRF54L05 / nRF54L10 / nRF54L15) — Cortex-M33 with RRAM, targeting an Adafruit-style Arduino core on the s145 SoftDevice v9.0.0.

This repo holds no firmware source. It is the orchestration layer: platform.json declares the package set, builder/ drives the build and upload, boards/ defines the five board variants, examples/ holds runnable sketches (also the CI test matrix).

Out-of-tree platform: consumers install it directly from the repo URL, not from the PlatformIO Registry.

Companion repos

Repo Role PIO package
caveman99/nRF54_Arduino Arduino core / framework source, s145 SoftDevice headers + hex framework-arduinoadafruitnrf54
caveman99/nRF54_Bootloader DFU bootloader source + per-board hex framework-arduinoadafruitnrf54-bootloader

Both are referenced as git URLs in platform.json and are public — PIO clones them with no authentication. PIO re-clones the framework at its current default-branch HEAD on every fresh CI runner (--depth 1, no cross-run cache), so a framework fix is picked up by a platform CI re-run without any platform-side change.

Project conventions

Commit messages

  • Never add Co-Authored-By: Claude (or any AI attribution) trailers.
  • Imperative subject, terse but specific. Reference SHAs of related prior commits where helpful.
  • Multi-paragraph body for non-trivial changes: state the symptom, the root cause, and what the fix does. CI build-log excerpts make good citations.

Where a change belongs (cross-repo routing)

The platform <-> framework boundary follows one rule everywhere:

Change touches Goes in
Compiler invocation: -mcpu, -mfpu, include paths (CPPPATH), CPPDEFINES, force-includes, what BuildLibrary walks herebuilder/frameworks/arduino/adafruit.py
Board metadata: chip, MCU define, link script name, flash/RAM sizes, SD FWID, bootloader settings address, upload tooling hereboards/<variant>.json
Toolchain / tool package versions hereplatform.json
Upload / merge / DFU-package logic, upload targets herebuilder/main.py
Example sketches, CI matrix hereexamples/, .github/workflows/
C/C++ source, headers, linker scripts, nrfx_config.h, variants, bundled-library library.properties framework repo
Bootloader source, linker scripts, board defs, per-board hex bootloader repo

Read the full file on GitHub · 146 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. 8d ago First seen · 146 lines · 1,812 tokens per session scan A 70b28056c311

Subscribe to this mod's changes

platform-nordicnrf54 AGENTS.md is an instructions file published in the GitHub repository caveman99/platform-nordicnrf54 (2 stars, last pushed 3mo ago), licensed Apache-2.0. It adds 1,812 tokens to every session, about $0.0091 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 2026-08-31.

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