fiducial: Instructions file for Codex

AGENTS.md

fiducial AGENTS.md is an instructions file for Codex, OpenCode from sardonic-labs/fiducial. It costs 1,554 tokens per session, scanned A, original, MIT.

Project instructions for fiducial, a hardware-design project, covering design rules, available tools, and review practices for schematics and circuit boards.

In plain words
What is it for?
Use them when editing KiCad schematics or boards, running electrical and design-rule checks, exporting project reports, or auditing connectivity.
Why use it?
They reduce the risk of incorrect electrical connections by requiring datasheet checks and verification after changes.

Instructions file for CodexOpenCode

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

This is sardonic-labs/fiducial's own configuration. It tells Codex and OpenCode how to work on fiducial 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 fiducial configures →

Reuse

Borrowing it

Nothing to install: this file belongs to sardonic-labs/fiducial. 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/sardonic-labs/fiducial/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/sardonic-labs/fiducial

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.

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README.md
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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.

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Per session 1,554 This file is loaded in full into every session.
When invoked 1,554 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 $0.01554 $0.01554
Opus 5 $0.00777 $0.00777
Sonnet 5 $0.00311 $0.00311
Haiku 4.5 $0.00155 $0.00155

Measured 8d ago against content hash c5e7550eebae, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

fiducial 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 · 124 lines

How it starts

The opening of the file, as written. The whole thing — 124 lines — stays where its author put it; the contents beside it link to each section on GitHub.

fiducial — AI hardware design instructions

This file is the entry point. A project that includes this repo (usually as a submodule at fiducial/) imports it from its own AGENTS.md with:

@fiducial/AGENTS.md

Golden rules

  1. Never guess pinouts, net names, or electrical characteristics. Verify against the datasheet and against the actual files on disk.
  2. Verify after every change. Run erc, drc, and the connectivity audit (see Tools below). An unverified schematic is a broken schematic.
  3. Read before editing. KiCad files are S-expressions. Read the relevant section, understand it, then make a minimal, targeted edit.
  4. Prefer kicad-cli over hand-editing for anything it can do (exports, reports, BOMs). Hand-edit only what it cannot.

Tools

All tools are Python 3 stdlib-only. Run them from the project root:

python fiducial/scripts/fiducial.py <command>
Command Purpose
doctor Check kicad-cli availability and version
erc <project.kicad_sch> Run ERC, summarize JSON report, exit code reflects errors
drc <project.kicad_pcb> Run DRC, same behavior. Read-only unless you pass --save-board
netlist <project.kicad_sch> Export netlist to <project>-netlist.sexpr
nets <project.kicad_sch> Dump every net with its connected pins
pins <project.kicad_sch> <REF> Dump one symbol's pins and their nets
check-intent <project.kicad_sch> intent.csv Compare expected connections (ref,pin,expected_net) against reality; --orphans also flags single-pin nets
lint <project.kicad_sch> Structural checks: duplicate refs, missing fields, unconnected pins, single-use labels, dangling nets
check-rules <project.kicad_sch> rules.csv Verify house-style rules from CSV (see docs/rules.md)
render <project...> --outdir DIR Export SVG renders of schematic and/or PCB so you can look at them
bom <project.kicad_sch> Export CSV bill of materials

Read the full file on GitHub · 124 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 · 124 lines · 1,554 tokens per session scan A c5e7550eebae

Subscribe to this mod's changes

fiducial AGENTS.md is an instructions file published in the GitHub repository sardonic-labs/fiducial (2 stars, last pushed 2d ago), licensed MIT. It adds 1,554 tokens to every session, about $0.0078 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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