fallow-skills: Instructions file for Codex

AGENTS.md

fallow-skills AGENTS.md is an instructions file for Codex, OpenCode from fallow-rs/fallow-skills. It costs 276 tokens per session, scanned A, original, MIT.

A guide for maintaining Fallow's public coding-agent skills, including where skill files belong and how their source contracts are checked.

In plain words
What is it for?
Use it when editing Fallow skills, checking their pinned source, validating changes, or ensuring destructive operations require a dry run.
Why use it?
It prevents public skills from drifting from the released Fallow product and keeps private or machine-specific material out of the repository.

Instructions file for CodexOpenCode

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

This is fallow-rs/fallow-skills's own configuration. It tells Codex and OpenCode how to work on fallow-skills 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 fallow-skills configures →

Reuse

Borrowing it

Nothing to install: this file belongs to fallow-rs/fallow-skills. 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/fallow-rs/fallow-skills/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/fallow-rs/fallow-skills

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 fallow-skills AGENTS.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/fallow-rs/fallow-skills/agents-md.svg)](https://agentmods.dev/instructions/fallow-rs/fallow-skills/agents-md)
Your own site
<a href="https://agentmods.dev/instructions/fallow-rs/fallow-skills/agents-md"><img src="https://agentmods.dev/badge/instructions/fallow-rs/fallow-skills/agents-md.svg" alt="Measured on agentmods" height="20"></a>
Per session 276 This file is loaded in full into every session.
When invoked 276 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 5.1 $0.00276 $0.00276
Opus 5 $0.00138 $0.00138
Sonnet 5 $0.00055 $0.00055
Haiku 4.5 $0.00028 $0.00028

Measured today against content hash 1ffbb40448ad, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

fallow-skills 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 today.

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 · 36 lines

What it actually says

Fallow public skills

This public repository owns portable end-user skills for the released Fallow product. It does not own Fallow maintainer workflows, private cloud knowledge, or public user documentation.

Start here

  • Skill content lives under fallow/skills/.
  • fallow/skills/fallow/ follows the pinned public product contract in source-lock.json.
  • Agent-specific interface files may wrap a skill, but must not fork its authored instructions.
  • Public user guidance belongs in fallow-rs/docs.
  • Open-source maintainer workflows belong in fallow-rs/fallow.

Validation

Run:

node --test scripts/*.test.mjs
python3 -m unittest discover -s scripts -p 'test_*.py'
python3 scripts/validate_skill_frontmatter.py .
FALLOW_SOURCE_DIR=/path/to/pinned/fallow node scripts/check-source-contract.mjs

The source contract check fails closed when the pinned source is absent, incorrect, or has drifted. Never copy private content or machine-local paths into this repository.

Keep skills concise, use progressive disclosure through direct references, and require a dry run before destructive Fallow operations.

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. today Changed · +2 lines · +27 tokens per session 1ffbb40448ad
  2. 6d ago First seen · 34 lines · 249 tokens per session scan A 612efa5edf68

Subscribe to this mod's changes

fallow-skills AGENTS.md is an instructions file published in the GitHub repository fallow-rs/fallow-skills (118 stars, last pushed today), licensed MIT. It adds 276 tokens to every session, about $0.0014 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.

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