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agentos: Instructions file for Claude Code

CLAUDE.md

agentos CLAUDE.md is an instructions file for Claude Code from jordanhubbard/agentos. It costs 1,613 tokens per session, scanned A, original, BSD-2-Clause.

A repository rulebook for AI coding agents working on agentOS, a secure operating system built on the seL4 microkernel. It defines the project’s purpose, allowed languages, and non-negotiable rules.

In plain words
What is it for?
Use it before changing, deleting, or proposing code in the agentOS repository. It guides decisions about the operating system, its security model, and permitted technologies.
Why use it?
It prevents agents from misunderstanding the project or proposing code that conflicts with its architecture and language policy.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md.

This is jordanhubbard/agentos's own configuration. It tells Claude Code how to work on agentos 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 agentos configures →

not rated 53repo +2 changed 1mo ago A scan 1,613 tokens original BSD-2-Clause
View source ↗ jordanhubbard/agentos
Reuse

Borrowing it

Nothing to install: this file belongs to jordanhubbard/agentos. 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/jordanhubbard/agentos/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/jordanhubbard/agentos

Made for: Claude Code.

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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Your own site
<a href="https://agentmods.dev/instructions/jordanhubbard/agentos/claude-md"><img src="https://agentmods.dev/badge/instructions/jordanhubbard/agentos/claude-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.

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<a href="https://agentmods.dev/instructions/jordanhubbard/agentos/claude-md"><img src="https://agentmods.dev/badge/instructions/jordanhubbard/agentos/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 1,613 This file is loaded in full into every session.
When invoked 1,613 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 $0.01613 $0.01613
Opus 5.5 $0.00645 $0.00645
Sonnet 5.5 $0.00323 $0.00323
Haiku 4.5 $0.00161 $0.00161

Measured 1mo ago against content hash 1f945e45ed7f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

agentos CLAUDE.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.

CLAUDE.md · 182 lines

How it starts

The opening of the file, as written. The whole thing — 182 lines — stays where its author put it; the contents beside it link to each section on GitHub.

agentOS — Project Constitution for AI Agents

This document is binding. Read docs/TCB.md first. Do not make exceptions.

What agentOS Is

agentOS is a bootable, capability-secured operating system on the seL4 microkernel. It is the I/O and isolation platform for:

  • Linux and FreeBSD as guests (in-tree virtio drivers only)
  • Native purpose-driven PDs / agents that never run a legacy OS

QEMU is a hardware emulator for fast prototyping. The same driver PDs that own QEMU virtio-mmio as a stand-in NIC/disk will own real devices on bare metal.

agentOS is not a thin hypervisor slave to QEMU. It is not a web app. It is not a dashboard. It boots on bare metal.

Trusted Computing Base

See docs/TCB.md. Short form:

  • seL4 is the only kernel-mode code. Never modify it.
  • Root task distributes untyped memory, CSpace, VSpace, and initial caps. It does not enforce policy after spawn.
  • Driver PDs own exactly one device class (frame + IRQ).
  • Virtualizer PDs mux that class over sDDF-shaped shared-memory queues.
  • VMM PDs run vCPUs/vGIC and emulate virtio for guests.
  • Everyone else is a client or is quarantined (docs/TCB.md museum list).

There is no "Ring 1–5". Those numbers mixed Intel rings with ARM ELs with seL4 PDs and were wrong. Guest userspace runs in the guest VSpace.

Language Policy

C, Rust, Assembly only. This applies to target code, host tools, tests, generators, and skill helpers. Python, JavaScript, HTML, CSS, Go, Zig, and other implementation languages are forbidden; vendored code is not exempt.

CMake / Make orchestrate builds. Shell is CI glue and one-line wrappers.

WASM is a guest/agent binary format only. WASM runtime is C or Rust. WASM is not a NIC, disk, or UART.

UI Policy

No human UI in this repository: no dashboards, HTML, JavaScript, CSS, interactive terminal UI, or WebSocket terminal emulators.

Exceptions:

  • agentctl — CLI, structured stdout, exits
  • ../agentos_gui — external consumer of CC-PD / contracts

Read the full file on GitHub · 182 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. 1mo ago Changed · +2 lines · +71 tokens per session 1f945e45ed7f
  2. 1mo ago Changed · -10 lines · -87 tokens per session 28d95a3b8e25
  3. 1mo ago Changed · -96 lines · -2,075 tokens per session 491b5355186a
  4. 1mo ago First seen · 286 lines · 3,704 tokens per session scan A c3cbbdf08fe4

Subscribe to this mod's changes

agentos CLAUDE.md is an instructions file published in the GitHub repository jordanhubbard/agentos (53 stars, last pushed 8d ago), licensed BSD-2-Clause. It adds 1,613 tokens to every session, about $0.0065 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.

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