Citadel AGENTS.md

A guide to the Codex Harness, a system of agents, skills, hooks, and state files that helps coding agents work across projects.

In plain words
What is it for?
Use it when developing the harness, adding skills or agents, installing hooks, or managing project campaigns and coordinated work.
Why use it?
It explains where the harness stores agent instructions, project plans, session state, and automated checks.

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/sethgammon/citadel/agents-md
Clone the repo
git clone --depth 1 https://github.com/SethGammon/Citadel

Made for: Codex, OpenCode.

Per session 773 This file is loaded in full into every session.
When invoked 773 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 $0.00773 $0.00773
Opus 5 $0.00387 $0.00387
Sonnet 5 $0.00155 $0.00155
Haiku 4.5 $0.00077 $0.00077

Measured yesterday against content hash 96a1dd6adbd0, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

Citadel 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 yesterday.

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 · 70 lines

How it starts

The opening of the file, as written. The whole thing — 70 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Codex Harness

An agent orchestration system for Codex. This repo IS the harness.

What This Is

The harness is a collection of skills, agents, hooks, and state files that enable Codex to operate autonomously on any codebase. It provides:

  • Intent routing (/do) that dispatches tasks to the right tool
  • Campaign persistence across sessions
  • Parallel agent coordination with discovery sharing
  • Automated quality enforcement through lifecycle hooks

Key Conventions

  • Skills live in skills/. Each skill is a directory skills/{name}/SKILL.md.
  • Agents live in agents/. They spawn as sub-processes with their own context.
  • Hooks live in hooks_src/. Installed per-project via scripts/install-hooks.js.
  • The init-project hook auto-scaffolds per-project state on session start:
    • .planning/ — campaign state, fleet sessions, intake, telemetry
    • .citadel/scripts/ — utility scripts (telemetry, coordination, compression)
    • .claude/agent-context/ — rules injected into sub-agents
  • Campaign state lives in .planning/campaigns/ (per-project).
  • Fleet session state lives in .planning/fleet/ (per-project).
  • Templates live in .planning/_templates/ (copied from plugin on init).
  • Configuration lives in .claude/harness.json (generated by /do setup, per-project).

Testing

Always run tests after modifying hooks or skills. Five levels:

Command What it checks When to run
node scripts/test-all.js Hooks + skill structure (fast, no LLM) After any change
node hooks_src/smoke-test.js Hooks only After hook changes
node scripts/verify-hooks.js Hook install + runtime (synthetic payloads, no LLM) After hook changes
node scripts/integration-test.js Full Pre→tool→Post pipeline sequences (no LLM) After hook changes
node scripts/skill-lint.js All SKILL.md structure After skill changes
node scripts/skill-bench.js Scenario file validity After adding benchmarks
node scripts/skill-bench.js --execute Live scenario execution Before shipping
node scripts/skill-bench.js --execute --verify-hooks Live execution + confirms hooks fired Before shipping

Read the full file on GitHub · 70 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. yesterday First seen · 70 lines · 773 tokens per session scan A 96a1dd6adbd0

Subscribe to this mod's changes

Citadel AGENTS.md is an instructions file published in the GitHub repository SethGammon/Citadel (912 stars, last pushed 4d ago), licensed MIT. It adds 773 tokens to every session, about $0.0039 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.