What is codex-acp AGENTS.md?

Repository instructions for a Rust program that embeds a Codex agent and exposes it through the Agent Client Protocol, a standard way for applications to communicate with coding agents. They map the source files and describe the agent, sessions, prompts, logging, and filesystem bridge.

Use them when working on the library or command-line entry point, agent sessions, slash commands, streaming prompts, logging, configuration, or the standalone filesystem service.

They make the Rust architecture easier to navigate and help changes fit the existing session, authentication, command, and tool-handling paths.

How cola-io/codex-acp configures Codex and OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to cola-io/codex-acp. 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/cola-io/codex-acp/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/cola-io/codex-acp

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/cola-io/codex-acp/agents-md/github.svg)](https://agentmods.dev/instructions/cola-io/codex-acp/agents-md)

Your own site

<a href="https://agentmods.dev/instructions/cola-io/codex-acp/agents-md"><img src="https://agentmods.dev/badge/instructions/cola-io/codex-acp/agents-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.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/cola-io/codex-acp/agents-md"><img src="https://agentmods.dev/badge/instructions/cola-io/codex-acp/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 3,068 This file is loaded in full into every session.

When invoked 3,068 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.

Model	Per session	Once invoked
Fable 5.1	$0.03068	$0.03068
Opus 5.5	$0.01227	$0.01227
Sonnet 5.5	$0.00614	$0.00614
Haiku 4.5	$0.00307	$0.00307

Measured 2mo ago against content hash f7cddd0a2d3b, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

codex-acp 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 2mo 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 · 332 lines

How it starts

The opening of the file, as written. The whole thing — 332 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Repository Guidelines

This document describes how to work in this repo using idiomatic Rust patterns and the current module layout.

Project Structure

src/
- lib.rs — library crate root; exposes agent, fs, logging; re-exports CodexAgent, SessionManager, FsBridge, and init_from_env for embedders.
- main.rs — binary entrypoint; initializes tracing, loads config + profiles, boots the filesystem bridge, and wires the ACP runtime. Pass --acp-fs-mcp to run the standalone filesystem MCP server.
- logging.rs — tracing init helpers driven by env variables (init_from_env), including optional file logging and daily rotation.
- agent/
  - mod.rs — Agent trait façade; wires ACP trait methods into CodexAgent and re-exports ClientOp.
  - core.rs — defines CodexAgent and ClientOp, handles initialize/auth/new/load session, and applies session mode/model mutations while coordinating the auth/conversation managers.
  - prompt.rs — streaming prompt pipeline, slash-command detection, tool + reasoning updates, cancel handling, and extension method stubs.
  - commands.rs — slash command registry (AVAILABLE_COMMANDS) plus helpers like handle_slash_command and /status rendering.
  - events.rs — Codex Event → ACP update formatting (EventHandler), approval option helpers, and ReasoningAggregator for thought text.
  - config_builder.rs — builds per-session Config instances, injects filesystem guidance, and produces MCP server configs (prepare_fs_mcp_server_config, build_mcp_server).
  - session_manager.rs — session state store (SessionState, SessionManager), conversation caching, capability tracking, notification helpers, and apply_context_override.
  - utils.rs — shared helpers for session modes/models, provider detection, tool formatting (format_command_call, describe_mcp_tool, is_custom_provider, etc.).
- fs/
  - mod.rs, bridge.rs, mcp_server.rs — filesystem bridge runtime (FsBridge::start) and MCP server entry (run_mcp_server) communicating via ACP_FS_BRIDGE_ADDR/ACP_FS_SESSION_ID.
Cargo.toml, rust-toolchain.toml
README.md, AGENTS.md
Makefile, scripts/stdio-smoke.sh

Read the full file on GitHub · 332 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.

2mo ago First seen · 332 lines · 3,068 tokens per session scan A f7cddd0a2d3b

Subscribe to this mod's changes

codex-acp AGENTS.md is an instructions file published in the GitHub repository cola-io/codex-acp (143 stars, last pushed 10mo ago), licensed Apache-2.0. It adds 3,068 tokens to every session, about $0.0123 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.

Languages Rust acp agent-client-protocol codex zed

codex-acp AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
codex-acp AGENTS.mdcola-io/codex-acp	Instructions file	143	10mo ago	Apache-2.0	A	3,068	Codex, OpenCode
vscode buildNext.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	9,719	GitHub Copilot
next.js AGENTS.mdvercel/next.js	Instructions file	143k	yesterday	MIT	A	7,461	Codex, OpenCode
langchain AGENTS.mdlangchain-ai/langchain	Instructions file	149k	yesterday	MIT	A	4,680	Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	5,516	GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	3,093	GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness	Instructions file	274k	2d ago	MIT	A	4,313	Codex, OpenCode

codex-acp: Instructions file for Codex