agentmods.dev

charon: Instructions file for Codex

AGENTS.md

charon AGENTS.md is an instructions file for Codex, OpenCode from mingtheanlay/charon. It costs 1,393 tokens per session, scanned A, original, MIT.

Repository instructions for developing Charon, a Go command-line tool that switches several coding agents between saved endpoints and credential profiles. They focus on protecting real configuration files and credentials during development.

In plain words
What is it for?
For safely developing and testing Charon, including sandboxing the home directory, isolating configuration paths, and avoiding real Keychain access.
Why use it?
They prevent tests and development commands from changing live accounts, settings, or macOS Keychain entries.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md. Also seen: reads .claude/ paths; mentions Claude Code; reads ~/.codex paths.

This is mingtheanlay/charon's own configuration. It tells Codex and OpenCode how to work on charon 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 charon configures →

not rated 12repo 3mo ago A scan 1,393 tokens original MIT
View source ↗ mingtheanlay/charon
Reuse

Borrowing it

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

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 charon AGENTS.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/mingtheanlay/charon/agents-md/github.svg)](https://agentmods.dev/instructions/mingtheanlay/charon/agents-md)
Your own site
<a href="https://agentmods.dev/instructions/mingtheanlay/charon/agents-md"><img src="https://agentmods.dev/badge/instructions/mingtheanlay/charon/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.

agentmods 80×15 button for charon AGENTS.md

Your own site · 80×15
<a href="https://agentmods.dev/instructions/mingtheanlay/charon/agents-md"><img src="https://agentmods.dev/badge/instructions/mingtheanlay/charon/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 1,393 This file is loaded in full into every session.
When invoked 1,393 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 $0.01393 $0.01393
Opus 5.5 $0.00557 $0.00557
Sonnet 5.5 $0.00279 $0.00279
Haiku 4.5 $0.00139 $0.00139

Measured 2mo ago against content hash 52b7fe3d0626, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

charon 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 · 112 lines

How it starts

The opening of the file, as written. The whole thing — 112 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENTS.md

Guidance for AI coding agents (and humans) working in this repository. charon is a small Go CLI that detects the Codex, Claude Code, OpenCode, and Pi CLIs and switches each one's endpoint + credentials between named profiles.

Golden rule: this tool edits real user credentials

charon reads and writes live config for other tools (~/.codex, ~/.claude, ~/.config/opencode, ~/.local/share/opencode, ~/.pi/agent) and the macOS Keychain. It also reads ~/.claude.json (oauthAccount.emailAddress) solely to name an account-backup profile — that file is never written or snapshotted.

  • Never run charon add, charon switch, charon save, or the interactive menu against your real $HOME while developing. Always sandbox: 
    HOME=$(mktemp -d) go run ./cmd/charon status
  • Tests must never touch real config. Use t.Setenv("HOME", t.TempDir()) and t.Setenv("XDG_CONFIG_HOME", t.TempDir()). See internal/tools/tools_test.go and internal/profile/store_test.go for the pattern.
  • Do not add tests that read or write the real Keychain. The keychain shell-out (internal/secret/keychain_darwin.go) is intentionally left uncovered.
  • Preserve the safety guarantees: atomic writes (temp file + rename), 0600 on credential files / 0700 on dirs, and an auto-backup before every switch. Don't regress these.

Commands

make build      # build ./charon
make test       # go vet + go test -race ./...
make cover      # coverage summary
make lint       # golangci-lint run
make fmt        # gofmt -w .
make run        # build + open the interactive menu (sandbox your HOME first)

Always run make fmt and make test before finishing a change. CI (.github/workflows/ci.yml) runs fmt-check, vet, -race tests, build, and golangci-lint on Linux + macOS; keep all of them green.

Architecture

cmd/charon/         CLI entrypoint (thin; no business logic)
  main.go           main, subcommand dispatch, usage
  commands.go       one cmd* func per subcommand + requireTool
internal/artifact/  snapshot/restore primitives, no tool knowledge
  Artifact/Rotator/Merger/Peeker interfaces; FileArtifact,
  MergedFileArtifact, KeychainArtifact; AtomicWrite
internal/tools/   per-tool adapters
  tool.go           Tool struct, AuthSpec, registry (All/Find)
  providers.go      guards for the shared "charon" provider entry (codex/opencode)
  edit.go           JSON/TOML load-merge-write helpers (preserve unknown keys)
  codex.go / claude.go / opencode.go / pi.go   one file per tool
internal/profile/ snapshot store, split by concern:
  store.go (layout/config/name validation) · snapshot.go (Save/Add/Edit/EnsureDefault)
  apply.go (Apply/Undo/Drift/refresh) · backup.go (backups + prune) · manage.go (rm/mv/cp)
internal/models/  fetch model lists from a provider API (openai/anthropic wire)
internal/secret/  masking + platform keychain (darwin vs. other build tags)
internal/tui/     bubbletea interactive menu

Read the full file on GitHub · 112 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. 2mo ago First seen · 112 lines · 1,393 tokens per session scan A 52b7fe3d0626

Subscribe to this mod's changes

charon AGENTS.md is an instructions file published in the GitHub repository mingtheanlay/charon (12 stars, last pushed 3mo ago), licensed MIT. It adds 1,393 tokens to every session, about $0.0056 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.

9routerai-agentsbyokclicliproxyapi
Related

Other instructions, from other repositories

vscode buildNext.instructions.md

Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).

microsoft/vscode · 9,715 tokens

next.js AGENTS.md

AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.

vercel/next.js · 7,461 tokens

vscode oss-third-party-notices.instructions.md

Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).

microsoft/vscode · 5,262 tokens

langchain AGENTS.md

AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.

langchain-ai/langchain · 4,680 tokens

vscode copilot-instructions.md

Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).

microsoft/vscode · 2,750 tokens

deno copilot-instructions.md

Copilot instructions for denoland/deno, covering deno development guide for github copilot, network access, high level overview, key directories and key files to understand first.

denoland/deno · 3,077 tokens