maintain-cross-platform

maintain-cross-platform is a skill for Claude Code, Codex from agent-sh/agentsys. It costs 33 tokens per session (7,516 once invoked), scanned B, original, MIT.

A guide for maintaining one project across Claude Code, OpenCode, and Codex CLI, three tools for working with coding agents.

In plain words
What is it for?
Use it when preparing releases, checking compatibility, updating installation files, or validating the three-platform setup.
Why use it?
It helps keep configuration, versions, documentation, and release checks consistent across platforms.

Skill for Claude CodeCodex

Installs and runs on its own, but its text points at files inside its plugin — anything it tells you to read at a ${CLAUDE_PLUGIN_ROOT} path is only there once the plugin is installed. Installing the plugin gets both.

Part of the agentsys plugin — 28 skills, 1 hook shipped together

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 skills/agent-sh/agentsys/maintain-cross-platform
Any agent
npx skills add agent-sh/agentsys --skill maintain-cross-platform
Clone the repo
git clone --depth 1 https://github.com/agent-sh/agentsys

Made for: Claude Code, Codex.

Or install agentsys, the plugin that ships this one along with the rest of its 28 skills, 1 hook.

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 maintain-cross-platform

README.md
[![agentmods](https://agentmods.dev/badge/skills/agent-sh/agentsys/maintain-cross-platform.svg)](https://agentmods.dev/skills/agent-sh/agentsys/maintain-cross-platform)
Your own site
<a href="https://agentmods.dev/skills/agent-sh/agentsys/maintain-cross-platform"><img src="https://agentmods.dev/badge/skills/agent-sh/agentsys/maintain-cross-platform.svg" alt="Measured on agentmods" height="20"></a>
Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 7,516 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. 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 $0.00033 $0.07516
Opus 5 $0.00016 $0.03758
Sonnet 5 $0.00007 $0.01503
Haiku 4.5 $0.00003 $0.00752

Measured 5d ago against content hash c107ac52c72e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

maintain-cross-platform scanned grade B with 1 finding 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 5d 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.

Reads agent configuration directoriesmediumAgent snooping

.claude/, .codex/, .gemini/ hold keys, settings and other credentials a mod has no legitimate need for.

| **Config location** | `~/.claude/settings.json` | `~/.config/opencode/opencode.json` | `~/.codex/config.toml` |
meta/skills/maintain-cross-platform/SKILL.md · 1,024 lines

How it starts

The opening of the file, as written. The whole thing — 1,024 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Maintain Cross-Platform Architecture

Purpose: Comprehensive knowledge of AgentSys's cross-platform infrastructure for release preparation, validation, and maintenance.

Scope: LOCAL skill for this repository only. Contains specific file locations, transformation rules, and automation patterns for maintaining Claude Code + OpenCode + Codex CLI compatibility.

Critical Rules

  1. 3 platforms MUST work - Claude Code, OpenCode, Codex CLI. No exceptions.
  2. Validation before every push - Pre-push hook runs 6 validators automatically.
  3. All version fields must align - 11 files total (package.json + 10 plugin.json files).
  4. Documentation must be accurate - Counts, paths, and platform references validated by CI.
  5. Update this skill - If you find misalignments or automation opportunities, update this file.

Platform Differences (The Complete Matrix)

Configuration

Aspect Claude Code OpenCode Codex CLI
Config format JSON JSON/JSONC TOML
Config location ~/.claude/settings.json ~/.config/opencode/opencode.json ~/.codex/config.toml
State directory .claude/ .opencode/ .codex/
Command prefix / / $
Project instructions CLAUDE.md AGENTS.md (reads CLAUDE.md) AGENTS.md

Component Locations

Component Claude Code OpenCode Codex CLI
Commands Plugin commands/ ~/.config/opencode/commands/ N/A (use skills)
Agents Plugin agents/ ~/.config/opencode/agents/ N/A (use MCP)
Skills Plugin skills/ .opencode/skills/ (singular) ~/.codex/skills/
Hooks Plugin hooks/ Plugin hooks/ Plugin hooks/

Install Locations (This Repo)

Platform Package Copy Commands Agents Skills Config
Claude Code Via marketplace Plugin bundled Plugin bundled Plugin bundled N/A
OpenCode ~/.agentsys/ ~/.config/opencode/commands/ ~/.config/opencode/agents/ (29 files) N/A ~/.config/opencode/opencode.json
Codex CLI ~/.agentsys/ N/A N/A ~/.codex/skills/ (9 directories) ~/.codex/config.toml

Read the full file on GitHub · 1,024 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. 5d ago First seen · 1,024 lines · 33 tokens per session scan B c107ac52c72e

Subscribe to this mod's changes

maintain-cross-platform is a skill published in the GitHub repository agent-sh/agentsys (982 stars, last pushed yesterday), licensed MIT. It adds 33 tokens to every session and 7,516 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it B with 1 finding (reads agent configuration directories). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.