Platform Paths

cmx can install agents and skills to any supported AI coding assistant platform. With no --platform, install/uninstall act across every platform already in use (falling back to Claude Code when nothing is tracked yet), and single-target commands default to Claude Code. Use the --platform flag or the CMX_PLATFORM environment variable to target one specific platform — Claude Code's unsuffixed lock file (below) preserves backward compatibility with installs made before platform selection existed.

Selecting a platform

# Install to Cursor globally
cmx agent install python-craftsperson --platform cursor

# Install to Windsurf locally
cmx skill install skill-creator --platform windsurf --local

# Set the platform via environment variable
export CMX_PLATFORM=copilot
cmx agent install python-craftsperson

The --platform flag is global — it applies to all subcommands.

Supported platforms

¹ Codex agents are TOML, not markdown. cmx agents are markdown files with YAML frontmatter; the Codex CLI defines subagents as standalone TOML files. When you install an agent with --platform codex, cmx transforms the source markdown into a Codex subagent document (<name>.toml): name, description, developer_instructions (the markdown body), and model, model_reasoning_effort, and sandbox_mode when the frontmatter sets them. Codex rejects any key it does not define, so every other frontmatter entry — including metadata.version — is kept at the top of the file as a # ----fenced comment block; Codex ignores it, and cmx agent list and cmx doctor read the version back from it.

² Skills-only platforms. Pi, Crush, Amp, Zed, OpenHands, Hermes, and Devin have no file-droppable agent concept (their "agents" are tool-gating profiles, runtime delegations, executable plugins, or trigger-activated skills), so cmx agent install --platform <tool> fails with a clear error. They support skills only.

³ Amp resolves user-scoped skills under XDG (~/.config/agents/skills/) rather than ~/.agents/skills/. Project skills still use .agents/skills/.

⁴ Hermes is global-centric. Its auto-read source of truth is ~/.hermes/skills/, so cmx installs user-scoped skills there. Project skills use the shared .agents/skills/, which Hermes reads only if you add it to skills.external_dirs in ~/.hermes/config.yaml.

⁵ Devin's skill discovery is repository-scoped. Devin (Cognition's cloud software engineer) discovers SKILL.md files in the repositories connected to it, with .agents/skills/ as its recommended location — so project-scoped installs are the ones Devin actually reads. It has no user-global discovery on your machine; a global install lands in the shared ~/.agents/skills/ for consistency with the cohort, but only reaches Devin once committed to a repo it can see.

The shared .agents skills convention

The .agents/skills/ directory (project) and ~/.agents/skills/ (user) is an emerging cross-tool standard — the agentskills.io SKILL.md format. opencode, Codex, Pi, Crush, Zed, OpenHands, and Devin all read it natively, so cmx installs skills there for the whole cohort. (Amp and Hermes read the project .agents/skills/ too but resolve user-scoped skills elsewhere — see notes ³ and ⁴.) This is a shared directory: a skill installed under one of these platforms is visible to the others.

A practical consequence: because each platform keeps its own lock file (below), uninstalling a skill with one of these platforms removes the underlying .agents/skills/<name> directory for all tools that read it. Reinstall it under the other platform if you only meant to stop tracking it for one.

Per-platform lock files

Each platform maintains its own lock file so installations for different tools do not interfere with each other.

Claude Code keeps cmx-lock.json (no suffix) for backward compatibility with installations made before platform selection was introduced.