Crosstrain

CLI tool and OpenCode plugin for converting Claude Code extensions to OpenCode format.

What It Does

Crosstrain bridges Claude Code's extension ecosystem to OpenCode:

Claude Code	→	OpenCode
Skills (.claude/skills/)	→	Plugin tools
Agents (.claude/agents/)	→	Agents (.opencode/agent/)
Commands (.claude/commands/)	→	Commands (.opencode/command/)
Hooks (settings.json)	→	Event handlers
MCP Servers (.mcp.json)	→	MCP config (opencode.json)

Installation

Quick Install

# Install globally with bun
bun install -g @fwdslsh/crosstrain"

# Or run directly
bunx crosstrain --help

From Source

git clone https://github.com/fwdslsh/crosstrain.git
cd crosstrain
bun install
bun link  # Makes 'crosstrain' available globally

CLI Usage

crosstrain <command> [path] [options]

Commands

Command	Description
command <path>	Convert a Claude Code command (.md file)
skill <path>	Convert a skill to OpenCode plugin tool
agent <path>	Convert an agent to OpenCode format
hook	Display Claude Code hooks configuration
mcp [path]	Convert MCP servers to OpenCode config
plugin <source>	Convert a full plugin (local or remote)
list <source>	List plugins in a marketplace
all	Convert all Claude Code assets in project
init	Initialize a new skills plugin
settings	Import Claude Code settings to opencode.json

Options

Option	Description
-o, --output-dir <path>	Output directory (default: .opencode)
-p, --prefix <prefix>	File prefix for generated files (default: claude_)
-v, --verbose	Enable verbose output
--dry-run	Preview changes without writing files
--no-user	Skip user-level assets from ~/.claude

Examples

# Convert all assets in current project
crosstrain all

# Preview changes without writing
crosstrain all --dry-run

# Convert a single command
crosstrain command .claude/commands/create-feature.md

# Convert a skill to a plugin tool
crosstrain skill .claude/skills/pdf-extractor

# Convert a plugin from GitHub
crosstrain plugin anthropics/claude-plugins/code-review

# Browse a marketplace
crosstrain list anthropics/claude-plugins

# Convert a specific version
crosstrain plugin org/repo/plugin@v1.0.0

OpenCode Plugin

Crosstrain also works as an OpenCode plugin, exposing tools that let the AI agent assist with conversion.

Plugin Installation

# Clone to your plugin directory
git clone https://github.com/fwdslsh/crosstrain.git .opencode/plugin/crosstrain
cd .opencode/plugin/crosstrain
bun install

Plugin Tools

When installed as a plugin, the AI agent can use these tools:

• crosstrain - Run any CLI command
• crosstrain_convert_all - Convert all assets
• crosstrain_convert_plugin - Convert a plugin
• crosstrain_list_marketplace - Browse marketplaces
• crosstrain_convert_command - Convert single command
• crosstrain_convert_skill - Convert single skill
• crosstrain_convert_agent - Convert single agent
• crosstrain_convert_mcp - Convert MCP servers
• crosstrain_show_hooks - Display hooks config
• crosstrain_init - Initialize skills plugin
• crosstrain_import_settings - Import Claude Code settings to opencode.json

Plugin Configuration

Optional settings in .opencode/plugin/crosstrain/settings.json:

{
  "enabled": true,
  "verbose": false
}

Asset Conversion Details

Skills → Plugin Tools

Claude Code skills become OpenCode plugin tools:

.claude/skills/commit-helper/SKILL.md → .opencode/plugin/crosstrain-skills/tools/skill_commit_helper.ts

Agents → Agents

.claude/agents/code-review.md → .opencode/agent/claude_code-review.md

Model mapping:

• sonnet → anthropic/claude-sonnet-4-20250514
• opus → anthropic/claude-opus-4-20250514
• haiku → anthropic/claude-haiku-4-20250514

Commands → Commands

.claude/commands/run-tests.md → .opencode/command/claude_run-tests.md

Hooks → Event Handlers

Event mapping:

• PreToolUse → tool.execute.before
• PostToolUse → tool.execute.after
• SessionStart → session.created
• SessionEnd → session.idle

MCP Servers → OpenCode Config

.mcp.json → opencode.json (mcp section)

Settings → opencode.json

Claude Code settings are converted to OpenCode configuration:

# Import settings
crosstrain settings

# Preview first
crosstrain settings --dry-run

Permission mode mapping:

• acceptEdits → { edit: "allow" }
• bypassPermissions → { edit: "allow", bash: "allow" }
• plan → { edit: "deny", bash: "deny" }

Not converted (no direct equivalent):

• hooks - Use OpenCode plugins instead
• env - Set environment variables before running OpenCode
• companyAnnouncements - Not supported
• sandbox - OpenCode uses different sandboxing

Remote Plugins

Convert plugins directly from GitHub:

# GitHub shorthand
crosstrain plugin org/repo/plugin-name

# With version tag
crosstrain plugin org/repo/plugin-name@v1.0.0

# Full URL
crosstrain plugin https://github.com/org/repo

Browsing Marketplaces

List available plugins in a Claude Code marketplace:

crosstrain list anthropics/claude-plugins

Output shows plugin names, descriptions, and the command to convert each one.

Crosstrainer Configuration

Plugin authors can customize conversion by adding a crosstrainer.json or crosstrainer.js file to their plugin root.

JSON Configuration

For simple customization (model mappings, asset filtering):

{
  "name": "my-plugin",
  "prefix": "myplugin_",
  "models": {
    "sonnet": "anthropic/claude-sonnet-4-20250514"
  },
  "agents": {
    "exclude": ["deprecated-agent"]
  }
}

JavaScript Configuration

For full control with transform hooks:

export default {
  name: "my-plugin",

  transformAgent(agent, ctx) {
    // Modify agent before conversion
    agent.model = "opus"
    return agent
  },

  transformCommand(command, ctx) {
    // Return null to skip
    if (command.name.startsWith("internal-")) return null
    return command
  },

  onConversionComplete(ctx, results) {
    console.log(`Converted ${results.agents.length} agents`)
  }
}

Only one crosstrainer file per plugin. See CLI Reference for full documentation.

Development

bun install          # Install dependencies
bun test             # Run tests
bun run typecheck    # Type check
bun run build        # Build

Documentation

• CLI Reference - Full CLI documentation
• CLAUDE.md - Architecture and development guide

License

CC-BY-4.0