Plugin forge

Plugin Forge

Helps users create and manage Claude Code plugins with correct directory structure, manifests, and marketplace registration. For plugin authors who need structure and registration handled without touching plugin logic.

When to use

• Creating a new Claude Code plugin from scratch
• Bumping a plugin's semver version (major, minor, patch)
• Adding a command, skill, agent, hook, or MCP server to an existing plugin
• Registering or updating a plugin entry in marketplace.json
• Checking that plugin.json and marketplace.json versions are in sync

Workflows

Scaffold new plugin

Inputs: plugin name, marketplace root path, author name, author email, description, keywords, category.

1. Interview the user for all inputs above and save them.
2. Check whether a plugin with that name already exists; if it does, ask for confirmation before overwriting and stop if not confirmed.
3. Create the plugin directory under the marketplace root.
4. Generate .claude-plugin/plugin.json with name, author, description, keywords, and category.
5. Generate README.md.
6. Optionally create commands/, skills/, agents/, hooks/ directories if the user wants them.
7. Draft the new marketplace.json entry and show it to the user for review.
8. After approval, write the entry into marketplace.json.

Check: plugin.json parses, directory structure matches the requested components, and the marketplace.json entry points at the correct source path. Output: the created file tree and the marketplace.json entry that was added.

Bump plugin version

Inputs: plugin name, semver increment type (major, minor, or patch).

1. Interview the user for the plugin name and increment type.
2. Locate the plugin and read the current version from plugin.json. If the plugin is not found, report that and stop.
3. Compute the new version from the increment type.
4. Draft the updated plugin.json and marketplace.json and show both to the user for review.
5. After approval, write both files.
6. Validate that both files carry the same version.

Check: plugin.json and marketplace.json show identical versions. Output: old version, new version, and confirmation that both files are in sync.

Add plugin components

Inputs: plugin name, component type (command, skill, agent, hook, MCP server), component name.

1. Interview the user for the plugin name, component type, and component name.
2. Locate the plugin; confirm it exists before proceeding.
3. Create the file or directory using the correct naming convention, e.g. commands/namespace/command.md for namespaced commands.
4. Update plugin.json keywords if the new component makes them relevant.
5. Draft the plugin.json change and show it to the user for review before writing.

Check: the new component sits at the correct path and plugin.json still parses. Output: the path of the created component and any plugin.json keyword changes.

Manage marketplace registration

Inputs: plugin name, source path, description, version, keywords, category.

1. Read the existing marketplace.json.
2. Check for a duplicate entry for the plugin.
3. Draft the add-or-update entry with source path, description, version, keywords, and category.
4. Show the draft to the user for review.
5. After approval, write the entry into marketplace.json.
6. Record which plugins have been registered so later runs do not duplicate entries.

Check: no duplicate entries exist for the plugin and the entry fields match the plugin's plugin.json. Output: the final marketplace.json entry and a note of whether it was added or updated.

Tools and data

• Use file system access to plugin and marketplace directories when available; if not available, ask the user to provide the file contents or connect the directory.

Guardrails

• Never modify plugin logic, code, or content beyond structure, manifests, and registration.
• Always draft changes to plugin.json and marketplace.json for user review before writing.
• Never delete a plugin or its components without explicit user confirmation.
• Never overwrite an existing plugin without confirmation.
• Do not modify existing components without explicit approval.
• Never publish or distribute plugins to any external marketplace.

Getting started

Ask the user for the marketplace root path and whether they want to create a new plugin, bump a version, add a component, or manage marketplace registration.

Credits

Adapted from an open-source original (MIT): https://www.aitmpl.com/component/skills/development/plugin-forge