Plugin & skill marketplace setup

Ship skills (portable instructions), plugins (runtime wiring), and marketplaces (catalogs) without mixing them up.

Three layers (normative)

Layer	What it is	Install unit	Skill Steward home
Skill	SKILL.md per agentskills.io	npx skills add owner/repo --skill name	skills/{name}/
Plugin	Open Plugin or vendor manifest + hooks/MCP/rules/commands	Per-agent (see matrix)	plugins/{id}/ (ADR 0004)
Marketplace	Catalog of plugins/skills	Add marketplace, then install plugin	Product repos; Skill Steward uses public Git + skills.sh

Rule: Instructions only → skill. Event hooks or multi-file wiring → plugin (references skills by id, do not fork SKILL.md).

Skill Steward meta-plugin means: a declarative manifest, referenced skill IDs, hook/rule snippets, and validated wiring artifacts. It does not mean a host marketplace submission has happened, and it must not silently mutate Cursor/Codex/Claude configuration. Host-specific install steps remain explicit in README/docs.

Public vs private (decision)

Goal	Recommended channel	Notes
Public discovery	GitHub public repo + skills.sh	npx skills add owner/repo; index needs valid skills/*/SKILL.md
Team-only skills (any agent)	Private GitHub/GitLab repo	Same npx skills add org/private-repo if agents can clone; use deploy keys / SSO
Cursor team plugins	Team marketplace — Dashboard → Settings → Plugins → Import repo	Teams/Enterprise; private GitHub repo with .cursor-plugin/marketplace.json
Claude Code team	Private git marketplace	/plugin marketplace add with token env for auto-update (Claude docs)
Codex team	$REPO_ROOT/.agents/plugins/marketplace.json or ~/.agents/plugins/marketplace.json	Repo/personal marketplace; install from app or CLI
Zed skills	.agents/skills/ or ~/.agents/skills/	Skills only; Zed has no remote skill registry or custom search paths
npm-private skills packages	Claude marketplace source.type: npm	For npm-hosted plugin bundles; uncommon for plain SKILL.md trees

Skill Steward default: public arenukvern/skill_steward for meta-skills; hooks documented separately (npx skills does not install Cursor hooks).

Cross-agent install matrix (skills)

Use vercel-labs/skills as the shared installer:

npx skills add owner/repo                    # all skills, project scope
npx skills add owner/repo --skill my-skill   # one skill
npx skills add owner/repo -a cursor -a claude-code -a codex -a zed -y
npx skills add owner/repo -g                 # global (~/.agents/skills/)
npx skills add owner/repo --copy             # copy instead of symlink

Discovery also reads .claude-plugin/plugin.json and .claude-plugin/marketplace.json skill paths (Claude marketplace compatibility).

Agent	--agent flag	Project skills path	Global skills path
Cursor	cursor	.agents/skills/ (Cursor also reads .cursor/skills/)	~/.cursor/skills/
Claude Code	claude-code	.claude/skills/	~/.claude/skills/
Codex	codex	.agents/skills/	~/.codex/skills/
Zed	zed	.agents/skills/	~/.agents/skills/
Copilot, Windsurf, Cline, …	see npx skills --help	per CLI table	per CLI table

Hooks: supported on Claude Code, Cline, Kiro—not Cursor via npx skills. Cursor hooks need .cursor/hooks.json (Skill Steward example).

Cross-agent install matrix (plugins)

Agent	Manifest dir	Marketplace file	Install (typical)
Cursor	.cursor-plugin/plugin.json	.cursor-plugin/marketplace.json (multi-plugin repo)	Marketplace UI, team import, or init script → .cursor/plugins/local/
Claude Code	.claude-plugin/plugin.json	.claude-plugin/marketplace.json	/plugin marketplace add owner/repo then /plugin install name@marketplace
Codex	.codex-plugin/plugin.json	$REPO_ROOT/.agents/plugins/marketplace.json or ~/.agents/plugins/marketplace.json	App plugin directory or codex plugin add name@marketplace
Open Plugin v1	.plugin/plugin.json	host-specific	Portable baseline; add vendor manifests only for host-specific overrides
Open skills only	N/A	N/A	npx skills add — no MCP/hooks

Reference product layout: product repository marketplace distribution configs.

Workflow: repo-local copy/init pattern

Use this when a product repo needs agents to generate a local installer like flutter-mcp-toolkit init: a repo-owned script that copies canonical skills, host plugin manifests, MCP config, hooks, assets, and marketplace catalog files into Codex/Cursor/Claude layouts.

1. Inspect source truth — find canonical skills/, existing plugins/, .mcp.json/mcp.json, hooks, package/version metadata, assets, and current install docs. Do not generate host manifests from memory alone.
2. Choose the channel — use npx skills add --copy for skills-only distribution; use a repo-local copy/init script when skills must ship with MCP, hooks, commands, or assets; use host marketplace manifests only when the repo needs Codex/Cursor/Claude plugin install flows.
3. Create a product-owned plugin payload — keep canonical skills in the product repo, then copy or generate the install payload under plugin/ or plugins/{id}/ with .codex-plugin/, .cursor-plugin/, .claude-plugin/, optional .plugin/, skills/, hooks, MCP config, and assets.
4. Write explicit local scripts — generate an idempotent script owned by the product repo (tool/install_agent_bundle.dart, bin/<tool> init, or equivalent). The script should plan/copy directories, create host manifest directories, write marketplace root files, and report changed paths.
5. Document exact install commands — include separate Codex, Cursor, Claude, and skills-only commands. Name cache refresh/reinstall behavior and rollback steps.
6. Keep claims bounded — "local copy pattern implemented" does not mean public marketplace submission, host review, runtime MCP correctness, or fresh-agent proof.

See local-copy-pattern.md for a reusable layout, script skeleton, and validation checklist.

Codex plugin notes

• Keep only plugin.json in .codex-plugin/; put skills/, .mcp.json, .app.json, hooks/, and assets/ at plugin root.
• Include skills, mcpServers, apps, or hooks in .codex-plugin/plugin.json only when the companion files/directories exist. Codex also checks default hooks/hooks.json.
• Marketplace files live at $REPO_ROOT/.agents/plugins/marketplace.json for repo/team catalogs or ~/.agents/plugins/marketplace.json for personal catalogs.
• Each marketplace entry must include policy.installation, policy.authentication, and category; keep source.path relative to the marketplace root and inside that root.
• Codex installs marketplace plugins into ~/.codex/plugins/cache/$MARKETPLACE_NAME/$PLUGIN_NAME/$VERSION/; local source edits require reinstall/cache refresh before new threads see them.

Open Plugin portability

• Use .plugin/plugin.json when a plugin should be vendor-neutral across Open Plugin hosts.
• Add .codex-plugin/plugin.json, .cursor-plugin/plugin.json, or .claude-plugin/plugin.json only when the host needs a vendor-specific manifest.
• Do not confuse Skill Steward plugin.yaml with a host marketplace manifest. It is a local meta-plugin manifest for documenting Skill Steward wiring.

Scaffold a new marketplace repo

A. Skills-only marketplace (simplest — Skill Steward style)

my-skills/
├── skills/
│   └── my-skill/
│       └── SKILL.md
├── skills.sh.json          # optional: skills.sh categories
├── README.md               # install commands
└── package.json            # optional: pnpm run validate

Publish: push public → npx skills add org/my-skills. No plugin manifest required. For customizing the repository page by defining groupings and categories in skills.sh.json, see the skills.sh customization docs.

B. Codex / Claude / Cursor marketplace (multi-plugin)

my-marketplace/
├── .agents/plugins/
│   └── marketplace.json    # Codex catalog
├── .claude-plugin/
│   └── marketplace.json    # Claude catalog, when needed
├── .cursor-plugin/
│   └── marketplace.json    # Cursor catalog, when needed
└── plugins/
    └── my-plugin/
        ├── .plugin/plugin.json
        ├── .codex-plugin/plugin.json
        ├── .claude-plugin/plugin.json
        ├── .cursor-plugin/plugin.json
        ├── skills/
        ├── hooks/
        └── .mcp.json

Codex entry: "source": {"source": "local", "path": "./plugins/my-plugin"} plus policy/category. Claude and Cursor keep their own marketplace shapes. Use only the vendor trees the target agents need.

C. Skill Steward meta-plugin (hooks + skill refs)

plugins/my-hook-pack/
├── plugin.yaml
├── README.md               # manual .cursor/hooks.json steps
├── hooks.json.snippet
└── hooks/

Canonical skills stay in skills/. See templates/plugin/.

Private marketplace checklist

1. Repo access — team can git clone (HTTPS token, SSH, or GHE app for Cursor team marketplaces).
2. Secrets — never commit tokens; document GITHUB_TOKEN / GITLAB_TOKEN for Claude auto-update on private marketplaces.
3. Install docs — one README block per channel (skills CLI vs Claude /plugin vs Cursor dashboard).
4. Versioning — bump version in plugin manifest per release; skills use git SHA via npx skills update.
5. CI — validate skills (pnpm run validate / dart run :steward validate in Skill Steward); product repos add contract tests.
6. Scope — project install (committed .agents/skills/) vs -g global; document team norm.

Skill Steward vs product repo

Concern	Skill Steward	Product (e.g. product MCP)
Skills	Meta only (skill-authoring-lifecycle, repository-governance-lifecycle, …)	Domain + MCP skills
Plugins	Meta hooks (steward-validate-on-save)	Full bundle: MCP + skills + init
CLI	steward validate	[toolkit-cli] init <agent>
Marketplace	Public Git + skills.sh	Claude/Codex git + Cursor submit + Smithery
Copy/init scripts	Skills teach the pattern	Product repo owns generated script, host payloads, and install proof

Do not put product MCP servers in Skill Steward. Cross-promote: npx skills add arenukvern/skill_steward --skill mcp-harness-repo-maintainer.

Workflow: add a distributable skill to Skill Steward

1. Follow skill-authoring-lifecycle — skills/{name}/SKILL.md.
2. Register in skills.sh.json + root README.md.
3. pnpm run validate in skill_steward.
4. After merge to main, public repo is installable via npx skills add arenukvern/skill_steward --skill {name}.
5. Optional: submit to skills.sh leaderboard (automatic for public repos with valid skills).

Workflow: add a Skill Steward plugin

1. Copy templates/plugin/ → plugins/{id}/.
2. List referenced skills in plugin.yaml (ids only).
3. Document install (Cursor hooks merge, etc.).
4. Update plugins/README.md.

Anti-patterns

• Putting hooks only in skills/ and expecting npx skills to wire Cursor
• Duplicating SKILL.md inside every plugin directory
• Calling a repo-local copy/init script "public marketplace readiness" without host install proof
• Moving product-specific installer code into steward_cli before repeated repo evidence proves a generic Steward module is useful
• Private marketplace docs that only mention one agent
• Eternal plan files in marketplace repos (see plan hygiene)

Additional resources

• distribution-matrix.md — full channel table
• manifest-snippets.md — minimal JSON/YAML examples
• local-copy-pattern.md — repo-local copy/init script pattern
• ADR 0004
• ADR 0006
• skills.sh customization docs

Install this skill

npx skills add arenukvern/skill_steward --skill plugin-marketplace-setup

Sources

See references/sources.md. When researching, follow skill-source-citations.