Engineer Plugin Marketplace

Plugin Marketplace Engineer

Use this skill when the user asks to create, assess, or plan a plugin marketplace for AI IDE plugins. Focus on marketplace-level distribution: catalog roots, per-host payloads, release sync, install flows, local dogfood, cache refresh, trust, and validation.

For a single plugin package, prefer engineer-ai-ide-plugin. For one MCP server or hook adapter, prefer the focused skills listed in references/related-skills.md.

Evidence First

Before giving implementation details, verify the current official docs for each target host. Record the consulted links and separate:

• Verified host contract: manifest paths, component fields, marketplace shape, install commands, trust prompts, and validation commands.
• Local inference: patterns copied from nearby repos such as flowai, flowai-workflow, or FoxCode.
• Unknowns: host features that must be checked before writing files.

Use these official anchors first:

• Claude Code plugins: https://code.claude.com/docs/en/plugins
• Claude Code marketplaces: https://code.claude.com/docs/en/plugin-marketplaces
• Codex plugins: https://developers.openai.com/codex/plugins
• Codex build guide: https://developers.openai.com/codex/plugins/build
• OpenCode plugins: https://opencode.ai/docs/plugins/
• Cursor MCP: https://cursor.com/docs/mcp
• Agent Skills: https://agentskills.io/

Workflow

1. Classify scope.
   • Marketplace design only -> produce requirements and risks; do not create files.
   • Marketplace implementation -> design first, then create source, build, validate, install-smoke, and docs.
   • Existing marketplace audit -> inspect manifests, payload roots, install docs, sync scripts, cache behavior, and validation evidence.
2. Define the marketplace contract.
   • Technical marketplace name, display name, owner, repository, license, version source, target hosts, supported install scopes, and trust model.
   • Plugin inventory: plugin IDs, descriptions, categories, tags, capabilities, auth policy, and source paths.
   • Payload inventory: skills, commands, agents, MCP servers, hooks, apps, assets, scripts, binaries, and runtime dependencies.
3. Split shared source from host outputs.
   • Shared source: skill bodies, MCP code, assets, schemas, scripts, docs.
   • Host output: marketplace root, plugin manifest, component paths, hook format, MCP config, app config, install commands, cache paths, trust prompts.
   • Do not claim one universal marketplace format unless current docs prove it.
4. Specify packaging transforms.
   • Deterministic file enumeration and sorted output.
   • Version injection from one source.
   • Asset copy near the consuming component.
   • Namespace rewrite for slash commands where the host requires plugin namespaces.
   • Host-specific path rewrite instead of leaking one host's root variables into another host.
5. Specify local dogfood.
   • Use a distinct local marketplace name such as <name>-local.
   • Preserve disabled plugin state across reinstall.
   • Keep official and local marketplace installs side by side.
   • For Codex, run marketplace registration and plugin add/materialization.
6. Specify validation gates before publishing.
   • Schema/path validation for every marketplace and plugin manifest.
   • Rebuild from source and fail on stale generated files.
   • Byte-deterministic rebuild check.
   • Install smoke in isolated host homes or config dirs.
   • MCP handshake smoke: initialize and tools/list from installed payload.
   • Hook smoke: parse and execute declared command hooks with synthetic host env; mark real trust/enablement as user-reviewed when required by the host.
   • Cache refresh check for same-version local rebuilds.

Required Output

For design or requirements work, include:

• Official docs consulted.
• Requirements.
• Constraints.
• Anti-patterns.
• Canonical source layout.
• Host-specific output layout.
• Runtime, data, cache, and trust contracts.
• Local dogfood flow.
• Release sync plan.
• Validation gates.
• Risks and open questions.
• Related skills with links; read references/related-skills.md when the user asks for skill links or when routing adjacent work.

For implementation work, create files in this order:

1. Shared source and schemas.
2. Host-specific marketplace and plugin manifests.
3. Build/sync scripts.
4. Validation and install-smoke tests.
5. User documentation.

Rules

• Keep generated marketplace payloads out of source control unless the downstream repo is intentionally generated.
• Never edit generated dist/ payloads by hand.
• Never publish from an unvalidated local tree.
• Never overwrite user-disabled plugin state during local reinstall.
• Never require manual config edits when the host supports native plugin wiring; if a manual edit is unavoidable, label it as a host limitation.
• Never treat hook trust prompts as implementation noise; they are product behavior.
• Never package Codex agents/subagents unless current Codex plugin docs define that component. Represent worker behavior as skills when in doubt.