feat(plugin-builder): add plugin creation MCP app

.agents/plugins/marketplace.json

@@ -1465,6 +1465,18 @@
         "authentication": "ON_INSTALL"
       },
       "category": "Engineering"
+    },
+    {
+      "name": "plugin-builder",
+      "source": {
+        "source": "local",
+        "path": "./plugins/plugin-builder"
+      },
+      "policy": {
+        "installation": "AVAILABLE",
+        "authentication": "ON_INSTALL"
+      },
+      "category": "Engineering"
     }
   ]
 }

.agents/skills/plugin-creator/SKILL.md

@@ -151,12 +151,16 @@ python3 .agents/skills/plugin-creator/scripts/create_basic_plugin.py my-plugin \
 - Add `policy.products` only when the user explicitly asks for that override.
 - Keep marketplace `source.path` relative to the selected marketplace root as `./plugins/<plugin-name>`.
 - When the workflow created or updated a marketplace-backed plugin, end the final user-facing
-  response with these two Markdown links, in this order, and do not add any text after them:
-  - `[View <normalized plugin name>](codex://plugins/view-local?marketplacePath=<absolute marketplace.json path>&pluginName=<normalized plugin name>)`
-  - `[Share <normalized plugin name>](codex://plugins/share-local?marketplacePath=<absolute marketplace.json path>&pluginName=<normalized plugin name>)`
-- Replace the link-label placeholder and both deeplink placeholders with the real normalized plugin
-  name plus the real absolute marketplace path from the scaffolded plugin. URL-encode query
-  parameter values when needed.
+  response with this Codex app handoff block, in this order, and do not add any text after the links.
+  First write the standalone line `To view this in the Codex app:`. Then write:
+  - `[View <normalized plugin name>](codex://plugins/<normalized plugin name>?marketplacePath=<absolute marketplace.json path>)`
+  - `[Share <normalized plugin name>](codex://plugins/<normalized plugin name>?marketplacePath=<absolute marketplace.json path>&mode=share)`
+- Replace the normalized plugin-name placeholder in both the Markdown label and the deeplink path
+  segment with the real normalized plugin name. Replace the marketplace path placeholder with the
+  real absolute `marketplace.json` path from the scaffolded plugin. URL-encode the path segment and
+  query value when needed.
+- Do not add `pluginName` or `hostId` query parameters to these deeplinks. Codex derives both after
+  the user clicks the link.
 - Do not emit the `View <normalized plugin name>` or `Share <normalized plugin name>` links when no marketplace entry was
   created or updated.
 

plugins/plugin-builder/.codex-plugin/plugin.json

@@ -0,0 +1,30 @@
+{
+  "name": "plugin-builder",
+  "version": "0.1.0",
+  "description": "Create local Codex plugins with the bundled Plugin Creator skill, then review and share the result from a polished right-side app.",
+  "author": {
+    "name": "OpenAI",
+    "url": "https://openai.com/"
+  },
+  "homepage": "https://openai.com/",
+  "license": "Proprietary",
+  "keywords": [
+    "plugin",
+    "builder",
+    "sharing",
+    "mcp-app"
+  ],
+  "skills": "./skills/",
+  "mcpServers": "./.mcp.json",
+  "interface": {
+    "displayName": "Plugin Builder",
+    "shortDescription": "Create, review, and share newly built local plugins",
+    "longDescription": "Use the bundled Plugin Creator skill to scaffold a local plugin, then open a read-only Codex app that inspects the plugin's real local contents and continues into View or Share in the desktop app.",
+    "developerName": "OpenAI",
+    "category": "Developer Tools",
+    "websiteURL": "https://openai.com/",
+    "privacyPolicyURL": "https://openai.com/policies/row-privacy-policy/",
+    "termsOfServiceURL": "https://openai.com/policies/row-terms-of-use/",
+    "screenshots": []
+  }
+}

plugins/plugin-builder/.mcp.json

@@ -0,0 +1,11 @@
+{
+  "mcpServers": {
+    "plugin-builder": {
+      "command": "node",
+      "args": [
+        "./mcp/server.js"
+      ],
+      "cwd": "."
+    }
+  }
+}

plugins/plugin-builder/app/.gitignore

@@ -0,0 +1,2 @@
+node_modules/
+dist/raw/

plugins/plugin-builder/app/index.html

@@ -0,0 +1,12 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>Plugin Builder</title>
+  </head>
+  <body>
+    <div id="root"></div>
+    <script type="module" src="/src/main.tsx"></script>
+  </body>
+</html>