Add Codex-native plugin marketplace manifest

.agents/plugins/marketplace.json

@@ -0,0 +1,66 @@
+{
+  "name": "dotnet-agent-skills",
+  "owner": {
+    "name": ".NET Team at Microsoft"
+  },
+  "interface": {
+    "displayName": ".NET Agent Skills"
+  },
+  "plugins": [
+    {
+      "name": "dotnet",
+      "source": "./plugins/dotnet",
+      "description": "Collection of core .NET skills for handling common .NET coding tasks."
+    },
+    {
+      "name": "dotnet-data",
+      "source": "./plugins/dotnet-data",
+      "description": "Skills for .NET data access and Entity Framework related tasks."
+    },
+    {
+      "name": "dotnet-diag",
+      "source": "./plugins/dotnet-diag",
+      "description": "Skills for .NET performance investigations, debugging, and incident analysis."
+    },
+    {
+      "name": "dotnet-msbuild",
+      "source": "./plugins/dotnet-msbuild",
+      "description": "Comprehensive MSBuild and .NET build skills: failure diagnosis, performance optimization, code quality, and modernization."
+    },
+    {
+      "name": "dotnet-nuget",
+      "source": "./plugins/dotnet-nuget",
+      "description": "NuGet and .NET package management: dependency management and modernization."
+    },
+    {
+      "name": "dotnet-upgrade",
+      "source": "./plugins/dotnet-upgrade",
+      "description": "Skills for migrating and upgrading .NET projects across framework versions, language features, and compatibility targets."
+    },
+    {
+      "name": "dotnet-maui",
+      "source": "./plugins/dotnet-maui",
+      "description": "Skills for .NET MAUI development: environment setup, diagnostics, troubleshooting, navigation, data binding, dependency injection, layout, and theming."
+    },
+    {
+      "name": "dotnet-ai",
+      "source": "./plugins/dotnet-ai",
+      "description": "AI and ML skills for .NET: technology selection, LLM integration, agentic workflows, RAG pipelines, MCP, and classic ML with ML.NET."
+    },
+    {
+      "name": "dotnet-template-engine",
+      "source": "./plugins/dotnet-template-engine",
+      "description": ".NET Template Engine skills: template discovery, project scaffolding, and template authoring."
+    },
+    {
+      "name": "dotnet-test",
+      "source": "./plugins/dotnet-test",
+      "description": "Skills for running, diagnosing, and migrating .NET tests: test execution, filtering, platform detection, and MSTest workflows."
+    },
+    {
+      "name": "dotnet-aspnet",
+      "source": "./plugins/dotnet-aspnet",
+      "description": "ASP.NET Core web development skills including middleware, endpoints, real-time communication, and API patterns."
+    }
+  ]
+}

CONTRIBUTING.md

@@ -51,7 +51,7 @@ If your skill does not fit any existing plugin, consider creating a new one.
 To create a new plugin:
 
 1. Add `plugins/<plugin-name>/plugin.json` and a `skills/` directory beneath it.
-2. Add a matching entry in `.github/plugin/marketplace.json`, `.claude-plugin/marketplace.json`, and `.cursor-plugin/marketplace.json`. Keep plugin entries consistent across all marketplace manifests (including `plugins[].source` format) to reduce drift and make future updates safer.
+2. Add a matching entry in `.github/plugin/marketplace.json`, `.claude-plugin/marketplace.json`, `.cursor-plugin/marketplace.json`, and `.agents/plugins/marketplace.json`. Keep plugin entries consistent across all marketplace manifests (including `plugins[].source` format) to reduce drift and make future updates safer.
 3. Add a CODEOWNERS entry for the new plugin and its tests (see [Code ownership](#code-ownership)).
 4. Add the plugin to the **What's Included** table in the root `README.md`.
 5. Create a `tests/<plugin-name>/` directory for skill tests.

README.md

@@ -80,7 +80,29 @@ For local development or unpublished changes, import plugins from a local checko
 Skills in this repository follow the [agentskills.io](https://agentskills.io) open standard
 and are compatible with [OpenAI Codex](https://developers.openai.com/codex/skills).
 
-Install individual skills using the `skill-installer` CLI with the GitHub URL:
+#### Plugin marketplace (recommended)
+
+Codex CLI v0.121.0 and later supports a [plugin marketplace](https://developers.openai.com/codex/plugins).
+This repository ships a Codex-native marketplace manifest at `.agents/plugins/marketplace.json`,
+so you can register `dotnet/skills` as a marketplace and install plugins from it directly.
+
+1. Add the marketplace:
+   ```bash
+   codex plugin marketplace add dotnet/skills
+   ```
+2. Launch Codex and open the plugin browser:
+   ```
+   /plugins
+   ```
+3. Browse the `dotnet-agent-skills` tab and install the desired plugins.
+4. Update plugins on demand:
+   ```bash
+   codex plugin marketplace upgrade dotnet-agent-skills
+   ```
+
+#### Individual skills
+
+You can also install individual skills using the `skill-installer` CLI with the GitHub URL:
 
 ```bash
 $ skill-installer install https://github.com/dotnet/skills/tree/main/plugins/<plugin>/skills/<skill-name>