feat(codex): add plugin manifest

.codex-plugin/plugin.json

@@ -0,0 +1,37 @@
+{
+  "author": {
+    "name": "Anton Babenko",
+    "url": "https://github.com/antonbabenko"
+  },
+  "description": "Terraform and OpenTofu best-practices skill for writing, reviewing, debugging, testing, CI, scans, and state operations.",
+  "homepage": "https://github.com/antonbabenko/terraform-skill",
+  "interface": {
+    "capabilities": [
+      "Interactive",
+      "Read",
+      "Write"
+    ],
+    "category": "Development",
+    "developerName": "Anton Babenko",
+    "displayName": "Terraform Skill",
+    "longDescription": "Diagnose-first Terraform and OpenTofu guidance with version-aware guardrails for module design, testing strategy, CI/CD workflows, security scanning, compliance checks, and state management.",
+    "shortDescription": "Terraform and OpenTofu guidance for modules, tests, CI, scans, and state operations.",
+    "websiteURL": "https://github.com/antonbabenko/terraform-skill"
+  },
+  "keywords": [
+    "ci-cd",
+    "iac",
+    "infrastructure-as-code",
+    "modules",
+    "opentofu",
+    "security-scanning",
+    "state-management",
+    "terraform",
+    "testing"
+  ],
+  "license": "Apache-2.0",
+  "name": "terraform-skill",
+  "repository": "https://github.com/antonbabenko/terraform-skill",
+  "skills": "./skills",
+  "version": "1.8.0"
+}

README.md

@@ -122,6 +122,24 @@ git clone https://github.com/antonbabenko/terraform-skill.git ~/.agents/skills/t
 
 Codex auto-discovers skills from `~/.agents/skills/` and `.agents/skills/`. Update with `cd ~/.agents/skills/terraform-skill && git pull`.
 
+Or add the following lines to your `~/.agents/plugins/marketplace.json` file under `plugins[]` to install this skill as a plugin:
+
+```json
+{
+  "category": "Productivity",
+  "name": "terraform-skill",
+  "policy": {
+    "authentication": "ON_INSTALL",
+    "installation": "AVAILABLE"
+  },
+  "source": {
+    "ref": "master",
+    "source": "url",
+    "url": "git@github.com:antonbabenko/terraform-skill.git"
+  }
+}
+```
+
 </details>
 
 <details>