add gemini cli extension

Author: jsneedles

README.md

@@ -17,6 +17,7 @@ This repository is a portable [Agent Plugin](https://agent-plugins.org/) package
 | `.claude-plugin/plugin.json` | Claude Code plugin manifest. |
 | `.cursor-plugin/plugin.json` | Cursor Marketplace manifest. |
 | `.grok-plugin/plugin.json` | Grok Build marketplace manifest. |
+| `gemini-extension.json` | Gemini CLI extension manifest. |
 | `kimi.plugin.json` | Kimi Code plugin manifest. |
 | `skills/hcti-image-generation/` | Image generation and template workflow guidance. |
 | `skills/hcti-open-graph-images/` | Dynamic Open Graph image configuration guidance. |
@@ -40,6 +41,18 @@ Run `/mcp-config login hcti` and complete authorization in your browser. Then us
 
 To test a local checkout, use `/plugins install /path/to/agent-plugins`. Kimi copies installed plugins into its managed plugin directory, so reinstall after changing the local source.
 
+## Gemini CLI
+
+Install the extension directly from GitHub:
+
+```bash
+gemini extensions install https://github.com/htmlcsstoimage/agent-plugins
+```
+
+Restart Gemini CLI, run `/extensions list` to confirm the extension is enabled, then run `/mcp auth hcti` and complete authorization in your browser. Use `/mcp list` to confirm the HCTI tools are connected. Gemini CLI automatically discovers the included HCTI Agent Skills.
+
+To test a local checkout during development, run `gemini extensions link /path/to/agent-plugins`, restart Gemini CLI, and inspect it with `/extensions list`.
+
 ## GitHub Copilot
 
 ### Install a local checkout
@@ -187,6 +200,7 @@ Our AI agent plugins are registered in the [HOL Plugin Registry](https://hol.org
 - [Official ChatGPT and Codex plugin](https://chatgpt.com/plugins/plugin_asdk_app_6a4d168031448191abcd6540497efb7b)
 - [OpenAI plugin packaging documentation](https://developers.openai.com/codex/plugins/build)
 - [Kimi Code plugin documentation](https://github.com/MoonshotAI/kimi-code/blob/main/docs/en/customization/plugins.md)
+- [Gemini CLI extension documentation](https://geminicli.com/docs/extensions/)
 - [GitHub Copilot plugin documentation](https://docs.github.com/en/copilot/concepts/agents/about-plugins)
 - [Cline MCP installation instructions](llms-install.md)
 - [Cursor plugin documentation](https://cursor.com/docs/plugins)

gemini-extension.json

@@ -0,0 +1,12 @@
+{
+  "name": "html-css-to-image",
+  "version": "0.2.0",
+  "description": "Create images, website screenshots, and PDFs from HTML/CSS, URLs, or reusable templates.",
+  "mcpServers": {
+    "hcti": {
+      "type": "http",
+      "url": "https://mcp.hcti.io",
+      "description": "Hosted HTML/CSS to Image MCP server with browser-based OAuth."
+    }
+  }
+}

scripts/validate-template.mjs

@@ -426,6 +426,53 @@ async function validateKimiAdapter(expectedName, expectedVersion) {
   }
 }
 
+async function validateGeminiAdapter(expectedName, expectedVersion) {
+  const manifestPath = path.join(repoRoot, "gemini-extension.json");
+  const manifest = await readJsonFile(manifestPath, "Gemini CLI extension manifest");
+  if (!manifest) {
+    return;
+  }
+
+  if (typeof manifest.name !== "string" || !marketplaceNamePattern.test(manifest.name)) {
+    addError("Gemini CLI extension name must be lowercase kebab-case.");
+  } else if (manifest.name !== expectedName) {
+    addError(`Gemini CLI extension name "${manifest.name}" does not match "${expectedName}".`);
+  }
+
+  for (const field of ["version", "description"]) {
+    if (typeof manifest[field] !== "string" || manifest[field].trim().length === 0) {
+      addError(`Gemini CLI extension: "${field}" is required.`);
+    }
+  }
+
+  if (manifest.version !== expectedVersion) {
+    addError(
+      `Gemini CLI extension version "${manifest.version}" does not match adapter version "${expectedVersion}".`
+    );
+  }
+
+  if (!manifest.mcpServers || typeof manifest.mcpServers !== "object" || Array.isArray(manifest.mcpServers)) {
+    addError('Gemini CLI extension must contain an "mcpServers" object.');
+    return;
+  }
+
+  const hctiServer = manifest.mcpServers.hcti;
+  if (!hctiServer || typeof hctiServer !== "object" || Array.isArray(hctiServer)) {
+    addError('Gemini CLI extension must declare the "hcti" MCP server.');
+    return;
+  }
+
+  if (hctiServer.type !== "http") {
+    addError('Gemini CLI MCP server "hcti" must use type "http" for Streamable HTTP.');
+  }
+  if (typeof hctiServer.url !== "string" || !hctiServer.url.startsWith("https://")) {
+    addError('Gemini CLI MCP server "hcti" must use an HTTPS URL.');
+  }
+  if (hctiServer.command || hctiServer.headers || hctiServer.env) {
+    addError('Gemini CLI MCP server "hcti" must use hosted OAuth without a local command, headers, or environment variables.');
+  }
+}
+
 async function main() {
   const marketplacePath = path.join(repoRoot, ".cursor-plugin", "marketplace.json");
   const rootManifestPath = path.join(repoRoot, ".cursor-plugin", "plugin.json");
@@ -441,6 +488,7 @@ async function main() {
       await validatePluginDirectory(repoRoot, expectedName, rootManifest);
       await validateClaudeAdapter(expectedName);
       await validateKimiAdapter(expectedName, rootManifest.version);
+      await validateGeminiAdapter(expectedName, rootManifest.version);
     }
     summarizeAndExit();
     return;