Add HTML/CSS to Image plugin (MCP)

[jsneedles]

What this PR does

Adds the official HTML/CSS to Image API integration for Grok Build. The plugin connects to HCTI's hosted OAuth MCP server and includes a focused skill for rendering HTML/CSS, capturing public webpages, generating PDFs and batches, and working with reusable templates.

• Plugin name: html-css-to-image
• Type: Remote source
• Source URL + pinned SHA: https://github.com/htmlcsstoimage/agent-plugins.git at 0c0481e6e0444bece910a2270f6b8e602c0a5401
• Homepage: https://htmlcsstoimage.com

Ownership

• I own this plugin or have the right to distribute it.
• The source repo is published under our official org.

Checklist

• Added exactly one entry in .grok-plugin/marketplace.json with a kebab-case name.
• Remote source pins a full 40-character lowercase commit SHA that is public and reachable.
• Regenerated .grok-plugin/plugin-index.json.
• python3 scripts/validate-catalog.py passes locally.
• python3 scripts/generate-plugin-index.py --check passes locally.
• Homepage and clear description are set.
• The source repository includes a README, .grok-plugin/plugin.json, and MIT license.

Security

• No curl | bash, remote-code download/exec, or postinstall RCE.
• No reading or exfiltration of secrets, tokens, .env, or environment variables.
• No lifecycle hooks; MCP scope is limited to the hosted HCTI server.
• Network endpoints this plugin calls: https://mcp.hcti.io, the hosted HTML/CSS to Image MCP endpoint. For URL screenshot requests, the HCTI service fetches the public URL supplied by the user.
• Credentials/permissions it requires: An HTML/CSS to Image account authorized through browser-based OAuth. No API key or access token is stored in the plugin repository.

Notes for reviewers

The source is maintained under the official htmlcsstoimage GitHub organization.

The generated component index identifies:

• MCP server: hcti using HTTP
• Skill: hcti-image-generation
• Plugin version: 0.1.0

The plugin’s description follows the canonical HTML/CSS to Image MCP product copy.

Reviewers can create a free HTML/CSS to Image account to test the integration. If the review requires additional credits or access to higher-tier functionality, contact us at support@htmlcsstoimage.com and we’ll provide complimentary review access.