The Agent Skills Directory

[EXTERNAL_DOWNLOADS]: The skill relies on the Playwright library which requires the installation of browser binaries. The screenshot.js utility includes logic to trigger the download and installation of the Chromium browser using the command npx playwright install chromium from Microsoft's official package registry if it is not present at runtime.
[COMMAND_EXECUTION]: The screenshot.js script utilizes execSync to run the Playwright installation command. This is an expected initialization step for tools utilizing browser-based screenshot capabilities.
[INDIRECT_PROMPT_INJECTION]: The skill processes user-supplied data from thread.json and interpolates it into an HTML template for rendering. While this constitutes an indirect prompt injection surface, the risk is mitigated by built-in sanitization.
Ingestion points: The render.js entry point reads the thread.json input file, which is then parsed and processed by generate.js.
Boundary markers: The skill does not explicitly define delimiters in its instructions to separate user-provided content from the agent's context during the mockup composition phase.
Capability inventory: The skill has the ability to write files to the local disk (index.html, screenshot.png) and uses a headless browser (Playwright) to render local and remote content.
Sanitization: The generate.js file implements a robust escapeHTML function that sanitizes special characters (e.g., <, >, &, ") before text is interpolated into the HTML structure, effectively preventing cross-site scripting (XSS) or HTML injection within the generated mockup.

create-chatgpt-mockup