Short answer: probably not entirely, and you likely don't know which parts. Most sites were built and tested against a browser and Googlebot, not against a language model deciding, in one pass, whether your page is even worth reading.
It means the plain-text content, structure, and meaning of a page survive the trip from your server to whatever system is looking at it: whether that's OAI-SearchBot indexing your page ahead of time, or ChatGPT-User fetching it live when a person clicks a citation. If the important content only exists after client-side JavaScript runs, or is buried without headings a model can use to segment the page, it can effectively not exist for that request.
Both, depending on the feature. OAI-SearchBot builds ChatGPT's own search index ahead of time, similar in spirit to how Googlebot builds Google's. ChatGPT-User does a live fetch of a specific URL when a user's conversation references it directly. Neither is guaranteed to execute heavy client-side JavaScript the way a browser does. Treat 'view page source', not 'inspect element after render', as the more honest test.
The most common causes: content that only renders after JavaScript executes, no real heading structure (so a model can't tell what's a topic versus a caption), robots.txt accidentally blocking OAI-SearchBot or ChatGPT-User, thin or duplicate content across pages, and missing or broken structured data that would otherwise make the page's purpose unambiguous.
Fetch the URL the way a crawler would (no browser, no JS execution) and read what comes back. If the content you care about isn't in that raw response, that's your answer. Fetchling's free scan automates this and also runs live citation tests against real AI engines, so you see whether you're actually being cited, not just theoretically crawlable.
Server-render (or statically render) the content that matters, use real heading tags instead of styled divs, confirm robots.txt allows OAI-SearchBot and ChatGPT-User if you want ChatGPT traffic, and add structured data so your page's purpose is explicit rather than inferred.
Paste your URL into Fetchling's free scan and you'll get two separate scores (one for traditional SEO, one for AI visibility) because a site can rank fine on Google and still be nearly invisible to ChatGPT.
Curious where your own site stands? Run a free scan, or see what's in the $19 full report.