What could come next after base: its own properties, or everything in scope at top level when base is ''.

What both the greyed-out suggestion and TAB are drawn from, so the two agree by construction rather than by two lists kept in step. One caller, completion.ts, which feeds both — and which caches these, so repl.completionCache is the cached front and this is the page itself.

It has to come from the page: the completions for document.body. are a list only the page holds, and one assembled in Node would offer names this document does not have. Resolves empty for anything it cannot answer — a base that is not a plain dotted path, a closed session — because a completion is a convenience and never a reason for a prompt to report an error.

import type { ReplSession } from './session.ts';

// Defined, not invoked: a real session owns a browser and a bound port.
async function offer(session: ReplSession) {
  await session.completions('document'); // ['body', 'title', 'querySelector', …]

  return await session.completions(''); // what is in scope, including what you declared
}