Rescaling only changes the size the file claims to be — the viewBox keeps full precision, so no detail is lost and the drawing stays as editable. Original size is exact, but very large drawings make browsers, Inkscape and PDF viewers misbehave, and a PDF page cannot exceed 200in (14400pt) per side at all.
Each download is checked against the SHA-256 digest above before a single line of it runs, and is kept in memory only. Nothing is fetched until you allow it.