A <a href="#faq"> whose target was renamed does nothing when clicked, and an aria-labelledby that points at a missing id leaves a control with no accessible name. Neither throws an error, so a rename that misses one goes unnoticed.
We swept all 3,081 HTML pages under ventures/ for three kinds of in-page reference: #anchor links, aria-labelledby/aria-describedby and aria-controls. The result was zero broken references. The same pass found no page missing lang, a viewport tag, a charset or a title, no target="_blank" link without noopener, and no real <img> without alt (two grep hits were example strings inside tool pages).
A clean result is still worth keeping, so the sweep is now platform/ci/check_inpage_refs.py with unit tests, wired into the portfolio-validate workflow next to the duplicate-id check. It reads markup only, skipping scripts and comments. Caveat: it checks references within one page, not links between pages, which check_pages_links.py covers.