The live region keeps your place: focus, an announcement, and what someone is typing #49

refresh() in static/live.js swaps every matching region with el.replaceWith(next). Whatever had focus inside that region is gone — focus falls to <body>, a keyboard user loses their place mid-form, and a screen reader is told nothing happened at all. Today the regions hold a remark thread; the moment #44 and #38 land they hold vote buttons and reply forms, which is exactly where someone's hands are when an event arrives.

What done looks like

• Before a swap, live.js records the active element's id (or its name within the region) and its selection; after the swap, if the same control exists in the fresh markup, focus and caret go back to it. If it does not exist any more, focus goes to the region's heading rather than to <body>.
• A control a person is typing in is not replaced at all: a region swap leaves any <input>, <textarea> or <select> inside it that holds focus and has a value the fresh markup does not carry, and the region retries after they leave it. Losing half a written remark to somebody else's vote is the failure this prevents.
• Each live region carries aria-live="polite" and a one-line role="status" summary of what just changed ("A vote was cast", "A new remark"), written server-side from the event type, so the announcement is text the app wrote and not a re-read of the whole region.
• The summary line is visually quiet but not display:none — a screen reader must reach it; static/app.css gets one small visually-hidden class if it has none.
• Nothing regresses for a mouse: no scroll jump when a region grows, and the page still renders once, server-side, with live.js remaining a progressive enhancement that the app works entirely without.
• live.js stays dependency-free and small — this should add tens of lines, not hundreds. If it stops being readable in one sitting, split the focus code into its own tiny file rather than growing this one.
• Tests: src/live.test.ts covers what the server sends (the summary text per event type). The focus behaviour is proved by a small DOM test over refresh() with a stub document if bun test can host one; if it cannot, the pull says so plainly and lists the manual steps taken on the preview, with the keyboard, to prove each bullet.
• bun test is green.

Files I expect to change: static/live.js, static/app.css, src/pages/proposal.ts, src/pages/home.ts, src/live.ts (the summary text only), src/live.test.ts.

Risks: this touches the same regions as #38 and #44 — land it before them if it can be, so they inherit the behaviour rather than each inventing it, and rebase rather than racing. Do not reach for a diffing library: the fix is to preserve two things across a replace, not to become a framework. aria-live on a region that swaps wholesale will read the entire region on every change in some readers — that is why the announcement is a separate one-line status and the region itself is polite, not assertive.

Fit: Hearth — the page as it is actually used, by someone whose hands are already on it. A person assigns; I do not.