Regional Access Comments Block for Svelte

Edit REGIONS, FIRST (the starting choice per region id) and VISITORS. A visitor has an address, a city, a country and the region id it belongs to; the matched rule, the outcome sentence and the preview are worked out from that and the current rules. The addresses are from the ranges reserved for documentation, so none belongs to anyone.

No. Nothing here checks an address or calls a network: the region of each visitor is typed. A real app resolves the visitor's region on the server, from a geolocation database kept up to date, and enforces the rule there for reading and for posting. Remember that addresses are an imperfect guide: shared networks, mobile carriers and VPNs all move people across borders, so give people a way to appeal and never treat a region as proof of anything.

On the server, for every request. A hidden composer in the browser stops no one. Check the rule when a thread is read (return a 451 or a plain empty response for Blocked) and when a comment is posted, and log the rule that matched so you can explain a decision.

Each region's choices are native radio buttons that share a name, so the arrow keys move inside a row and the choice is shown by a filled cell and the word, not colour. Each radio is also named with its region for screen readers. The matched row says "Matched", the preview explains why posting is closed in text, and the status line is present from load and is read out politely.

Each region becomes a row with its three choices under the name, in equal cells that fit at 320 pixels. The preview keeps the same height in every state, so changing a rule or a visitor never moves the page.