For agents, on top of README.md, which they read first.

Notes for agents

• Handlers hold no state and read no request header. Do not read cf-connecting-ip or any client-identifying header, and do not add a cookie.
• public/ is generated working state and carries no docs (documentation rule, carve-out 1).
• A new route needs a log::Route entry, and nothing the visitor typed may reach a log line.
• The /tick interval and signals are described in src/view.rs's page; the server decides the choreography (site::demo). Do not move that logic into JavaScript.
• Every response carries the CSP (font-src 'self' is for jev-ui's fonts); a new kind of load needs its own directive and a test.
• Do not run wrangler deploy, wrangler login or wrangler secret.
• /preview/loop.mp4 must stay in run_worker_first and the [assets] block must keep binding = "ASSETS" (src/media.rs reads the file through it); without them a player's Range request gets a whole 200 again. Range parsing is site::range::select, pure and tested; do not hand-parse Range in the Worker.
• The canonical address is SITE_ORIGIN (the deploy passes it; config::SITE_ORIGIN is the default). A request to any other host that is not local is sent there with a 308 (GET/HEAD) or told 405 (site::host, called first in fetch). A request a page made for itself (Sec-Fetch-Mode not navigate: Datastar's POSTs, the scripts, styles, fonts) is answered where it arrives, so a page open on an old address finishes. The old address is not named in any tracked file: "elsewhere" is derived. /preview/* runs the Worker first so the PNG can be sent on too; on the canonical host image in lib.rs hands it to the assets.
• Local check of a host: wrangler dev --local --host <host> --port N --var SITE_ORIGIN:https://whiskers.lmjtfy.fun, one server per host (a Host header on a request is overwritten by the dev server, as in ~/lmjtfy/tools/check-hosts).