Speed up station guide startup

evolution/proposals/ECP-0123-instant-station-guide-and-player-warmup.md

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+# ECP-0123: Instant Station Guide and Player Warmup
+
+Status: Draft
+
+## Problem statement
+
+The hosted watch page can feel broken when `/api/public-streams` is slow, empty, or temporarily
+unreachable: the channel rail waits on the network before showing stations. Even after stations
+appear, the first channel tap pays the `@moq/watch` module import cost before the player element can
+mount. That increases time to first playing frame and makes channel selection feel unreliable.
+
+## Constraints
+
+- Keep the first screen a usable TV/player interface, not a marketing page.
+- Preserve manual tuning, share links, DVR mode, public station refresh, and existing relay fields.
+- Keep rollback simple: the live API remains authoritative after it answers.
+- Avoid Chrome-only transport assumptions and keep live playback failure messages actionable.
+- Keep the change static-site compatible so Cloudflare Worker asset deployment stays simple.
+
+## Decision
+
+Embed the current starter LA station guide in `index.html` and render it immediately on first load.
+Also keep a short-lived local guide cache, merge cached entries with the HTML seed, and refresh
+`/api/public-streams` in the background with a bounded timeout. A slow or empty refresh no longer
+clears already visible channels.
+
+Change the web client, publisher module defaults, runbook examples, and remote watch E2E default
+relay to `https://relay.every.channel/anon`. Preload/preconnect the primary player dependencies and
+warm the `@moq/watch` custom element after first paint. Let `@moq/watch` use its available live
+transport fallback instead of forcing WebTransport-only playback. Add client performance marks for
+guide first render, guide fetch, watch request, player module readiness, player mount, catalog/live
+status, and first observable canvas frame when the browser exposes it.
+
+## Alternatives considered
+
+- Wait only for `/api/public-streams`. Rejected because the UI becomes blank when the directory is
+  slow and because children should be able to tap visible channels immediately.
+- Make the API response cacheable at the CDN. Rejected as the only fix because active streams are
+  short TTL and stale-but-visible fallback belongs in the client.
+- Bundle `@moq/watch` into the static site. Deferred because CDN import fallback is already in use;
+  warming and modulepreload reduce tap latency without changing the build graph.
+
+## Rollout / teardown plan
+
+Ship the static web change with the existing Worker asset deploy. Validate with clean-cache
+desktop/mobile browser loads and check the app's `window.__ecPerf` marks. Teardown is removing the
+HTML seed/cache/warmup path and returning to live-API-only station rendering.