fix(liveness): don't bury WebTorrent-only content under hide-until-verified

A WebTorrent-only card's sole liveness signal is the swarm probe (20s timeout,
5min cache), and P2P liveness is slow + intermittent — a live-but-slow video is
indistinguishable from a dead one until that probe finishes. Hiding such a card
until the swarm verifies could bury perfectly good P2P content for minutes.

hide-until-verified now only suppresses a card while the FAST, reliable CDN probe
is still running. Once the CDN resolves dead (or is absent, i.e. P2P-only), it
falls back to show-pending for the WebTorrent part: shown while the swarm is
checked, hidden only once it too is confirmed dead. Burying live content is worse
than a brief flash of a dead one, and only the slow P2P probe is at issue.
cardNeedsEagerLivenessProbe likewise skips P2P-only cards (they start visible).

Tests: hide-foreign does-not-bury-WebTorrent-only coverage in
tests/video-card-source-visibility.test.mjs.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

js/utils/cardSourceVisibility.js

@@ -13,13 +13,16 @@ export function cardNeedsEagerLivenessProbe(cardLike) {
     return false;
   }
   const policy = getCardLivenessPolicy();
-  if (policy === "hide-all") {
-    return true;
+  const gated =
+    policy === "hide-all" ||
+    (policy === "hide-foreign" && card.dataset.foreign === "true");
+  if (!gated) {
+    return false;
   }
-  if (policy === "hide-foreign") {
-    return card.dataset.foreign === "true";
-  }
-  return false;
+  // Only cards backed by a fast CDN probe are hidden-until-verified (so they need
+  // eager probing while hidden). P2P-only cards fall back to show-pending — they
+  // start visible and are probed normally on scroll, so no eager kick is needed.
+  return Boolean(card.dataset.urlHealthUrl);
 }
 
 function resolveCardElement(cardLike) {
@@ -99,12 +102,28 @@ export function updateVideoCardSourceVisibility(cardLike) {
   const hideUntilVerified =
     policy === "hide-all" || (policy === "hide-foreign" && isForeign);
 
-  const shouldHide = hideUntilVerified
-    ? // Hidden until at least one source proves playable (covers the pending
-      // window too, so a dead foreign stranger never flashes in).
-      !cdnHealthy && !streamHealthy
-    : // Default: only hide once every source has come back dead.
-      !cdnHealthy && !streamHealthy && !cdnPending && !streamPending;
+  // Default policy: hide only once every source has come back dead.
+  const confirmedDead =
+    !cdnHealthy && !streamHealthy && !cdnPending && !streamPending;
+
+  let shouldHide;
+  if (!hideUntilVerified) {
+    shouldHide = confirmedDead;
+  } else if (cdnHealthy || streamHealthy) {
+    shouldHide = false; // proven playable → show
+  } else if (cdnPending) {
+    // Still waiting on the FAST, reliable CDN probe (~4s) — keep it hidden so a
+    // dead foreign card never flashes in.
+    shouldHide = true;
+  } else {
+    // CDN is resolved dead (or absent) and the only remaining signal is the slow,
+    // unreliable WebTorrent swarm probe (20s + 5min cache). Do NOT bury the card
+    // behind it — a live-but-slow P2P video is indistinguishable from a dead one
+    // until that probe finishes, and burying live content is worse than a brief
+    // flash. Fall back to show-pending for the stream: show while it's checked,
+    // hide only once it too is confirmed dead.
+    shouldHide = !streamHealthy && !streamPending;
+  }
 
   if (shouldHide) {
     if (!card.hidden) {