feat(client): list cast receivers as they answer

The scan still runs six seconds, but the picker polls what it has found
and shows each receiver immediately. A rescan no longer has its timer
cut short by the scan it replaced.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 28 insertions, 3 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/platform.js b/packages/meshbay-hub/src/meshbay_hub/static/platform.js
index 19f12a6..749f93e 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/platform.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/platform.js
@@ -430,6 +430,8 @@ export async function waitForRootsIndexed(groupId, onProgress,
  * Absent in a browser, where the relay cannot run: there is no main process
  * to bind a server socket in, and a page cannot open one.
  */
+const CAST_POLL_MS = 250;
+
 export const cast = {
   available: Boolean(bridge && bridge.cast),
   async start(opts) {
@@ -456,9 +458,32 @@ export const cast = {
     if (!bridge || !bridge.cast) return null;
     return bridge.cast.status();
   },
-  async discover() {
-    if (!bridge || !bridge.cast) return [];
-    return bridge.cast.discover();
+  // Lists receivers as they answer rather than at the end of the scan: most
+  // answer within two seconds, and the scan runs on for the ones coming back
+  // from a reset. `onUpdate(devices, scanning)` is called on each poll until
+  // the scan ends; the returned function stops it being called at all.
+  discover(onUpdate) {
+    if (!bridge || !bridge.cast) {
+      onUpdate([], false);
+      return () => {};
+    }
+    let stopped = false;
+    let timer = null;
+    const poll = async () => {
+      const snap = await bridge.cast.devices().catch(() => null);
+      if (stopped) return;
+      if (!snap) {
+        onUpdate([], false);
+        return;
+      }
+      onUpdate(snap.devices, snap.scanning);
+      if (snap.scanning) timer = setTimeout(poll, CAST_POLL_MS);
+    };
+    bridge.cast.scan().then(poll, () => { if (!stopped) onUpdate([], false); });
+    return () => {
+      stopped = true;
+      clearTimeout(timer);
+    };
   },
   async chromecastConnect(opts) {
     if (!bridge || !bridge.cast) return null;