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>

3 files changed, 50 insertions, 31 deletions

diff --git a/packages/meshbay-client/src/cast-chromecast.js b/packages/meshbay-client/src/cast-chromecast.js
index 1355cdd..7fc8079 100644
--- a/packages/meshbay-client/src/cast-chromecast.js
+++ b/packages/meshbay-client/src/cast-chromecast.js
@@ -78,19 +78,25 @@ class CastChromecast {
   constructor() {
     this._bonjour = null;
     this._browser = null;
+    this._scanTimer = null;
     this._devices = new Map();
     this._client = null;
     this._player = null;
     this._connectedDevice = null;
   }
 
-  async discover() {
+  /**
+   * Start a scan and return at once; `devices()` reads what it has found so far.
+   *
+   * The scan runs its full length because a receiver coming back from a reset
+   * can take several seconds to answer, but most answer within two, and a
+   * picker that waits the full length to show any of them is a picker that is
+   * slow every single time. So the page polls and lists each one as it lands.
+   * A scan started over an unfinished one replaces it, timer included.
+   */
+  startScan() {
     this._devices.clear();
-
-    if (this._browser) {
-      this._browser.stop();
-      this._browser = null;
-    }
+    this._stopScan();
 
     if (!this._bonjour) {
       this._bonjour = new Bonjour();
@@ -98,30 +104,39 @@ class CastChromecast {
 
     debug('[cast-chromecast] scanning for devices...');
 
-    return new Promise((resolve) => {
-      this._browser = this._bonjour.find({ type: 'googlecast' }, (service) => {
-        const id = service.txt?.id || service.name;
-        const name = service.txt?.fn || service.name;
-        const host = service.addresses?.find((a) => /^\d+\.\d+\.\d+\.\d+$/.test(a))
-          || (service.referer && service.referer.address);
-        const port = service.port || 8009;
+    this._browser = this._bonjour.find({ type: 'googlecast' }, (service) => {
+      const id = service.txt?.id || service.name;
+      const name = service.txt?.fn || service.name;
+      const host = service.addresses?.find((a) => /^\d+\.\d+\.\d+\.\d+$/.test(a))
+        || (service.referer && service.referer.address);
+      const port = service.port || 8009;
 
-        if (host && id) {
-          this._devices.set(id, { id, name, host, port });
-          debug(`[cast-chromecast] discovered: "${name}" at ${host}:${port}`);
-        }
-      });
-
-      setTimeout(() => {
-        if (this._browser) {
-          this._browser.stop();
-          this._browser = null;
-        }
-        const devices = Array.from(this._devices.values());
-        debug(`[cast-chromecast] scan complete: ${devices.length} device(s)`);
-        resolve(devices);
-      }, SCAN_DURATION_MS);
+      if (host && id) {
+        this._devices.set(id, { id, name, host, port });
+        debug(`[cast-chromecast] discovered: "${name}" at ${host}:${port}`);
+      }
     });
+
+    this._scanTimer = setTimeout(() => {
+      this._stopScan();
+      debug(`[cast-chromecast] scan complete: ${this._devices.size} device(s)`);
+    }, SCAN_DURATION_MS);
+  }
+
+  devices() {
+    return {
+      devices: Array.from(this._devices.values()),
+      scanning: this._browser !== null,
+    };
+  }
+
+  _stopScan() {
+    clearTimeout(this._scanTimer);
+    this._scanTimer = null;
+    if (this._browser) {
+      this._browser.stop();
+      this._browser = null;
+    }
   }
 
   async connect(deviceId, mediaUrl, subtitle) {
diff --git a/packages/meshbay-client/src/main.js b/packages/meshbay-client/src/main.js
index c1ff540..cbaabc4 100644
--- a/packages/meshbay-client/src/main.js
+++ b/packages/meshbay-client/src/main.js
@@ -2330,10 +2330,13 @@ function registerBridge() {
 
   // ── Chromecast discovery + control ──────────────────────────────────────
 
-  handle('cast:discover', async () => {
-    return castChromecast.discover();
+  handle('cast:scan', async () => {
+    castChromecast.startScan();
+    return true;
   });
 
+  handle('cast:devices', async () => castChromecast.devices());
+
   handle('cast:chromecast:connect', async (_e, { deviceId, mediaUrl, subtitle }) => {
     return castChromecast.connect(deviceId, mediaUrl,
       subtitle === undefined ? castRelay.subtitle : subtitle);
diff --git a/packages/meshbay-client/src/preload.js b/packages/meshbay-client/src/preload.js
index e9c34d2..665ec1f 100644
--- a/packages/meshbay-client/src/preload.js
+++ b/packages/meshbay-client/src/preload.js
@@ -175,7 +175,8 @@ contextBridge.exposeInMainWorld('meshbay', {
     subtitle: (sub) => ipcRenderer.invoke('cast:subtitle', sub),
     finish: () => ipcRenderer.invoke('cast:finish'),
     status: () => ipcRenderer.invoke('cast:status'),
-    discover: () => ipcRenderer.invoke('cast:discover'),
+    scan: () => ipcRenderer.invoke('cast:scan'),
+    devices: () => ipcRenderer.invoke('cast:devices'),
     chromecastConnect: (opts) => ipcRenderer.invoke('cast:chromecast:connect', opts),
     chromecastReload: (opts) => ipcRenderer.invoke('cast:chromecast:reload', opts),
     chromecastDisconnect: () => ipcRenderer.invoke('cast:chromecast:disconnect'),