feat(cast): photos on the TV, and a television chosen once for the session

A cast button in Videos' toolbar, at the top of Photos, in an album's bar and
in the lightbox, in a group and in Search alike. A television chosen there is
kept for the session: a film opened plays on it with the player as its remote
from the start, and a photo opened in the lightbox is shown on it, scaled to
1920x1080, upright, as JPEG. The lightbox gains a slideshow.

The relay serves one photo at /image behind the stream's token, on the desktop
and on Android; the shell, not the page, decides that the receiver loads it as
a picture.

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

1 files changed, 17 insertions, 4 deletions

diff --git a/packages/meshbay-client/src/main.js b/packages/meshbay-client/src/main.js
index fa4f3ec..1c371f5 100644
--- a/packages/meshbay-client/src/main.js
+++ b/packages/meshbay-client/src/main.js
@@ -2333,14 +2333,27 @@ function registerBridge() {
 
   handle('cast:devices', async () => castChromecast.devices());
 
+  // One photo at a time, scaled and re-encoded by the page.
+  handle('cast:image', async (_e, img) => {
+    return castRelay.showImage({ bytes: Buffer.from(img.bytes), type: img.type });
+  });
+
+  // The relay's photo is loaded as a picture, anything else as the stream;
+  // the page does not get to say which.
+  const loadOf = (mediaUrl, subtitle) => (
+    mediaUrl && mediaUrl === castRelay.imageUrl
+      ? { subtitle: null, contentType: castRelay.imageType }
+      : { subtitle: subtitle === undefined ? castRelay.subtitle : subtitle,
+          contentType: 'video/mp4' });
+
   handle('cast:chromecast:connect', async (_e, { deviceId, mediaUrl, subtitle }) => {
-    return castChromecast.connect(deviceId, mediaUrl,
-      subtitle === undefined ? castRelay.subtitle : subtitle);
+    const l = loadOf(mediaUrl, subtitle);
+    return castChromecast.connect(deviceId, mediaUrl, l.subtitle, l.contentType);
   });
 
   handle('cast:chromecast:reload', async (_e, { mediaUrl, subtitle }) => {
-    return castChromecast.reload(mediaUrl,
-      subtitle === undefined ? castRelay.subtitle : subtitle);
+    const l = loadOf(mediaUrl, subtitle);
+    return castChromecast.reload(mediaUrl, l.subtitle, l.contentType);
   });
 
   // The player becomes a remote while casting: these drive the receiver.