feat(cast): music on the TV, the music bar as its remote

A cast button in Music's toolbar and in the music bar. With a television
chosen, each decrypted track goes to the relay with its cover — found as the
album card finds it — and plays there as music with its title, artist and
album; the bar's play, pause, seek, previous and next drive the receiver, its
clock is the receiver's, and the end of a track there moves the queue on.
A film or a photo taking the television pauses the bar; stopping the cast
carries the track on locally.

Photos and tracks now share one path: a whole file sent to the relay in
pieces (binary frames on Android, written to disk there), served at /file
with byte ranges and its cover at /cover, and loaded as what the relay says
it is. cast:image is gone; cast:chromecast:seek is new.

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

1 files changed, 13 insertions, 1 deletions

diff --git a/packages/meshbay-client/src/preload.js b/packages/meshbay-client/src/preload.js
index f12d68e..0de76db 100644
--- a/packages/meshbay-client/src/preload.js
+++ b/packages/meshbay-client/src/preload.js
@@ -178,7 +178,18 @@ contextBridge.exposeInMainWorld('meshbay', {
     push: (data) => ipcRenderer.invoke('cast:push', data),
     stop: () => ipcRenderer.invoke('cast:stop'),
     subtitle: (sub) => ipcRenderer.invoke('cast:subtitle', sub),
-    image: (img) => ipcRenderer.invoke('cast:image', img),
+    // A file in pieces of a few megabytes, as the Android bridge sends it.
+    file: async (f) => {
+      const bytes = f.bytes;
+      await ipcRenderer.invoke('cast:file:begin', {
+        type: f.type, size: bytes.length, cover: f.cover || null,
+        title: f.title, artist: f.artist, album: f.album,
+      });
+      for (let at = 0; at < bytes.length; at += 4 * 1024 * 1024) {
+        await ipcRenderer.invoke('cast:file:write', bytes.subarray(at, at + 4 * 1024 * 1024));
+      }
+      return ipcRenderer.invoke('cast:file:end');
+    },
     finish: () => ipcRenderer.invoke('cast:finish'),
     status: () => ipcRenderer.invoke('cast:status'),
     scan: () => ipcRenderer.invoke('cast:scan'),
@@ -188,6 +199,7 @@ contextBridge.exposeInMainWorld('meshbay', {
     chromecastDisconnect: () => ipcRenderer.invoke('cast:chromecast:disconnect'),
     chromecastPause: () => ipcRenderer.invoke('cast:chromecast:pause'),
     chromecastPlay: () => ipcRenderer.invoke('cast:chromecast:play'),
+    chromecastSeek: (seconds) => ipcRenderer.invoke('cast:chromecast:seek', seconds),
   },
 
   // A sink that writes to disk as chunks arrive, never a buffer handed over at