fix(sidecar): stop prefixing the speaker into the channel content

sidecar/src/index.ts

@@ -196,7 +196,10 @@ function pushToChannel(frame: SayFrame): void {
   void mcp.notification({
     method: "notifications/claude/channel",
     params: {
-      content: `${user}: ${content}`,
+      // Body only. The speaker rides in meta, which the host renders itself —
+      // putting the name here too produced "マスター: マスター: ハロ～" (#28),
+      // and it leaves the body no longer equal to what was said.
+      content,
       meta: {
         chat_id: CHAT_ID,
         message_id: frame.message_id ?? randomUUID(),

sidecar/test/round-trip.test.mjs

@@ -179,7 +179,9 @@ test("room say reaches the channel, and say_to_room reaches the room", async (t)
   );
 
   const pushed = await nextNotification("notifications/claude/channel");
-  assert.match(pushed.params.content, /Master: 聞こえる？/);
+  // Body only: the speaker belongs in meta, and the host renders it. Mixing it
+  // into the body showed the name twice on screen (#28).
+  assert.equal(pushed.params.content, "聞こえる？");
   assert.equal(pushed.params.meta.chat_id, "test-room");
   assert.equal(pushed.params.meta.message_id, "m-1");
   assert.equal(pushed.params.meta.user, "Master");