feat(client): add setOnHold to pause and resume a voice conversation

.changeset/conversation-on-hold.md

@@ -0,0 +1,5 @@
+---
+"@elevenlabs/client": minor
+---
+
+Add `setOnHold` / `isOnHold` to voice conversations, for apps that hand control back and forth between the agent and something else on the page. Putting a conversation on hold stops the agent mid-utterance instead of letting it play to completion, silences audio that keeps arriving, mutes the microphone so nothing nearby starts a turn, and sends `user_activity` periodically so the agent does not speak up on its own while it is held. The connection, conversation id and context all stay, so releasing the hold costs no reconnect: the microphone and the volume the caller asked for come back, and audio buffered during the hold is dropped rather than resumed mid-sentence. `setVolume` and `setMicMuted` calls made during a hold are applied when it is released.

packages/client/src/BaseConversation.test.ts

@@ -40,6 +40,10 @@ class TestConversation extends BaseConversation {
 
   public setVolume(): void {}
   public setMicMuted(): void {}
+  public setOnHold(): void {}
+  public isOnHold(): boolean {
+    return false;
+  }
   public getInputByteFrequencyData(): Uint8Array {
     return new Uint8Array(0);
   }

packages/client/src/BaseConversation.ts

@@ -816,6 +816,14 @@ export abstract class BaseConversation {
 
   public abstract setVolume(options: { volume: number }): void;
   public abstract setMicMuted(isMuted: boolean): void;
+  /**
+   * Puts the conversation on hold, or takes it off hold again. A held
+   * conversation keeps its connection, its id and its context, but the agent
+   * is neither heard nor spoken to until the hold is released.
+   */
+  public abstract setOnHold(isOnHold: boolean): void;
+  /** Whether the conversation is currently on hold. */
+  public abstract isOnHold(): boolean;
   /**
    * Returns byte frequency data (0-255) for the input audio, focused on the
    * human voice range (100-8000 Hz).

packages/client/src/TextConversation.ts

@@ -16,6 +16,14 @@ export class TextConversation extends BaseConversation {
     throw new Error("setMicMuted is not supported in text conversations");
   }
 
+  public setOnHold(): void {
+    throw new Error("setOnHold is not supported in text conversations");
+  }
+
+  public isOnHold(): boolean {
+    return false;
+  }
+
   public getInputByteFrequencyData(): Uint8Array {
     return EMPTY_FREQUENCY_DATA;
   }