From 62ca826c6c622ea00733ed173b56f8f070130a5d Mon Sep 17 00:00:00 2001
From: Your Name <brian.yin@livekit.io>
Date: Tue, 18 Nov 2025 21:05:39 +0800
Subject: [PATCH 1/2] Update realtime_api.ts

---
 plugins/google/src/beta/realtime/realtime_api.ts | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/plugins/google/src/beta/realtime/realtime_api.ts b/plugins/google/src/beta/realtime/realtime_api.ts
index a1d888bd0..30a8404f0 100644
--- a/plugins/google/src/beta/realtime/realtime_api.ts
+++ b/plugins/google/src/beta/realtime/realtime_api.ts
@@ -1176,14 +1176,20 @@ export class RealtimeSession extends llm.RealtimeSession {
     };
 
     // Close audio stream if audio output is not supported by the model
-    if (!this.options.responseModalities.includes(Modality.AUDIO)) {
+    if (!this._realtimeModel.capabilities.audioOutput) {
       this.currentGeneration.audioChannel.close();
     }
 
+    // Determine modalities based on the model's audio_output capability
+    const modalities: ('text' | 'audio')[] = this._realtimeModel.capabilities.audioOutput
+      ? ['audio', 'text']
+      : ['text'];
+
     this.currentGeneration.messageChannel.write({
       messageId: responseId,
       textStream: this.currentGeneration.textChannel.stream(),
       audioStream: this.currentGeneration.audioChannel.stream(),
+      modalities: Promise.resolve(modalities),
     });
 
     const generationEvent: llm.GenerationCreatedEvent = {

From a9909c147fff3a6b51dcd3529f559592d0dd60b9 Mon Sep 17 00:00:00 2001
From: Brian Yin <brian.yin@livekit.io>
Date: Tue, 18 Nov 2025 05:10:09 -0800
Subject: [PATCH 2/2] Create friendly-dragons-approve.md

---
 .changeset/friendly-dragons-approve.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/friendly-dragons-approve.md

diff --git a/.changeset/friendly-dragons-approve.md b/.changeset/friendly-dragons-approve.md
new file mode 100644
index 000000000..a906c486d
--- /dev/null
+++ b/.changeset/friendly-dragons-approve.md
@@ -0,0 +1,5 @@
+---
+'@livekit/agents-plugin-google': patch
+---
+
+Fix Google Realtime API missing modalities field on MessageGeneration. This resolves the "Text message received from Realtime API with audio modality" error introduced in version 1.0.18.