From b40af7976b847269e0cf4f41b32dcd0e0b1af04f Mon Sep 17 00:00:00 2001
From: Swayam Gupta <gupta.swayam123@gmail.com>
Date: Fri, 7 Aug 2026 21:38:10 +0530
Subject: [PATCH] fix(llm): ensure Google chats end with a user turn

---
 .changeset/fair-google-turns.md               |  5 ++++
 agents/src/llm/provider_format/google.test.ts | 25 +++++++++++++++++++
 agents/src/llm/provider_format/google.ts      |  2 +-
 3 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/fair-google-turns.md

diff --git a/.changeset/fair-google-turns.md b/.changeset/fair-google-turns.md
new file mode 100644
index 000000000..928d1e9fb
--- /dev/null
+++ b/.changeset/fair-google-turns.md
@@ -0,0 +1,5 @@
+---
+'@livekit/agents': patch
+---
+
+Ensure Google chat formatting ends with a user turn when an empty trailing user message is omitted.
diff --git a/agents/src/llm/provider_format/google.test.ts b/agents/src/llm/provider_format/google.test.ts
index c895a4bde..bd07487e2 100644
--- a/agents/src/llm/provider_format/google.test.ts
+++ b/agents/src/llm/provider_format/google.test.ts
@@ -536,6 +536,31 @@ describe('Google Provider Format - toChatCtx', () => {
     expect(formatData.systemMessages).toBeNull();
   });
 
+  it('should inject dummy user message when trailing user message is empty', async () => {
+    const ctx = ChatContext.empty();
+    ctx.addMessage({ role: 'user', content: 'Hello' });
+    ctx.addMessage({ role: 'assistant', content: 'Partial reply' });
+    ctx.addMessage({ role: 'user', content: '' });
+
+    const [result, formatData] = await toChatCtx(ctx, true);
+
+    expect(result).toEqual([
+      {
+        role: 'user',
+        parts: [{ text: 'Hello' }],
+      },
+      {
+        role: 'model',
+        parts: [{ text: 'Partial reply' }],
+      },
+      {
+        role: 'user',
+        parts: [{ text: '.' }],
+      },
+    ]);
+    expect(formatData.systemMessages).toBeNull();
+  });
+
   it('should not inject dummy user message when disabled', async () => {
     const ctx = ChatContext.empty();
     ctx.addMessage({ role: 'user', content: 'Hello' });
diff --git a/agents/src/llm/provider_format/google.ts b/agents/src/llm/provider_format/google.ts
index d7d2197d2..98b356c82 100644
--- a/agents/src/llm/provider_format/google.ts
+++ b/agents/src/llm/provider_format/google.ts
@@ -101,7 +101,7 @@ export async function toChatCtx(
   }
 
   // Gemini requires the last message to end with user's turn before they can generate
-  if (injectDummyUserMessage && currentRole !== 'user') {
+  if (injectDummyUserMessage && turns[turns.length - 1]?.role !== 'user') {
     turns.push({ role: 'user', parts: [{ text: '.' }] });
   }