From 4f3a1215a048eb5fdb8f87f9c86309977ef80eb9 Mon Sep 17 00:00:00 2001
From: tejas ghatte <tejas@tejass-MacBook-Pro.local>
Date: Mon, 18 May 2026 18:44:51 +0530
Subject: [PATCH] fix: emit role chunk from anthropic message start in chat
 stream

---
 core/providers/anthropic/chat.go | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/core/providers/anthropic/chat.go b/core/providers/anthropic/chat.go
index d9431bba077..bdb2236ffba 100644
--- a/core/providers/anthropic/chat.go
+++ b/core/providers/anthropic/chat.go
@@ -1090,6 +1090,23 @@ func (chunk *AnthropicStreamEvent) ToBifrostChatCompletionStream(ctx *schemas.Bi
 
 	switch chunk.Type {
 	case AnthropicStreamEventTypeMessageStart:
+		if chunk.Message != nil && chunk.Message.Role != "" {
+			role := chunk.Message.Role
+			streamResponse := &schemas.BifrostChatResponse{
+				Object: "chat.completion.chunk",
+				Choices: []schemas.BifrostResponseChoice{
+					{
+						Index: 0,
+						ChatStreamResponseChoice: &schemas.ChatStreamResponseChoice{
+							Delta: &schemas.ChatStreamResponseChoiceDelta{
+								Role: &role,
+							},
+						},
+					},
+				},
+			}
+			return streamResponse, nil, false
+		}
 		return nil, nil, false
 
 	case AnthropicStreamEventTypeMessageStop: