diff --git a/pkg/providers/anthropic/provider.go b/pkg/providers/anthropic/provider.go
index 6f4aadb8b..a3704cdf3 100644
--- a/pkg/providers/anthropic/provider.go
+++ b/pkg/providers/anthropic/provider.go
@@ -11,6 +11,7 @@ import (
 	"github.com/anthropics/anthropic-sdk-go/option"
 
 	"github.com/sipeed/picoclaw/pkg/providers/common"
+	"github.com/sipeed/picoclaw/pkg/providers/messageutil"
 	"github.com/sipeed/picoclaw/pkg/providers/protocoltypes"
 )
 
@@ -170,8 +171,11 @@ func buildParams(
 					anthropic.NewUserMessage(anthropic.NewToolResultBlock(msg.ToolCallID, msg.Content, false)),
 				)
 			} else {
+				// Anthropic has no per-message author identity; render any
+				// sender attribution as a `[name] ` prefix without mutating
+				// the persisted message.
 				anthropicMessages = append(anthropicMessages,
-					anthropic.NewUserMessage(anthropic.NewTextBlock(msg.Content)),
+					anthropic.NewUserMessage(anthropic.NewTextBlock(messageutil.ApplyUserNamePrefix(msg))),
 				)
 			}
 		case "assistant":