Format exec events with $ prefix instead of code blocks

session/session.go

@@ -758,7 +758,11 @@ func FormatEvent(ev agent.Event) []byte {
 	case "reasoning":
 		return []byte(ev.Content)
 	case "exec":
-		return []byte("```\n" + ev.Content + "\n```\n")
+		lines := strings.Split(ev.Content, "\n")
+		for i := range lines {
+			lines[i] = "$ " + lines[i]
+		}
+		return []byte(strings.Join(lines, "\n") + "\n")
 	case "info":
 		return []byte(":: " + ev.Content)
 	default: