Frontend optimization part 2

frontend/src/utils/messageIdentity.ts

@@ -0,0 +1,10 @@
+import type { Message } from '../types';
+
+// Content identity matches the frontend's message-level dedup contract.
+export function getMessageContentKey(msg: Message): string {
+  // When sender_timestamp exists, dedup by content (catches radio-path duplicates with different IDs).
+  // When null, include msg.id so each message gets a unique key — avoids silently dropping
+  // different messages that share the same text and received_at second.
+  const ts = msg.sender_timestamp ?? `r${msg.received_at}-${msg.id}`;
+  return `${msg.type}-${msg.conversation_key}-${msg.text}-${ts}`;
+}