Fix out of order path WS broadcasts overwriting each other

frontend/AGENTS.md

@@ -91,6 +91,10 @@ Specialized logic is delegated to hooks:
 - WebSocket: realtime deltas/events.
 - On WS connect, backend sends `health` only; contacts/channels still come from REST.
 
+### New Message modal
+
+`NewMessageModal` intentionally preserves form state (tab, inputs, checkboxes) when closed and reopened. The component instance persists across open/close cycles. This is by design so users don't lose in-progress input if they accidentally dismiss the dialog.
+
 ### Message behavior
 
 - Outgoing sends are optimistic in UI and persisted server-side.

frontend/src/messageCache.ts

@@ -70,11 +70,13 @@ export function updateAck(messageId: number, ackCount: number, paths?: MessagePa
   for (const entry of cache.values()) {
     const idx = entry.messages.findIndex((m) => m.id === messageId);
     if (idx >= 0) {
+      const current = entry.messages[idx];
       const updated = [...entry.messages];
       updated[idx] = {
-        ...entry.messages[idx],
-        acked: ackCount,
-        ...(paths !== undefined && { paths }),
+        ...current,
+        acked: Math.max(current.acked, ackCount),
+        ...(paths !== undefined &&
+          paths.length >= (current.paths?.length ?? 0) && { paths }),
       };
       entry.messages = updated;
       return; // Message IDs are unique, stop after first match