fix: optimistic message send — no full timeline reload

Instead of calling openCommunicationThread() after sending (which triggered
a full timeline refetch, destroyed audio waveforms, and caused the chat to
jump), we now:
- Optimistically append the sent message to clientTimelineItems
- Scroll to bottom smoothly
- Refresh contacts sidebar for lastMessageText preview
- Auto-scroll only fires on thread switch (empty→loaded), not on every
  timeline update, preserving audio waveform DOM elements

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/app/components/workspace/CrmWorkspaceApp.vue

@@ -844,17 +844,17 @@ async function sendCommMessage() {
   const text = commDraft.value.trim();
   if (!text || commSending.value || !selectedCommThread.value) return;
   commSending.value = true;
+  const contactId = selectedCommThreadId.value;
+  const contactName = selectedCommThread.value.contact;
   try {
     const channel = commSendChannel.value;
     if (!channel) return;
     const { useMutation } = await import("@vue/apollo-composable");
-    const { CreateCommunicationMutationDocument, CommunicationsQueryDocument, ContactInboxesQueryDocument } = await import("~~/graphql/generated");
-    const { mutate: doCreateCommunication } = useMutation(CreateCommunicationMutationDocument, {
-      refetchQueries: [{ query: CommunicationsQueryDocument }, { query: ContactInboxesQueryDocument }],
-    });
-    await doCreateCommunication({
+    const { CreateCommunicationMutationDocument } = await import("~~/graphql/generated");
+    const { mutate: doCreateCommunication } = useMutation(CreateCommunicationMutationDocument);
+    const result = await doCreateCommunication({
       input: {
-        contact: selectedCommThread.value.contact,
+        contact: contactName,
         channel,
         kind: "message",
         direction: "out",
@@ -862,7 +862,36 @@ async function sendCommMessage() {
       },
     });
     commDraft.value = "";
-    openCommunicationThread(selectedCommThread.value.contact);
+
+    // Optimistically append the sent message to timeline (no full reload)
+    const newId = result?.data?.createCommunication?.id ?? `temp-${Date.now()}`;
+    const now = new Date().toISOString();
+    clientTimelineItems.value = [
+      ...clientTimelineItems.value,
+      {
+        id: newId,
+        contactId,
+        contentType: "message",
+        contentId: newId,
+        datetime: now,
+        message: {
+          id: newId,
+          at: now,
+          contact: contactName,
+          contactInboxId: "",
+          sourceExternalId: "",
+          sourceTitle: "",
+          channel: channel as CommItem["channel"],
+          kind: "message",
+          direction: "out",
+          text,
+        },
+      },
+    ];
+    scrollCommThreadToBottom();
+
+    // Refresh sidebar preview (lastMessageText) — lightweight
+    void refetchContacts();
   } finally {
     commSending.value = false;
   }
@@ -1145,9 +1174,9 @@ function scrollCommThreadToBottom() {
   });
 }
 
-// Scroll to bottom whenever timeline items change (thread switch or new message)
-watch(clientTimelineItems, (items) => {
-  if (items.length) scrollCommThreadToBottom();
+// Scroll to bottom when a new thread loads (items go from [] → [items])
+watch(clientTimelineItems, (items, oldItems) => {
+  if (items.length && (!oldItems || oldItems.length === 0)) scrollCommThreadToBottom();
 });
 
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