Group conversations by date in chat sidebar

Conversations are bucketed into: Today, Yesterday, This week, This month,
and older entries sub-grouped by calendar month (e.g. "February 2026").
Group labels are sticky so they stay visible while scrolling. Older
buckets use month+year sub-grouping rather than a single "Older" catch-all.

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

frontend/src/views/ChatView.vue

@@ -64,18 +64,49 @@ function formatConvDate(dateStr: string): string {
   const diffMin = Math.floor(diffMs / 60_000);
   const diffHrs = Math.floor(diffMs / 3_600_000);
 
-  // Relative time for < 10 hours
   if (diffMin < 1) return "Just now";
   if (diffMin < 60) return `${diffMin}m ago`;
   if (diffHrs < 10) return `${diffHrs}h ago`;
-
-  // Date for older
   if (date.getFullYear() === now.getFullYear()) {
     return date.toLocaleDateString(undefined, { month: "short", day: "numeric" });
   }
   return date.toLocaleDateString(undefined, { month: "short", day: "numeric", year: "numeric" });
 }
 
+interface ConvGroup { label: string; convs: typeof store.conversations }
+
+const groupedConversations = computed((): ConvGroup[] => {
+  const now = new Date();
+  const startOfToday = new Date(now.getFullYear(), now.getMonth(), now.getDate());
+  const startOfYesterday = new Date(startOfToday.getTime() - 86_400_000);
+  const startOfWeek = new Date(startOfToday.getTime() - 6 * 86_400_000);
+  const startOfMonth = new Date(now.getFullYear(), now.getMonth(), 1);
+
+  const buckets: Record<string, typeof store.conversations> = {};
+  const order: string[] = [];
+
+  for (const conv of store.conversations) {
+    const d = new Date(conv.updated_at);
+    let key: string;
+    if (d >= startOfToday) {
+      key = "Today";
+    } else if (d >= startOfYesterday) {
+      key = "Yesterday";
+    } else if (d >= startOfWeek) {
+      key = "This week";
+    } else if (d >= startOfMonth) {
+      key = "This month";
+    } else {
+      // Sub-group older by "Month Year"
+      key = d.toLocaleDateString(undefined, { month: "long", year: "numeric" });
+    }
+    if (!buckets[key]) { buckets[key] = []; order.push(key); }
+    buckets[key].push(conv);
+  }
+
+  return order.map((label) => ({ label, convs: buckets[label] }));
+});
+
 const streamingRendered = computed(() => {
   if (!store.streamingContent) return "";
   return renderMarkdown(store.streamingContent);
@@ -422,25 +453,28 @@ onUnmounted(() => {
       </div>
 
       <div class="conv-list">
-        <div
-          v-for="conv in store.conversations"
-          :key="conv.id"
-          class="conv-item"
-          :class="{ active: convId === conv.id }"
-          @click="selectConversation(conv.id)"
-        >
-          <div class="conv-info">
-            <span class="conv-title">{{ conv.title || "Untitled" }}</span>
-            <span class="conv-date">{{ formatConvDate(conv.updated_at) }}</span>
-          </div>
-          <button
-            class="btn-delete-conv"
-            @click.stop="removeConversation(conv.id)"
-            title="Delete conversation"
+        <template v-for="group in groupedConversations" :key="group.label">
+          <div class="conv-group-label">{{ group.label }}</div>
+          <div
+            v-for="conv in group.convs"
+            :key="conv.id"
+            class="conv-item"
+            :class="{ active: convId === conv.id }"
+            @click="selectConversation(conv.id)"
           >
-            &times;
-          </button>
-        </div>
+            <div class="conv-info">
+              <span class="conv-title">{{ conv.title || "Untitled" }}</span>
+              <span class="conv-date">{{ formatConvDate(conv.updated_at) }}</span>
+            </div>
+            <button
+              class="btn-delete-conv"
+              @click.stop="removeConversation(conv.id)"
+              title="Delete conversation"
+            >
+              &times;
+            </button>
+          </div>
+        </template>
         <p v-if="!store.conversations.length" class="empty-msg">
           No conversations yet
         </p>
@@ -763,7 +797,20 @@ onUnmounted(() => {
 .conv-list {
   flex: 1;
   overflow-y: auto;
-  padding: 0 0.5rem;
+  padding: 0 0.5rem 0.5rem;
+}
+
+.conv-group-label {
+  font-size: 0.68rem;
+  font-weight: 700;
+  text-transform: uppercase;
+  letter-spacing: 0.06em;
+  color: var(--color-text-muted);
+  padding: 0.6rem 0.75rem 0.2rem;
+  position: sticky;
+  top: 0;
+  background: var(--color-surface);
+  z-index: 1;
 }
 
 .conv-item {