feat: RSS embeddings, semantic news in chat, article-to-chat, richer briefings

- Embed RSS items at fetch time (nomic-embed-text); backfill at startup
- Semantic news search injected into chat system prompt ("Recent News You've Seen")
  when items match query above 0.55 cosine threshold (independent of note RAG)
- "Discuss in chat" button on news cards — creates a seeded conversation with
  the article title + full content, navigates directly to the new chat
- Briefing compilation now passes 500-char article excerpts (not just headlines)
  to the LLM and uses 8192 num_ctx to accommodate the larger prompt

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

frontend/src/api/client.ts

@@ -426,6 +426,10 @@ export async function deleteRssReaction(rssItemId: number): Promise<void> {
   return apiDelete(`/api/briefing/rss-reactions/${rssItemId}`);
 }
 
+export async function openArticleInChat(itemId: number): Promise<{ conversation_id: number }> {
+  return apiPost(`/api/chat/from-article/${itemId}`, {});
+}
+
 export async function geocodeAddress(address: string): Promise<{ lat: number; lon: number; display_name: string } | null> {
   try {
     const r = await apiPost<{ lat: number; lon: number; label: string }>('/api/briefing/weather/geocode', { query: address });

frontend/src/views/NewsView.vue

@@ -1,14 +1,18 @@
 <script setup lang="ts">
 import { ref, onMounted } from 'vue'
+import { useRouter } from 'vue-router'
 import {
   getBriefingFeeds,
   postRssReaction,
   deleteRssReaction,
   getNewsItems,
+  openArticleInChat,
   type BriefingFeed,
 } from '@/api/client'
 import type { NewsItem } from '@/types/news'
 
+const router = useRouter()
+
 const LIMIT = 40
 
 const items = ref<NewsItem[]>([])
@@ -20,6 +24,8 @@ const selectedFeedId = ref<number | null>(null)
 
 // Reactions map: item id → current reaction
 const reactions = ref<Record<number, 'up' | 'down' | null>>({})
+// Track which items are currently being opened in chat
+const openingChat = ref<Set<number>>(new Set())
 
 async function loadMore() {
   if (loading.value || !hasMore.value) return
@@ -79,6 +85,19 @@ function formatRelativeDate(iso: string | null): string {
   return d.toLocaleDateString(undefined, { month: 'short', day: 'numeric' })
 }
 
+async function openInChat(itemId: number) {
+  if (openingChat.value.has(itemId)) return
+  openingChat.value.add(itemId)
+  try {
+    const result = await openArticleInChat(itemId)
+    router.push(`/chat/${result.conversation_id}`)
+  } catch {
+    // silently fail — button returns to enabled state
+  } finally {
+    openingChat.value.delete(itemId)
+  }
+}
+
 onMounted(async () => {
   feeds.value = await getBriefingFeeds().catch(() => [])
   await loadMore()
@@ -145,6 +164,13 @@ onMounted(async () => {
             @click="handleReaction(item.id, 'down')"
             title="Not interested"
           >👎</button>
+          <button
+            class="reaction-btn open-chat-btn"
+            :class="{ busy: openingChat.has(item.id) }"
+            :disabled="openingChat.has(item.id)"
+            @click="openInChat(item.id)"
+            title="Discuss in chat"
+          >{{ openingChat.has(item.id) ? '…' : '💬' }}</button>
         </div>
       </div>
 
@@ -335,6 +361,15 @@ a.news-card-title:hover {
   background: color-mix(in srgb, var(--color-primary) 12%, transparent);
 }
 
+.open-chat-btn {
+  margin-left: auto;
+}
+
+.open-chat-btn.busy {
+  opacity: 0.4;
+  cursor: wait;
+}
+
 .news-footer {
   display: flex;
   justify-content: center;