diff --git a/internal/httpapi/static/app.js b/internal/httpapi/static/app.js
index e910e1b..04f9c19 100644
--- a/internal/httpapi/static/app.js
+++ b/internal/httpapi/static/app.js
@@ -1,5 +1,5 @@
 // Shared state
-const st = { tailLoading: false, atBottom: true, current: '#', earliest: null, sse: null, channels: [], twLoaded: false };
+const st = { tailLoading: false, atBottom: true, current: '#', earliest: null, sse: null, channels: [], twLoaded: false, seen: new Set(), loadingHistory: false };
 
 function measureBars(){
   const hdr = document.querySelector('header.nav');
@@ -13,6 +13,8 @@ function escapeHtml(s){ return s.replace(/[&<>"]/g, c=>({'&':'&amp;','<':'&lt;',
 function linkify(t){ return t.replace(/https?:\/\/\S+/g, function(u){ return '<a href="' + u + '" target="_blank" rel="noopener">' + u + '</a>'; }); }
 function lineHTML(m){ const ts = '<span class=ts>[' + m.time + ']</span>'; const nick = '<b style="color:' + colorFor(m.author) + '">' + m.author + '</b>'; const body = escapeHtml(m.body); return ts + ' ' + nick + ': ' + linkify(body); }
 
+function msgKey(m){ return m.time + '|' + m.author + '|' + m.body; }
+
 function snapBottom(){ window.scrollTo(0, document.documentElement.scrollHeight); }
 function pinBottomMulti(){ if(!st.atBottom) return; [0,16,64,200].forEach(d=> setTimeout(()=>requestAnimationFrame(snapBottom), d)); }
 
@@ -28,8 +30,8 @@ async function api(path, params){
 
 function ensureTwitterWidgets(){ if(st.twLoaded) return; st.twLoaded = true; const s=document.createElement('script'); s.async=true; s.src='https://platform.twitter.com/widgets.js'; document.head.appendChild(s); }
 
-function appendBatch(arr){ const el=document.getElementById('tail'); const frag=document.createDocumentFragment(); arr.forEach(m=>{ const div=document.createElement('div'); div.className='msg'; div.innerHTML=lineHTML(m); frag.appendChild(div); processLinks(div); }); el.appendChild(frag); pinBottomMulti(); }
-function prependBatch(arr){ const el=document.getElementById('tail'); const oldTop=el.firstChild; const beforeTop = oldTop ? oldTop.getBoundingClientRect().top : 0; const frag=document.createDocumentFragment(); arr.forEach(m=>{ const div=document.createElement('div'); div.className='msg'; div.innerHTML=lineHTML(m); frag.appendChild(div); processLinks(div); }); el.insertBefore(frag, el.firstChild); if(oldTop){ const afterTop = oldTop.getBoundingClientRect().top; const delta = afterTop - beforeTop; window.scrollBy(0, delta); } }
+function appendBatch(arr){ const el=document.getElementById('tail'); const frag=document.createDocumentFragment(); arr.forEach(m=>{ const key=msgKey(m); if(st.seen.has(key)) return; st.seen.add(key); const div=document.createElement('div'); div.className='msg'; div.dataset.key=key; div.innerHTML=lineHTML(m); frag.appendChild(div); processLinks(div); }); el.appendChild(frag); pinBottomMulti(); }
+function prependBatch(arr){ const el=document.getElementById('tail'); const oldTop=el.firstChild; const beforeTop = oldTop ? oldTop.getBoundingClientRect().top : 0; const frag=document.createDocumentFragment(); arr.forEach(m=>{ const key=msgKey(m); if(st.seen.has(key)) return; st.seen.add(key); const div=document.createElement('div'); div.className='msg'; div.dataset.key=key; div.innerHTML=lineHTML(m); frag.appendChild(div); processLinks(div); }); el.insertBefore(frag, el.firstChild); if(oldTop){ const afterTop = oldTop.getBoundingClientRect().top; const delta = afterTop - beforeTop; window.scrollBy(0, delta); } }
 
 function processLinks(scope){ const links = scope.querySelectorAll('a[href]:not([data-card])'); links.forEach(a=>{ a.setAttribute('data-card','1');
   // Fetch and render card
@@ -77,8 +79,8 @@ function processLinks(scope){ const links = scope.querySelectorAll('a[href]:not(
 async function loadChannels(){ try{ const data = await api('/api/channels'); st.channels = data; renderChannels(); if(data.length>0){ selectChannel(data[0]); } } catch(e){} }
 function renderChannels(){ const list=document.getElementById('nav-chans') || document.getElementById('brand-chans')?.querySelector('ul'); if(!list) return; list.innerHTML=''; st.channels.forEach(c=>{ const li=document.createElement('li'); const a=document.createElement('a'); a.href='#'; a.textContent=c + (c===st.current? ' ✓':''); a.onclick=(ev)=>{ev.preventDefault(); selectChannel(c);}; li.appendChild(a); list.appendChild(li); }); }
 
-async function selectChannel(ch){ if(st.sse){ st.sse.close(); st.sse=null; } st.current=ch; renderChannels(); const el=document.getElementById('tail'); if(!el) return; el.textContent=''; const data = await api('/api/tail',{query:{channel:ch,limit:50}}); appendBatch(data); requestAnimationFrame(()=>{ snapBottom(); st.atBottom=true; }); st.earliest = data.length? data[0].time : null; startStream(); initScrollHandlers(); }
-function initScrollHandlers(){ const el=document.getElementById('tail'); if(!el) return; const onScroll = async ()=>{ const nearBottom = (window.innerHeight + window.pageYOffset + 16) >= document.documentElement.scrollHeight; st.atBottom = nearBottom; const nearTop = window.pageYOffset <= 4; if(nearTop && st.earliest){ try{ const older = await api('/api/history',{query:{channel:st.current,before:st.earliest,limit:50}}); if(older.length){ prependBatch(older); st.earliest = older[0].time; } } catch(e){} } }; window.removeEventListener('scroll', st._scrollHandler || (()=>{})); st._scrollHandler = onScroll; window.addEventListener('scroll', onScroll, {passive:true}); }
+async function selectChannel(ch){ if(st.sse){ st.sse.close(); st.sse=null; } st.current=ch; st.seen = new Set(); st.loadingHistory = false; renderChannels(); const el=document.getElementById('tail'); if(!el) return; el.textContent=''; const data = await api('/api/tail',{query:{channel:ch,limit:50}}); appendBatch(data); requestAnimationFrame(()=>{ snapBottom(); st.atBottom=true; }); st.earliest = data.length? data[0].time : null; startStream(); initScrollHandlers(); }
+function initScrollHandlers(){ const el=document.getElementById('tail'); if(!el) return; const onScroll = async ()=>{ const nearBottom = (window.innerHeight + window.pageYOffset + 16) >= document.documentElement.scrollHeight; st.atBottom = nearBottom; const nearTop = window.pageYOffset <= 4; if(nearTop && st.earliest && !st.loadingHistory){ try{ st.loadingHistory = true; const before = st.earliest; const older = await api('/api/history',{query:{channel:st.current,before:before,limit:50}}); if(older.length){ prependBatch(older); st.earliest = older[0].time; } } catch(e){} finally { st.loadingHistory = false; } } }; window.removeEventListener('scroll', st._scrollHandler || (()=>{})); st._scrollHandler = onScroll; window.addEventListener('scroll', onScroll, {passive:true}); }
 
 function startStream(){ const el=document.getElementById('tail'); if(!el) return; const url=new URL('/api/stream', window.location.origin); url.searchParams.set('channel', st.current); const es=new EventSource(url); st.sse=es; es.onmessage=(ev)=>{ try{ const m=JSON.parse(ev.data); appendBatch([m]); }catch(e){} }; es.onerror=()=>{ es.close(); st.sse=null; setTimeout(startStream, 3000); } }
 
diff --git a/internal/summarizer/openai.go b/internal/summarizer/openai.go
index 04c9940..f380036 100644
--- a/internal/summarizer/openai.go
+++ b/internal/summarizer/openai.go
@@ -194,16 +194,20 @@ func (o *OpenAI) SummarizeLink(ctx context.Context, rawURL string) (string, erro
 		oembed := "https://www.youtube.com/oembed?format=json&url=" + url.QueryEscape(watchURL)
 		req, _ := http.NewRequestWithContext(ctx2, http.MethodGet, oembed, nil)
 		if resp, err := http.DefaultClient.Do(req); err == nil {
-			func(){
+			func() {
 				defer resp.Body.Close()
 				if resp.StatusCode >= 200 && resp.StatusCode < 300 {
-					var oem struct{
+					var oem struct {
 						Title string `json:"title"`
 						Thumb string `json:"thumbnail_url"`
 					}
 					if err := json.NewDecoder(resp.Body).Decode(&oem); err == nil {
-						if oem.Title != "" { title = oem.Title }
-						if oem.Thumb != "" { img = oem.Thumb }
+						if oem.Title != "" {
+							title = oem.Title
+						}
+						if oem.Thumb != "" {
+							img = oem.Thumb
+						}
 					}
 				}
 			}()
@@ -226,13 +230,17 @@ func (o *OpenAI) SummarizeLink(ctx context.Context, rawURL string) (string, erro
 							if art, err := readability.FromReader(strings.NewReader(text), base); err == nil {
 								if at := strings.TrimSpace(art.TextContent); at != "" {
 									text = at
-									if title == "" && strings.TrimSpace(art.Title) != "" { title = strings.TrimSpace(art.Title) }
+									if title == "" && strings.TrimSpace(art.Title) != "" {
+										title = strings.TrimSpace(art.Title)
+									}
 								}
 							}
 						}
 						text = strings.ReplaceAll(text, "\r", "")
 						text = strings.TrimSpace(text)
-						if len(text) > 6000 { text = text[:6000] }
+						if len(text) > 6000 {
+							text = text[:6000]
+						}
 						content = text
 					}
 				}()
@@ -247,7 +255,11 @@ func (o *OpenAI) SummarizeLink(ctx context.Context, rawURL string) (string, erro
 	b.WriteString("URL: ")
 	b.WriteString(rawURL)
 	b.WriteString("\n")
-	if title != "" { b.WriteString("Title: "); b.WriteString(title); b.WriteString("\n") }
+	if title != "" {
+		b.WriteString("Title: ")
+		b.WriteString(title)
+		b.WriteString("\n")
+	}
 	b.WriteString("\n")
 	if content != "" {
 		b.WriteString("Extracted content (may be truncated):\n")
@@ -274,11 +286,17 @@ func (o *OpenAI) SummarizeLink(ctx context.Context, rawURL string) (string, erro
 		},
 		MaxCompletionTokens: o.maxTokens,
 	}
-	if !reasoningLike { req.Temperature = 0.2 }
+	if !reasoningLike {
+		req.Temperature = 0.2
+	}
 
 	resp, err := client.CreateChatCompletion(ctx, req)
-	if err != nil { return "", err }
-	if len(resp.Choices) == 0 { return "", nil }
+	if err != nil {
+		return "", err
+	}
+	if len(resp.Choices) == 0 {
+		return "", nil
+	}
 	return strings.TrimSpace(resp.Choices[0].Message.Content), nil
 }