feat: implement saved resolvers feature with UI prompt and API integration

internal/client/fetcher.go

@@ -120,6 +120,21 @@ func (f *Fetcher) SetRateLimit(qps float64) {
 	f.rateQPS = qps
 }
 
+// ScanConcurrency returns how many resolvers the scanner should probe in
+// parallel, derived from the configured rate limit.
+// Rule: concurrency = max(1, floor(rateQPS)).
+// If rateQPS is 0 (unlimited), falls back to the default of 10.
+func (f *Fetcher) ScanConcurrency() int {
+	if f.rateQPS <= 0 {
+		return 10
+	}
+	n := int(f.rateQPS)
+	if n < 1 {
+		n = 1
+	}
+	return n
+}
+
 // SetTimeout sets the per-query DNS timeout.
 func (f *Fetcher) SetTimeout(d time.Duration) {
 	f.timeout = d
@@ -146,6 +161,7 @@ func (f *Fetcher) SetActiveResolvers(resolvers []string) {
 	defer f.mu.Unlock()
 	f.activeResolvers = make([]string, len(resolvers))
 	copy(f.activeResolvers, resolvers)
+	f.log("active resolvers updated: %d/%d healthy", len(resolvers), len(f.allResolvers))
 }
 
 // SetResolvers replaces the full resolver list and resets the active pool.
@@ -344,6 +360,7 @@ func (f *Fetcher) scatterQuery(ctx context.Context, resolvers []string, qname st
 // Call once per fetcher configuration; creating a new fetcher replaces the old one.
 func (f *Fetcher) Start(ctx context.Context) {
 	if f.rateQPS > 0 {
+		f.log("fetcher started: %d configured resolvers, rate=%.1f q/s, scatter=%d", len(f.allResolvers), f.rateQPS, f.scatter)
 		f.rateCh = make(chan struct{}, 1)
 		go f.runRateLimiter(ctx)
 		go f.runNoise(ctx)
@@ -473,9 +490,6 @@ func (f *Fetcher) FetchBlock(ctx context.Context, channel, block uint16) ([]byte
 		if err != nil {
 			return nil, fmt.Errorf("encode query: %w", err)
 		}
-		if f.debug {
-			f.log("[debug] query ch=%d blk=%d attempt=%d qname=%s", channel, block, attempt+1, qname)
-		}
 
 		scatter := f.scatter
 		if scatter < 1 {
@@ -485,6 +499,10 @@ func (f *Fetcher) FetchBlock(ctx context.Context, channel, block uint16) ([]byte
 		if len(picked) == 0 {
 			return nil, fmt.Errorf("no active resolvers")
 		}
+		if f.debug {
+			f.log("[debug] query ch=%d blk=%d attempt=%d qname=%s resolvers=[%s]",
+				channel, block, attempt+1, qname, strings.Join(picked, ","))
+		}
 
 		data, err := f.scatterQuery(ctx, picked, qname)
 		if err == nil {

internal/client/resolver.go

@@ -3,6 +3,7 @@ package client
 import (
 	"context"
 	"fmt"
+	"math/rand"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -20,6 +21,7 @@ type ResolverChecker struct {
 	fetcher    *Fetcher
 	timeout    time.Duration
 	logFunc    LogFunc
+	onScanDone func([]string)     // called after each completed scan with healthy resolvers
 	started    atomic.Bool        // guards against double-start
 	scanMu     sync.Mutex         // protects scanCancel
 	scanRunMu  sync.Mutex         // only one CheckNow at a time (via TryLock)
@@ -43,6 +45,12 @@ func (rc *ResolverChecker) SetLogFunc(fn LogFunc) {
 	rc.logFunc = fn
 }
 
+// SetOnScanDone registers a callback invoked after each completed CheckNow pass
+// with the list of healthy resolver addresses. Not called when the scan is cancelled.
+func (rc *ResolverChecker) SetOnScanDone(fn func([]string)) {
+	rc.onScanDone = fn
+}
+
 // Start begins the periodic health-check loop in the background.
 // An initial check runs immediately; subsequent checks happen every 10 minutes.
 // ctx controls the lifetime — cancel it to stop the checker.
@@ -82,35 +90,51 @@ func (rc *ResolverChecker) StartAndNotify(ctx context.Context, onFirstDone func(
 			onFirstDone()
 		}
 
-		// Periodic re-check every 30 minutes.
-		ticker := time.NewTicker(30 * time.Minute)
-		defer ticker.Stop()
-		for {
-			select {
-			case <-ctx.Done():
-				return
-			case <-ticker.C:
-				rc.CheckNow(ctx)
-				// If the periodic check leaves us with no resolvers,
-				// fall back into the retry-every-minute loop.
-				if ctx.Err() == nil && len(rc.fetcher.Resolvers()) == 0 {
-					rc.log("All resolvers lost — scanning every minute until one recovers...")
-					for {
-						select {
-						case <-ctx.Done():
-							return
-						case <-time.After(1 * time.Minute):
-						}
-						rc.CheckNow(ctx)
-						if ctx.Err() != nil || len(rc.fetcher.Resolvers()) > 0 {
-							break
-						}
-						rc.log("Still no healthy resolvers — retrying in 1 minute...")
+		rc.runPeriodicLoop(ctx)
+	}()
+}
+
+// StartPeriodic starts only the periodic 30-minute health-check loop without
+// running an initial scan. Use when resolvers are already available (e.g.
+// loaded from a saved last-scan file on startup).
+// Safe to call only once per checker instance; subsequent calls are no-ops.
+func (rc *ResolverChecker) StartPeriodic(ctx context.Context) {
+	if !rc.started.CompareAndSwap(false, true) {
+		return
+	}
+	go rc.runPeriodicLoop(ctx)
+}
+
+// runPeriodicLoop is the shared 30-minute ticker loop used by both
+// StartAndNotify and StartPeriodic.
+func (rc *ResolverChecker) runPeriodicLoop(ctx context.Context) {
+	ticker := time.NewTicker(30 * time.Minute)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-ticker.C:
+			rc.CheckNow(ctx)
+			// If the periodic check leaves us with no resolvers,
+			// fall back into the retry-every-minute loop.
+			if ctx.Err() == nil && len(rc.fetcher.Resolvers()) == 0 {
+				rc.log("All resolvers lost — scanning every minute until one recovers...")
+				for {
+					select {
+					case <-ctx.Done():
+						return
+					case <-time.After(1 * time.Minute):
 					}
+					rc.CheckNow(ctx)
+					if ctx.Err() != nil || len(rc.fetcher.Resolvers()) > 0 {
+						break
+					}
+					rc.log("Still no healthy resolvers — retrying in 1 minute...")
 				}
 			}
 		}
-	}()
+	}
 }
 
 // CancelCurrentScan cancels any in-progress CheckNow call, causing it to
@@ -155,20 +179,43 @@ func (rc *ResolverChecker) CheckNow(ctx context.Context) bool {
 		return true
 	}
 
+	// Shuffle so each scan probes resolvers in a fresh random order, preventing
+	// the same resolvers from always being probed first (more even load distribution).
+	rand.Shuffle(len(resolvers), func(i, j int) { resolvers[i], resolvers[j] = resolvers[j], resolvers[i] })
+
 	total := len(resolvers)
+	concurrency := rc.fetcher.ScanConcurrency()
 	rc.log("RESOLVER_SCAN start %d", total)
+	rc.log("scanner started: probing %d resolvers (concurrency=%d, batch-pause every 50)", total, concurrency)
 
 	var healthy []string
 	var mu sync.Mutex
 	var done int
 	wg := &sync.WaitGroup{}
-	sem := make(chan struct{}, 10) // probe up to 10 resolvers concurrently
+	sem := make(chan struct{}, concurrency)
 
+	launched := 0
 	for _, r := range resolvers {
 		// Stop launching new probes if context was cancelled.
 		if scanCtx.Err() != nil {
 			break
 		}
+		// Rate-limit pause: every 50 launched probes, sleep 3-10 s so we don't
+		// flood resolver rate limits before moving to the next batch.
+		if launched > 0 && launched%50 == 0 {
+			pause := 3*time.Second + time.Duration(rand.Intn(8))*time.Second
+			timer := time.NewTimer(pause)
+			select {
+			case <-scanCtx.Done():
+				timer.Stop()
+				break
+			case <-timer.C:
+			}
+			if scanCtx.Err() != nil {
+				break
+			}
+		}
+		launched++
 		wg.Add(1)
 		go func(r string) {
 			defer wg.Done()
@@ -198,10 +245,13 @@ func (rc *ResolverChecker) CheckNow(ctx context.Context) bool {
 	if len(healthy) == 0 {
 		rc.log("Resolver check done: 0/%d healthy", len(resolvers))
 		rc.log("RESOLVER_SCAN done 0/%d", total)
-		return true
+	} else {
+		rc.log("Resolver check done: %d/%d healthy", len(healthy), len(resolvers))
+		rc.log("RESOLVER_SCAN done %d/%d", len(healthy), total)
+	}
+	if rc.onScanDone != nil {
+		rc.onScanDone(healthy)
 	}
-	rc.log("Resolver check done: %d/%d healthy", len(healthy), len(resolvers))
-	rc.log("RESOLVER_SCAN done %d/%d", len(healthy), total)
 	return true
 }
 

internal/web/static/index.html

@@ -20,7 +20,7 @@ input,textarea,select{font-family:inherit}
 /* ===== LAYOUT ===== */
 .app{display:flex;height:100vh;direction:ltr}
 .sidebar{width:280px;min-width:280px;background:var(--sidebar-bg);display:flex;flex-direction:column;border-right:1px solid var(--border);overflow:hidden}
-.chat-area{flex:1;display:flex;flex-direction:column;background:var(--bg);overflow:hidden}
+.chat-area{flex:1;display:flex;flex-direction:column;background:var(--bg);overflow:hidden;position:relative}
 
 /* ===== SIDEBAR HEADER ===== */
 .sidebar-header{padding:10px 12px;display:flex;flex-direction:column;gap:8px;border-bottom:1px solid var(--border)}
@@ -104,6 +104,13 @@ input,textarea,select{font-family:inherit}
 .refresh-has-new{animation:badge-pulse 2s ease-in-out infinite;color:var(--accent)!important}
 .msg-copy-btn{background:none;border:none;color:var(--text-dim);font-size:14px;cursor:pointer;padding:0 3px;line-height:1;flex-shrink:0;opacity:.45;transition:opacity .15s}.msg-copy-btn:hover{opacity:1}
 
+/* ===== SCROLL-TO-BOTTOM ===== */
+.scroll-down-btn{position:absolute;bottom:70px;right:16px;width:36px;height:36px;border:none;border-radius:50%;background:var(--surface2);color:var(--text);font-size:18px;display:none;align-items:center;justify-content:center;box-shadow:0 2px 10px rgba(0,0,0,.45);z-index:10;cursor:pointer;border:1px solid var(--border)}
+.scroll-down-btn.visible{display:flex}
+.scroll-down-btn:hover{background:var(--hover)}
+.scroll-down-badge{position:absolute;top:-4px;right:-4px;background:var(--accent);color:#fff;font-size:9px;font-weight:700;min-width:16px;height:16px;border-radius:8px;display:none;align-items:center;justify-content:center;padding:0 3px}
+.scroll-down-badge.visible{display:flex}
+
 /* ===== LOG ===== */
 .log-toggle{display:flex;align-items:center;justify-content:space-between;padding:3px 14px;background:var(--bg2);cursor:pointer;user-select:none;font-size:10px;color:var(--text-dim);letter-spacing:.5px;border-top:1px solid var(--border)}
 .log-toggle:hover{color:var(--text)}
@@ -260,6 +267,7 @@ html[dir=ltr] .active-badge{margin-left:0;margin-right:6px}
       <input class="send-input" id="sendInput" data-i18n-ph="write_message" placeholder="Write a message..." maxlength="4000">
       <button class="send-btn" onclick="sendMessage()">&#10148;</button>
     </div>
+    <button class="scroll-down-btn" id="scrollDownBtn" onclick="scrollToBottom()" title="Jump to latest">&#8595;<span class="scroll-down-badge" id="scrollDownBadge"></span></button>
     <div class="progress-panel" id="progressPanel"></div>
     <div class="log-toggle" onclick="toggleLog()"><span>LOG</span><span id="logToggleIcon">&#9654;</span></div>
     <div class="log-panel hidden" id="logPanel"></div>
@@ -269,6 +277,19 @@ html[dir=ltr] .active-badge{margin-left:0;margin-right:6px}
 <!-- TOAST -->
 <div id="toast"></div>
 
+<!-- ===== SAVED RESOLVERS POPUP ===== -->
+<div class="modal-overlay" id="savedResolversModal">
+<div class="modal" style="max-width:380px">
+  <h2 data-i18n="saved_resolvers_title">Quick Start</h2>
+  <p id="savedResolversMsg" style="font-size:13px;color:var(--text-dim);margin-bottom:16px;line-height:1.6"></p>
+  <div class="modal-actions">
+    <button class="btn btn-flat" onclick="savedResolversSkip()" data-i18n="saved_resolvers_skip">Skip</button>
+    <button class="btn btn-outline" onclick="savedResolversRescan()" data-i18n="saved_resolvers_rescan">Scan Again</button>
+    <button class="btn btn-primary" onclick="savedResolversUseNow()" data-i18n="saved_resolvers_use">Use Now</button>
+  </div>
+</div>
+</div>
+
 <!-- ===== SETTINGS MODAL ===== -->
 <div class="modal-overlay" id="settingsModal">
 <div class="modal">
@@ -401,6 +422,14 @@ var I18N = {
     add_manual:'✎ ساخت دستی',rescan:'بررسی مجدد',
     new_messages:'پیام جدید',missed_messages:'{n} پیام از دست رفته یا حذف شده',
     clear_cache:'پاک کردن کش',cache_cleared:'کش پاک شد!',
+    saved_resolvers_title:'شروع سریع',
+    saved_resolvers_msg:'آخرین اسکن ({t}) نتیجه داد: {n} سرور DNS سالم پیدا شد. همین‌ها را استفاده کنیم یا دوباره اسکن کنیم؟',
+    saved_resolvers_use:'استفاده کن (بدون اسکن)',
+    saved_resolvers_rescan:'اسکن مجدد',
+    saved_resolvers_skip:'بعداً',
+    saved_resolvers_applied:'سرورهای DNS ذخیره‌شده اعمال شدند',
+    minutes_ago:'دقیقه پیش',
+    hours_ago:'ساعت پیش',
   },
   en: {
     search:'Search...',settings:'Settings',profiles:'Profiles',
@@ -435,6 +464,14 @@ var I18N = {
     add_manual:'✎ Create Manually',rescan:'Rescan',
     new_messages:'New messages',missed_messages:'{n} messages missed or deleted',
     clear_cache:'Clear Cache',cache_cleared:'Cache cleared!',
+    saved_resolvers_title:'Quick Start',
+    saved_resolvers_msg:'Last scan ({t}) found {n} healthy DNS servers. Use them now (no scan needed), or scan again to re-verify.',
+    saved_resolvers_use:'Use Now (skip scan)',
+    saved_resolvers_rescan:'Scan Again',
+    saved_resolvers_skip:'Later',
+    saved_resolvers_applied:'Saved DNS servers applied!',
+    minutes_ago:'min ago',
+    hours_ago:'hr ago',
   }
 };
 var lang = localStorage.getItem('thefeed_lang') || 'fa';
@@ -476,6 +513,7 @@ async function init(){
     var r=await fetch('/api/status');var st=await r.json();
     await loadProfiles();
     if(!st.configured){openProfiles();return}
+    checkAndShowSavedResolversPrompt(st);
     telegramLoggedIn=!!st.telegramLoggedIn;
     serverNextFetch=st.nextFetch||0;
     updateNextFetchDisplay();
@@ -514,6 +552,35 @@ async function clearCache(){
   try{var r=await fetch('/api/cache/clear',{method:'POST'});var j=await r.json();if(j.ok){alert(t('cache_cleared'))}}catch(e){}
 }
 
+// ===== SAVED RESOLVERS PROMPT =====
+function checkAndShowSavedResolversPrompt(status){
+  if(sessionStorage.getItem('thefeed_scan_prompt_shown'))return;
+  if(!status.lastScan||!status.lastScan.count)return;
+  var ls=status.lastScan;
+  var ageSec=Math.floor(Date.now()/1000)-ls.scannedAt;
+  var ageStr;
+  if(ageSec<3600)ageStr=Math.max(1,Math.round(ageSec/60))+' '+t('minutes_ago');
+  else ageStr=Math.round(ageSec/3600)+' '+t('hours_ago');
+  var msg=t('saved_resolvers_msg').replace('{n}',ls.count).replace('{t}',ageStr);
+  document.getElementById('savedResolversMsg').textContent=msg;
+  document.getElementById('savedResolversModal').classList.add('active');
+}
+function savedResolversSkip(){
+  // "Later" — just close, server already applied saved resolvers and refresh is underway
+  document.getElementById('savedResolversModal').classList.remove('active');
+  sessionStorage.setItem('thefeed_scan_prompt_shown','1');
+}
+function savedResolversUseNow(){
+  // Server already applied saved resolvers at startup; just close the popup
+  savedResolversSkip();
+  showToast(t('saved_resolvers_applied'));
+}
+async function savedResolversRescan(){
+  savedResolversSkip();
+  try{await fetch('/api/rescan',{method:'POST'})}catch(e){}
+  showToast(t('rescan_started'));
+}
+
 // ===== SSE =====
 function connectSSE(){
   if(eventSource)eventSource.close();
@@ -902,6 +969,7 @@ async function selectChannel(num){
   document.getElementById('chatName').textContent=name;
   renderChannels();updateSendPanel();
   document.getElementById('messages').innerHTML='<div class="empty-state"><p>'+t('loading')+'</p></div>';
+  document.getElementById('scrollDownBtn').classList.remove('visible');
   // Show immediate feedback progress bar
   showChannelFetchProgress(num,name);
   await loadMessages(num);
@@ -1017,7 +1085,7 @@ function renderMessages(msgs){
     html+='<div class="msg'+(isPersian(text)?' rtl-msg':'')+'" dir="auto">'+mediaHtml+textHtml+'<div class="msg-meta"><button class="msg-copy-btn" onclick="copyMsg('+i+')" title="'+t('copy')+'">&#128203;</button><span>#'+id+'</span><span>'+timeStr+'</span></div></div>';
   }
   el.innerHTML=html;
-  if(isFirstRender||wasAtBottom)el.scrollTop=el.scrollHeight;
+  if(isFirstRender||wasAtBottom){el.scrollTop=el.scrollHeight;document.getElementById('scrollDownBtn').classList.remove('visible');}
 }
 
 // ===== LOG =====
@@ -1270,6 +1338,25 @@ function copyMsg(idx){
   navigator.clipboard.writeText(text).then(function(){showToast(t('msg_copied'))}).catch(function(){});
 }
 
+// ===== SCROLL TO BOTTOM =====
+(function(){
+  var messagesEl=null;
+  function initScrollBtn(){
+    messagesEl=document.getElementById('messages');
+    if(!messagesEl)return;
+    messagesEl.addEventListener('scroll',function(){
+      var atBottom=messagesEl.scrollHeight-messagesEl.scrollTop-messagesEl.clientHeight<150;
+      document.getElementById('scrollDownBtn').classList.toggle('visible',!atBottom);
+    });
+  }
+  // Init after DOM is ready
+  document.addEventListener('DOMContentLoaded',initScrollBtn,{once:true});
+})();
+function scrollToBottom(){
+  var el=document.getElementById('messages');
+  if(el)el.scrollTop=el.scrollHeight;
+}
+
 // ===== TOAST =====
 function showToast(msg){
   var el=document.getElementById('toast');el.textContent=msg;el.classList.add('show');

internal/web/web.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"io/fs"
 	"log"
+	mrand "math/rand/v2"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -57,6 +58,12 @@ type ProfileList struct {
 	Debug    bool `json:"debug,omitempty"`
 }
 
+// lastScanData is the on-disk structure for last_scan.json.
+type lastScanData struct {
+	Resolvers []string `json:"resolvers"`
+	ScannedAt int64    `json:"scannedAt"`
+}
+
 // Server is the web UI server for thefeed client.
 type Server struct {
 	dataDir  string
@@ -165,6 +172,7 @@ func (s *Server) Run() error {
 	mux.HandleFunc("/api/profiles/switch", s.handleProfileSwitch)
 	mux.HandleFunc("/api/settings", s.handleSettings)
 	mux.HandleFunc("/api/cache/clear", s.handleClearCache)
+	mux.HandleFunc("/api/resolvers/apply-saved", s.handleApplySavedResolvers)
 	mux.HandleFunc("/", s.handleIndex)
 
 	addr := fmt.Sprintf("127.0.0.1:%d", s.port)
@@ -172,7 +180,16 @@ func (s *Server) Run() error {
 	fmt.Printf("\n  Open in browser: http://%s\n\n", addr)
 
 	if s.fetcher != nil {
-		s.startCheckerThenRefresh()
+		if ls := s.loadLastScan(); ls != nil {
+			// Fast path: apply saved healthy resolvers immediately and skip the
+			// initial full scan. Only the periodic 30-min checker starts.
+			// This gives the UI near-instant channel data on app open.
+			s.fetcher.SetActiveResolvers(ls.Resolvers)
+			s.checker.StartPeriodic(s.fetcherCtx)
+			go s.refreshMetadataOnly()
+		} else {
+			s.startCheckerThenRefresh()
+		}
 	}
 
 	var handler http.Handler = mux
@@ -227,6 +244,14 @@ func (s *Server) handleStatus(w http.ResponseWriter, r *http.Request) {
 		status["channels"] = s.channels
 		status["telegramLoggedIn"] = s.telegramLoggedIn
 		status["nextFetch"] = s.nextFetch
+		// Include last resolver scan if recent (<24 h) so the frontend can offer a quick-start.
+		if ls := s.loadLastScan(); ls != nil {
+			status["lastScan"] = map[string]any{
+				"resolvers": ls.Resolvers,
+				"scannedAt": ls.ScannedAt,
+				"count":     len(ls.Resolvers),
+			}
+		}
 	}
 	writeJSON(w, status)
 }
@@ -344,7 +369,24 @@ func (s *Server) handleRescan(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	go func() {
+		// Cancel any in-progress metadata refresh so it doesn't race with the
+		// scan — we want fresh resolver data before we hit DNS again.
+		s.refreshMu.Lock()
+		if s.refreshCancel != nil {
+			s.refreshCancel()
+			s.refreshCancel = nil
+		}
+		s.refreshMu.Unlock()
+
 		if checker.CheckNow(baseCtx) {
+			// Cool-down: give resolvers time to recover from the scan's DNS
+			// queries before we immediately hit them again with a fetch.
+			sleep := 3*time.Second + time.Duration(mrand.IntN(13))*time.Second // 3–15 s
+			select {
+			case <-baseCtx.Done():
+				return
+			case <-time.After(sleep):
+			}
 			s.refreshMetadataOnly()
 		}
 	}()
@@ -610,6 +652,11 @@ func (s *Server) initFetcher() error {
 	checker.SetLogFunc(func(msg string) {
 		s.addLog(msg)
 	})
+	checker.SetOnScanDone(func(healthy []string) {
+		if len(healthy) > 0 {
+			s.saveLastScan(healthy)
+		}
+	})
 	s.checker = checker
 
 	s.fetcher = fetcher
@@ -727,7 +774,7 @@ func (s *Server) refreshMetadataOnly() {
 		s.refreshMu.Unlock()
 	}()
 
-	s.addLog("Fetching metadata...")
+	s.addLog(fmt.Sprintf("Fetching metadata... (%d active resolvers)", len(fetcher.Resolvers())))
 
 	// If the server's next Telegram fetch is imminent (within 5 s), wait for it first.
 	if dl := s.nextFetchDeadline(); !dl.IsZero() && time.Until(dl) < 5*time.Second {
@@ -961,6 +1008,57 @@ func (s *Server) loadConfig() (*Config, error) {
 	return &cfg, nil
 }
 
+// saveLastScan persists the healthy resolver list from the most recent scan.
+func (s *Server) saveLastScan(resolvers []string) {
+	d := lastScanData{Resolvers: resolvers, ScannedAt: time.Now().Unix()}
+	b, err := json.MarshalIndent(d, "", "  ")
+	if err != nil {
+		return
+	}
+	_ = os.WriteFile(filepath.Join(s.dataDir, "last_scan.json"), b, 0600)
+}
+
+// loadLastScan reads the most recent resolver scan result.
+// Returns nil when the file doesn't exist or is older than 24 hours.
+func (s *Server) loadLastScan() *lastScanData {
+	b, err := os.ReadFile(filepath.Join(s.dataDir, "last_scan.json"))
+	if err != nil {
+		return nil
+	}
+	var d lastScanData
+	if err := json.Unmarshal(b, &d); err != nil {
+		return nil
+	}
+	if len(d.Resolvers) == 0 || time.Since(time.Unix(d.ScannedAt, 0)) > 24*time.Hour {
+		return nil
+	}
+	return &d
+}
+
+// handleApplySavedResolvers immediately activates the resolvers from the last
+// scan file, letting the UI skip the current scan and start fetching channels.
+func (s *Server) handleApplySavedResolvers(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		http.Error(w, "method not allowed", 405)
+		return
+	}
+	ls := s.loadLastScan()
+	if ls == nil {
+		http.Error(w, "no saved scan", 400)
+		return
+	}
+	s.mu.RLock()
+	fetcher := s.fetcher
+	s.mu.RUnlock()
+	if fetcher == nil {
+		http.Error(w, "not configured", 400)
+		return
+	}
+	fetcher.SetActiveResolvers(ls.Resolvers)
+	go s.refreshMetadataOnly()
+	writeJSON(w, map[string]any{"ok": true, "count": len(ls.Resolvers)})
+}
+
 func (s *Server) saveConfig(cfg *Config) error {
 	path := filepath.Join(s.dataDir, "config.json")
 	data, err := json.MarshalIndent(cfg, "", "  ")