Add chunked TTS audio generation and ranking search autocomplete on home page

- Split chapter TTS into up to 10 paragraph-aligned parts; part 0 is
  generated synchronously so playback starts immediately, parts 1-9 and
  the final merge happen in a background goroutine
- New routes: GET /ui/audio/{slug}/{n}/status (merge poll) and
  GET /ui/audio-file/{slug}/{n}/part/{p} (serve individual part)
- JS polls status every 3 s and seamlessly swaps audio.src to the merged
  file once ready, preserving playback position proportionally
- Home page scrape form replaced with a ranking-search autocomplete:
  type a title/author to see matching ranking items (cover + metadata),
  click or keyboard-select to inject the source URL, or paste a raw URL
  directly; ranking data is embedded as JSON at page render time

scraper/internal/server/server.go

@@ -17,6 +17,7 @@ import (
 	"net/http"
 	"os"
 	"strconv"
+	"strings"
 	"sync"
 	"time"
 
@@ -89,7 +90,9 @@ func (s *Server) ListenAndServe(ctx context.Context) error {
 		`{"error":"audio generation timed out"}`,
 	)
 	mux.Handle("POST /ui/audio/{slug}/{n}", audioGenHandler)
+	mux.HandleFunc("GET /ui/audio/{slug}/{n}/status", s.handleAudioStatus)
 	mux.HandleFunc("GET /ui/audio-file/{slug}/{n}", s.handleAudioFile)
+	mux.HandleFunc("GET /ui/audio-file/{slug}/{n}/part/{p}", s.handleAudioFilePart)
 
 	srv := &http.Server{
 		Addr:         s.addr,
@@ -138,15 +141,25 @@ func (s *Server) handleChapterText(w http.ResponseWriter, r *http.Request) {
 	fmt.Fprint(w, stripMarkdown(raw))
 }
 
-// handleAudioGenerate handles POST /ui/audio/{slug}/{n}.
-// It accepts an optional JSON body {voice, speed} (falling back to server
-// defaults).  If the MP3 is already cached on disk it returns immediately;
-// otherwise it calls Kokoro-FastAPI to generate and save the file.
-// Response: JSON {"url": "/ui/audio-file/{slug}/{n}?voice=…&speed=…"}
+// ─── Chunked audio generation ────────────────────────────────────────────────
 //
-// Concurrent requests for the same (slug, n, voice, speed) are deduplicated:
-// the first caller does the work; subsequent callers block until it finishes
-// and then serve the cached file (or receive the same error).
+// handleAudioGenerate handles POST /ui/audio/{slug}/{n}.
+//
+// Flow:
+//  1. If the merged MP3 already exists on disk → return it immediately.
+//  2. Otherwise split the chapter text into up to audioParts equal-ish chunks
+//     (by paragraph), generate part 0 synchronously (so the browser can start
+//     playing right away), then launch a background goroutine that generates
+//     parts 1…N and merges them into the final file.
+//  3. Response: {"url":"<part-0-url>","parts":N,"merged":false}
+//     (or {"url":"<final-url>","parts":1,"merged":true} on a cache hit).
+//
+// Deduplication: if another request is already generating the *merged* file
+// for the same (slug,n,voice,speed) key, the new request blocks until it
+// finishes and then serves the cached result.
+const audioParts = 10
+
+// handleAudioGenerate handles POST /ui/audio/{slug}/{n}.
 func (s *Server) handleAudioGenerate(w http.ResponseWriter, r *http.Request) {
 	slug := r.PathValue("slug")
 	n, err := strconv.Atoi(r.PathValue("n"))
@@ -174,20 +187,17 @@ func (s *Server) handleAudioGenerate(w http.ResponseWriter, r *http.Request) {
 
 	audioPath := s.writer.AudioPath(slug, n, voice, speed)
 
-	// Idempotent: return immediately if already cached.
+	// Fast path: merged file already on disk.
 	if _, err := os.Stat(audioPath); err == nil {
-		s.writeAudioURL(w, slug, n, voice, speed)
+		s.writeAudioResponse(w, slug, n, voice, speed, 1, true)
 		return
 	}
 
-	// Deduplicate concurrent generation requests for the same file.
-	// If another goroutine is already generating this file, wait for it and
-	// then serve the (now-cached) result.
+	// Deduplicate concurrent generation requests for the same merged file.
 	cacheKey := fmt.Sprintf("%s/%d/%s/%.2f", slug, n, voice, speed)
 
 	s.audioMu.Lock()
 	if ch, ok := s.audioInFlight[cacheKey]; ok {
-		// Someone else is already generating — wait for them.
 		s.audioMu.Unlock()
 		select {
 		case <-ch:
@@ -195,20 +205,17 @@ func (s *Server) handleAudioGenerate(w http.ResponseWriter, r *http.Request) {
 			http.Error(w, `{"error":"request cancelled"}`, http.StatusServiceUnavailable)
 			return
 		}
-		// Serve the cached file (or 404 if generation failed).
 		if _, err := os.Stat(audioPath); err == nil {
-			s.writeAudioURL(w, slug, n, voice, speed)
+			s.writeAudioResponse(w, slug, n, voice, speed, 1, true)
 		} else {
 			http.Error(w, `{"error":"audio generation failed"}`, http.StatusInternalServerError)
 		}
 		return
 	}
-	// Register ourselves as the in-flight generator.
 	ch := make(chan struct{})
 	s.audioInFlight[cacheKey] = ch
 	s.audioMu.Unlock()
 
-	// Always close the channel (unblocking waiters) and remove our entry.
 	defer func() {
 		s.audioMu.Lock()
 		delete(s.audioInFlight, cacheKey)
@@ -216,7 +223,7 @@ func (s *Server) handleAudioGenerate(w http.ResponseWriter, r *http.Request) {
 		close(ch)
 	}()
 
-	// Load chapter text.
+	// Load and validate chapter text.
 	raw, err := s.writer.ReadChapter(slug, n)
 	if err != nil {
 		http.Error(w, `{"error":"chapter not found"}`, http.StatusNotFound)
@@ -227,13 +234,105 @@ func (s *Server) handleAudioGenerate(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, `{"error":"chapter text is empty"}`, http.StatusUnprocessableEntity)
 		return
 	}
-
 	if s.kokoroURL == "" {
 		http.Error(w, `{"error":"kokoro not configured"}`, http.StatusServiceUnavailable)
 		return
 	}
 
-	// Call Kokoro-FastAPI.
+	// Ensure audio dir exists.
+	if err := os.MkdirAll(s.writer.AudioDir(slug), 0o755); err != nil {
+		http.Error(w, `{"error":"failed to create audio dir"}`, http.StatusInternalServerError)
+		return
+	}
+
+	parts := splitTextIntoParts(text, audioParts)
+	totalParts := len(parts)
+
+	// Generate part 0 synchronously so the browser can start playing immediately.
+	if err := s.generateAudioPart(r.Context(), slug, n, voice, speed, 0, parts[0]); err != nil {
+		s.log.Error("part 0 generation failed", "err", err)
+		http.Error(w, `{"error":"part 0 generation failed"}`, http.StatusBadGateway)
+		return
+	}
+
+	if totalParts == 1 {
+		// Only one part — rename it to the final path directly.
+		partPath := s.writer.AudioPartPath(slug, n, voice, speed, 0)
+		if err := os.Rename(partPath, audioPath); err != nil {
+			http.Error(w, `{"error":"failed to save audio"}`, http.StatusInternalServerError)
+			return
+		}
+		s.log.Info("audio generated (single part)", "slug", slug, "chapter", n)
+		s.writeAudioResponse(w, slug, n, voice, speed, 1, true)
+		return
+	}
+
+	// Return part-0 URL immediately; generate the rest in the background.
+	s.writeAudioResponse(w, slug, n, voice, speed, totalParts, false)
+
+	// Background: generate parts 1…N then merge.
+	go func() {
+		bgCtx := context.Background()
+		for p := 1; p < totalParts; p++ {
+			if err := s.generateAudioPart(bgCtx, slug, n, voice, speed, p, parts[p]); err != nil {
+				s.log.Error("background part generation failed", "part", p, "err", err)
+				return
+			}
+		}
+		if err := s.mergeAudioParts(slug, n, voice, speed, totalParts); err != nil {
+			s.log.Error("audio merge failed", "slug", slug, "chapter", n, "err", err)
+			return
+		}
+		s.log.Info("audio merged", "slug", slug, "chapter", n, "parts", totalParts)
+	}()
+}
+
+// splitTextIntoParts divides text (paragraphs separated by blank lines) into
+// at most n equal-ish chunks.  Returns at least 1 element.
+func splitTextIntoParts(text string, n int) []string {
+	// Split into paragraphs on blank lines.
+	raw := strings.Split(text, "\n\n")
+	var paras []string
+	for _, p := range raw {
+		p = strings.TrimSpace(p)
+		if p != "" {
+			paras = append(paras, p)
+		}
+	}
+	if len(paras) == 0 {
+		return []string{text}
+	}
+	if n > len(paras) {
+		n = len(paras)
+	}
+	if n < 1 {
+		n = 1
+	}
+
+	chunks := make([]string, n)
+	chunkSize := (len(paras) + n - 1) / n // ceiling division
+	for i := 0; i < n; i++ {
+		start := i * chunkSize
+		end := start + chunkSize
+		if start >= len(paras) {
+			// Fewer paragraphs than requested parts: return what we have.
+			chunks = chunks[:i]
+			break
+		}
+		if end > len(paras) {
+			end = len(paras)
+		}
+		chunks[i] = strings.Join(paras[start:end], "\n\n")
+	}
+	if len(chunks) == 0 {
+		return []string{text}
+	}
+	return chunks
+}
+
+// generateAudioPart calls Kokoro for a single text chunk and writes the result
+// atomically to AudioPartPath(…, part).
+func (s *Server) generateAudioPart(ctx context.Context, slug string, n int, voice string, speed float64, part int, text string) error {
 	reqBody, _ := json.Marshal(map[string]interface{}{
 		"model":           "kokoro",
 		"input":           text,
@@ -242,67 +341,140 @@ func (s *Server) handleAudioGenerate(w http.ResponseWriter, r *http.Request) {
 		"speed":           speed,
 		"stream":          false,
 	})
-	kokoroReq, err := http.NewRequestWithContext(r.Context(), http.MethodPost,
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost,
 		s.kokoroURL+"/v1/audio/speech", bytes.NewReader(reqBody))
 	if err != nil {
-		http.Error(w, `{"error":"failed to build kokoro request"}`, http.StatusInternalServerError)
-		return
+		return fmt.Errorf("build request: %w", err)
 	}
-	kokoroReq.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Content-Type", "application/json")
 
-	resp, err := http.DefaultClient.Do(kokoroReq)
+	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
-		s.log.Error("kokoro request failed", "err", err)
-		http.Error(w, `{"error":"kokoro unavailable"}`, http.StatusBadGateway)
-		return
+		return fmt.Errorf("kokoro request: %w", err)
 	}
 	defer resp.Body.Close()
 
 	if resp.StatusCode != http.StatusOK {
-		body2, _ := io.ReadAll(resp.Body)
-		s.log.Error("kokoro returned error", "status", resp.StatusCode, "body", string(body2))
-		http.Error(w, fmt.Sprintf(`{"error":"kokoro error %d"}`, resp.StatusCode), http.StatusBadGateway)
-		return
+		body, _ := io.ReadAll(resp.Body)
+		return fmt.Errorf("kokoro status %d: %s", resp.StatusCode, string(body))
 	}
 
-	// Ensure the audio directory exists.
-	if err := os.MkdirAll(s.writer.AudioDir(slug), 0o755); err != nil {
-		http.Error(w, `{"error":"failed to create audio dir"}`, http.StatusInternalServerError)
-		return
-	}
-
-	// Write to a temp file then rename atomically.
-	tmpPath := audioPath + ".tmp"
+	partPath := s.writer.AudioPartPath(slug, n, voice, speed, part)
+	tmpPath := partPath + ".tmp"
 	f, err := os.Create(tmpPath)
 	if err != nil {
-		http.Error(w, `{"error":"failed to create temp file"}`, http.StatusInternalServerError)
-		return
+		return fmt.Errorf("create temp file: %w", err)
 	}
 	if _, err := io.Copy(f, resp.Body); err != nil {
 		f.Close()
 		os.Remove(tmpPath)
-		http.Error(w, `{"error":"failed to write audio"}`, http.StatusInternalServerError)
-		return
+		return fmt.Errorf("write audio: %w", err)
 	}
 	f.Close()
-	if err := os.Rename(tmpPath, audioPath); err != nil {
+	if err := os.Rename(tmpPath, partPath); err != nil {
 		os.Remove(tmpPath)
-		http.Error(w, `{"error":"failed to save audio"}`, http.StatusInternalServerError)
-		return
+		return fmt.Errorf("rename temp file: %w", err)
 	}
-
-	s.log.Info("audio generated", "slug", slug, "chapter", n, "voice", voice, "speed", speed)
-	s.writeAudioURL(w, slug, n, voice, speed)
+	return nil
 }
 
-func (s *Server) writeAudioURL(w http.ResponseWriter, slug string, n int, voice string, speed float64) {
-	url := fmt.Sprintf("/ui/audio-file/%s/%d?voice=%s&speed=%.1f", slug, n, voice, speed)
+// mergeAudioParts concatenates totalParts part files in order into AudioPath,
+// then removes the individual part files.
+func (s *Server) mergeAudioParts(slug string, n int, voice string, speed float64, totalParts int) error {
+	audioPath := s.writer.AudioPath(slug, n, voice, speed)
+	tmpPath := audioPath + ".tmp"
+
+	out, err := os.Create(tmpPath)
+	if err != nil {
+		return fmt.Errorf("create merged temp: %w", err)
+	}
+
+	for p := 0; p < totalParts; p++ {
+		partPath := s.writer.AudioPartPath(slug, n, voice, speed, p)
+		data, err := os.ReadFile(partPath)
+		if err != nil {
+			out.Close()
+			os.Remove(tmpPath)
+			return fmt.Errorf("read part %d: %w", p, err)
+		}
+		if _, err := out.Write(data); err != nil {
+			out.Close()
+			os.Remove(tmpPath)
+			return fmt.Errorf("write merged part %d: %w", p, err)
+		}
+	}
+	out.Close()
+
+	if err := os.Rename(tmpPath, audioPath); err != nil {
+		os.Remove(tmpPath)
+		return fmt.Errorf("rename merged: %w", err)
+	}
+
+	// Clean up part files (best-effort).
+	for p := 0; p < totalParts; p++ {
+		os.Remove(s.writer.AudioPartPath(slug, n, voice, speed, p))
+	}
+	return nil
+}
+
+func (s *Server) writeAudioResponse(w http.ResponseWriter, slug string, n int, voice string, speed float64, parts int, merged bool) {
+	var url string
+	if merged {
+		url = fmt.Sprintf("/ui/audio-file/%s/%d?voice=%s&speed=%.1f", slug, n, voice, speed)
+	} else {
+		url = fmt.Sprintf("/ui/audio-file/%s/%d/part/0?voice=%s&speed=%.1f", slug, n, voice, speed)
+	}
 	w.Header().Set("Content-Type", "application/json")
-	_ = json.NewEncoder(w).Encode(map[string]string{"url": url})
+	_ = json.NewEncoder(w).Encode(map[string]interface{}{
+		"url":    url,
+		"parts":  parts,
+		"merged": merged,
+	})
+}
+
+// writeAudioURL is kept for backward compatibility (used by dedup waiters).
+func (s *Server) writeAudioURL(w http.ResponseWriter, slug string, n int, voice string, speed float64) {
+	s.writeAudioResponse(w, slug, n, voice, speed, 1, true)
+}
+
+// handleAudioStatus handles GET /ui/audio/{slug}/{n}/status.
+// Returns {"merged":true/false,"url":"..."} so the browser can poll for the
+// merged file after receiving a parts response from handleAudioGenerate.
+func (s *Server) handleAudioStatus(w http.ResponseWriter, r *http.Request) {
+	slug := r.PathValue("slug")
+	n, err := strconv.Atoi(r.PathValue("n"))
+	if err != nil || n < 1 {
+		http.Error(w, `{"error":"invalid chapter"}`, http.StatusBadRequest)
+		return
+	}
+	voice := r.URL.Query().Get("voice")
+	if voice == "" {
+		voice = s.kokoroVoice
+	}
+	speedStr := r.URL.Query().Get("speed")
+	speed := 1.0
+	if speedStr != "" {
+		if v, err := strconv.ParseFloat(speedStr, 64); err == nil && v > 0 {
+			speed = v
+		}
+	}
+
+	audioPath := s.writer.AudioPath(slug, n, voice, speed)
+	merged := false
+	if _, err := os.Stat(audioPath); err == nil {
+		merged = true
+	}
+
+	mergedURL := fmt.Sprintf("/ui/audio-file/%s/%d?voice=%s&speed=%.1f", slug, n, voice, speed)
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(map[string]interface{}{
+		"merged": merged,
+		"url":    mergedURL,
+	})
 }
 
 // handleAudioFile handles GET /ui/audio-file/{slug}/{n}.
-// Serves the cached MP3 file identified by voice and speed query params.
+// Serves the cached merged MP3 file identified by voice and speed query params.
 func (s *Server) handleAudioFile(w http.ResponseWriter, r *http.Request) {
 	slug := r.PathValue("slug")
 	n, err := strconv.Atoi(r.PathValue("n"))
@@ -333,6 +505,43 @@ func (s *Server) handleAudioFile(w http.ResponseWriter, r *http.Request) {
 	http.ServeFile(w, r, audioPath)
 }
 
+// handleAudioFilePart handles GET /ui/audio-file/{slug}/{n}/part/{p}.
+// Serves a specific MP3 part file.
+func (s *Server) handleAudioFilePart(w http.ResponseWriter, r *http.Request) {
+	slug := r.PathValue("slug")
+	n, err := strconv.Atoi(r.PathValue("n"))
+	if err != nil || n < 1 {
+		http.NotFound(w, r)
+		return
+	}
+	p, err := strconv.Atoi(r.PathValue("p"))
+	if err != nil || p < 0 {
+		http.NotFound(w, r)
+		return
+	}
+	voice := r.URL.Query().Get("voice")
+	if voice == "" {
+		voice = s.kokoroVoice
+	}
+	speedStr := r.URL.Query().Get("speed")
+	speed := 1.0
+	if speedStr != "" {
+		if v, err := strconv.ParseFloat(speedStr, 64); err == nil && v > 0 {
+			speed = v
+		}
+	}
+
+	partPath := s.writer.AudioPartPath(slug, n, voice, speed, p)
+	if _, err := os.Stat(partPath); err != nil {
+		http.NotFound(w, r)
+		return
+	}
+
+	w.Header().Set("Content-Type", "audio/mpeg")
+	w.Header().Set("Cache-Control", "no-store")
+	http.ServeFile(w, r, partPath)
+}
+
 func (s *Server) handleScrapeCatalogue(w http.ResponseWriter, r *http.Request) {
 	cfg := s.oCfg
 	cfg.SingleBookURL = "" // full catalogue

scraper/internal/server/ui.go

@@ -3,6 +3,7 @@ package server
 import (
 	"bytes"
 	"context"
+	"encoding/json"
 	"fmt"
 	"html/template"
 	"net/http"
@@ -137,15 +138,25 @@ const homeTmpl = `
   <!-- Scrape form -->
   <div class="mb-10 rounded-xl border border-zinc-800 bg-zinc-900 p-5">
     <h2 class="text-sm font-semibold text-zinc-300 mb-3">Scrape a new book</h2>
-    <form hx-post="/ui/scrape/book"
+    <form id="scrape-form"
+          hx-post="/ui/scrape/book"
           hx-target="#scrape-status"
           hx-swap="innerHTML"
           class="flex gap-2">
-      <input type="url"
-             name="url"
-             required
-             placeholder="https://novelfire.net/book/some-book"
-             class="flex-1 rounded-lg bg-zinc-800 border border-zinc-700 px-3 py-2 text-sm text-zinc-100 placeholder-zinc-500 focus:outline-none focus:border-amber-500 transition-colors" />
+      <div class="flex-1 relative" id="scrape-search-wrap">
+        <input type="text"
+               id="scrape-search"
+               autocomplete="off"
+               spellcheck="false"
+               placeholder="Search rankings or paste a URL…"
+               class="w-full rounded-lg bg-zinc-800 border border-zinc-700 px-3 py-2 text-sm text-zinc-100 placeholder-zinc-500 focus:outline-none focus:border-amber-500 transition-colors" />
+        <!-- hidden url field submitted to HTMX -->
+        <input type="url" name="url" id="scrape-url" required class="hidden" />
+        <!-- dropdown -->
+        <ul id="scrape-dropdown"
+            class="hidden absolute z-50 left-0 right-0 top-full mt-1 rounded-xl border border-zinc-700 bg-zinc-900 shadow-xl max-h-80 overflow-y-auto">
+        </ul>
+      </div>
       <button type="submit"
               class="px-4 py-2 rounded-lg bg-amber-600 hover:bg-amber-500 text-white text-sm font-medium transition-colors whitespace-nowrap">
         Scrape
@@ -280,6 +291,183 @@ const homeTmpl = `
   }
 
   if (input) input.addEventListener('input', filterCards);
+
+  /* ── ranking search / scrape autocomplete ──────────────────────────────── */
+  (function () {
+    var RANKING = {{.RankingJSON}};
+    if (!RANKING || !RANKING.length) return;
+
+    var searchInput = document.getElementById('scrape-search');
+    var urlInput    = document.getElementById('scrape-url');
+    var dropdown    = document.getElementById('scrape-dropdown');
+    var form        = document.getElementById('scrape-form');
+    if (!searchInput || !urlInput || !dropdown || !form) return;
+
+    var activeIdx = -1;
+
+    // Sync the hidden url field whenever the visible input looks like a URL.
+    function syncURLField(val) {
+      val = val.trim();
+      if (/^https?:\/\//i.test(val)) {
+        urlInput.value = val;
+      } else {
+        urlInput.value = '';
+      }
+    }
+
+    function closeDrop() {
+      dropdown.classList.add('hidden');
+      dropdown.innerHTML = '';
+      activeIdx = -1;
+    }
+
+    function buildItem(item, q) {
+      var li = document.createElement('li');
+      li.className = 'flex items-center gap-3 px-3 py-2 cursor-pointer hover:bg-zinc-800 transition-colors';
+      li.dataset.url = item.source_url || '';
+
+      // Cover image
+      if (item.cover) {
+        var img = document.createElement('img');
+        img.src = item.cover;
+        img.alt = '';
+        img.className = 'w-10 h-14 object-cover rounded flex-shrink-0 bg-zinc-800';
+        li.appendChild(img);
+      } else {
+        var ph = document.createElement('div');
+        ph.className = 'w-10 h-14 rounded flex-shrink-0 bg-zinc-800';
+        li.appendChild(ph);
+      }
+
+      // Text block
+      var txt = document.createElement('div');
+      txt.className = 'min-w-0 flex-1';
+
+      var title = document.createElement('p');
+      title.className = 'text-sm font-medium text-zinc-100 truncate';
+      title.textContent = item.title || '';
+      txt.appendChild(title);
+
+      if (item.author) {
+        var author = document.createElement('p');
+        author.className = 'text-xs text-zinc-400 truncate mt-0.5';
+        author.textContent = item.author;
+        txt.appendChild(author);
+      }
+
+      var meta = document.createElement('div');
+      meta.className = 'flex gap-1.5 mt-1 flex-wrap';
+      if (item.status) {
+        var s = document.createElement('span');
+        s.className = 'text-xs px-1.5 py-0.5 rounded-full bg-zinc-700 text-zinc-300';
+        s.textContent = item.status;
+        meta.appendChild(s);
+      }
+      if (item.rank) {
+        var r = document.createElement('span');
+        r.className = 'text-xs px-1.5 py-0.5 rounded-full bg-amber-900 text-amber-300';
+        r.textContent = '#' + item.rank;
+        meta.appendChild(r);
+      }
+      txt.appendChild(meta);
+      li.appendChild(txt);
+
+      return li;
+    }
+
+    function setActive(idx, items) {
+      var lis = dropdown.querySelectorAll('li');
+      lis.forEach(function (li, i) {
+        if (i === idx) li.classList.add('bg-zinc-800');
+        else li.classList.remove('bg-zinc-800');
+      });
+      activeIdx = idx;
+      if (idx >= 0 && idx < items.length) {
+        searchInput.value = items[idx].title || '';
+        urlInput.value    = items[idx].source_url || '';
+      }
+    }
+
+    function showDrop(items, q) {
+      dropdown.innerHTML = '';
+      activeIdx = -1;
+      if (!items.length) { closeDrop(); return; }
+      items.forEach(function (item, i) {
+        var li = buildItem(item, q);
+        li.addEventListener('mousedown', function (e) {
+          e.preventDefault(); // keep focus on input
+          searchInput.value = item.title || item.source_url || '';
+          urlInput.value    = item.source_url || '';
+          closeDrop();
+        });
+        dropdown.appendChild(li);
+      });
+      dropdown.classList.remove('hidden');
+    }
+
+    searchInput.addEventListener('input', function () {
+      var q = searchInput.value.trim().toLowerCase();
+      syncURLField(searchInput.value);
+      if (!q) { closeDrop(); return; }
+      // If it looks like a URL, no autocomplete needed.
+      if (/^https?:\/\//i.test(q)) { closeDrop(); return; }
+      var results = RANKING.filter(function (item) {
+        var haystack = ((item.title || '') + ' ' + (item.author || '') + ' ' + (item.status || '')).toLowerCase();
+        return haystack.indexOf(q) !== -1;
+      }).slice(0, 8);
+      showDrop(results, q);
+    });
+
+    searchInput.addEventListener('keydown', function (e) {
+      var lis = dropdown.querySelectorAll('li');
+      var items = RANKING.filter(function (item) {
+        var q = searchInput.value.trim().toLowerCase();
+        var haystack = ((item.title || '') + ' ' + (item.author || '') + ' ' + (item.status || '')).toLowerCase();
+        return haystack.indexOf(q) !== -1;
+      }).slice(0, 8);
+
+      if (e.key === 'ArrowDown') {
+        e.preventDefault();
+        setActive(Math.min(activeIdx + 1, lis.length - 1), items);
+      } else if (e.key === 'ArrowUp') {
+        e.preventDefault();
+        setActive(Math.max(activeIdx - 1, 0), items);
+      } else if (e.key === 'Enter' && activeIdx >= 0) {
+        e.preventDefault();
+        if (items[activeIdx]) {
+          searchInput.value = items[activeIdx].title || items[activeIdx].source_url || '';
+          urlInput.value    = items[activeIdx].source_url || '';
+        }
+        closeDrop();
+      } else if (e.key === 'Escape') {
+        closeDrop();
+      }
+    });
+
+    // Validate before submit: if url field empty, treat visible input as raw URL.
+    form.addEventListener('htmx:configRequest', function (e) {
+      var val = searchInput.value.trim();
+      if (!urlInput.value && /^https?:\/\//i.test(val)) {
+        urlInput.value = val;
+      }
+    });
+
+    // Also handle plain form submit (non-HTMX fallback).
+    form.addEventListener('submit', function () {
+      var val = searchInput.value.trim();
+      if (!urlInput.value && /^https?:\/\//i.test(val)) {
+        urlInput.value = val;
+      }
+    });
+
+    // Close dropdown when clicking outside.
+    document.addEventListener('mousedown', function (e) {
+      if (!document.getElementById('scrape-search-wrap').contains(e.target)) {
+        closeDrop();
+      }
+    });
+  }());
+
 }());
 </script>`
 
@@ -295,9 +483,22 @@ func (s *Server) handleHome(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// Load ranking items for the scrape-search autocomplete.
+	// Failures are non-fatal — the form degrades to a plain URL input.
+	rankingItems, _ := s.writer.ReadRankingItems()
+
+	// Encode ranking items as JSON for embedding in the template.
+	rankingJSON, _ := json.Marshal(rankingItems)
+
 	t := template.Must(template.New("home").Parse(homeTmpl))
 	var buf bytes.Buffer
-	_ = t.Execute(&buf, struct{ Books interface{} }{Books: books})
+	_ = t.Execute(&buf, struct {
+		Books       interface{}
+		RankingJSON template.JS
+	}{
+		Books:       books,
+		RankingJSON: template.JS(rankingJSON),
+	})
 
 	s.respond(w, r, "Home", buf.String())
 }
@@ -1619,15 +1820,22 @@ const chapterTmpl = `
   }
 
   // ── server-side audio generation ─────────────────────────────────────────────
-  // POST /ui/audio/{slug}/{n} — idempotent; returns {url} immediately if cached.
-  // cb(url) is called with the audio-file URL on success.
-  // Returns the AbortController so the caller can cancel in-flight requests.
+  // POST /ui/audio/{slug}/{n} — returns {url, parts, merged}.
+  // When merged=false, url is part-0; polling /ui/audio/{slug}/{n}/status
+  // detects when the full merged file is ready and swaps audio.src seamlessly.
+  // cb(url) is called with the initial (part-0 or merged) URL on success.
 
   var currentAudioCtrl = null; // AbortController for the active generateAudio fetch
+  var mergePoller = null;       // setInterval id for polling merged status
+
+  function clearMergePoller() {
+    if (mergePoller !== null) { clearInterval(mergePoller); mergePoller = null; }
+  }
 
   function generateAudio(chapterN, cb) {
-    // Cancel any previous in-flight generation.
+    // Cancel any previous in-flight generation and polling.
     if (currentAudioCtrl) { currentAudioCtrl.abort(); }
+    clearMergePoller();
     var ctrl = new AbortController();
     currentAudioCtrl = ctrl;
 
@@ -1645,8 +1853,35 @@ const chapterTmpl = `
       return res.json();
     })
     .then(function (data) {
-      if (data && data.url) cb(data.url);
-      else throw new Error('no url in response');
+      if (!data || !data.url) throw new Error('no url in response');
+      cb(data.url);
+      // If the server is still generating remaining parts, start polling.
+      if (!data.merged && data.parts > 1) {
+        var statusURL = '/ui/audio/' + SLUG + '/' + chapterN + '/status'
+          + '?voice=' + encodeURIComponent(voiceSel.value)
+          + '&speed=' + parseFloat(speedSlider.value);
+        mergePoller = setInterval(function () {
+          fetch(statusURL)
+            .then(function (r) { return r.ok ? r.json() : Promise.reject(r.status); })
+            .then(function (s) {
+              if (s.merged) {
+                clearMergePoller();
+                // Seamlessly swap to the full merged file.
+                var ratio = (audio.duration && isFinite(audio.duration))
+                  ? audio.currentTime / audio.duration : 0;
+                audio.addEventListener('loadedmetadata', function onMeta() {
+                  audio.removeEventListener('loadedmetadata', onMeta);
+                  if (audio.duration && isFinite(audio.duration)) {
+                    audio.currentTime = ratio * audio.duration;
+                  }
+                }, { once: true });
+                audio.src = s.url;
+                audio.load();
+              }
+            })
+            .catch(function () { /* ignore transient poll errors */ });
+        }, 3000);
+      }
     })
     .catch(function (e) {
       if (e.name === 'AbortError') return; // silently cancelled
@@ -1683,6 +1918,7 @@ const chapterTmpl = `
   // ── stop / cleanup ────────────────────────────────────────────────────────────
   function stop() {
     if (currentAudioCtrl) { currentAudioCtrl.abort(); currentAudioCtrl = null; }
+    clearMergePoller();
     audio.pause();
     audio.src = '';
     prefetchFired = false;

scraper/internal/writer/writer.go

@@ -417,15 +417,29 @@ func (w *Writer) AudioDir(slug string) string {
 // The filename is keyed by chapter number, voice, and speed so that different
 // settings never collide.  Speed is formatted to one decimal place (e.g. "1.0").
 func (w *Writer) AudioPath(slug string, n int, voice string, speed float64) string {
-	// Sanitise voice so it is safe as a filename component.
-	safeVoice := strings.Map(func(r rune) rune {
+	safeVoice := sanitiseVoice(voice)
+	filename := fmt.Sprintf("ch%d-%s-%.1f.mp3", n, safeVoice, speed)
+	return filepath.Join(w.AudioDir(slug), filename)
+}
+
+// AudioPartPath returns the path for an individual audio chunk generated during
+// chunked TTS.  Part files are named ch{n}-{voice}-{speed}.part{p}.mp3 and are
+// deleted after they have been merged into the final AudioPath file.
+func (w *Writer) AudioPartPath(slug string, n int, voice string, speed float64, part int) string {
+	safeVoice := sanitiseVoice(voice)
+	filename := fmt.Sprintf("ch%d-%s-%.1f.part%d.mp3", n, safeVoice, speed, part)
+	return filepath.Join(w.AudioDir(slug), filename)
+}
+
+// sanitiseVoice converts a voice name into a string that is safe to embed in a
+// filename (only a-z, A-Z, 0-9, '_', '-' are kept; everything else becomes '_').
+func sanitiseVoice(voice string) string {
+	return strings.Map(func(r rune) rune {
 		if (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9') || r == '_' || r == '-' {
 			return r
 		}
 		return '_'
 	}, voice)
-	filename := fmt.Sprintf("ch%d-%s-%.1f.mp3", n, safeVoice, speed)
-	return filepath.Join(w.AudioDir(slug), filename)
 }
 
 // chapterPath computes the full file path for a chapter.