Fix: Attempt to fix Reader Page-Misfiring Bug & Optimize Loading (Auth Only)

src/components/reader/Reader.svelte

@@ -642,8 +642,8 @@
     if (style === "double" && pageGroups.length) { advanceGroup(true); return; }
     if (!store.pageUrls.length) return;
     if (store.pageNumber < lastPage) {
-      if (style === "fade") { animateFade(() => { store.pageNumber++; }); }
-      else { store.pageNumber++; }
+      if (style === "fade") { animateFade(() => { store.pageNumber = Math.min(lastPage, store.pageNumber + pageStep); }); }
+      else { store.pageNumber = Math.min(lastPage, store.pageNumber + pageStep); }
     } else if (adjacent.next) {
       maybeMarkCurrentRead();
       store.pageNumber = 1;
@@ -660,11 +660,13 @@
     if (style === "double" && pageGroups.length) { advanceGroup(false); return; }
     if (!store.pageUrls.length) return;
     if (store.pageNumber > 1) {
-      if (style === "fade") { animateFade(() => { store.pageNumber--; }); }
-      else { store.pageNumber--; }
+      if (style === "fade") { animateFade(() => { store.pageNumber = Math.max(1, store.pageNumber - pageStep); }); }
+      else { store.pageNumber = Math.max(1, store.pageNumber - pageStep); }
     } else if (adjacent.prev) { startAtLastPage = true; openReader(adjacent.prev, store.activeChapterList); }
   }
 
+  const pageStep = $derived(style === "double" ? 2 : 1);
+
   const goNext = $derived(rtl ? goBack    : goForward);
   const goPrev = $derived(rtl ? goForward : goBack);
 
@@ -1019,11 +1021,11 @@
           <button class="mode-btn" class:active={autoNext} onclick={() => updateSettings({ autoNextChapter: !autoNext })}>
             <span class="mode-label">Auto</span>
           </button>
-        {/if}
-        {#if !autoNext}
-          <button class="mode-btn" class:active={markOnNext} onclick={() => updateSettings({ markReadOnNext: !markOnNext })}>
-            <span class="mode-label">Mk.Read</span>
-          </button>
+          {#if !autoNext}
+            <button class="mode-btn" class:active={markOnNext} onclick={() => updateSettings({ markReadOnNext: !markOnNext })}>
+              <span class="mode-label">Mk.Read</span>
+            </button>
+          {/if}
         {/if}
       </div>
 

src/lib/imageCache.ts

@@ -4,7 +4,7 @@ import { store } from "../store/state.svelte";
 const cache    = new Map<string, string>();
 const inflight = new Map<string, Promise<string>>();
 
-const MAX_CONCURRENT = 14;
+const MAX_CONCURRENT = 6;
 let   active         = 0;
 
 interface QueueEntry {
@@ -30,9 +30,18 @@ async function doFetch(url: string): Promise<string> {
   return blobUrl;
 }
 
+function insertSorted(entry: QueueEntry) {
+  let lo = 0, hi = queue.length;
+  while (lo < hi) {
+    const mid = (lo + hi) >>> 1;
+    if (queue[mid].priority > entry.priority) lo = mid + 1;
+    else hi = mid;
+  }
+  queue.splice(lo, 0, entry);
+}
+
 function drain() {
   while (active < MAX_CONCURRENT && queue.length > 0) {
-    queue.sort((a, b) => b.priority - a.priority);
     const entry = queue.shift()!;
     active++;
     doFetch(entry.url)
@@ -47,7 +56,7 @@ function drain() {
 
 function enqueue(url: string, priority: number): Promise<string> {
   const promise = new Promise<string>((resolve, reject) => {
-    queue.push({ url, priority, resolve, reject });
+    insertSorted({ url, priority, resolve, reject });
   });
   inflight.set(url, promise);
   drain();
@@ -62,8 +71,12 @@ export function getBlobUrl(url: string, priority = 0): Promise<string> {
 
   const existing = inflight.get(url);
   if (existing) {
-    const entry = queue.find(e => e.url === url);
-    if (entry && priority > entry.priority) entry.priority = priority;
+    const idx = queue.findIndex(e => e.url === url);
+    if (idx !== -1 && priority > queue[idx].priority) {
+      const [entry] = queue.splice(idx, 1);
+      entry.priority = priority;
+      insertSorted(entry);
+    }
     return existing;
   }