fix(reader): use range-request-only mode for PDF lazy loading

client/src/features/reader/components/PdfReaderView.vue

@@ -13,7 +13,7 @@ import type { PageDim } from '../composables/usePdf'
 const props = defineProps<{ bookId: number; fileId: number }>()
 const router = useRouter()
 
-const { pdfDoc, totalPages, loading, error, load, getAllPageDims, renderPage, getTextContent } = usePdf()
+const { pdfDoc, totalPages, loading, error, load, getPageDim, renderPage, getTextContent } = usePdf()
 const progress = useReaderProgress(props.bookId, props.fileId)
 const { headerVisible, showHeader } = useVisibility()
 
@@ -51,7 +51,13 @@ const { scale, zoomMode, customScale, zoomLabel, adjustZoom, applyZoomPreset } =
 const layout = usePdfLayout(scrollRef, totalPages, effectiveDims, scale, containerH, spread)
 const { scrollMode, currentPage, pageInput, pageRows, rowHeights, goToPage, onScroll } = layout
 
-const renderer = usePdfRenderer(renderPage, getTextContent, scale, rotation, totalPages)
+function onDimUpdate(pageNum: number, dim: PageDim) {
+  const prev = pageDims.value[pageNum - 1]
+  if (prev && prev.width === dim.width && prev.height === dim.height) return
+  pageDims.value = pageDims.value.map((d, i) => (i === pageNum - 1 ? dim : d))
+}
+
+const renderer = usePdfRenderer(renderPage, getTextContent, scale, rotation, totalPages, onDimUpdate)
 const { canvasMap, textLayerMap, invalidate, setupIO, reset, destroy } = renderer
 
 // ── Invalidation ──────────────────────────────────────────────────────────────
@@ -178,7 +184,11 @@ onMounted(async () => {
   await load(props.fileId)
   if (!pdfDoc.value) return
 
-  pageDims.value = await getAllPageDims()
+  // Load only page 1 to establish initial layout dims. All pages are seeded with
+  // page 1's size (uniform assumption). onDimUpdate corrects individual pages
+  // lazily as they are rendered — no upfront full-document traversal.
+  const firstDim = await getPageDim(1)
+  pageDims.value = Array.from({ length: totalPages.value }, () => ({ ...firstDim }))
   reset()
 
   await nextTick()

client/src/features/reader/composables/usePdf.ts

@@ -22,11 +22,10 @@ export function usePdf() {
     loading.value = true
     error.value = null
     try {
-      // Pass URL directly so PDF.js can use HTTP range requests (206 Partial Content).
-      // This avoids downloading the entire file upfront and allows rendering to start immediately.
       const doc = await pdfjsLib.getDocument({
         url: `/api/books/files/${fileId}/serve`,
-        rangeChunkSize: 512 * 1024,
+        rangeChunkSize: 65536,
+        disableStream: true,
         disableAutoFetch: true,
       }).promise
       pdfDoc.value = doc
@@ -38,26 +37,13 @@ export function usePdf() {
     }
   }
 
-  // Fetch ALL page natural dims in parallel (capped at 10 concurrent).
-  async function getAllPageDims(): Promise<PageDim[]> {
+  async function getPageDim(pageNum: number): Promise<PageDim> {
     const doc = pdfDoc.value
-    if (!doc) return []
-    const total = doc.numPages
-    const results: PageDim[] = new Array(total)
-    const CONCURRENCY = 10
-
-    async function fetchDim(i: number) {
-      const page = await doc.getPage(i + 1)
-      const vp = page.getViewport({ scale: 1 })
-      page.cleanup()
-      results[i] = { width: vp.width, height: vp.height }
-    }
-
-    for (let start = 0; start < total; start += CONCURRENCY) {
-      const batch = Array.from({ length: Math.min(CONCURRENCY, total - start) }, (_, k) => fetchDim(start + k))
-      await Promise.all(batch)
-    }
-    return results
+    if (!doc) return { width: 595, height: 842 }
+    const page = await doc.getPage(pageNum)
+    const vp = page.getViewport({ scale: 1 })
+    page.cleanup()
+    return { width: vp.width, height: vp.height }
   }
 
   async function renderPage(pageNum: number, canvas: HTMLCanvasElement, scale: number): Promise<void> {
@@ -86,5 +72,5 @@ export function usePdf() {
     pdfDoc.value = null
   })
 
-  return { pdfDoc, totalPages, loading, error, load, getAllPageDims, renderPage, getTextContent }
+  return { pdfDoc, totalPages, loading, error, load, getPageDim, renderPage, getTextContent }
 }

client/src/features/reader/composables/usePdfRenderer.ts

@@ -1,9 +1,11 @@
 import { nextTick, ref } from 'vue'
 import type * as pdfjsLib from 'pdfjs-dist'
 import type { ComputedRef, Ref } from 'vue'
+import type { PageDim } from './usePdf'
 
 type RenderPageFn = (pageNum: number, canvas: HTMLCanvasElement, scale: number) => Promise<void>
 type GetTextContentFn = (pageNum: number) => Promise<{ content: pdfjsLib.TextContent; viewport: pdfjsLib.PageViewport } | null>
+type OnDimUpdateFn = (pageNum: number, dim: PageDim) => void
 
 export function usePdfRenderer(
   renderPageFn: RenderPageFn,
@@ -11,6 +13,7 @@ export function usePdfRenderer(
   scale: ComputedRef<number>,
   rotation: Ref<0 | 90 | 180 | 270>,
   totalPages: Ref<number>,
+  onDimUpdate: OnDimUpdateFn,
 ) {
   const canvasMap = ref(new Map<number, HTMLCanvasElement>())
   const textLayerMap = ref(new Map<number, HTMLElement>())
@@ -35,6 +38,8 @@ export function usePdfRenderer(
       const canvas = canvasMap.value.get(pageNum)
       if (!canvas) continue
       await renderPageFn(pageNum, canvas, scale.value)
+      // Report natural dim back so layout can correct any initial estimate.
+      onDimUpdate(pageNum, { width: canvas.width / scale.value, height: canvas.height / scale.value })
       rendered.add(pageNum)
       await buildTextLayer(pageNum)
     }

server/src/db/migrations/meta/_journal.json

@@ -5,28 +5,28 @@
     {
       "idx": 0,
       "version": "7",
-      "when": 1767433168702,
+      "when": 1767491359647,
       "tag": "0000_init_schema",
       "breakpoints": true
     },
     {
       "idx": 1,
       "version": "7",
-      "when": 1767433168702,
+      "when": 1767491359647,
       "tag": "0001_lethal_pixie",
       "breakpoints": true
     },
     {
       "idx": 2,
       "version": "7",
-      "when": 1767433168702,
+      "when": 1767491359647,
       "tag": "0002_powerful_thundra",
       "breakpoints": true
     },
     {
       "idx": 3,
       "version": "7",
-      "when": 1767433168702,
+      "when": 1767491359647,
       "tag": "0003_reading_progress_by_file",
       "breakpoints": true
     }