mozilla/pdf.js

web/app.js

@@ -1,6 +1,7 @@
 let state;
 let groups = [];
 let selectedIndex = -1;
+let loadedIndex = -1; // which document the PDF viewer currently shows/loads
 let pdfViewer = null;
 let loadRequestId = 0;
 
@@ -116,10 +117,14 @@ async function loadPdf(index) {
   const doc = state.documents[index];
   if (!doc) return;
 
-  // Deduplicate: don't reload the same document
-  if (index === selectedIndex && pdfViewer) {
+  // Deduplicate: don't reload the document that is already shown.
+  // NOTE: must compare against loadedIndex, NOT selectedIndex --
+  // select() updates selectedIndex before calling loadPdf(), so a
+  // selectedIndex comparison is always true and blocks every reload.
+  if (index === loadedIndex && pdfViewer) {
     return;
   }
+  loadedIndex = index;
 
   if (pdfViewer) {
     pdfViewer.destroy();
@@ -164,6 +169,7 @@ async function loadPdf(index) {
     console.log(`[BizMatch QC] PDF ${reqId} rendering complete`);
   } catch (error) {
     if (index !== selectedIndex) return;
+    loadedIndex = -1; // allow retry: clicking the same document again reloads it
     const message = error instanceof Error ? error.message : String(error);
     pdfMessage.textContent = `Cannot open PDF: ${message}`;
     pdfMessage.hidden = false;
@@ -281,6 +287,7 @@ async function load() {
       throw new Error(`State request failed with HTTP ${response.status}.`);
     }
     state = await response.json();
+    loadedIndex = -1; // document set changed; index-based dedup is invalid now
     groups = buildGroups(state.documents);
     showError(state.loadError || "");
     renderList();
@@ -290,4 +297,4 @@ async function load() {
   }
 }
 
-void load();
+void load();

web/pdf_viewer.js

@@ -71,6 +71,13 @@ class PdfViewer {
         url,
         rangeChunkSize: 65536,
         disableAutoFetch: false,
+        // PDF.js >= 5 decodes CCITT-G4/JBIG2 (B/W scans), JPEG2000 and ICC
+        // color via WASM modules fetched from wasmUrl. Without these URLs
+        // the decoders fail silently (ignoreErrors default) and scanned
+        // pages render as blank white canvases of the correct size.
+        wasmUrl: "/pdfjs/wasm/",
+        standardFontDataUrl: "/pdfjs/standard_fonts/",
+        iccUrl: "/pdfjs/iccs/",
       });
       this.loadingTask = task;
 
@@ -259,4 +266,4 @@ function errorMsg(err) {
   return err instanceof Error ? err.message : String(err);
 }
 
-globalThis.PdfViewer = PdfViewer;
+globalThis.PdfViewer = PdfViewer;