Fix Arabic text rendering in generated PDFs

Add Arabic text shaping functionality to convert base characters to their contextual presentation forms before bidi reordering and PDF rendering. Includes a new regression test to verify correct shaping by asserting the presence of presentation form codepoints in the PDF's embedded ToUnicode CMap.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 77cfe984-2c65-4152-bb7a-0df28274fe66
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Replit-Commit-Event-Id: 18d38e3a-cfe8-4b69-a02c-380283320b78
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artifacts/api-server/package.json

@@ -16,6 +16,7 @@
     "@swc/helpers": "^0.5.21",
     "@workspace/api-zod": "workspace:*",
     "@workspace/db": "workspace:*",
+    "arabic-persian-reshaper": "1.0.1",
     "bcryptjs": "^3.0.3",
     "bidi-js": "^1.0.3",
     "connect-pg-simple": "^10.0.0",

artifacts/api-server/src/lib/pdf-renderer.ts

@@ -3,11 +3,51 @@ import path from "node:path";
 import { readFileSync, existsSync } from "node:fs";
 import bidiFactory from "bidi-js";
 import PDFDocument from "pdfkit";
+// CommonJS module — pulled in via createRequire so the TS->ESM build
+// doesn't try to statically resolve a default export that doesn't exist.
+import { createRequire } from "node:module";
 
 import sanitizeHtml from "sanitize-html";
 
 const bidi = bidiFactory();
 
+const reshaperRequire = createRequire(import.meta.url);
+const { ArabicShaper } = reshaperRequire("arabic-persian-reshaper") as {
+  ArabicShaper: { convertArabic: (input: string) => string };
+};
+
+// Convert base Arabic letters (U+0600..U+06FF) to their contextual
+// presentation forms (Arabic Presentation Forms-A/B). PDFKit has no
+// built-in OpenType layout / HarfBuzz, so without this every Arabic
+// character renders in its isolated form and — combined with the bidi
+// visual reorder — the printed text looks both disconnected and
+// reversed (e.g. "الاجتماعات" prints as "تاعامتجالا"). Must run BEFORE
+// `bidi.getReorderedString`: shaping needs the original logical order
+// to know each letter's neighbours, and the resulting presentation
+// forms are still classified as RTL so bidi reorders them correctly.
+// Idempotent on text that contains only presentation forms / Latin.
+export function shapeArabic(text: string): string {
+  if (!text) return text;
+  // Fast skip: nothing to shape if there are no base-form Arabic chars.
+  // Covers Arabic (0600-06FF), Arabic Supplement (0750-077F), and
+  // Arabic Extended-A (08A0-08FF) so non-standard Arabic-script letters
+  // also trigger the shaping pass.
+  let hasBaseArabic = false;
+  for (const ch of text) {
+    const c = ch.codePointAt(0) ?? 0;
+    if (
+      (c >= 0x0600 && c <= 0x06ff) ||
+      (c >= 0x0750 && c <= 0x077f) ||
+      (c >= 0x08a0 && c <= 0x08ff)
+    ) {
+      hasBaseArabic = true;
+      break;
+    }
+  }
+  if (!hasBaseArabic) return text;
+  return ArabicShaper.convertArabic(text);
+}
+
 export type PdfFontPrefs = {
   fontFamily: string;
   fontSize: number;
@@ -259,8 +299,9 @@ function splitRunsByScript(text: string): Run[] {
 // otherwise-RTL line gets digit-reversed by the renderer).
 function visualOrderRuns(text: string, baseDirection: "ltr" | "rtl"): Run[] {
   if (!text) return [];
-  const embeddingLevels = bidi.getEmbeddingLevels(text, baseDirection);
-  const reordered = bidi.getReorderedString(text, embeddingLevels);
+  const shaped = shapeArabic(text);
+  const embeddingLevels = bidi.getEmbeddingLevels(shaped, baseDirection);
+  const reordered = bidi.getReorderedString(shaped, embeddingLevels);
   return splitRunsByScript(reordered);
 }
 
@@ -417,12 +458,13 @@ function drawWrappingLine(
   const dominantArabic = arabicChars * 2 > text.length;
   const fk = fontKeyFor(dominantArabic, opts.weight, opts.mapping);
   doc.font(fk).fontSize(opts.fontSize).fillColor(opts.color ?? "black");
-  // For Arabic text, run bidi on the whole string so the font sees runs
-  // already in visual order — this matches what drawMixedLine does for
-  // single-line cells.
+  // For Arabic text, shape contextual joining forms first, then run bidi
+  // so the font sees runs already in visual order — this matches what
+  // drawMixedLine does for single-line cells.
+  const shaped = shapeArabic(text);
   const reordered = bidi.getReorderedString(
-    text,
-    bidi.getEmbeddingLevels(text, opts.baseDirection),
+    shaped,
+    bidi.getEmbeddingLevels(shaped, opts.baseDirection),
   );
   const before = doc.y;
   doc.text(reordered, opts.x, opts.y, {
@@ -571,9 +613,10 @@ export async function renderSchedulePdf(input: RenderPdfInput): Promise<Buffer>
       const dominantArabic = arabicChars * 2 > label.length;
       const fk = fontKeyFor(dominantArabic, "bold", mapping);
       doc.font(fk).fontSize(input.font.fontSize).fillColor("white");
+      const shapedLabel = shapeArabic(label);
       const reordered = bidi.getReorderedString(
-        label,
-        bidi.getEmbeddingLevels(label, baseDir),
+        shapedLabel,
+        bidi.getEmbeddingLevels(shapedLabel, baseDir),
       );
       doc.text(reordered, cx + cellPadX, headerY + cellPadY, {
         width: headerWidths[i] - cellPadX * 2,
@@ -667,7 +710,10 @@ export async function renderSchedulePdf(input: RenderPdfInput): Promise<Buffer>
           h += lineHeight;
           continue;
         }
-        const w = doc.widthOfString(line);
+        // Measure with shaped text — presentation forms are typically
+        // narrower than chained isolated glyphs, so probing the raw
+        // string would over-count wraps and reserve excess row height.
+        const w = doc.widthOfString(shapeArabic(line));
         const wraps = Math.max(1, Math.ceil(w / (widths[i] - cellPadX * 2)));
         h += wraps * lineHeight;
       }

artifacts/api-server/tests/executive-meetings.test.mjs

@@ -1024,6 +1024,73 @@ test("PDF content: title label, rowColor tint, dropped isHighlighted, fontColor"
   void ascii;
 });
 
+test("PDF Arabic shaping: title renders in connected presentation forms (not isolated)", async () => {
+  // Regression for the bug where Arabic in the printed PDF appeared as
+  // disconnected, visually-reversed letters (e.g. "الاجتماعات" →
+  // "تاعامتجالا"). PDFKit has no built-in HarfBuzz, so we now run a
+  // pre-shaping pass that converts base Arabic letters (U+0600..U+06FF)
+  // to their contextual presentation forms (FE80..FEFF, plus FEFB
+  // lam-alef ligature) BEFORE handing text to bidi + PDFKit. We assert
+  // the rendered PDF contains presentation-form codepoints in its
+  // embedded ToUnicode CMap (proves shaped glyphs were drawn).
+
+  // End-to-end: render a real PDF and assert the inflated streams
+  // (which include the embedded ToUnicode CMap) reference at least one
+  // Arabic Presentation Forms-B codepoint. Without shaping the CMap
+  // would only contain base U+06xx hex values.
+  const shapedDate = "2099-05-04";
+  const shapedMeeting = await api(adminCookie, "POST", "/api/executive-meetings", {
+    titleAr: "اجتماع الاختبار",
+    titleEn: "Shaping Smoke Test",
+    meetingDate: shapedDate,
+    attendees: [
+      { name: "محمد عبدالله", attendanceType: "internal", sortOrder: 0 },
+    ],
+  });
+  assert.equal(shapedMeeting.status, 201);
+  created.meetingIds.push((await shapedMeeting.json()).id);
+
+  const res = await api(
+    adminCookie,
+    "GET",
+    `/api/executive-meetings/pdf?date=${shapedDate}&lang=ar`,
+  );
+  assert.equal(res.status, 200);
+  const buf = Buffer.from(await res.arrayBuffer());
+
+  // Inflate every FlateDecode stream and concat — same trick as the
+  // existing PDF content test. ToUnicode CMaps are inflate-able and
+  // contain pairs like `<XX> <FE8D>`, so a regex over the joined
+  // payload is enough.
+  let cursor = 0;
+  const decoded = [];
+  while (true) {
+    const start = buf.indexOf("stream\n", cursor);
+    if (start < 0) break;
+    const end = buf.indexOf("\nendstream", start);
+    if (end < 0) break;
+    try {
+      decoded.push(
+        zlib
+          .inflateSync(buf.slice(start + "stream\n".length, end))
+          .toString("latin1"),
+      );
+    } catch {
+      // not a deflate stream
+    }
+    cursor = end + "\nendstream".length;
+  }
+  const allDecoded = decoded.join("\n");
+  // Match any FE80..FEFF or FB50..FDFF hex literal — these are the
+  // Arabic Presentation Forms ranges. Without shaping none would appear.
+  const presFormsRegex = /<(?:FE[89A-F][0-9A-F]|FEF[0-9A-F]|FE[7][0-9A-F]|FB[5-9A-F][0-9A-F]|FC[0-9A-F]{2}|FD[0-9A-F]{2})>/i;
+  assert.match(
+    allDecoded,
+    presFormsRegex,
+    "rendered PDF must reference Arabic Presentation Forms codepoints (proves shaping ran before PDFKit)",
+  );
+});
+
 test("PDF embeds the brand logo when set in global font settings", async () => {
   // Build a real 1x1 RGB PNG (png-js rejects most base64 fixtures).
   const u32 = (n) => {