PDF Text editor changes (#5726)

# Description of Changes

 - Reduced lightweight editor JSON size:
- Omit heavy page resources and contentStreams in lazy/lightweight
flows.
      - Omit form fields in lazy metadata/editor bootstrapping flows.
      - Strip inline font program blobs from lazy initial payloads.
  - Added page-based font loading:
      - New endpoint to fetch fonts for a specific cached page:
        GET /api/v1/convert/pdf/text-editor/fonts/{jobId}/{pageNumber}
- Frontend now loads page fonts alongside page data and merges into
local doc state.
  - Reduced save payload duplication:
- Partial export now sends only changed pages (no repeated full-document
font/metadata payload each save).
  - Preserved round-trip/export safety:
- Missing lightweight fields (resources/contentStreams) are interpreted
as “preserve existing from cached PDF.”
- Annotation semantics fixed so explicit empty annotation lists can
clear annotations.
- Fixed a regression where lazy mode could fall back to full export and
lose overlays; lazy now stays on cached
        partial export path when dirty pages exist.
  - Logging/noise reduction
  - Transport optimization:
- Enabled HTTP compression for JSON/problem responses. (might remove
later tho in testing)
      
      
      ### Outcome

  - Much smaller JSON payloads for giant PDFs.
  - Fewer duplicated bytes over the wire.
  - Page-scoped loading of heavy font data.
- Better reliability for preserving overlays/vector/background content
during export.


## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### Translations (if applicable)

- [ ] I ran
[`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

frontend/src/core/tools/pdfTextEditor/PdfTextEditor.tsx

@@ -16,6 +16,7 @@ import { pdfWorkerManager } from '@app/services/pdfWorkerManager';
 import { Util } from 'pdfjs-dist/legacy/build/pdf.mjs';
 import {
   PdfJsonDocument,
+  PdfJsonFont,
   PdfJsonImageElement,
   PdfJsonPage,
   TextGroup,
@@ -450,14 +451,25 @@ const PdfTextEditor = ({ onComplete, onError }: BaseToolProps) => {
       const start = performance.now();
 
       try {
-        const response = await apiClient.get(
-          `/api/v1/convert/pdf/text-editor/page/${cachedJobId}/${pageNumber}`,
-          {
-            responseType: 'json',
-          },
-        );
+        const [pageResponse, pageFontsResponse] = await Promise.all([
+          apiClient.get(
+            `/api/v1/convert/pdf/text-editor/page/${cachedJobId}/${pageNumber}`,
+            {
+              responseType: 'json',
+            },
+          ),
+          apiClient.get(
+            `/api/v1/convert/pdf/text-editor/fonts/${cachedJobId}/${pageNumber}`,
+            {
+              responseType: 'json',
+            },
+          ),
+        ]);
 
-        const pageData = response.data as PdfJsonPage;
+        const pageData = pageResponse.data as PdfJsonPage;
+        const pageFonts = Array.isArray(pageFontsResponse.data)
+          ? (pageFontsResponse.data as PdfJsonFont[])
+          : [];
         const normalizedImages = (pageData.imageElements ?? []).map(cloneImageElement);
 
         if (imagesByPageRef.current.length <= pageIndex) {
@@ -471,12 +483,31 @@ const PdfTextEditor = ({ onComplete, onError }: BaseToolProps) => {
           }
           const nextPages = [...prevDoc.pages];
           const existingPage = nextPages[pageIndex] ?? {};
+          const fontMap = new Map<string, PdfJsonFont>();
+          for (const existingFont of prevDoc.fonts ?? []) {
+            if (!existingFont) {
+              continue;
+            }
+            const existingKey = existingFont.uid || `${existingFont.pageNumber ?? -1}:${existingFont.id ?? ''}`;
+            fontMap.set(existingKey, existingFont);
+          }
+          if (pageFonts.length > 0) {
+            for (const font of pageFonts) {
+              if (!font) {
+                continue;
+              }
+              const key = font.uid || `${font.pageNumber ?? -1}:${font.id ?? ''}`;
+              fontMap.set(key, font);
+            }
+          }
+          const nextFonts = Array.from(fontMap.values());
           nextPages[pageIndex] = {
             ...existingPage,
             imageElements: normalizedImages.map(cloneImageElement),
           };
           return {
             ...prevDoc,
+            fonts: nextFonts,
             pages: nextPages,
           };
         });
@@ -1087,8 +1118,7 @@ const PdfTextEditor = ({ onComplete, onError }: BaseToolProps) => {
       const canUseIncremental =
         isLazyMode &&
         cachedJobId &&
-        dirtyPageIndices.length > 0 &&
-        dirtyPageIndices.length < totalPages;
+        dirtyPageIndices.length > 0;
 
       if (canUseIncremental) {
         await ensureImagesForPages(dirtyPageIndices);
@@ -1105,10 +1135,8 @@ const PdfTextEditor = ({ onComplete, onError }: BaseToolProps) => {
             document.pages?.filter((_, index) => dirtyPageSet.has(index)) ?? [];
 
           const partialDocument: PdfJsonDocument = {
-            metadata: document.metadata,
-            xmpMetadata: document.xmpMetadata,
-            fonts: document.fonts,
-            lazyImages: true,
+            // Incremental export only needs changed pages.
+            // Fonts/resources/content streams are resolved from server-side cache.
             pages: partialPages,
           };
 
@@ -1135,11 +1163,13 @@ const PdfTextEditor = ({ onComplete, onError }: BaseToolProps) => {
           setErrorMessage(null);
           return;
         } catch (incrementalError) {
+          if (isLazyMode && cachedJobIdRef.current) {
+            throw new Error('Incremental export failed for cached document. Please reload and retry.');
+          }
           console.warn(
             '[handleGeneratePdf] Incremental export failed, falling back to full export',
             incrementalError,
           );
-          // Fall through to full export below
         }
       }
 
@@ -1272,8 +1302,7 @@ const PdfTextEditor = ({ onComplete, onError }: BaseToolProps) => {
       const canUseIncremental =
         isLazyMode &&
         cachedJobId &&
-        dirtyPageIndices.length > 0 &&
-        dirtyPageIndices.length < totalPages;
+        dirtyPageIndices.length > 0;
 
       if (canUseIncremental) {
         await ensureImagesForPages(dirtyPageIndices);
@@ -1290,10 +1319,8 @@ const PdfTextEditor = ({ onComplete, onError }: BaseToolProps) => {
             document.pages?.filter((_, index) => dirtyPageSet.has(index)) ?? [];
 
           const partialDocument: PdfJsonDocument = {
-            metadata: document.metadata,
-            xmpMetadata: document.xmpMetadata,
-            fonts: document.fonts,
-            lazyImages: true,
+            // Incremental export only needs changed pages.
+            // Fonts/resources/content streams are resolved from server-side cache.
             pages: partialPages,
           };
 
@@ -1312,6 +1339,9 @@ const PdfTextEditor = ({ onComplete, onError }: BaseToolProps) => {
           downloadName = detectedName || expectedName;
           pdfBlob = response.data;
         } catch (incrementalError) {
+          if (isLazyMode && cachedJobId) {
+            throw new Error('Incremental export failed for cached document. Please reload and retry.');
+          }
           console.warn(
             '[handleSaveToWorkbench] Incremental export failed, falling back to full export',
             incrementalError,

frontend/src/core/tools/pdfTextEditor/pdfTextEditorUtils.ts

@@ -1209,7 +1209,7 @@ export const buildUpdatedDocument = (
       ...page,
       textElements: updatedElements,
       imageElements: images.map(cloneImageElement),
-      contentStreams: page.contentStreams ?? [],
+      contentStreams: page.contentStreams ?? null,
     };
   });
 
@@ -1282,7 +1282,7 @@ export const restoreGlyphElements = (
       ...page,
       textElements: rebuiltElements,
       imageElements: images.map(cloneImageElement),
-      contentStreams: page.contentStreams ?? [],
+      contentStreams: page.contentStreams ?? null,
     };
   });