feat: implement segment-based PDF download functionality with a dedicated UI for multi-page export

paperless-backend/src/inbox/inbox.controller.ts

@@ -176,14 +176,15 @@ export class InboxController {
     await this.inboxService.updateSource(id, body.source, preferredUsername);
   }
 
-  @Get(':id/download')
-  async download(
+  @Post(':id/download-segment')
+  async downloadSegment(
     @Param('id') id: string,
+    @Body() body: { pages: number[] },
     @Request() req: any,
     @Res({ passthrough: true }) res: Response,
   ): Promise<StreamableFile> {
     const preferredUsername: string | null = req.user?.preferredUsername ?? null;
-    const { buffer, filename } = await this.inboxService.getEditedPdfBuffer(id, preferredUsername);
+    const { buffer, filename } = await this.inboxService.getSegmentPdfBuffer(id, preferredUsername, body.pages ?? []);
     const { Readable } = await import('stream');
     res.setHeader('Content-Type', 'application/pdf');
     res.setHeader('Content-Disposition', `attachment; filename="${encodeURIComponent(filename)}"`);

paperless-backend/src/inbox/inbox.service.ts

@@ -15,7 +15,7 @@ import {
   type InboxSource,
 } from '../database/entities/inbox-document.entity';
 import { MailService } from '../postprocessing/mail.service';
-import { applyEditsToTemp, cleanupTemp } from '../inbox-postprocessor/edit-applier';
+import { applyEditsToTemp, cleanupTemp, buildSegmentBuffer } from '../inbox-postprocessor/edit-applier';
 
 export interface InboxFile {
   id: string;
@@ -253,19 +253,16 @@ export class InboxService {
     return this.barcodeScanner.scanRegion(doc, pdfPath, page, x, y, w, h);
   }
 
-  async getEditedPdfBuffer(
+  async getSegmentPdfBuffer(
     id: string,
     preferredUsername: string | null,
+    pages: number[],
   ): Promise<{ buffer: Buffer; filename: string }> {
     const { doc, pdfPath } = await this.resolveDocument(id, preferredUsername);
-    let tmpPath: string | null = null;
-    try {
-      tmpPath = await applyEditsToTemp(doc, pdfPath);
-      const buffer = await fs.readFile(tmpPath);
-      return { buffer, filename: doc.OriginalName };
-    } finally {
-      await cleanupTemp(tmpPath);
-    }
+    const deleted = new Set(doc.DeletedPages ?? []);
+    const safePages = pages.filter((p) => p >= 1 && p <= doc.PageCount && !deleted.has(p));
+    const buffer = await buildSegmentBuffer(doc, pdfPath, safePages);
+    return { buffer, filename: doc.OriginalName };
   }
 
   async sendAsEmail(