diff --git a/backend/__tests__/services/photoExportService.txt.test.js b/backend/__tests__/services/photoExportService.txt.test.js
new file mode 100644
index 00000000..f2985113
--- /dev/null
+++ b/backend/__tests__/services/photoExportService.txt.test.js
@@ -0,0 +1,71 @@
+/**
+ * exportAsTxt — issue #623 regression test.
+ *
+ * The admin UI labels the TXT export "for Lightroom search". Lightroom's
+ * filename search wants ONE comma-separated line WITHOUT file extensions
+ * (the gallery JPEGs may map to RAW files in the catalog). The frontend
+ * now passes separator='comma' + include_extension=false for the TXT
+ * format; this test pins the resulting shape so a future refactor can't
+ * silently regress it back to the newline-separated form the bug reported.
+ *
+ * Also pins backward compatibility: a direct API caller passing no options
+ * still gets the original newline-with-extension behaviour, so existing
+ * integrations don't break.
+ */
+jest.mock('../../src/database/db', () => ({ db: jest.fn() }));
+jest.mock('../../src/services/xmpGenerator', () => ({ XmpGenerator: class {} }));
+
+const { PhotoExportService } = require('../../src/services/photoExportService');
+const service = new PhotoExportService();
+
+const PHOTOS = [
+  { original_filename: 'IMG_0001.jpg', filename: 'abc123.jpg' },
+  { original_filename: 'IMG_0002.JPEG', filename: 'def456.jpeg' },
+  { original_filename: 'shoot.final.tif', filename: 'ghi789.tif' },
+  { original_filename: null, filename: 'fallback.png' }, // null original → falls back to filename
+];
+
+describe('exportAsTxt (issue #623)', () => {
+  it('Lightroom mode: comma-joined, no extension, no space', () => {
+    const result = service.exportAsTxt(PHOTOS, {
+      separator: 'comma',
+      include_extension: false,
+    });
+    expect(result.content).toBe('IMG_0001,IMG_0002,shoot.final,fallback');
+    expect(result.contentType).toBe('text/plain');
+  });
+
+  it('backward compatible: no options → newline-joined with extensions', () => {
+    const result = service.exportAsTxt(PHOTOS);
+    expect(result.content).toBe(
+      'IMG_0001.jpg\nIMG_0002.JPEG\nshoot.final.tif\nfallback.png',
+    );
+  });
+
+  it('semicolon separator joins without a trailing space', () => {
+    const result = service.exportAsTxt(PHOTOS, {
+      separator: 'semicolon',
+      include_extension: false,
+    });
+    expect(result.content).toBe('IMG_0001;IMG_0002;shoot.final;fallback');
+  });
+
+  it('filename_format=picpeak uses photo.filename (hashed) instead of original', () => {
+    const result = service.exportAsTxt(PHOTOS, {
+      filename_format: 'picpeak',
+      separator: 'comma',
+      include_extension: false,
+    });
+    expect(result.content).toBe('abc123,def456,ghi789,fallback');
+  });
+
+  it('extension stripping uses only the last segment ("a.b.c" → "a.b")', () => {
+    // path.parse('shoot.final.tif').name === 'shoot.final' — Lightroom
+    // catalogs that store basenames like "shoot.final" still match.
+    const result = service.exportAsTxt(
+      [{ original_filename: 'shoot.final.tif', filename: 'x.tif' }],
+      { separator: 'comma', include_extension: false },
+    );
+    expect(result.content).toBe('shoot.final');
+  });
+});
diff --git a/backend/src/services/photoExportService.js b/backend/src/services/photoExportService.js
index 0f48d245..5b424112 100644
--- a/backend/src/services/photoExportService.js
+++ b/backend/src/services/photoExportService.js
@@ -81,21 +81,36 @@ class PhotoExportService {
 
   /**
    * Export as plain text filename list
+   *
+   * include_extension defaults to true for backward compatibility with any
+   * direct API consumer. The admin UI sets it to false for the Lightroom
+   * search use case — the gallery JPEGs may correspond to RAW files in the
+   * photographer's catalog, so the search has to match on the stem only.
+   *
+   * The comma separator joins without a space, the form Lightroom's filename
+   * search expects (per issue #623).
    */
   exportAsTxt(photos, options = {}) {
-    const { filename_format = 'original', separator = 'newline' } = options;
+    const {
+      filename_format = 'original',
+      separator = 'newline',
+      include_extension = true,
+    } = options;
 
-    const filenames = photos.map(photo =>
-      filename_format === 'original' ? (photo.original_filename || photo.filename) : photo.filename
-    );
+    const filenames = photos.map(photo => {
+      const name = filename_format === 'original'
+        ? (photo.original_filename || photo.filename)
+        : photo.filename;
+      return include_extension ? name : path.parse(name).name;
+    });
 
     let content;
     switch (separator) {
       case 'comma':
-        content = filenames.join(', ');
+        content = filenames.join(',');
         break;
       case 'semicolon':
-        content = filenames.join('; ');
+        content = filenames.join(';');
         break;
       default:
         content = filenames.join('\n');
diff --git a/frontend/src/components/admin/PhotoExportMenu.tsx b/frontend/src/components/admin/PhotoExportMenu.tsx
index 69c7a7b4..ef8a3e60 100644
--- a/frontend/src/components/admin/PhotoExportMenu.tsx
+++ b/frontend/src/components/admin/PhotoExportMenu.tsx
@@ -64,6 +64,11 @@ export const PhotoExportMenu: React.FC<PhotoExportMenuProps> = ({
       format,
       options: {
         filename_format: 'original',
+        // TXT is labelled "for Lightroom search" — Lightroom's filename
+        // search field takes one comma-separated line, and the gallery
+        // JPEGs may correspond to RAW files in the catalog so the search
+        // has to match on the stem only (issue #623).
+        ...(format === 'txt' ? { separator: 'comma' as const, include_extension: false } : {}),
         include_rating: true,
         include_label: true,
         include_description: true,
diff --git a/frontend/src/services/photos.service.ts b/frontend/src/services/photos.service.ts
index 004f92d7..629ba4d7 100644
--- a/frontend/src/services/photos.service.ts
+++ b/frontend/src/services/photos.service.ts
@@ -345,6 +345,7 @@ export interface ExportOptions {
   options?: {
     filename_format?: 'original' | 'picpeak';
     separator?: 'newline' | 'comma' | 'semicolon';
+    include_extension?: boolean;
     include_rating?: boolean;
     include_label?: boolean;
     include_description?: boolean;