📄 feat: accept PowerPoint template MIME type (#14761)

2026-08-27 04:07:05 +00:00 · 2026-08-14 06:22:01 +02:00 · 2026-08-14 06:22:01 +02:00 · 6c46fd1252
commit 6c46fd1252
parent 6cbfd82772
14 changed files with 102 additions and 41 deletions
--- a/.env.example
+++ b/.env.example
@ -991,7 +991,7 @@ HELP_AND_FAQ_URL=https://librechat.ai
 # such as the below example of 250 mib
 # CONVERSATION_IMPORT_MAX_FILE_SIZE_BYTES=262144000

-# Max size (bytes) of a code-execution artifact (docx/xlsx/csv/pptx/text/pdf) rendered as an
+# Max size (bytes) of a code-execution artifact (docx/xlsx/csv/pptx/potx/text/pdf) rendered as an
 # inline preview. Larger files fall back to download-only. Default: 2 MB (2097152). Note the
 # rendered HTML is independently capped at 512 KB, so very rich files may still skip preview.
 # FILE_PREVIEW_MAX_EXTRACT_BYTES=2097152
--- a/client/src/data-provider/Files/sharepoint.ts
+++ b/client/src/data-provider/Files/sharepoint.ts
@ -204,6 +204,7 @@ function getMimeTypeFromFileName(fileName: string): string {
    xlsx: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
    ppt: 'application/vnd.ms-powerpoint',
    pptx: 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
+    potx: 'application/vnd.openxmlformats-officedocument.presentationml.template',
    txt: 'text/plain',
    csv: 'text/csv',

--- a/client/src/utils/tests/artifacts.test.ts
+++ b/client/src/utils/tests/artifacts.test.ts
@ -66,6 +66,7 @@ describe('detectArtifactTypeFromFile', () => {
    ['legacy.xls', TOOL_ARTIFACT_TYPES.SPREADSHEET],
    ['sheet.ods', TOOL_ARTIFACT_TYPES.SPREADSHEET],
    ['slides.pptx', TOOL_ARTIFACT_TYPES.PRESENTATION],
+    ['template.potx', TOOL_ARTIFACT_TYPES.PRESENTATION],
  ])('classifies %s by extension', (filename, expected) => {
    /* Office types require `textFormat: 'html'` to route to their HTML
     * preview buckets — the security gate added for Codex P1 review on
@ -155,6 +156,10 @@ describe('detectArtifactTypeFromFile', () => {
      'application/vnd.openxmlformats-officedocument.presentationml.presentation',
      TOOL_ARTIFACT_TYPES.PRESENTATION,
    ],
+    [
+      'application/vnd.openxmlformats-officedocument.presentationml.template',
+      TOOL_ARTIFACT_TYPES.PRESENTATION,
+    ],
  ])('routes office MIME %s to its preview bucket when extension is missing', (mime, expected) => {
    /* `textFormat: 'html'` is required so the security gate (Codex P1 on
     * PR #12934) lets routing proceed to the office HTML bucket — without
--- a/client/src/utils/tests/getViableUploadOptions.spec.ts
+++ b/client/src/utils/tests/getViableUploadOptions.spec.ts
@ -3,6 +3,7 @@ import type { FileConfig } from 'librechat-data-provider';
 import { getViableUploadOptions, type UploadOptionContext } from '../files';

 const XLSX = 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet';
+const POTX = 'application/vnd.openxmlformats-officedocument.presentationml.template';

 /** context accepts plain text + csv (text), pdf + xlsx (ocr); nothing else */
 const fileConfig = {
@ -49,6 +50,13 @@ describe('getViableUploadOptions', () => {
      ]);
    });

+    it('routes a PowerPoint template to file search and code, not the provider', () => {
+      expect(getViableUploadOptions([file(POTX, 'brand-template.potx')], baseCtx())).toEqual([
+        EToolResources.file_search,
+        EToolResources.execute_code,
+      ]);
+    });
+
    it('offers every destination for a PDF', () => {
      expect(getViableUploadOptions([file('application/pdf', 'doc.pdf')], baseCtx())).toEqual([
        undefined,
--- a/client/src/utils/artifacts.ts
+++ b/client/src/utils/artifacts.ts
@ -590,6 +590,7 @@ const EXTENSION_TO_TOOL_ARTIFACT_TYPE: Record<string, ToolArtifactType> = {
  xls: TOOL_ARTIFACT_TYPES.SPREADSHEET,
  ods: TOOL_ARTIFACT_TYPES.SPREADSHEET,
  pptx: TOOL_ARTIFACT_TYPES.PRESENTATION,
+  potx: TOOL_ARTIFACT_TYPES.PRESENTATION,
 };

 /* Append every entry in `CODE_EXTENSION_TO_LANGUAGE` to the routing map
@ -667,6 +668,8 @@ const MIME_TO_TOOL_ARTIFACT_TYPE: Record<string, ToolArtifactType> = {
  'text/comma-separated-values': TOOL_ARTIFACT_TYPES.SPREADSHEET,
  'application/vnd.openxmlformats-officedocument.presentationml.presentation':
    TOOL_ARTIFACT_TYPES.PRESENTATION,
+  'application/vnd.openxmlformats-officedocument.presentationml.template':
+    TOOL_ARTIFACT_TYPES.PRESENTATION,
  // Note: bare `text/plain` is NOT mapped here. The extension map handles
  // `.txt` explicitly; routing every unrecognized-extension `text/plain`
  // file (extensionless scripts, .env, etc.) through the panel would be a
--- a/packages/api/src/agents/handlers.ts
+++ b/packages/api/src/agents/handlers.ts
@ -1211,6 +1211,7 @@ const BINARY_EXTENSIONS_NEVER_READABLE = new Set([
  '.xlsx',
  '.ppt',
  '.pptx',
+  '.potx',
  '.odt',
  '.ods',
  '.odp',
--- a/packages/api/src/files/code/classify.spec.ts
+++ b/packages/api/src/files/code/classify.spec.ts
@ -79,18 +79,14 @@ describe('classifyCodeArtifact', () => {
    });
  });

-  describe('pptx', () => {
-    it('classifies .pptx by extension', () => {
-      expect(classifyCodeArtifact('slides.pptx', 'application/octet-stream')).toBe('pptx');
-    });
-
-    it('classifies pptx by mime', () => {
-      expect(
-        classifyCodeArtifact(
-          'unknown',
-          'application/vnd.openxmlformats-officedocument.presentationml.presentation',
-        ),
-      ).toBe('pptx');
+  describe('presentation', () => {
+    it.each([
+      ['slides.pptx', 'application/octet-stream'],
+      ['template.potx', 'application/octet-stream'],
+      ['unknown', 'application/vnd.openxmlformats-officedocument.presentationml.presentation'],
+      ['unknown', 'application/vnd.openxmlformats-officedocument.presentationml.template'],
+    ])('classifies %s with MIME %s as a presentation', (name, mime) => {
+      expect(classifyCodeArtifact(name, mime)).toBe('presentation');
    });
  });

--- a/packages/api/src/files/code/classify.ts
+++ b/packages/api/src/files/code/classify.ts
@ -1,6 +1,6 @@
 import { excelMimeTypes } from 'librechat-data-provider';

-export type CodeArtifactCategory = 'utf8-text' | 'document' | 'pptx' | 'other';
+export type CodeArtifactCategory = 'utf8-text' | 'document' | 'presentation' | 'other';

 const UTF8_TEXT_EXTENSIONS = new Set<string>([
  // plaintext / data
@ -119,9 +119,10 @@ const UTF8_TEXT_MIME_EXACT = new Set<string>([
 const DOCX_MIME = 'application/vnd.openxmlformats-officedocument.wordprocessingml.document';
 const ODT_MIME = 'application/vnd.oasis.opendocument.text';
 const PPTX_MIME = 'application/vnd.openxmlformats-officedocument.presentationml.presentation';
+const POTX_MIME = 'application/vnd.openxmlformats-officedocument.presentationml.template';

 const DOCUMENT_EXTENSIONS = new Set<string>(['docx', 'odt', 'xlsx', 'xls', 'ods']);
-const PPTX_EXTENSIONS = new Set<string>(['pptx']);
+const PRESENTATION_EXTENSIONS = new Set<string>(['pptx', 'potx']);

 const extensionOf = (name: string): string => {
  const dot = name.lastIndexOf('.');
@ -176,8 +177,8 @@ export function classifyCodeArtifact(name: string, mimeType: string): CodeArtifa
  if (ext && DOCUMENT_EXTENSIONS.has(ext)) {
    return 'document';
  }
-  if (ext && PPTX_EXTENSIONS.has(ext)) {
-    return 'pptx';
+  if (ext && PRESENTATION_EXTENSIONS.has(ext)) {
+    return 'presentation';
  }
  const bare = bareNameOf(name);
  if (bare && UTF8_TEXT_EXTENSIONS.has(bare)) {
@ -189,8 +190,8 @@ export function classifyCodeArtifact(name: string, mimeType: string): CodeArtifa
  if (isDocumentMime(mimeType)) {
    return 'document';
  }
-  if (mimeType === PPTX_MIME) {
-    return 'pptx';
+  if (mimeType === PPTX_MIME || mimeType === POTX_MIME) {
+    return 'presentation';
  }
  return 'other';
 }
--- a/packages/api/src/files/code/extract.spec.ts
+++ b/packages/api/src/files/code/extract.spec.ts
@ -203,13 +203,13 @@ describe('extractCodeArtifactText', () => {
  });

  describe('skipped categories', () => {
-    it('returns null for pptx when HTML rendering also fails', async () => {
+    it('returns null for presentations when HTML rendering also fails', async () => {
      mockOfficeHtml.mockResolvedValueOnce(null);
      const text = await extractCodeArtifactText(
        Buffer.from('PK'),
        'slides.pptx',
        'application/vnd.openxmlformats-officedocument.presentationml.presentation',
-        'pptx',
+        'presentation',
      );
      expect(text).toBeNull();
    });
@ -249,11 +249,23 @@ describe('extractCodeArtifactText', () => {
        Buffer.from('PK'),
        'deck.pptx',
        'application/vnd.openxmlformats-officedocument.presentationml.presentation',
-        'pptx',
+        'presentation',
      );
      expect(text).toContain('slides');
    });

+    it('returns the HTML rendering for a potx when the producer succeeds', async () => {
+      const html = '<!DOCTYPE html><html><body>template</body></html>';
+      mockOfficeHtml.mockResolvedValueOnce(html);
+      const text = await extractCodeArtifactText(
+        Buffer.from('PK'),
+        'template.potx',
+        'application/vnd.openxmlformats-officedocument.presentationml.template',
+        'presentation',
+      );
+      expect(text).toBe(html);
+    });
+
    it('returns the HTML rendering for csv (overriding utf8-text raw output)', async () => {
      mockOfficeHtml.mockResolvedValueOnce('<!DOCTYPE html><table><tr><td>a</td></tr></table>');
      const text = await extractCodeArtifactText(
@ -422,9 +434,9 @@ describe('extractCodeArtifactText', () => {
      ['deck', 'application/vnd.openxmlformats-officedocument.presentationml.presentation'],
    ])('routes extensionless office files by MIME alone (%s, %s)', async (name, mime) => {
      mockOfficeHtml.mockResolvedValueOnce('<!DOCTYPE html><body>x</body></html>');
-      let category: 'pptx' | 'utf8-text' | 'document' = 'document';
+      let category: 'presentation' | 'utf8-text' | 'document' = 'document';
      if (mime.includes('presentation')) {
-        category = 'pptx';
+        category = 'presentation';
      } else if (mime.startsWith('text/')) {
        category = 'utf8-text';
      }
--- a/packages/api/src/files/code/extract.ts
+++ b/packages/api/src/files/code/extract.ts
@ -260,13 +260,13 @@ const renderOfficeHtml = async (
 * rendering. Returns `null` for binary, oversized, or unsupported files; the
 * caller should fall back to the standard download UI in that case.
 *
- * Office types (docx, xlsx/xls/ods, csv, pptx) are rendered as sanitized
+ * Office types (docx, xlsx/xls/ods, csv, pptx/potx) are rendered as sanitized
 * HTML by the producers in `~/files/documents/html`. The frontend feeds the
 * HTML into the Sandpack `static` template via `index.html`. CSV is special-
 * cased here — its category is `utf8-text` (raw CSV is text), but we want
 * the styled-table preview when the file extension says CSV.
 *
- * - office (docx/xlsx/xls/ods/csv/pptx): sanitized HTML preview
+ * - office (docx/xlsx/xls/ods/csv/pptx/potx): sanitized HTML preview
 * - utf8-text: decodes the buffer (with a binary safety net)
 * - document: dispatches to the existing PDF/ODT parser
 * - other: returns null (binary file, no inline preview)
@ -318,8 +318,8 @@ export async function extractCodeArtifactText(
       * the markdown viewer with proper escaping). Plain text is safe. */
      return await extractDocument(buffer, name, mimeType);
    }
-    /* category === 'pptx' that didn't go through the office HTML path
-     * (shouldn't happen — pptx ext is in OFFICE_HTML_EXTENSIONS — but
+    /* category === 'presentation' that didn't go through the office HTML path
+     * (shouldn't happen — presentation extensions use the office HTML path — but
     * defended in depth). */
    return null;
  } catch (error) {
--- a/packages/api/src/files/documents/html.spec.ts
+++ b/packages/api/src/files/documents/html.spec.ts
@ -729,11 +729,17 @@ describe('Office HTML producers', () => {
      ['noext', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet', 'spreadsheet'],
      ['noext', 'application/vnd.ms-excel', 'spreadsheet'],
      ['noext', 'application/vnd.oasis.opendocument.spreadsheet', 'spreadsheet'],
-      ['deck.pptx', '', 'pptx'],
+      ['deck.pptx', '', 'presentation'],
+      ['template.potx', '', 'presentation'],
      [
        'noext',
        'application/vnd.openxmlformats-officedocument.presentationml.presentation',
-        'pptx',
+        'presentation',
+      ],
+      [
+        'noext',
+        'application/vnd.openxmlformats-officedocument.presentationml.template',
+        'presentation',
      ],
    ])('classifies (%s, %s) as %s', (name, mime, expected) => {
      expect(officeHtmlBucket(name, mime)).toBe(expected);
@ -760,7 +766,7 @@ describe('Office HTML producers', () => {
     * documented "extension wins" precedence is enforced by checking
     * extensions exhaustively before any MIME pattern fires. */
    it.each([
-      ['deck.pptx', 'text/csv', 'pptx'],
+      ['deck.pptx', 'text/csv', 'presentation'],
      ['workbook.xlsx', 'text/csv', 'spreadsheet'],
      [
        'legacy.xls',
@ -838,7 +844,7 @@ describe('Office HTML producers', () => {
      [
        'deck',
        'application/vnd.openxmlformats-officedocument.presentationml.presentation; foo=bar',
-        'pptx',
+        'presentation',
      ],
    ])('strips MIME parameters before matching: (%s, %s) → %s', (name, mime, expected) => {
      expect(officeHtmlBucket(name, mime)).toBe(expected);
--- a/packages/api/src/files/documents/html.ts
+++ b/packages/api/src/files/documents/html.ts
@ -1501,6 +1501,7 @@ export const _internal: {

 const DOCX_MIME = 'application/vnd.openxmlformats-officedocument.wordprocessingml.document';
 const PPTX_MIME = 'application/vnd.openxmlformats-officedocument.presentationml.presentation';
+const POTX_MIME = 'application/vnd.openxmlformats-officedocument.presentationml.template';
 const ODS_MIME = 'application/vnd.oasis.opendocument.spreadsheet';
 const CSV_MIME_PATTERN = /^(text\/csv|application\/csv|text\/comma-separated-values)$/i;

@ -1541,7 +1542,7 @@ function baseMime(mime: string): string {
 * `text/csv`), which then routed to the SPREADSHEET bucket on the
 * client expecting full HTML and got raw text instead.
 */
-export type OfficeHtmlBucket = 'docx' | 'spreadsheet' | 'csv' | 'pptx';
+export type OfficeHtmlBucket = 'docx' | 'spreadsheet' | 'csv' | 'presentation';

 const OFFICE_EXTENSIONS: Record<string, OfficeHtmlBucket> = {
  docx: 'docx',
@ -1549,7 +1550,8 @@ const OFFICE_EXTENSIONS: Record<string, OfficeHtmlBucket> = {
  xlsx: 'spreadsheet',
  xls: 'spreadsheet',
  ods: 'spreadsheet',
-  pptx: 'pptx',
+  pptx: 'presentation',
+  potx: 'presentation',
 };

 /**
@ -1608,8 +1610,8 @@ export function officeHtmlBucket(name: string, mimeType: string): OfficeHtmlBuck
  if (excelMimeTypes.test(normalized) || normalized === ODS_MIME) {
    return 'spreadsheet';
  }
-  if (normalized === PPTX_MIME) {
-    return 'pptx';
+  if (normalized === PPTX_MIME || normalized === POTX_MIME) {
+    return 'presentation';
  }
  return null;
 }
@ -1632,7 +1634,7 @@ export async function bufferToOfficeHtml(
      return csvToHtml(buffer);
    case 'spreadsheet':
      return excelSheetToHtml(buffer);
-    case 'pptx':
+    case 'presentation':
      return pptxToHtml(buffer);
    default:
      return null;
--- a/packages/data-provider/src/file-config.spec.ts
+++ b/packages/data-provider/src/file-config.spec.ts
@ -98,12 +98,16 @@ describe('inferMimeType', () => {
    expect(inferMimeType('deck.pptx', '')).toBe(
      'application/vnd.openxmlformats-officedocument.presentationml.presentation',
    );
+    expect(inferMimeType('template.potx', '')).toBe(
+      'application/vnd.openxmlformats-officedocument.presentationml.template',
+    );
  });

  it('produces Office types accepted by checkType after inference', () => {
    expect(baseFileConfig.checkType(inferMimeType('report.docx', ''))).toBe(true);
    expect(baseFileConfig.checkType(inferMimeType('sheet.xlsx', ''))).toBe(true);
    expect(baseFileConfig.checkType(inferMimeType('legacy.doc', ''))).toBe(true);
+    expect(baseFileConfig.checkType(inferMimeType('template.potx', ''))).toBe(true);
  });
 });

@ -170,7 +174,8 @@ describe('defaultOCRMimeTypes', () => {
    'application/vnd.oasis.opendocument.spreadsheet',
    'application/vnd.oasis.opendocument.presentation',
    'application/vnd.oasis.opendocument.graphics',
-  ])('matches ODF type for OCR: %s', (mimeType) => {
+    'application/vnd.openxmlformats-officedocument.presentationml.template',
+  ])('matches configured OCR type: %s', (mimeType) => {
    expect(checkOCRType(mimeType)).toBe(true);
  });
 });
@ -184,7 +189,8 @@ describe('supportedMimeTypes', () => {
    'application/vnd.oasis.opendocument.spreadsheet',
    'application/vnd.oasis.opendocument.presentation',
    'application/vnd.oasis.opendocument.graphics',
-  ])('ODF type flows through supportedMimeTypes: %s', (mimeType) => {
+    'application/vnd.openxmlformats-officedocument.presentationml.template',
+  ])('document type flows through supportedMimeTypes: %s', (mimeType) => {
    expect(checkSupported(mimeType)).toBe(true);
  });

@ -1491,6 +1497,20 @@ describe('getConfiguredMimeAccept', () => {
    expect(accept.has('video/*')).toBe(false);
  });

+  it('translates a PowerPoint template allowlist to the template extension and MIME', () => {
+    const templateMime = 'application/vnd.openxmlformats-officedocument.presentationml.template';
+    const accept = toSet(
+      getConfiguredMimeAccept(
+        convertStringsToRegex([
+          '^application/vnd\\.openxmlformats-officedocument\\.presentationml\\.template$',
+        ]),
+        IMAGE_DOC,
+      ),
+    );
+
+    expect(accept).toEqual(new Set(['.potx', templateMime]));
+  });
+
  it('emits image/* for an image-only allowlist', () => {
    const accept = toSet(getConfiguredMimeAccept([/^image\/(jpeg|png)$/], IMAGE_DOC));
    expect(accept.has('image/*')).toBe(true);
--- a/packages/data-provider/src/file-config.ts
+++ b/packages/data-provider/src/file-config.ts
@ -39,6 +39,7 @@ export const fullMimeTypesList = [
  'application/pdf',
  'text/x-php',
  'application/vnd.openxmlformats-officedocument.presentationml.presentation',
+  'application/vnd.openxmlformats-officedocument.presentationml.template',
  'text/x-python',
  'text/x-script.python',
  'text/x-ruby',
@ -106,6 +107,7 @@ export const codeInterpreterMimeTypesList = [
  'application/pdf',
  'text/x-php',
  'application/vnd.openxmlformats-officedocument.presentationml.presentation',
+  'application/vnd.openxmlformats-officedocument.presentationml.template',
  'text/x-python',
  'text/x-script.python',
  'text/x-ruby',
@ -139,6 +141,7 @@ export const retrievalMimeTypesList = [
  'application/pdf',
  'text/x-php',
  'application/vnd.openxmlformats-officedocument.presentationml.presentation',
+  'application/vnd.openxmlformats-officedocument.presentationml.template',
  'text/x-python',
  'text/x-script.python',
  'text/x-ruby',
@ -217,7 +220,7 @@ export const textMimeTypes =
  /^(text\/(x-c|x-csharp|tab-separated-values|x-c\+\+|x-h|x-java|html|markdown|x-php|x-python|x-script\.python|x-ruby|x-tex|plain|css|vtt|javascript|csv|xml|calendar))$/;

 export const applicationMimeTypes =
-  /^(application\/(epub\+zip|csv|json|msword|pdf|x-tar|x-sh|x-zip-compressed|typescript|sql|yaml|x-parquet|vnd\.apache\.parquet|vnd\.coffeescript|vnd\.openxmlformats-officedocument\.(wordprocessingml\.document|presentationml\.presentation|spreadsheetml\.sheet)|vnd\.oasis\.opendocument\.(text|spreadsheet|presentation|graphics)|xml|zip))$/;
+  /^(application\/(epub\+zip|csv|json|msword|pdf|x-tar|x-sh|x-zip-compressed|typescript|sql|yaml|x-parquet|vnd\.apache\.parquet|vnd\.coffeescript|vnd\.openxmlformats-officedocument\.(wordprocessingml\.document|presentationml\.(presentation|template)|spreadsheetml\.sheet)|vnd\.oasis\.opendocument\.(text|spreadsheet|presentation|graphics)|xml|zip))$/;

 export const imageMimeTypes = /^image\/(jpeg|gif|png|webp|heic|heif)$/;

@ -231,6 +234,7 @@ export const defaultOCRMimeTypes = [
  excelMimeTypes,
  /^application\/pdf$/,
  /^application\/vnd\.openxmlformats-officedocument\.(wordprocessingml\.document|presentationml\.presentation)$/,
+  /^application\/vnd\.openxmlformats-officedocument\.presentationml\.template$/,
  /^application\/vnd\.ms-(word|powerpoint)$/,
  /^application\/epub\+zip$/,
  /^application\/vnd\.oasis\.opendocument\.(text|spreadsheet|presentation|graphics)$/,
@ -394,6 +398,7 @@ export const codeTypeMapping: { [key: string]: string } = {
  xlsx: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet', // .xlsx - Excel
  ppt: 'application/vnd.ms-powerpoint', // .ppt - PowerPoint (legacy)
  pptx: 'application/vnd.openxmlformats-officedocument.presentationml.presentation', // .pptx - PowerPoint
+  potx: 'application/vnd.openxmlformats-officedocument.presentationml.template', // .potx - PowerPoint template
  ics: 'text/calendar', // .ics - iCalendar
  ical: 'text/calendar', // .ical - iCalendar
  ifb: 'text/calendar', // .ifb - iCalendar free/busy
@ -431,7 +436,7 @@ export function inferMimeType(fileName: string, currentType: string): string {

 export const retrievalMimeTypes = [
  /^(text\/(x-c|x-c\+\+|x-h|html|x-java|markdown|x-php|x-python|x-script\.python|x-ruby|x-tex|plain|vtt|xml))$/,
-  /^(application\/(json|pdf|vnd\.openxmlformats-officedocument\.(wordprocessingml\.document|presentationml\.presentation)))$/,
+  /^(application\/(json|pdf|vnd\.openxmlformats-officedocument\.(wordprocessingml\.document|presentationml\.(presentation|template))))$/,
 ];

 export const megabyte = 1024 * 1024;
@ -682,6 +687,7 @@ const documentMimeExtensions: ReadonlyArray<readonly [string, readonly string[]]
  ['application/vnd.openxmlformats-officedocument.spreadsheetml.sheet', ['.xlsx']],
  ['application/vnd.ms-powerpoint', ['.ppt']],
  ['application/vnd.openxmlformats-officedocument.presentationml.presentation', ['.pptx']],
+  ['application/vnd.openxmlformats-officedocument.presentationml.template', ['.potx']],
  ['application/vnd.oasis.opendocument.text', ['.odt']],
  ['application/vnd.oasis.opendocument.spreadsheet', ['.ods']],
  ['application/vnd.oasis.opendocument.presentation', ['.odp']],