add support for GFM inline math delimiters

src/js/utils/markdown-editor.ts

@@ -84,6 +84,7 @@ const ESCAPED_MATH: ReadonlyArray<[string, string, boolean]> = [
   ['\\\\[', '\\\\]', true],
   ['\\\\(', '\\\\)', false],
   ['\\[', '\\]', true],
+  ['$`', '`$', false],
 ];
 
 function escapedMath(state: StateInline, silent: boolean): boolean {

src/tests/markdown-editor-render.test.ts

@@ -58,10 +58,17 @@ describe('Markdown to PDF rendering', () => {
         '',
         '```math\n\\int x\n```',
         '',
+        'GitHub $`\\sqrt{3}`$ inline.',
+        '',
         'Price $5 and $10, escaped \\$3, code `$q$`.',
       ].join('\n')
     );
-    expect(root.querySelectorAll('.katex').length).toBe(8);
+    expect(root.querySelectorAll('.katex').length).toBe(9);
+    const github = [...root.querySelectorAll('p')].find((p) =>
+      p.textContent?.startsWith('GitHub')
+    );
+    expect(github?.querySelector('.katex')).not.toBeNull();
+    expect(github?.textContent).not.toMatch(/[$`‘’]/);
     expect(root.querySelectorAll('.katex-display').length).toBe(5);
     expect(root.querySelector('em')).toBeNull();
     expect(root.textContent).toContain('Price $5 and $10, escaped $3');