🧮 feat: Improve LaTeX rendering consistency (#3763)

* refactor: simplify LaTeX pre-processing for more consistent rendering, disables `singleDollarTextMath`

* refactor: disable singleDollarTextMath in all markdown components

* wip: first pass

* refactor: preserve code blocks and convert rather than preserve LaTeX delimiters

* refactor: remove unused escapeDollarNumber function from latex.ts

client/src/utils/latex.spec.ts

@@ -1,4 +1,5 @@
-import { processLaTeX } from './latex';
+/* eslint-disable no-useless-escape */
+import { processLaTeX, preprocessLaTeX } from './latex';
 
 describe('processLaTeX', () => {
   test('returns the same string if no LaTeX patterns are found', () => {
@@ -103,3 +104,92 @@ describe('processLaTeX', () => {
     });
   });
 });
+
+describe('preprocessLaTeX', () => {
+  test('returns the same string if no LaTeX patterns are found', () => {
+    const content = 'This is a test string without LaTeX';
+    expect(preprocessLaTeX(content)).toBe(content);
+  });
+
+  test('escapes dollar signs followed by digits', () => {
+    const content = 'Price is $50 and $100';
+    const expected = 'Price is \\$50 and \\$100';
+    expect(preprocessLaTeX(content)).toBe(expected);
+  });
+
+  test('does not escape dollar signs not followed by digits', () => {
+    const content = 'This $variable is not escaped';
+    expect(preprocessLaTeX(content)).toBe(content);
+  });
+
+  test('preserves existing LaTeX expressions', () => {
+    const content = 'Inline $x^2 + y^2 = z^2$ and block $$E = mc^2$$';
+    expect(preprocessLaTeX(content)).toBe(content);
+  });
+
+  test('handles mixed LaTeX and currency', () => {
+    const content = 'LaTeX $x^2$ and price $50';
+    const expected = 'LaTeX $x^2$ and price \\$50';
+    expect(preprocessLaTeX(content)).toBe(expected);
+  });
+
+  test('converts LaTeX delimiters', () => {
+    const content = 'Brackets \\[x^2\\] and parentheses \\(y^2\\)';
+    const expected = 'Brackets $$x^2$$ and parentheses $y^2$';
+    expect(preprocessLaTeX(content)).toBe(expected);
+  });
+
+  test('escapes mhchem commands', () => {
+    const content = '$\\ce{H2O}$ and $\\pu{123 J}$';
+    const expected = '$\\\\ce{H2O}$ and $\\\\pu{123 J}$';
+    expect(preprocessLaTeX(content)).toBe(expected);
+  });
+
+  test('handles complex mixed content', () => {
+    const content = `
+      LaTeX inline $x^2$ and block $$y^2$$
+      Currency $100 and $200
+      Chemical $\\ce{H2O}$
+      Brackets \\[z^2\\]
+    `;
+    const expected = `
+      LaTeX inline $x^2$ and block $$y^2$$
+      Currency \\$100 and \\$200
+      Chemical $\\\\ce{H2O}$
+      Brackets $$z^2$$
+    `;
+    expect(preprocessLaTeX(content)).toBe(expected);
+  });
+
+  test('handles empty string', () => {
+    expect(preprocessLaTeX('')).toBe('');
+  });
+
+  test('preserves code blocks', () => {
+    const content = '```\n$100\n```\nOutside $200';
+    const expected = '```\n$100\n```\nOutside \\$200';
+    expect(preprocessLaTeX(content)).toBe(expected);
+  });
+
+  test('handles multiple currency values in a sentence', () => {
+    const content = 'I have $50 in my wallet and $100 in the bank.';
+    const expected = 'I have \\$50 in my wallet and \\$100 in the bank.';
+    expect(preprocessLaTeX(content)).toBe(expected);
+  });
+
+  test('preserves LaTeX expressions with numbers', () => {
+    const content = 'The equation is $f(x) = 2x + 3$ where x is a variable.';
+    expect(preprocessLaTeX(content)).toBe(content);
+  });
+
+  test('handles currency values with commas', () => {
+    const content = 'The price is $1,000,000 for this item.';
+    const expected = 'The price is \\$1,000,000 for this item.';
+    expect(preprocessLaTeX(content)).toBe(expected);
+  });
+
+  test('preserves LaTeX expressions with special characters', () => {
+    const content = 'The set is defined as $\\{x | x > 0\\}$.';
+    expect(preprocessLaTeX(content)).toBe(content);
+  });
+});