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fix(math): set displaystyle on MathML output for proper sizing (SD-2404) #2622

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fix(math): set displaystyle on MathML output for proper sizing (SD-2404) #2622

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3 changes: 3 additions & 0 deletions packages/layout-engine/painters/dom/src/features/math/omml-to-mathml.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ describe('convertOmmlToMathml', () => {
expect(result).not.toBeNull();
expect(result!.namespaceURI).toBe(MATHML_NS);
expect(result!.localName).toBe('math');
expect(result!.getAttribute('displaystyle')).toBe('true');

// Should contain an <mi> for the identifier 'x'
const mi = result!.querySelector('mi');
Expand Down Expand Up @@ -94,6 +95,8 @@ describe('convertOmmlToMathml', () => {
const result = convertOmmlToMathml(omml, doc);
expect(result).not.toBeNull();
expect(result!.localName).toBe('math');
expect(result!.getAttribute('displaystyle')).toBe('true');
expect(result!.getAttribute('display')).toBe('block');
// The m:oMathParaPr should be skipped (it ends with 'Pr')
// The m:oMath child should produce content
expect(result!.textContent).toBe('y');
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5 changes: 5 additions & 0 deletions packages/layout-engine/painters/dom/src/features/math/omml-to-mathml.ts
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Expand Up @@ -157,6 +157,11 @@ export function convertOmmlToMathml(ommlJson: unknown, doc: Document): Element |

const root = ommlJson as OmmlJsonNode;
const mathEl = doc.createElementNS(MATHML_NS, 'math');
mathEl.setAttribute('displaystyle', 'true');
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@chatgpt-codex-connector chatgpt-codex-connector bot Mar 28, 2026

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P1 Badge Recompute math metrics when enabling displaystyle

Setting displaystyle="true" on every generated <math> increases the rendered size of fractions and large operators, but the layout pipeline still reserves the old fixed estimates (MATH_DEFAULT_HEIGHT = 24 in pm-adapter/src/converters/math-constants.ts) and consumes run.width/run.height as-is during line measurement (measuring/dom/src/index.ts math-run path). In documents containing tall formulas (for example fractions/summations), the MathML can now exceed the reserved line box and overlap adjacent lines or wrap incorrectly; this regression appears specifically after this flag was introduced.

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if (root.name === 'm:oMathPara') {
mathEl.setAttribute('display', 'block');
}

// For m:oMathPara, iterate over child m:oMath elements
// For m:oMath, process directly
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