feat(monospace): add settings schema with safe defaults

src/main/settings/monospaceSettings.js

@@ -0,0 +1,49 @@
+'use strict';
+
+const FAMILY_BY_KEY = {
+  'jetbrains-mono': 'JetBrains Mono',
+  'fira-code': 'Fira Code',
+};
+
+const ALLOWED_FONTS = Object.keys(FAMILY_BY_KEY);
+
+const DEFAULT_SETTINGS = Object.freeze({
+  monospaceFont: 'jetbrains-mono',
+  monospaceLigatures: false,
+});
+
+function getActiveMonoFont(settings) {
+  const key = settings && settings.monospaceFont;
+  if (typeof key === 'string' && Object.prototype.hasOwnProperty.call(FAMILY_BY_KEY, key)) {
+    return FAMILY_BY_KEY[key];
+  }
+  return FAMILY_BY_KEY[DEFAULT_SETTINGS.monospaceFont];
+}
+
+function isLigaturesEnabled(settings) {
+  return !!(settings && settings.monospaceLigatures === true);
+}
+
+function safeMonospaceSettings(input) {
+  const safe = { ...DEFAULT_SETTINGS };
+  if (input && typeof input === 'object') {
+    if (ALLOWED_FONTS.includes(input.monospaceFont)) {
+      safe.monospaceFont = input.monospaceFont;
+    }
+    if (typeof input.monospaceLigatures === 'boolean') {
+      safe.monospaceLigatures = input.monospaceLigatures;
+    } else if (input.monospaceLigatures === 1 || input.monospaceLigatures === 'true') {
+      safe.monospaceLigatures = true;
+    }
+  }
+  return safe;
+}
+
+module.exports = {
+  FAMILY_BY_KEY,
+  ALLOWED_FONTS,
+  DEFAULT_SETTINGS,
+  getActiveMonoFont,
+  isLigaturesEnabled,
+  safeMonospaceSettings,
+};

tests/unit/main/monospace/monospaceSettings.test.js

@@ -0,0 +1,40 @@
+const {
+  FAMILY_BY_KEY,
+  getActiveMonoFont,
+  isLigaturesEnabled,
+  safeMonospaceSettings,
+  DEFAULT_SETTINGS,
+} = require('../../../../src/main/settings/monospaceSettings');
+
+describe('monospaceSettings', () => {
+  test('FAMILY_BY_KEY maps jetbrains-mono → "JetBrains Mono"', () => {
+    expect(FAMILY_BY_KEY['jetbrains-mono']).toBe('JetBrains Mono');
+  });
+  test('getActiveMonoFont returns family for valid key', () => {
+    expect(getActiveMonoFont({ monospaceFont: 'fira-code' })).toBe('Fira Code');
+  });
+  test('getActiveMonoFont falls back to default for unknown key', () => {
+    expect(getActiveMonoFont({ monospaceFont: 'unknown' })).toBe('JetBrains Mono');
+  });
+  test('getActiveMonoFont returns default when key missing', () => {
+    expect(getActiveMonoFont({})).toBe('JetBrains Mono');
+  });
+  test('isLigaturesEnabled is true only when explicitly true', () => {
+    expect(isLigaturesEnabled({ monospaceLigatures: true })).toBe(true);
+    expect(isLigaturesEnabled({ monospaceLigatures: false })).toBe(false);
+    expect(isLigaturesEnabled({ monospaceLigatures: 'yes' })).toBe(false);
+    expect(isLigaturesEnabled({})).toBe(false);
+  });
+  test('safeMonospaceSettings rejects unknown fonts', () => {
+    expect(safeMonospaceSettings({ monospaceFont: 'comic-sans' })).toEqual(DEFAULT_SETTINGS);
+  });
+  test('safeMonospaceSettings coerces ligatures to boolean', () => {
+    expect(safeMonospaceSettings({ monospaceLigatures: 1 })).toEqual({
+      monospaceFont: 'jetbrains-mono',
+      monospaceLigatures: true,
+    });
+  });
+  test('safeMonospaceSettings returns DEFAULT_SETTINGS for empty input', () => {
+    expect(safeMonospaceSettings({})).toEqual(DEFAULT_SETTINGS);
+  });
+});