diff --git a/src/lib/stores/preferences.svelte.js b/src/lib/stores/preferences.svelte.js
new file mode 100644
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+++ b/src/lib/stores/preferences.svelte.js
@@ -0,0 +1,117 @@
+// src/lib/stores/preferences.svelte.js
+import { invoke } from '@tauri-apps/api/core';
+
+const DEFAULTS = {
+  theme: 'dark',
+  zone: 'default',
+  accessibility: {
+    fontFamily: 'lexend',
+    fontSize: 16,
+    letterSpacing: 0,
+    lineHeight: 1.5,
+    transcriptSize: 16,
+    bionicReading: false,
+    reduceMotion: 'system'
+  }
+};
+
+const FONT_FAMILIES = {
+  lexend: "'Lexend', system-ui, sans-serif",
+  atkinson: "'Atkinson Hyperlegible Next', system-ui, sans-serif",
+  opendyslexic: "'OpenDyslexic', system-ui, sans-serif"
+};
+
+function readFromDOM() {
+  const el = document.documentElement;
+  return {
+    theme: el.dataset.theme || DEFAULTS.theme,
+    zone: el.dataset.zone || DEFAULTS.zone,
+    accessibility: {
+      fontFamily: el.dataset.fontFamily || DEFAULTS.accessibility.fontFamily,
+      fontSize: parseFloat(el.style.getPropertyValue('--font-size-body')) || DEFAULTS.accessibility.fontSize,
+      letterSpacing: parseFloat(el.style.getPropertyValue('--letter-spacing-body')) || DEFAULTS.accessibility.letterSpacing,
+      lineHeight: parseFloat(el.style.getPropertyValue('--line-height-body')) || DEFAULTS.accessibility.lineHeight,
+      transcriptSize: DEFAULTS.accessibility.transcriptSize,
+      bionicReading: el.dataset.bionicReading === 'true',
+      reduceMotion: el.dataset.reduceMotion || DEFAULTS.accessibility.reduceMotion
+    }
+  };
+}
+
+function applyToDOM(prefs) {
+  const el = document.documentElement;
+
+  // Theme — resolve 'system' to actual value
+  el.dataset.theme = prefs.theme === 'system'
+    ? (window.matchMedia('(prefers-color-scheme: light)').matches ? 'light' : 'dark')
+    : prefs.theme;
+
+  // Zone
+  if (prefs.zone === 'default') {
+    delete el.dataset.zone;
+  } else {
+    el.dataset.zone = prefs.zone;
+  }
+
+  // Accessibility — inline styles for highest specificity
+  const a = prefs.accessibility;
+  el.style.setProperty('--font-family-body', FONT_FAMILIES[a.fontFamily] || FONT_FAMILIES.lexend);
+  el.style.setProperty('--font-size-body', `${a.fontSize}px`);
+  el.style.setProperty('--letter-spacing-body', `${a.letterSpacing}em`);
+  el.style.setProperty('--line-height-body', String(a.lineHeight));
+
+  el.dataset.bionicReading = String(a.bionicReading);
+  el.dataset.fontFamily = a.fontFamily;
+
+  // Reduce motion — three-value resolution
+  const motionReduced = a.reduceMotion === 'on'
+    || (a.reduceMotion === 'system' && window.matchMedia('(prefers-reduced-motion: reduce)').matches);
+  if (motionReduced) {
+    el.dataset.reduceMotion = 'true';
+  } else {
+    delete el.dataset.reduceMotion;
+  }
+}
+
+let saveTimeout = null;
+function persistToSQLite(prefs) {
+  clearTimeout(saveTimeout);
+  saveTimeout = setTimeout(async () => {
+    try {
+      await invoke('save_preferences', { preferences: JSON.stringify(prefs) });
+    } catch (e) {
+      console.error('Failed to save preferences:', e);
+    }
+  }, 500);
+}
+
+let preferences = $state(readFromDOM());
+
+export function getPreferences() {
+  return preferences;
+}
+
+export function updatePreferences(updates) {
+  preferences = { ...preferences, ...updates };
+  applyToDOM(preferences);
+  persistToSQLite(preferences);
+}
+
+export function updateAccessibility(updates) {
+  preferences = {
+    ...preferences,
+    accessibility: { ...preferences.accessibility, ...updates }
+  };
+  applyToDOM(preferences);
+  persistToSQLite(preferences);
+}
+
+// Re-resolve when OS preferences change
+if (typeof window !== 'undefined') {
+  window.matchMedia('(prefers-color-scheme: light)').addEventListener('change', () => {
+    if (preferences.theme === 'system') applyToDOM(preferences);
+  });
+  window.matchMedia('(prefers-reduced-motion: reduce)').addEventListener('change', () => {
+    if (preferences.accessibility.reduceMotion === 'system') applyToDOM(preferences);
+  });
+}