diff --git a/src/renderer/ascii-controller.js b/src/renderer/ascii-controller.js
new file mode 100644
index 0000000..648969a
--- /dev/null
+++ b/src/renderer/ascii-controller.js
@@ -0,0 +1,168 @@
+/**
+ * ASCII Art Generator — renderer controller for the standalone window.
+ *
+ * Drives the DOM in src/ascii-generator.html. Fetches the font list from
+ * the main process once on mount, renders previews on input, and exposes
+ * Insert / Copy / Save actions. Last-used font is restored from
+ * electron-store (via main) and saved on every change.
+ *
+ * No bundler, no framework — pure DOM + window.electronAPI bridge.
+ */
+(function () {
+  'use strict';
+
+  const api =
+    window.electronAPI && window.electronAPI.generators && window.electronAPI.generators.ascii;
+  const els = {
+    textInput: document.getElementById('text-input'),
+    fontPicker: document.getElementById('font-picker'),
+    fontSearch: document.getElementById('font-search'),
+    preview: document.getElementById('preview'),
+    btnInsert: document.getElementById('btn-insert'),
+    btnCopy: document.getElementById('btn-copy'),
+    btnSave: document.getElementById('btn-save'),
+    btnGenerate: document.getElementById('btn-generate'),
+    warning: document.getElementById('ascii-warning'),
+  };
+
+  let _fonts = [];
+  let _currentFont = 'standard';
+  let _previewText = '';
+  let _searchDebounce = null;
+
+  function showWarning(msg) {
+    if (!els.warning) return;
+    els.warning.textContent = msg || '';
+    els.warning.style.display = msg ? 'block' : 'none';
+  }
+
+  function debounce(fn, ms) {
+    let t = null;
+    return function () {
+      const args = arguments;
+      clearTimeout(t);
+      t = setTimeout(() => fn.apply(null, args), ms);
+    };
+  }
+
+  async function refreshPreview() {
+    if (!api) return;
+    const text = els.textInput ? els.textInput.value : 'HELLO';
+    _previewText = text;
+    try {
+      const out = await api.generate({ text, font: _currentFont });
+      els.preview.textContent = out;
+      showWarning('');
+    } catch (err) {
+      els.preview.textContent = '';
+      showWarning(`Failed to render: ${err.message || err}`);
+    }
+  }
+
+  function renderFontList(filter) {
+    if (!els.fontPicker) return;
+    const f = (filter || '').toLowerCase();
+    const filtered = _fonts.filter((font) => {
+      if (!f) return true;
+      return font.label.toLowerCase().includes(f) || font.id.toLowerCase().includes(f);
+    });
+    els.fontPicker.innerHTML = '';
+    for (const font of filtered.slice(0, 500)) {
+      const opt = document.createElement('option');
+      opt.value = font.id;
+      opt.textContent = `${font.label} (${font.kind})`;
+      if (font.id === _currentFont) opt.selected = true;
+      els.fontPicker.appendChild(opt);
+    }
+  }
+
+  async function loadFonts() {
+    if (!api) return;
+    try {
+      _fonts = await api.listFonts();
+    } catch {
+      _fonts = [];
+      showWarning('Could not load font list. Hand-coded fonts only.');
+    }
+    try {
+      const last = await api.lastFont(null);
+      if (last && _fonts.some((f) => f.id === last)) _currentFont = last;
+    } catch {
+      /* ignore */
+    }
+    renderFontList('');
+  }
+
+  function wireEvents() {
+    if (els.textInput) {
+      els.textInput.addEventListener('input', debounce(refreshPreview, 200));
+    }
+    if (els.fontPicker) {
+      els.fontPicker.addEventListener('change', () => {
+        _currentFont = els.fontPicker.value;
+        if (api) api.lastFont(_currentFont).catch(() => {});
+        refreshPreview();
+      });
+    }
+    if (els.fontSearch) {
+      els.fontSearch.addEventListener('input', () => {
+        clearTimeout(_searchDebounce);
+        _searchDebounce = setTimeout(() => renderFontList(els.fontSearch.value), 100);
+      });
+    }
+    if (els.btnGenerate) {
+      els.btnGenerate.addEventListener('click', refreshPreview);
+    }
+    if (els.btnInsert) {
+      els.btnInsert.addEventListener('click', () => {
+        const wrapped =
+          '```\n' + (_previewText ? document.getElementById('preview').textContent : '') + '\n```';
+        if (window.electronAPI && window.electronAPI.send) {
+          window.electronAPI.send('insert-generated-content', wrapped);
+          window.close();
+        }
+      });
+    }
+    if (els.btnCopy) {
+      els.btnCopy.addEventListener('click', async () => {
+        const text = els.preview.textContent;
+        if (!text) return;
+        try {
+          await api.copy(text);
+          showWarning('Copied to clipboard.');
+          setTimeout(() => showWarning(''), 1500);
+        } catch (err) {
+          showWarning('Copy failed: ' + (err.message || err));
+        }
+      });
+    }
+    if (els.btnSave) {
+      els.btnSave.addEventListener('click', async () => {
+        const text = els.preview.textContent;
+        if (!text) return;
+        try {
+          const result = await api.save({ text, defaultName: 'ascii-art.txt' });
+          if (!result.canceled) {
+            showWarning(`Saved to ${result.path}`);
+            setTimeout(() => showWarning(''), 2000);
+          }
+        } catch (err) {
+          showWarning('Save failed: ' + (err.message || err));
+        }
+      });
+    }
+  }
+
+  async function bootstrap() {
+    wireEvents();
+    await loadFonts();
+    await refreshPreview();
+  }
+
+  window.ASCIIController = { bootstrap };
+  if (document.readyState === 'loading') {
+    document.addEventListener('DOMContentLoaded', bootstrap);
+  } else {
+    bootstrap();
+  }
+})();