Preserve preview harness, editor, email and task improvements

Snapshot current maintainer-preview application changes and regression fixtures for integration into lab. Excludes local runtime data, evaluation outputs and source backups. Focused Python regression selection: 140 passed; full suite not certified.

tests/editorSuggestionApply.mjs

@@ -0,0 +1,71 @@
+import { readFileSync } from 'node:fs';
+import assert from 'node:assert/strict';
+import { chromium } from 'playwright';
+
+const source = readFileSync('static/js/document.js', 'utf8');
+const start = source.indexOf('  function _applySuggestions(');
+const end = source.indexOf('  /** Animate transition to next suggestion */', start);
+assert.ok(start >= 0 && end > start);
+const applySource = source.slice(start, end);
+
+const browser = await chromium.launch({ headless: true });
+try {
+  const page = await browser.newPage();
+  await page.setContent('<textarea id="doc-editor-textarea"></textarea><div id="doc-email-richbody"></div><iframe id="doc-html-preview"></iframe>');
+  const results = await page.evaluate((fn) => {
+    const textarea = document.getElementById('doc-editor-textarea');
+    const rich = document.getElementById('doc-email-richbody');
+    const docs = new Map();
+    const activeDocId = 'test-doc';
+    let saves = 0;
+    const errors = [];
+    const uiModule = { showError: message => errors.push(message) };
+    const saveCurrentToMap = () => {
+      const doc = docs.get(activeDocId);
+      doc.content = doc.language === 'richtext' ? rich.innerHTML :
+        doc.language === 'email' ? `To: person@example.com\n\n${rich.innerHTML}` : textarea.value;
+    };
+    const _isRichTextLang = lang => lang === 'richtext';
+    const _showRichTextEditor = doc => { rich.innerHTML = doc.content; textarea.value = doc.content; };
+    const _showEmailFields = doc => { rich.innerHTML = doc.content.split('\n\n').slice(1).join('\n\n'); };
+    const _refreshMarkdownPreviewIfVisible = () => {};
+    const _htmlPreviewActive = true;
+    const _isRenderLang = lang => lang === 'svg';
+    const _themedRenderSrcdoc = content => content;
+    const syncHighlighting = () => {};
+    const saveDocument = () => { saveCurrentToMap(); saves++; };
+    return eval(fn + `
+      const outcome = {};
+      for (const language of ['richtext', 'email', 'markdown', 'javascript', 'svg']) {
+        const original = language === 'email' ? 'To: person@example.com\\n\\n<p>old phrase</p>' :
+          language === 'richtext' ? '<p>old phrase</p>' : 'old phrase';
+        docs.set(activeDocId, { id: activeDocId, language, content: original });
+        if (language === 'email' || language === 'richtext') rich.innerHTML = '<p>old phrase</p>';
+        else textarea.value = original;
+        const applied = _applySuggestions([{ id: 'one', find: 'old phrase', replace: 'new phrase' }]);
+        outcome[language] = {
+          applied, content: docs.get(activeDocId).content,
+          preview: document.getElementById('doc-html-preview').srcdoc,
+          visible: language === 'email' || language === 'richtext' ? rich.innerHTML : textarea.value,
+        };
+      }
+      const before = saves;
+      const unmatched = _applySuggestions([{ id: 'missing', find: 'absent phrase', replace: 'x' }]);
+      ({ outcome, saves, before, unmatched, errors });
+    `);
+  }, applySource);
+  for (const language of ['richtext', 'email', 'markdown', 'javascript', 'svg']) {
+    assert.deepEqual(results.outcome[language].applied, ['one']);
+    assert.match(results.outcome[language].content, /new phrase/);
+    assert.match(results.outcome[language].visible, /new phrase/);
+  }
+  assert.match(results.outcome.svg.preview, /new phrase/);
+  assert.equal(results.saves, 5);
+  assert.equal(results.before, 5);
+  assert.deepEqual(results.unmatched, []);
+  assert.equal(results.errors.length, 1);
+  console.log('PASS: accepting suggestions updates and saves rich text, email, markdown, and code documents.');
+  console.log('PASS: stale suggestions remain pending and do not save an unchanged document.');
+} finally {
+  await browser.close();
+}