diff --git a/src/web/public/settings-ui.js b/src/web/public/settings-ui.js
index 83864b7f1..0fc0e6667 100644
--- a/src/web/public/settings-ui.js
+++ b/src/web/public/settings-ui.js
@@ -1945,7 +1945,7 @@ Object.assign(CodemanApp.prototype, {
       const empty = document.getElementById('lifecycleEmpty');
 
       if (!data.entries || data.entries.length === 0) {
-        tbody.innerHTML = '';
+        tbody.replaceChildren();
         empty.style.display = '';
         return;
       }
@@ -1957,21 +1957,34 @@ Object.assign(CodemanApp.prototype, {
         server_started: '#666', server_stopped: '#666',
       };
 
-      tbody.innerHTML = data.entries.map(e => {
+      const makeCell = (text, style) => {
+        const cell = document.createElement('td');
+        cell.style.cssText = style;
+        cell.textContent = String(text ?? '');
+        return cell;
+      };
+
+      tbody.replaceChildren(...data.entries.map(e => {
         const time = new Date(e.ts).toLocaleString();
         const color = eventColors[e.event] || '#888';
         const name = e.name || (e.sessionId === '*' ? '—' : this.getShortId(e.sessionId));
         const extra = [];
         if (e.exitCode !== undefined && e.exitCode !== null) extra.push(`code=${e.exitCode}`);
         if (e.mode) extra.push(e.mode);
-        return `<tr style="border-bottom:1px solid #1a1a2e">
-          <td style="padding:3px 8px;color:#888;white-space:nowrap">${time}</td>
-          <td style="padding:3px 8px;color:${color};font-weight:600">${e.event}</td>
-          <td style="padding:3px 8px;color:#e0e0e0" title="${e.sessionId}">${name}</td>
-          <td style="padding:3px 8px;color:#aaa">${e.reason || ''}</td>
-          <td style="padding:3px 8px;color:#666">${extra.join(', ')}</td>
-        </tr>`;
-      }).join('');
+
+        const row = document.createElement('tr');
+        row.style.borderBottom = '1px solid #1a1a2e';
+        const sessionCell = makeCell(name, 'padding:3px 8px;color:#e0e0e0');
+        sessionCell.title = String(e.sessionId);
+        row.append(
+          makeCell(time, 'padding:3px 8px;color:#888;white-space:nowrap'),
+          makeCell(e.event, `padding:3px 8px;color:${color};font-weight:600`),
+          sessionCell,
+          makeCell(e.reason, 'padding:3px 8px;color:#aaa'),
+          makeCell(extra.join(', '), 'padding:3px 8px;color:#666')
+        );
+        return row;
+      }));
     } catch (err) {
       console.error('Failed to load lifecycle log:', err);
     }
diff --git a/test/lifecycle-log-xss.test.ts b/test/lifecycle-log-xss.test.ts
new file mode 100644
index 000000000..370aa8720
--- /dev/null
+++ b/test/lifecycle-log-xss.test.ts
@@ -0,0 +1,77 @@
+/**
+ * @fileoverview Regression coverage for lifecycle-log DOM rendering.
+ * Port: N/A (JSDOM exercises the real settings-ui.js renderer).
+ */
+
+import { readFileSync } from 'node:fs';
+import { describe, expect, it, vi } from 'vitest';
+import { JSDOM } from 'jsdom';
+
+const SETTINGS_UI = readFileSync(new URL('../src/web/public/settings-ui.js', import.meta.url), 'utf8');
+
+interface LifecycleApp {
+  loadLifecycleLog(): Promise<void>;
+}
+
+function boot(entries: Record<string, unknown>[]) {
+  const dom = new JSDOM(
+    `<!doctype html><html><body>
+      <select id="lifecycleFilterEvent"><option value=""></option></select>
+      <input id="lifecycleFilterSession" value="">
+      <table><tbody id="lifecycleTableBody"></tbody></table>
+      <div id="lifecycleEmpty"></div>
+    </body></html>`,
+    { runScripts: 'outside-only', url: 'http://localhost/' }
+  );
+  const win = dom.window as unknown as Window &
+    typeof globalThis & {
+      __CodemanApp: new () => LifecycleApp;
+      fetch: ReturnType<typeof vi.fn>;
+    };
+
+  win.fetch = vi.fn(async () => ({
+    json: async () => ({ success: true, data: { entries } }),
+  }));
+  (win as unknown as { eval: (source: string) => void }).eval(
+    `class CodemanApp { getShortId(id) { return id.slice(0, 8); } }
+${SETTINGS_UI}
+window.__CodemanApp = CodemanApp;`
+  );
+
+  return { dom, app: Object.create(win.__CodemanApp.prototype) as LifecycleApp };
+}
+
+describe('lifecycle log rendering', () => {
+  it('renders persisted lifecycle fields as text instead of executable markup', async () => {
+    const payload = `<img src=x onerror="document.body.dataset.xss='executed'">`;
+    const sessionId = `session-"><svg id="session-id-xss" onload="alert(1)"></svg>`;
+    const reason = `<script>document.body.dataset.xss='reason'</script>`;
+    const mode = `<iframe srcdoc="<script>alert(1)</script>"></iframe>`;
+    const { dom, app } = boot([
+      {
+        ts: Date.now(),
+        event: 'exit',
+        sessionId,
+        name: payload,
+        reason,
+        mode,
+        exitCode: 1,
+      },
+    ]);
+
+    await app.loadLifecycleLog();
+
+    const cells = dom.window.document.querySelectorAll('#lifecycleTableBody td');
+    expect(cells[2]?.textContent).toBe(payload);
+    expect(cells[2]?.getAttribute('title')).toBe(sessionId);
+    expect(cells[3]?.textContent).toBe(reason);
+    expect(cells[4]?.textContent).toBe(`code=1, ${mode}`);
+    expect(
+      dom.window.document.querySelector(
+        '#lifecycleTableBody img, #lifecycleTableBody svg, #lifecycleTableBody script, #lifecycleTableBody iframe'
+      )
+    ).toBeNull();
+    expect(dom.window.document.body.dataset.xss).toBeUndefined();
+    dom.window.close();
+  });
+});