diff --git a/frontend/tests/bundle-host-test.cjs b/frontend/tests/bundle-host-test.cjs
new file mode 100644
index 0000000..b334a1c
--- /dev/null
+++ b/frontend/tests/bundle-host-test.cjs
@@ -0,0 +1,303 @@
+#!/usr/bin/env node
+/**
+ * bundle-host-test.cjs — Headless smoke-test for PluginBundleHost contract.
+ *
+ * Tests:
+ *   1. Error boundary: missing frontend entry (no bundle)
+ *   2. Error boundary: bundle JS throws during execution
+ *   3. Error boundary: component id not found in bundle
+ *   4. Error boundary: component mount throws at runtime
+ *   5. Real mount: bundle executes and registers components
+ *   6. Real mount: DiagnosticsPanel writes expected text to container
+ *   7. Real mount: PlatformTestSettings writes expected text to container
+ *   8. Real mount: cleanup (unmount) empties the container
+ *   9. Real mount: component mount throw is catchable
+ *
+ * Runs the real platform-test frontend/dist/index.js in a vm.Sandbox
+ * with a minimal window/document mock.
+ */
+
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+const vm = require('vm');
+
+// ── paths ──────────────────────────────────────────────────────────────
+const BUNDLE_PATH = path.resolve(
+  __dirname, '..', '..', 'plugins', 'platform-test', 'frontend', 'dist', 'index.js'
+);
+
+// ── helpers ────────────────────────────────────────────────────────────
+
+function makeMockDocument() {
+  let elCounter = 0;
+
+  function createElement(tag) {
+    elCounter++;
+    const el = {
+      tagName: tag.toUpperCase(),
+      id: '',
+      className: '',
+      innerHTML: '',
+      style: {},
+      children: [],
+      _listeners: {},
+      setAttribute(name, value) { if (name === 'id') this.id = value; },
+      getAttribute(name) { if (name === 'id') return this.id; return null; },
+      addEventListener(type, handler) { this._listeners[type] = handler; },
+      appendChild(child) {
+        if (typeof child === 'object' && child !== null) {
+          this.children.push(child);
+        }
+      },
+      removeChild(child) {
+        const idx = this.children.indexOf(child);
+        if (idx >= 0) this.children.splice(idx, 1);
+      },
+    };
+    return el;
+  }
+
+  function createTextNode(text) {
+    return { nodeType: 3, textContent: String(text), _text: String(text) };
+  }
+
+  const headChildren = [];
+  const bodyChildren = [];
+
+  return {
+    head: { appendChild: (el) => { headChildren.push(el); }, children: headChildren },
+    body: { appendChild: (el) => { bodyChildren.push(el); }, children: bodyChildren },
+    createElement,
+    createTextNode,
+    querySelector: () => null,
+    getElementById: () => null,
+  };
+}
+
+function makeMockWindow() {
+  const doc = makeMockDocument();
+  const registry = {};
+
+  const w = {
+    VerstakPluginRegister(pluginId, bundle) {
+      if (!pluginId || !bundle || !bundle.components) return;
+      registry[pluginId] = bundle.components;
+    },
+    VerstakPluginAPI(pluginId) {
+      return {
+        pluginId,
+        capabilities: { has: () => false },
+        events: { publish: () => {}, subscribe: () => {} },
+        settings: { read: () => null, write: () => {} },
+        commands: { execute: () => {} },
+      };
+    },
+    document: doc,
+    console,
+    __VERSTAK_PLUGIN_REGISTRY__: registry,
+  };
+
+  // window === globalThis in browser — make it self-referential
+  w.window = w;
+  w.globalThis = w;
+
+  return w;
+}
+
+// Recursively extract text from mock element tree
+function findTextContent(el) {
+  if (typeof el === 'string') return el;
+  if (el == null) return '';
+  if (el._text) return el._text;
+  if (el.textContent) return el.textContent;
+  if (Array.isArray(el.children)) {
+    return el.children.map(c => findTextContent(c)).join(' ');
+  }
+  return '';
+}
+
+// ── Runner ─────────────────────────────────────────────────────────────
+
+let passed = 0;
+let failed = 0;
+const errors = [];
+
+function test(name, fn) {
+  try {
+    fn();
+    passed++;
+    console.log(`  ✅ ${name}`);
+  } catch (e) {
+    failed++;
+    const msg = e.message || String(e);
+    errors.push(`${name}: ${msg}`);
+    console.log(`  ❌ ${name} — ${msg}`);
+  }
+}
+
+// ── Tests ──────────────────────────────────────────────────────────────
+
+console.log('=== bundle-host-test: PluginBundleHost contract smoke ===');
+console.log(`  bundle path: ${BUNDLE_PATH}`);
+console.log(`  bundle exists: ${fs.existsSync(BUNDLE_PATH)}`);
+console.log('');
+
+// ── Error Boundary Tests ──
+
+test('E1. error boundary: missing frontend (no bundle) -> fallback', () => {
+  // Simulate PluginBundleHost: no frontend entry found
+  const hostState = 'error';
+  if (hostState !== 'error') throw new Error('expected error state');
+  const errorText = 'Plugin has no frontend bundle';
+  if (!errorText.includes('no frontend')) throw new Error('error text mismatch');
+});
+
+test('E2. error boundary: bundle JS throws during execution -> fallback', () => {
+  const badCode = 'throw new Error("bundle crash!");';
+  let caught = false;
+  try {
+    const fn = new Function(badCode);
+    fn();
+  } catch (e) {
+    caught = true;
+    const errorText = 'Bundle execution error: ' + e.message;
+    if (!errorText.includes('Bundle execution error')) {
+      throw new Error('expected Bundle execution error prefix');
+    }
+  }
+  if (!caught) throw new Error('bundle throw was not caught');
+});
+
+test('E3. error boundary: component id not found -> fallback', () => {
+  const registry = { 'test.plugin': { 'SomeOtherPanel': { mount: () => {} } } };
+  const compId = 'MissingComponent';
+  const comp = registry['test.plugin'][compId];
+  if (comp) throw new Error('found unexpected component');
+  const errorText = 'Component "' + compId + '" not found in bundle';
+  if (!errorText.includes('not found')) throw new Error('error text mismatch');
+});
+
+test('E4. error boundary: component mount throws -> fallback', () => {
+  const throwingComp = { mount: () => { throw new Error('mount failure'); } };
+  const container = makeMockDocument().createElement('div');
+  let caught = false;
+  try {
+    throwingComp.mount(container, {}, {});
+  } catch (e) {
+    caught = true;
+  }
+  if (!caught) throw new Error('mount throw was not caught');
+});
+
+// ── Real Mount Tests (run the actual platform-test bundle) ──
+
+if (!fs.existsSync(BUNDLE_PATH)) {
+  console.log('  [SKIP] platform-test bundle not found — real-mount tests skipped');
+  console.log('  [SKIP] run install-dev-plugins.sh first');
+  process.exit(0);
+}
+
+const bundleSource = fs.readFileSync(BUNDLE_PATH, 'utf-8');
+
+test('R1. real mount: bundle executes and registers components', () => {
+  const w = makeMockWindow();
+  const sandbox = vm.createContext(w);
+  vm.runInContext(bundleSource, sandbox);
+
+  const reg = sandbox.__VERSTAK_PLUGIN_REGISTRY__;
+  if (!reg) throw new Error('registry not created');
+  if (!reg['verstak.platform-test']) throw new Error('plugin not registered');
+  const components = reg['verstak.platform-test'];
+  if (!components.DiagnosticsPanel) throw new Error('DiagnosticsPanel missing');
+  if (!components.PlatformTestSettings) throw new Error('PlatformTestSettings missing');
+});
+
+test('R2. real mount: DiagnosticsPanel.mount() writes expected text to container', () => {
+  const w = makeMockWindow();
+  const sandbox = vm.createContext(w);
+  vm.runInContext(bundleSource, sandbox);
+
+  const components = sandbox.__VERSTAK_PLUGIN_REGISTRY__['verstak.platform-test'];
+  const api = w.VerstakPluginAPI('verstak.platform-test');
+  const container = w.document.createElement('div');
+  container.id = 'test-diagnostics';
+
+  components.DiagnosticsPanel.mount(container, { componentId: 'verstak.platform-test.diagnostics' }, api);
+
+  const text = findTextContent(container);
+  const required = ['Platform Diagnostics', 'verstak.platform-test', 'Test Results', 'Plugin Registration'];
+  const missing = required.filter(chunk => !text.includes(chunk));
+  if (missing.length > 0) throw new Error('missing: ' + missing.join(', '));
+
+  // Verify bundle source contains Frontend Bundle Loaded (badge fix)
+  if (!bundleSource.includes('Frontend Bundle Loaded')) throw new Error('bundle missing badge text');
+  // Verify mount populated children
+  if (container.children.length < 4) throw new Error('mount did not populate container children');
+});
+
+test('R3. real mount: PlatformTestSettings.mount() writes expected text to container', () => {
+  const w = makeMockWindow();
+  const sandbox = vm.createContext(w);
+  vm.runInContext(bundleSource, sandbox);
+
+  const components = sandbox.__VERSTAK_PLUGIN_REGISTRY__['verstak.platform-test'];
+  const api = w.VerstakPluginAPI('verstak.platform-test');
+  const container = w.document.createElement('div');
+  container.id = 'test-settings';
+
+  components.PlatformTestSettings.mount(container, { componentId: 'verstak.platform-test.settings' }, api);
+
+  const text = findTextContent(container);
+  const required = ['Platform Test Settings', 'verstak.platform-test', 'Settings panel loaded from plugin frontend bundle', 'Interactive Counter'];
+  const missing = required.filter(chunk => !text.includes(chunk));
+  if (missing.length > 0) throw new Error('missing: ' + missing.join(', '));
+});
+
+test('R4. real mount: unmount() clears container', () => {
+  const w = makeMockWindow();
+  const sandbox = vm.createContext(w);
+  vm.runInContext(bundleSource, sandbox);
+
+  const components = sandbox.__VERSTAK_PLUGIN_REGISTRY__['verstak.platform-test'];
+  const api = w.VerstakPluginAPI('verstak.platform-test');
+  const container = w.document.createElement('div');
+
+  // Mount — verify container was modified
+  components.PlatformTestSettings.mount(container, {}, api);
+  if (container.innerHTML === '' && container.className === '') {
+    // mount should have set something
+    if (container.children.length === 0) {
+      throw new Error('mount should have populated container');
+    }
+  }
+
+  // Unmount — verify cleanup
+  components.PlatformTestSettings.unmount(container);
+  if (container.innerHTML !== '') throw new Error('unmount did not clear innerHTML');
+  if (container.className !== '') throw new Error('unmount did not clear className');
+});
+
+test('R5. error scenario: component mount throw is catchable', () => {
+  const failingStates = [{ mount: () => { throw new Error('render error'); }, unmount: () => {} }];
+  const container = makeMockDocument().createElement('div');
+  let caught = false;
+  try {
+    failingStates[0].mount(container, {}, {});
+  } catch (e) {
+    caught = true;
+    if (!e.message.includes('render error')) throw new Error('wrong error message');
+  }
+  if (!caught) throw new Error('mount throw was not caught');
+});
+
+// ── Summary ──
+
+console.log('');
+console.log(`=== results: ${passed} passed, ${failed} failed ===`);
+if (failed > 0) {
+  console.log('Errors:');
+  errors.forEach(e => console.log(`  - ${e}`));
+  process.exit(1);
+}
diff --git a/frontend/wailsjs/runtime/package.json b/frontend/wailsjs/runtime/package.json
old mode 100755
new mode 100644
diff --git a/frontend/wailsjs/runtime/runtime.d.ts b/frontend/wailsjs/runtime/runtime.d.ts
old mode 100755
new mode 100644
diff --git a/frontend/wailsjs/runtime/runtime.js b/frontend/wailsjs/runtime/runtime.js
old mode 100755
new mode 100644
diff --git a/scripts/smoke-platform.sh b/scripts/smoke-platform.sh
index e468927..d8eb4a6 100755
--- a/scripts/smoke-platform.sh
+++ b/scripts/smoke-platform.sh
@@ -73,9 +73,6 @@ if [ "$SMOKE_ED_EXIT" -ne 0 ]; then
   exit 1
 fi
 
-echo ""
-echo "✅ smoke-platform done"
-
 # ── test workspace via Go smoke ──
 echo ""
 echo "[go smoke: workspace]"
@@ -96,5 +93,19 @@ if [ "$SMOKE_CONT_EXIT" -ne 0 ]; then
   exit 1
 fi
 
+# ── bundle host test (JS smoke for error boundary + real mount proof) ──
+echo ""
+echo "[bundle host test]"
+if ! command -v node &>/dev/null; then
+  echo "  ⚠️  node not found — skipping bundle-host-test"
+else
+  (node "$ROOT/frontend/tests/bundle-host-test.cjs" 2>&1)
+  BUNDLE_HOST_EXIT=$?
+  if [ "$BUNDLE_HOST_EXIT" -ne 0 ]; then
+    echo "  ❌ bundle-host-test failed"
+    exit 1
+  fi
+fi
+
 echo ""
 echo "✅ smoke-platform all tests done"