Fix: vendor static-HTML parsers so skill installs detect fully (#434)

Skill and plugin copies of the detector had no htmlparser2/css-select/css-tree/domutils, so HTML scans silently fell back to regex and exited 0. Bundle those parsers into the engine tree and exit 1 if the fallback still fires.

AI assistance: Cursor Grok 4.6 implemented this change.

Co-authored-by: Cursor <cursoragent@cursor.com>

NOTICE.md

@@ -9,3 +9,15 @@ The `skill/reference/ios.md` and `skill/reference/android.md` platform reference
 **Original work:** https://github.com/ehmo/platform-design-skills
 **Original license:** MIT
 **Author:** ehmo
+
+## Static HTML parser bundle
+
+`cli/engine/vendor/static-html-parsers.mjs` is a generated bundle of the parser packages the static-HTML detector needs at runtime. Skill and plugin installs copy that file with the detector; they do not install these packages from npm.
+
+| Package | License |
+|---|---|
+| htmlparser2 | MIT |
+| css-select | BSD-2-Clause |
+| css-tree | MIT |
+| domutils | BSD-2-Clause |
+| source-map-js (via css-tree) | BSD-3-Clause |

cli/engine/cli/main.mjs

@@ -423,10 +423,11 @@ async function detectCli() {
       }
     }
     else process.stderr.write(formatFindings(allFindings, false) + '\n');
-    process.exit(primary.length > 0 ? 2 : 0);
+  } else if (jsonMode) {
+    process.stdout.write('[]\n');
   }
-  if (jsonMode) process.stdout.write('[]\n');
-  process.exit(0);
+  if (globalThis.__impeccableStaticHtmlDegraded) process.exit(1);
+  process.exit(primary.length > 0 ? 2 : 0);
 }
 
 export { formatFindings, handleStdin, confirm, printUsage, detectCli };

cli/engine/engines/static-html/detect-html.mjs

@@ -122,12 +122,8 @@ async function detectHtml(filePath, options = {}) {
       ruleId: 'import-static-parser',
       target: filePath,
     }, async () => {
-      const [htmlparser2, cssSelect, csstree, domutils] = await Promise.all([
-        import('htmlparser2'),
-        import('css-select'),
-        import('css-tree'),
-        import('domutils'),
-      ]);
+      const parsers = await import(new URL('../../vendor/static-html-parsers.mjs', import.meta.url).href);
+      const { htmlparser2, cssSelect, csstree, domutils } = parsers;
       return {
         parseDocument: htmlparser2.parseDocument,
         selectAll: cssSelect.selectAll,
@@ -137,21 +133,20 @@ async function detectHtml(filePath, options = {}) {
         domutils,
       };
     });
-  } catch (err) {
-  if (!globalThis.__impeccableStaticHtmlWarned) {
-    globalThis.__impeccableStaticHtmlWarned = true;
-
-    process.stderr.write(
-  'impeccable detect: DEGRADED - HTML parser modules unavailable ' +
-  '(htmlparser2, css-select, css-tree, domutils).\n' +
-  'Falling back to regex matching. Custom properties, selector matching and computed ' +
-  'contrast are NOT evaluated; findings are an undercount, not a clean bill of health.\n'
-);
+  } catch {
+    if (!globalThis.__impeccableStaticHtmlWarned) {
+      globalThis.__impeccableStaticHtmlWarned = true;
+      process.stderr.write(
+        'impeccable detect: DEGRADED - HTML parser modules unavailable ' +
+        '(htmlparser2, css-select, css-tree, domutils).\n' +
+        'Falling back to regex matching. Custom properties, selector matching and computed ' +
+        'contrast are NOT evaluated; findings are an undercount, not a clean bill of health.\n',
+      );
+    }
+    globalThis.__impeccableStaticHtmlDegraded = true;
+    return detectText(html, filePath, options);
   }
 
-  return detectText(html, filePath, options);
-}
-
   const resolvedPath = path.resolve(filePath);
   const fileDir = path.dirname(resolvedPath);
   const root = profileStep(profile, {

package.json

@@ -45,6 +45,7 @@
     "build": "bun run build:skills && mkdir -p build/_data && rm -rf build/_data/dist && cp -R dist build/_data/dist",
     "build:release": "bun run build:skills:release && mkdir -p build/_data && rm -rf build/_data/dist && cp -R dist build/_data/dist",
     "build:browser": "node scripts/build-browser-detector.js",
+    "build:static-html-parsers": "node scripts/build-static-html-parsers.js",
     "build:extension": "node scripts/build-extension.js",
     "clean": "rm -rf dist build",
     "rebuild": "bun run clean && bun run build",

scripts/build-static-html-parsers.js

@@ -0,0 +1,46 @@
+#!/usr/bin/env node
+
+/**
+ * Generates cli/engine/vendor/static-html-parsers.mjs
+ * by bundling htmlparser2, css-select, css-tree, and domutils for skill/plugin installs.
+ *
+ * Run: node scripts/build-static-html-parsers.js
+ */
+
+import fs from 'fs';
+import path from 'path';
+import { fileURLToPath } from 'url';
+import { spawnSync } from 'node:child_process';
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const ROOT = path.resolve(__dirname, '..');
+
+const ENTRY = path.join(__dirname, 'lib/static-html-parsers.entry.mjs');
+const OUT_DIR = path.join(ROOT, 'cli/engine/vendor');
+const OUTPUT = path.join(OUT_DIR, 'static-html-parsers.mjs');
+
+fs.mkdirSync(OUT_DIR, { recursive: true });
+
+const result = spawnSync(
+  'bun',
+  ['build', ENTRY, '--outfile', OUTPUT, '--target', 'node', '--format', 'esm'],
+  { cwd: ROOT, encoding: 'utf8' },
+);
+
+if (result.status !== 0) {
+  process.stderr.write(result.stderr || result.stdout || 'bun build failed\n');
+  process.exit(result.status ?? 1);
+}
+
+const bundled = fs.readFileSync(OUTPUT, 'utf8');
+const output = `/**
+ * GENERATED -- do not edit. Source: scripts/lib/static-html-parsers.entry.mjs
+ * Rebuild: node scripts/build-static-html-parsers.js
+ *
+ * Bundles htmlparser2, css-select, css-tree, and domutils for skill/plugin installs.
+ * Third-party licenses: see NOTICE.md.
+ */
+${bundled}`;
+
+fs.writeFileSync(OUTPUT, output);
+console.log(`Generated ${path.relative(ROOT, OUTPUT)} (${(output.length / 1024).toFixed(1)} KB)`);

scripts/lib/static-html-parsers.entry.mjs

@@ -0,0 +1,6 @@
+export * as htmlparser2 from 'htmlparser2';
+export * as cssSelect from 'css-select';
+export * as domutils from 'domutils';
+import parse from 'css-tree/parser';
+import generate from 'css-tree/generator';
+export const csstree = { parse, generate };

scripts/test-suites.mjs

@@ -25,7 +25,7 @@ export const SUITES = {
     description: 'Build, provider transforms, CLI helpers, context, and storage unit tests.',
     triggers: [
       ...COMMON_INFRA_PATTERNS,
-      /^scripts\/(?!benchmark-detector|build-browser-detector|build-extension)/,
+      /^scripts\/(?!benchmark-detector|build-browser-detector|build-static-html-parsers|build-extension)/,
       /^skill\/(SKILL\.src\.md|agents\/|reference\/|scripts\/(cleanup-deprecated|comp-diff|comp-spec|build-phase|font-match|data\/font-index|concept-seed|generate-image|context|context-signals|critique-storage|design-parser|doctor|hook|impeccable-paths|is-generated|lib\/(artifact-schema|png|raster|image-metrics|font-fingerprint|font-index|hero-checks|composition-catalog|concept-catalog|provider|staleness|staleness-deep|staleness-notice|surface-briefs|target-slug|template-extensions)|pin|surface-brief))/,
       /^README(\.npm)?\.md$/,
       /^cli\/bin\//,
@@ -92,7 +92,7 @@ export const SUITES = {
       ...COMMON_INFRA_PATTERNS,
       /^cli\/engine\//,
       /^extension\/(background|content|detector|devtools|popup|manifest\.json)/,
-      /^scripts\/(benchmark-detector|build-browser-detector|build-extension)\.js$/,
+      /^scripts\/(benchmark-detector|build-browser-detector|build-static-html-parsers|build-extension)\.js$/,
       /^site\/(pages\/detector|public\/antipattern|data\/anti-patterns-catalog\.js)/,
       /^tests\/fixtures\/antipatterns/,
     ],
@@ -116,6 +116,7 @@ export const SUITES = {
           'tests/detect-cli-design-contamination.test.mjs',
           'tests/detect-cli-design-monorepo.test.mjs',
           'tests/detect-cli-stdin-dispatch.test.mjs',
+          'tests/detect-static-html-skill-install.test.mjs',
         ],
       },
     ],

tests/detect-static-html-skill-install.test.mjs

@@ -0,0 +1,103 @@
+import { after, describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+import { spawnSync } from 'node:child_process';
+import { fileURLToPath } from 'node:url';
+
+const root = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
+const engineDir = path.join(root, 'cli', 'engine');
+const skillDetect = path.join(root, 'skill', 'scripts', 'detect.mjs');
+const configDep = path.join(root, 'cli', 'lib', 'impeccable-config.mjs');
+
+const CSS = ':root{--grad:linear-gradient(90deg,#7C3AED,#EC4899)}\n.hero h1{background:var(--grad);-webkit-background-clip:text;background-clip:text;color:transparent}';
+const HTML = '<html><head><link rel=stylesheet href=s.css></head><body><div class=hero><h1>Hi</h1></div></body></html>';
+
+function copyDir(src, dest) {
+  fs.mkdirSync(dest, { recursive: true });
+  for (const entry of fs.readdirSync(src, { withFileTypes: true })) {
+    const srcPath = path.join(src, entry.name);
+    const destPath = path.join(dest, entry.name);
+    if (entry.isDirectory()) copyDir(srcPath, destPath);
+    else fs.copyFileSync(srcPath, destPath);
+  }
+}
+
+function copyDetectorExternalDeps(scriptsDir) {
+  fs.mkdirSync(path.join(scriptsDir, 'lib'), { recursive: true });
+  fs.copyFileSync(configDep, path.join(scriptsDir, 'lib', 'impeccable-config.mjs'));
+}
+
+function writeFixture(dir) {
+  fs.writeFileSync(path.join(dir, 's.css'), CSS);
+  fs.writeFileSync(path.join(dir, 'p.html'), HTML);
+}
+
+function runDetect(cwd, detectRel, htmlRel = 'p.html') {
+  const detectPath = path.join(cwd, detectRel);
+  return spawnSync(
+    process.execPath,
+    [detectPath, '--json', '--no-config', '--no-design-system', htmlRel],
+    { cwd, encoding: 'utf8' },
+  );
+}
+
+function assertFullEngine(result) {
+  assert.doesNotMatch(result.stderr, /DEGRADED/);
+  const findings = JSON.parse(result.stdout);
+  assert.ok(findings.some((item) => item.antipattern === 'gradient-text'));
+  assert.equal(result.status, 2);
+}
+
+function assertDegraded(result) {
+  assert.match(result.stderr, /DEGRADED/);
+  assert.equal(result.status, 1);
+  JSON.parse(result.stdout);
+}
+
+const tempDirs = [];
+
+after(() => {
+  for (const dir of tempDirs) fs.rmSync(dir, { recursive: true, force: true });
+});
+
+describe('static HTML parsers in skill/plugin installs', () => {
+  it('resolves parsers from a skill-shaped scripts/ tree with no node_modules', () => {
+    const tmp = fs.mkdtempSync(path.join(os.tmpdir(), 'impeccable-skill-detect-'));
+    tempDirs.push(tmp);
+    fs.mkdirSync(path.join(tmp, 'scripts'), { recursive: true });
+    fs.copyFileSync(skillDetect, path.join(tmp, 'scripts', 'detect.mjs'));
+    copyDir(engineDir, path.join(tmp, 'scripts', 'detector'));
+    copyDetectorExternalDeps(path.join(tmp, 'scripts'));
+    writeFixture(tmp);
+
+    assertFullEngine(runDetect(tmp, path.join('scripts', 'detect.mjs')));
+  });
+
+  it('resolves parsers from a plugin cache skills/impeccable/scripts/ tree', () => {
+    const tmp = fs.mkdtempSync(path.join(os.tmpdir(), 'impeccable-plugin-detect-'));
+    tempDirs.push(tmp);
+    const scriptsDir = path.join(tmp, 'skills', 'impeccable', 'scripts');
+    fs.mkdirSync(scriptsDir, { recursive: true });
+    fs.copyFileSync(skillDetect, path.join(scriptsDir, 'detect.mjs'));
+    copyDir(engineDir, path.join(scriptsDir, 'detector'));
+    copyDetectorExternalDeps(scriptsDir);
+    writeFixture(tmp);
+
+    assertFullEngine(runDetect(tmp, path.join('skills', 'impeccable', 'scripts', 'detect.mjs')));
+  });
+
+  it('exits 1 when the vendor bundle is missing', () => {
+    const tmp = fs.mkdtempSync(path.join(os.tmpdir(), 'impeccable-skill-degraded-'));
+    tempDirs.push(tmp);
+    fs.mkdirSync(path.join(tmp, 'scripts'), { recursive: true });
+    fs.copyFileSync(skillDetect, path.join(tmp, 'scripts', 'detect.mjs'));
+    copyDir(engineDir, path.join(tmp, 'scripts', 'detector'));
+    copyDetectorExternalDeps(path.join(tmp, 'scripts'));
+    fs.unlinkSync(path.join(tmp, 'scripts', 'detector', 'vendor', 'static-html-parsers.mjs'));
+    writeFixture(tmp);
+
+    assertDegraded(runDetect(tmp, path.join('scripts', 'detect.mjs')));
+  });
+});

tests/lib/detector-bundle.test.js

@@ -16,6 +16,7 @@ describe('skill detector bundle', () => {
     expect(scriptNames.has('detector/detect-antipatterns-browser.js')).toBe(true);
     expect(scriptNames.has('detector/cli/main.mjs')).toBe(true);
     expect(scriptNames.has('detector/engines/static-html/detect-html.mjs')).toBe(true);
+    expect(scriptNames.has('detector/vendor/static-html-parsers.mjs')).toBe(true);
   });
 
   test('critique references the bundled detector command', () => {