Filter inactive linked CSS states

Keep valid empty pseudo-class matches authoritative and omit selector-less linked at-rules that cannot be tied to rendered nodes.

AI assistance disclosure: Codex helped implement and test this fix under maintainer direction.

tests/detect-antipatterns-browser.test.mjs

@@ -1408,8 +1408,10 @@ describe('detectUrl — browser-only fixtures', () => {
       const containerBackgrounds = await linkedPage.evaluate(() => ({
         inactive: getComputedStyle(document.querySelector('.inactive-container-stripes')).backgroundImage,
         active: getComputedStyle(document.querySelector('.active-container-halo')).backgroundImage,
+        pseudoClass: getComputedStyle(document.querySelector('.inactive-pseudo-stripes')).backgroundImage,
       }));
       assert.equal(containerBackgrounds.inactive, 'none');
+      assert.equal(containerBackgrounds.pseudoClass, 'none');
       assert.match(containerBackgrounds.active, /radial-gradient/i);
       const grids = linkedFindings.filter(finding => finding.type === 'codex-grid-background');
       assert.equal(grids.length, 1, JSON.stringify({ linkedFindings, linkedCssom }));
@@ -1421,7 +1423,16 @@ describe('detectUrl — browser-only fixtures', () => {
         JSON.stringify({ linkedFindings, linkedCssom }),
       );
       assert.equal(linkedFindings.some(finding => finding.type === 'radial-halo'), true);
-      assert.equal(linkedFindings.some(finding => finding.type === 'repeating-stripes-gradient'), false);
+      assert.equal(
+        linkedFindings.some(finding => finding.type === 'repeating-stripes-gradient'),
+        false,
+        JSON.stringify({ linkedFindings, linkedCssom, containerBackgrounds }),
+      );
+      assert.equal(
+        linkedFindings.some(finding => finding.type === 'gradient-text'),
+        false,
+        JSON.stringify({ linkedFindings, linkedCssom, containerBackgrounds }),
+      );
       assert.equal(linkedFindings.some(finding => finding.type === 'layout-transition'), false);
       await linkedPage.close();
 

tests/fixtures/antipatterns/linked-url-patterns.css

@@ -45,6 +45,11 @@ main > ::before {
   }
 }
 
+/* The host exists, but the complete pseudo-class selector is inactive. */
+.inactive-pseudo-stripes:not(.active) {
+  background: repeating-linear-gradient(45deg, #eee, #eee 10px, #fafafa 10px, #fafafa 20px);
+}
+
 .container-query-host {
   container-type: inline-size;
   width: 240px;
@@ -66,6 +71,18 @@ main > ::before {
   }
 }
 
+/* Non-selector at-rules in an inactive container must not enter page-level
+   pattern scans just because their CSSOM text is readable. */
+@container (width > 2000px) {
+  @keyframes inactive-container-gradient-text {
+    from {
+      background: linear-gradient(90deg, #111, #999);
+      background-clip: text;
+    }
+    to { background: none; }
+  }
+}
+
 .unused-linked-transition {
   transition: width 200ms ease;
 }

tests/fixtures/antipatterns/linked-url-patterns.html

@@ -11,6 +11,7 @@
     <div class="flag-linked-grid">Rendered decorative grid</div>
     <div class="inactive-media-stripes">Inactive media stripes</div>
     <div class="inactive-supports-stripes">Inactive supports stripes</div>
+    <div class="inactive-pseudo-stripes active">Inactive pseudo-class stripes</div>
     <div class="container-query-host">
       <div class="inactive-container-stripes">Inactive container-query stripes</div>
     </div>