diff --git a/skill/scripts/build-phase.mjs b/skill/scripts/build-phase.mjs
index d29b51ebf..73b367e8a 100644
--- a/skill/scripts/build-phase.mjs
+++ b/skill/scripts/build-phase.mjs
@@ -342,9 +342,24 @@ export function unreferencedPlates(spec, artifact = null) {
   const plates = (spec?.regions || []).filter((r) => r.medium === 'raster' && r.plate);
   if (!plates.length) return [];
   // The artifact narrows nothing: a plate may be referenced only from a
-  // stylesheet the artifact links (assets/hero.css), so the source walk runs
-  // either way and the artifact is simply guaranteed a seat in the corpus.
-  const files = [...new Set([...(artifact && fs.existsSync(artifact) ? [artifact] : []), ...sourceFiles()])];
+  // stylesheet the artifact links, so the source walk runs either way, the
+  // artifact keeps a seat in the corpus, and the stylesheets it links are
+  // added by name (resolved against the artifact's own directory), which
+  // covers a stylesheet outside the walk's root, depth, or file limit.
+  const linked = [];
+  if (artifact && fs.existsSync(artifact)) {
+    linked.push(artifact);
+    try {
+      const html = fs.readFileSync(artifact, 'utf8');
+      for (const m of html.matchAll(/<link\b[^>]*href=["']([^"']+)["'][^>]*>/gi)) {
+        const href = m[1];
+        if (/^(https?:|data:|\/\/)/i.test(href)) continue;
+        if (!/rel=["']?stylesheet/i.test(m[0]) && !/\.css(\?|$)/i.test(href)) continue;
+        linked.push(path.resolve(path.dirname(artifact), href.split('?')[0]));
+      }
+    } catch { /* the artifact still counts */ }
+  }
+  const files = [...new Set([...linked, ...sourceFiles()])];
   let corpus = '';
   for (const f of files) { try { corpus += fs.readFileSync(f, 'utf8') + '\n'; } catch { /* skip */ } }
   const missing = [];
diff --git a/tests/build-phase.test.mjs b/tests/build-phase.test.mjs
index 8bfa65654..cdcfa7162 100644
--- a/tests/build-phase.test.mjs
+++ b/tests/build-phase.test.mjs
@@ -478,7 +478,14 @@ describe('unreferencedPlates', () => {
       // an explicit artifact does not bypass the stylesheet walk
       fs.writeFileSync(path.join(d, 'index.html'), '<link rel="stylesheet" href="assets/hero.css"><main class="hero"></main>');
       assert.deepEqual(unreferencedPlates(spec, path.join(d, 'index.html')), [], 'the linked stylesheet still counts with --artifact set');
+      // a linked stylesheet beyond the walk's reach (deep path) still counts
+      const deep = path.join(d, 'a', 'b', 'c', 'e', 'f', 'g', 'h', 'styles');
+      fs.mkdirSync(deep, { recursive: true });
+      fs.writeFileSync(path.join(deep, 'deep.css'), ".hero { background-image: url('hero-plate.png'); }");
+      fs.writeFileSync(path.join(d, 'index.html'), `<link rel="stylesheet" href="a/b/c/e/f/g/h/styles/deep.css"><main class="hero"></main>`);
       fs.writeFileSync(path.join(d, 'assets', 'hero.css'), '.hero { background: red; }');
+      assert.deepEqual(unreferencedPlates(spec, path.join(d, 'index.html')), [], 'a stylesheet linked by the artifact counts wherever it lives');
+      fs.writeFileSync(path.join(deep, 'deep.css'), '.hero { background: red; }');
       assert.equal(unreferencedPlates(spec, null).length, 1, 'an unreferenced plate is still named');
       assert.equal(unreferencedPlates(spec, path.join(d, 'index.html')).length, 1, 'and with the artifact set too');
     } finally { process.chdir(prev); fs.rmSync(d, { recursive: true, force: true }); }