fix: first-recognized-token in decorative check; treat mustache empty string as empty label

- isExplicitlyDecorative now walks the role token list for the first
  recognised role (per WAI-ARIA §4.1), so `role="foo none"` is correctly
  treated as decorative instead of only checking the literal first token.
- hasNonEmptyLabelAttr now treats `aria-label={{""}}` (GlimmerMustache
  wrapping a GlimmerStringLiteral with an empty/whitespace value) as empty,
  consistent with a plain empty text-node value.
- Update misleading test comment: "No aria-label/labelledby" → "…or only
  empty values" to reflect the `aria-label=""` case in the same group.
- Add valid test cases for both fixed behaviours.

Author: johanrd

lib/rules/template-no-aria-label-misuse.js

@@ -139,7 +139,16 @@ function hasNonEmptyLabelAttr(node, name) {
   if (attr.value.type === 'GlimmerTextNode') {
     return attr.value.chars !== '';
   }
-  // Mustache — treat as non-empty (author has declared intent).
+  // Mustache with a static string literal path: `aria-label={{""}}` is still
+  // empty, so treat it the same as an empty text node.
+  if (
+    attr.value.type === 'GlimmerMustacheStatement' &&
+    attr.value.path?.type === 'GlimmerStringLiteral'
+  ) {
+    return attr.value.path.value.trim() !== '';
+  }
+  // All other mustache / concat forms — treat as non-empty (author has
+  // declared intent).
   return true;
 }
 
@@ -148,8 +157,16 @@ function isExplicitlyDecorative(node) {
   if (!role) {
     return false;
   }
-  const first = role.trim().split(/\s+/)[0]?.toLowerCase();
-  return first === 'presentation' || first === 'none';
+  // Walk the token list for the first *recognised* role, mirroring WAI-ARIA
+  // §4.1 fallback semantics (UAs skip unknown tokens). `role="foo none"` is
+  // decorative because the first recognised token is "none".
+  const tokens = role.trim().toLowerCase().split(/\s+/u);
+  for (const token of tokens) {
+    if (token && roles.get(token)) {
+      return token === 'presentation' || token === 'none';
+    }
+  }
+  return false;
 }
 
 // Escape hatch: any `tabindex` value signals author-intent-to-interact,

tests/lib/rules/template-no-aria-label-misuse.js

@@ -20,14 +20,20 @@ const validHbs = [
   // role="presentation" / "none" — author opted out; nothing to lint.
   '<div role="presentation" aria-label="decoration">x</div>',
   '<span role="none" aria-label="decoration">x</span>',
+  // First *recognised* token is "none"/"presentation" — still decorative.
+  '<div role="foo none" aria-label="decoration">x</div>',
+  '<div role="bogus presentation" aria-label="decoration">x</div>',
   // Tabindex escape hatch: real screen readers read aria-label on a
   // tabindexed element even when the implicit role is generic.
   '<span tabindex="0" aria-label="Focusable">x</span>',
   '<div tabindex="-1" aria-label="x">x</div>',
-  // No aria-label/labelledby.
+  // No aria-label/labelledby, or only empty values.
   '<div>plain</div>',
   '<span>text</span>',
   '<div aria-label=""></div>',
+  // Mustache with a static empty string — treated as empty, not as a label.
+  '<div aria-label={{""}}></div>',
+  '<span aria-label={{""}}></span>',
   // Ember component — skipped (role unknowable).
   '<MyButton aria-label="x" />',
   // Custom elements — not in HTML/SVG/MathML tag lists, skipped.