fix: apply <dialog> exemption to mustache form + update comment (Copilot review)

Author: johanrd

lib/rules/template-no-autofocus-attribute.js

@@ -9,10 +9,11 @@
  * boolean-attribute semantics. vue-a11y and lit-a11y are presence-based,
  * consistent with the spec. We follow the spec.
  *
- * The only exception is a mustache boolean-literal `{{false}}` in element
- * syntax — Glimmer authors writing `autofocus={{false}}` are expressing
- * intent to omit the attribute conditionally. Treat that narrow literal
- * case as opt-out (the rendered HTML will have no autofocus attr).
+ * The only exception is a boolean-literal `false` — in element syntax
+ * written as `autofocus={{false}}`, and in mustache hash syntax written as
+ * `{{input autofocus=false}}`. Both forms express intent to omit the
+ * attribute conditionally, and the rendered HTML will have no autofocus
+ * attribute. Treat both literal-false cases as opt-out.
  *
  * Verified against Glimmer VM's attribute-normalization source:
  * glimmer-vm/packages/@glimmer/runtime/lib/vm/attributes/dynamic.ts —
@@ -135,6 +136,12 @@ module.exports = {
           return;
         }
 
+        // MDN dialog exception: autofocus on a mustache component/helper
+        // nested inside a <dialog> is recommended behavior, not a defect.
+        if (isInsideDialog(node)) {
+          return;
+        }
+
         context.report({
           node: autofocusPair,
           messageId: 'noAutofocus',

tests/lib/rules/template-no-autofocus-attribute.js

@@ -48,6 +48,20 @@ ruleTester.run('template-no-autofocus-attribute', rule, {
         </div>
       </dialog>
     </template>`,
+    // Dialog exception also applies to the mustache form of the `<Input>`
+    // helper (`{{input autofocus=true}}`) — whether direct child or nested.
+    `<template>
+      <dialog>
+        {{input autofocus=true}}
+      </dialog>
+    </template>`,
+    `<template>
+      <dialog>
+        <div>
+          {{input autofocus=true}}
+        </div>
+      </dialog>
+    </template>`,
   ],
 
   invalid: [