From 54955c2b2504371deecdc38dfcf53574bed2e760 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johan=20R=C3=B8ed?= <johanroed@gmail.com>
Date: Tue, 21 Apr 2026 07:52:25 +0200
Subject: [PATCH 1/7] fix(template-require-iframe-title): flag
 title={{null|undefined|number}}
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Before: the rule only rejected title={{false}} among mustache literals.
title={{null}}, title={{undefined}}, and title={{42}} (any non-string
literal) were silently accepted even though none produces a useful
accessible name for an <iframe>.

Fix: extract isInvalidTitleLiteral(); treat boolean, null, undefined,
and numeric literals as invalid title values in both GlimmerMustacheStatement
and single-part GlimmerConcatStatement positions.

Six new invalid tests (3 literal types × 2 syntax forms).

Note: whitespace-only title values (e.g. title="   ") remain flagged —
the audit suggested upstream jsx-a11y accepts these, but an all-whitespace
title provides no accessible name, so our stricter behavior is kept.
---
 lib/rules/template-require-iframe-title.js    | 29 ++++++++++++++---
 .../rules/template-require-iframe-title.js    | 32 +++++++++++++++++++
 2 files changed, 57 insertions(+), 4 deletions(-)

diff --git a/lib/rules/template-require-iframe-title.js b/lib/rules/template-require-iframe-title.js
index d4f4b2f636..2ee9ebceee 100644
--- a/lib/rules/template-require-iframe-title.js
+++ b/lib/rules/template-require-iframe-title.js
@@ -1,3 +1,22 @@
+// Mustache path nodes that produce no accessible name. Booleans, null, undefined
+// all coerce to empty-ish strings; numeric literals ("42") are accepted by HTML
+// but provide no useful title for assistive tech.
+function isInvalidTitleLiteral(path) {
+  if (!path) {
+    return false;
+  }
+  if (path.type === 'GlimmerBooleanLiteral') {
+    return true;
+  }
+  if (path.type === 'GlimmerNullLiteral' || path.type === 'GlimmerUndefinedLiteral') {
+    return true;
+  }
+  if (path.type === 'GlimmerNumberLiteral') {
+    return true;
+  }
+  return false;
+}
+
 /** @type {import('eslint').Rule.RuleModule} */
 module.exports = {
   meta: {
@@ -93,19 +112,21 @@ module.exports = {
               break;
             }
             case 'GlimmerMustacheStatement': {
-              // title={{false}} → BooleanLiteral false is invalid
-              if (titleAttr.value.path?.type === 'GlimmerBooleanLiteral') {
+              // title={{false}} / title={{null}} / title={{undefined}} / title={{42}}
+              // — any literal that doesn't produce a meaningful accessible name.
+              if (isInvalidTitleLiteral(titleAttr.value.path)) {
                 context.report({ node, messageId: 'dynamicFalseTitle' });
               }
               break;
             }
             case 'GlimmerConcatStatement': {
-              // title="{{false}}" → ConcatStatement with single BooleanLiteral part
+              // title="{{false}}" / "{{undefined}}" / etc. — ConcatStatement
+              // with a single literal part that doesn't produce a name.
               const parts = titleAttr.value.parts || [];
               if (
                 parts.length === 1 &&
                 parts[0].type === 'GlimmerMustacheStatement' &&
-                parts[0].path?.type === 'GlimmerBooleanLiteral'
+                isInvalidTitleLiteral(parts[0].path)
               ) {
                 context.report({ node, messageId: 'dynamicFalseTitle' });
               }
diff --git a/tests/lib/rules/template-require-iframe-title.js b/tests/lib/rules/template-require-iframe-title.js
index 25d4f9545a..94fced6c92 100644
--- a/tests/lib/rules/template-require-iframe-title.js
+++ b/tests/lib/rules/template-require-iframe-title.js
@@ -104,6 +104,38 @@ ruleTester.run('template-require-iframe-title', rule, {
       output: null,
       errors: [{ messageId: 'emptyTitle' }],
     },
+
+    // Mustache literals that don't coerce to a useful accessible name.
+    {
+      code: '<template><iframe title={{null}} /></template>',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+    {
+      code: '<template><iframe title={{undefined}} /></template>',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+    {
+      code: '<template><iframe title={{42}} /></template>',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+    {
+      code: '<template><iframe title="{{null}}" /></template>',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+    {
+      code: '<template><iframe title="{{undefined}}" /></template>',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+    {
+      code: '<template><iframe title="{{42}}" /></template>',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
   ],
 });
 

From 6d4ed2323e1cdab769b047d287569078d85391b8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johan=20R=C3=B8ed?= <johanroed@gmail.com>
Date: Tue, 21 Apr 2026 17:54:21 +0200
Subject: [PATCH 2/7] test: add Phase 3 audit fixture translating iframe-title
 peer cases

Translates 33 cases from peer-plugin rules:
  - jsx-a11y iframe-has-title
  - vuejs-accessibility iframe-has-title
  - lit-a11y iframe-title

Fixture documents parity after this fix:
  - title={{null|undefined|number}} and concat `title="{{null}}"`
    / `title="{{42}}"` are now flagged via dynamicFalseTitle.

Remaining divergences (title={{""}} still accepted, aria-hidden /
hidden exemption, whitespace-only title over-flagged, duplicate-title
detection inherited from ember-template-lint) are annotated inline.
---
 tests/audit/iframe-title/peer-parity.js | 209 ++++++++++++++++++++++++
 1 file changed, 209 insertions(+)
 create mode 100644 tests/audit/iframe-title/peer-parity.js

diff --git a/tests/audit/iframe-title/peer-parity.js b/tests/audit/iframe-title/peer-parity.js
new file mode 100644
index 0000000000..de95a37bd0
--- /dev/null
+++ b/tests/audit/iframe-title/peer-parity.js
@@ -0,0 +1,209 @@
+// Audit fixture — peer-plugin parity for `ember/template-require-iframe-title`.
+// These tests are NOT part of the main suite and do not run in CI. They encode
+// the CURRENT behavior of our rule so that running this file reports pass.
+// Each divergence from an upstream plugin is annotated as "DIVERGENCE —".
+//
+// Source files (context/ checkouts):
+//   - eslint-plugin-jsx-a11y-main/__tests__/src/rules/iframe-has-title-test.js
+//   - eslint-plugin-vuejs-accessibility-main/src/rules/__tests__/iframe-has-title.test.ts
+//   - eslint-plugin-lit-a11y/tests/lib/rules/iframe-title.js
+
+'use strict';
+
+const rule = require('../../../lib/rules/template-require-iframe-title');
+const RuleTester = require('eslint').RuleTester;
+
+const ruleTester = new RuleTester({
+  parser: require.resolve('ember-eslint-parser'),
+  parserOptions: { ecmaVersion: 2022, sourceType: 'module' },
+});
+
+ruleTester.run('audit:iframe-title (gts)', rule, {
+  valid: [
+    // === Upstream parity — basic cases ===
+    // jsx-a11y / vue-a11y / lit-a11y: valid (no iframe, or titled iframe).
+    '<template><div /></template>',
+    '<template><iframe title="Unique title" /></template>',
+
+    // Dynamic title — jsx-a11y treats `title={foo}` as valid (expression is
+    // assumed to yield a truthy string). vue-a11y: valid for `:title="foo"`.
+    // lit-a11y: valid for `title=${foo}`. Ours: valid for `{{someValue}}`.
+    '<template><iframe title={{someValue}} /></template>',
+
+    // Ours: valid for concat-mustache (dynamic in concat).
+    // No direct jsx-a11y analogue because JSX has no string-interpolation; but
+    // the equivalent `title={`${foo}`}` is treated as valid by jsx-a11y.
+    '<template><iframe title="{{someValue}}" /></template>',
+
+    // === OUR behavior (no upstream peer equivalent) — exemptions ===
+    // Our rule skips iframes that are aria-hidden or hidden.
+    //   - jsx-a11y: does NOT exempt aria-hidden; `<iframe aria-hidden />`
+    //     without a title is still flagged.
+    //   - vue-a11y / lit-a11y: same — no aria-hidden/hidden exemption.
+    // Intentional: matches ember-template-lint upstream behavior.
+    '<template><iframe aria-hidden="true" /></template>',
+    '<template><iframe hidden /></template>',
+    '<template><iframe title="" aria-hidden /></template>',
+    '<template><iframe title="" hidden /></template>',
+
+    // === Remaining divergence — `title={{""}}` ===
+    // jsx-a11y flags `<iframe title={""} />` via getLiteralPropValue.
+    // Our rule inspects only GlimmerBooleanLiteral / GlimmerNullLiteral /
+    //   GlimmerUndefinedLiteral / GlimmerNumberLiteral — an empty-string
+    //   literal inside `{{}}` is not a GlimmerStringLiteral AST node but
+    //   a concat-of-nothing; we under-flag here.
+    '<template><iframe title={{""}} /></template>',
+
+    // === Disambiguation — distinct titles across iframes (all valid) ===
+    '<template><iframe title="foo" /><iframe title="bar" /></template>',
+  ],
+
+  invalid: [
+    // === Upstream parity — missing title ===
+    {
+      code: '<template><iframe /></template>',
+      output: null,
+      errors: [{ messageId: 'missingTitle' }],
+    },
+    {
+      code: '<template><iframe src="/content"></iframe></template>',
+      output: null,
+      errors: [{ messageId: 'missingTitle' }],
+    },
+
+    // === Upstream parity — empty title string ===
+    // jsx-a11y, vue-a11y, lit-a11y all flag `title=""`.
+    {
+      code: '<template><iframe title="" /></template>',
+      output: null,
+      errors: [{ messageId: 'emptyTitle' }],
+    },
+    // Whitespace-only title — ours trims then flags empty.
+    // jsx-a11y: `getLiteralPropValue("   ")` yields "   " which is truthy, so
+    // jsx-a11y would NOT flag. vue-a11y similarly does not trim. Ours trims.
+    // DIVERGENCE — we over-flag whitespace-only titles.
+    {
+      code: '<template><iframe title="   " /></template>',
+      output: null,
+      errors: [{ messageId: 'emptyTitle' }],
+    },
+
+    // === Parity — title is literal boolean / null / undefined / number ===
+    // jsx-a11y: INVALID for any non-string literal (via getLiteralPropValue
+    //   truthiness + string-check). vue-a11y: same. Our rule now rejects
+    //   GlimmerBooleanLiteral / GlimmerNullLiteral / GlimmerUndefinedLiteral
+    //   / GlimmerNumberLiteral in both `{{}}` and `"{{}}"` positions.
+    {
+      code: '<template><iframe title={{false}} /></template>',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+    {
+      code: '<template><iframe title={{true}} /></template>',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+    {
+      code: '<template><iframe title={{null}} /></template>',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+    {
+      code: '<template><iframe title={{undefined}} /></template>',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+    {
+      code: '<template><iframe title={{42}} /></template>',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+    // Concat form — `title="{{false}}"` / etc. also flagged.
+    {
+      code: '<template><iframe title="{{false}}" /></template>',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+    {
+      code: '<template><iframe title="{{null}}" /></template>',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+    {
+      code: '<template><iframe title="{{42}}" /></template>',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+
+    // === DIVERGENCE — duplicate-title detection ===
+    // jsx-a11y, vue-a11y, lit-a11y: do NOT check for duplicate titles across
+    // multiple iframes. Our rule does (inherited from ember-template-lint).
+    // Captured here as one of our OVER-flagging cases (intentional extension).
+    {
+      code: '<template><iframe title="foo" /><iframe title="foo" /></template>',
+      output: null,
+      errors: [
+        { message: 'This title is not unique. #1' },
+        {
+          message:
+            '<iframe> elements must have a unique title property. Value title="foo" already used for different iframe. #1',
+        },
+      ],
+    },
+  ],
+});
+
+const hbsRuleTester = new RuleTester({
+  parser: require.resolve('ember-eslint-parser/hbs'),
+  parserOptions: { ecmaVersion: 2022, sourceType: 'module' },
+});
+
+hbsRuleTester.run('audit:iframe-title (hbs)', rule, {
+  valid: [
+    '<iframe title="Welcome" />',
+    '<iframe title={{someValue}} />',
+    // DIVERGENCE — exempted (see gts section)
+    '<iframe aria-hidden="true" />',
+    '<iframe hidden />',
+  ],
+  invalid: [
+    {
+      code: '<iframe />',
+      output: null,
+      errors: [{ messageId: 'missingTitle' }],
+    },
+    {
+      code: '<iframe title="" />',
+      output: null,
+      errors: [{ messageId: 'emptyTitle' }],
+    },
+    // Parity — non-string literal titles.
+    {
+      code: '<iframe title={{false}} />',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+    {
+      code: '<iframe title={{undefined}} />',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+    {
+      code: '<iframe title={{42}} />',
+      output: null,
+      errors: [{ messageId: 'dynamicFalseTitle' }],
+    },
+    // DIVERGENCE — duplicate detection (upstream does not check).
+    {
+      code: '<iframe title="foo" /><iframe title="foo" />',
+      output: null,
+      errors: [
+        { message: 'This title is not unique. #1' },
+        {
+          message:
+            '<iframe> elements must have a unique title property. Value title="foo" already used for different iframe. #1',
+        },
+      ],
+    },
+  ],
+});

From b9cc09cffbe75c10f628a7ce914ce34c2aaa0df1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johan=20R=C3=B8ed?= <johanroed@gmail.com>
Date: Wed, 22 Apr 2026 10:50:09 +0200
Subject: [PATCH 3/7] feat(template-require-iframe-title): split strict
 whitespace-only check into opt-out option
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Two changes, both addressing fallacies flagged in review-pr-bodies.md:

1. Document that SC 4.1.2 (Name, Role, Value) is the normative requirement;
   H64 is a sufficient technique illustrating one way to meet it. Earlier
   framing attributed the requirement to H64 itself — same pattern as
   template-heading-level's miscited G141.

2. Whitespace-only `title="   "` is technically spec-compliant: ACCNAME 1.2
   step 2I (Tooltip) does not whitespace-trim like step 2D (aria-label)
   does. Keeping the strict flag as default (authoring hygiene — 3 spaces
   is useless as an accessible name in practice) but exposing
   `allowWhitespaceOnlyTitle: boolean` (default false) so teams that want
   spec-aligned behavior can opt out. Empty-string `title=""` and invalid
   mustache literals (null/undefined/number/boolean) remain always flagged:
   those are correctness, not style.
---
 docs/rules/template-require-iframe-title.md   | 47 ++++++++++++++++---
 lib/rules/template-require-iframe-title.js    | 30 ++++++++++--
 .../rules/template-require-iframe-title.js    | 20 ++++++++
 3 files changed, 87 insertions(+), 10 deletions(-)

diff --git a/docs/rules/template-require-iframe-title.md b/docs/rules/template-require-iframe-title.md
index 145f9bd4ec..22da0ecfd2 100644
--- a/docs/rules/template-require-iframe-title.md
+++ b/docs/rules/template-require-iframe-title.md
@@ -6,9 +6,11 @@
 
 ## `<iframe>`
 
-`<iframe>` elements must have a unique title property to indicate its content to the user.
-
-This rule takes no arguments.
+`<iframe>` elements must have a unique title property so assistive
+technology can convey their content to the user. The normative
+requirement is [WCAG SC 4.1.2 (Name, Role, Value)](https://www.w3.org/TR/UNDERSTANDING-WCAG20/ensure-compat-rsv.html);
+the `title` attribute is *one sufficient technique* for meeting it
+(sufficient technique [H64](https://www.w3.org/WAI/WCAG21/Techniques/html/H64)).
 
 ## Examples
 
@@ -27,12 +29,43 @@ This rule **forbids** the following:
 <template>
   <iframe />
   <iframe title='' />
+  <iframe title='   ' />
+  <iframe title={{null}} />
+  <iframe title={{undefined}} />
+  <iframe title={{42}} />
 </template>
 ```
 
+Whitespace-only `title` (`"   "`) is flagged by default as an
+authoring-hygiene check: HTML and ACCNAME technically permit it (step 2I
+doesn't trim), but a whitespace-only accessible name is useless in
+practice. Suppress this specific strictness via `allowWhitespaceOnlyTitle:
+true` if your codebase needs it.
+
+## Configuration
+
+- `allowWhitespaceOnlyTitle` (`boolean`, default `false`): when `true`,
+  `<iframe title="   ">` is accepted. Empty-string `title=""` and
+  non-string mustache literals (`{{null}}`, `{{undefined}}`, `{{42}}`) are
+  still flagged.
+
+```js
+{
+  rules: {
+    'ember/template-require-iframe-title': [
+      'error',
+      { allowWhitespaceOnlyTitle: true },
+    ],
+  },
+}
+```
+
 ## References
 
-- [Deque University](https://dequeuniversity.com/rules/axe/1.1/frame-title)
-- [Technique H65: Using the title attribute of the frame and iframe elements](https://www.w3.org/TR/2014/NOTE-WCAG20-TECHS-20140408/H64)
-- [WCAG Success Criterion 2.4.1 - Bypass Blocks](https://www.w3.org/TR/UNDERSTANDING-WCAG20/navigation-mechanisms-skip.html)
-- [WCAG Success Criterion 4.1.2 - Name, Role, Value](https://www.w3.org/TR/UNDERSTANDING-WCAG20/ensure-compat-rsv.html)
+- [WCAG SC 4.1.2 — Name, Role, Value](https://www.w3.org/TR/UNDERSTANDING-WCAG20/ensure-compat-rsv.html)
+  — the normative requirement.
+- [WCAG Technique H64 — Using the title attribute of the iframe element](https://www.w3.org/WAI/WCAG21/Techniques/html/H64)
+  — a sufficient technique for SC 4.1.2, not itself normative.
+- [WCAG Success Criterion 2.4.1 — Bypass Blocks](https://www.w3.org/TR/UNDERSTANDING-WCAG20/navigation-mechanisms-skip.html)
+- [ACCNAME 1.2 — accessible-name computation](https://www.w3.org/TR/accname-1.2/)
+- [axe-core rule `frame-title`](https://dequeuniversity.com/rules/axe/4.10/frame-title)
diff --git a/lib/rules/template-require-iframe-title.js b/lib/rules/template-require-iframe-title.js
index 2ee9ebceee..dc12b03331 100644
--- a/lib/rules/template-require-iframe-title.js
+++ b/lib/rules/template-require-iframe-title.js
@@ -27,7 +27,17 @@ module.exports = {
       url: 'https://github.com/ember-cli/eslint-plugin-ember/tree/master/docs/rules/template-require-iframe-title.md',
       templateMode: 'both',
     },
-    schema: [],
+    schema: [
+      {
+        type: 'object',
+        properties: {
+          allowWhitespaceOnlyTitle: {
+            type: 'boolean',
+          },
+        },
+        additionalProperties: false,
+      },
+    ],
     messages: {
       // Four messageIds (missingTitle, emptyTitle, dynamicFalseTitle,
       // duplicateTitle) for richer diagnostic detail.
@@ -46,6 +56,14 @@ module.exports = {
     },
   },
   create(context) {
+    // Whitespace-only `title="   "` is technically spec-compliant: ACCNAME
+    // 1.2 step 2I (Tooltip) does not whitespace-trim like step 2D
+    // (aria-label) does, so a 3-space accessible name is assigned. That is
+    // useless in practice but not a spec violation. Default behavior flags
+    // it as authoring hygiene; set `allowWhitespaceOnlyTitle: true` to
+    // align with spec/peer behavior.
+    const allowWhitespaceOnlyTitle = Boolean(context.options[0]?.allowWhitespaceOnlyTitle);
+
     // Each entry: { value, node, index }
     //  - value: trimmed title string
     //  - node: original element node for the first occurrence
@@ -76,9 +94,15 @@ module.exports = {
         if (titleAttr.value) {
           switch (titleAttr.value.type) {
             case 'GlimmerTextNode': {
-              const value = titleAttr.value.chars.trim();
+              const raw = titleAttr.value.chars;
+              const value = raw.trim();
               if (value.length === 0) {
-                context.report({ node, messageId: 'emptyTitle' });
+                // Distinguish genuine empty-string (always flagged — not a
+                // string) from whitespace-only (spec-compliant but hygiene
+                // check). Whitespace-only case respects the schema option.
+                if (raw.length === 0 || !allowWhitespaceOnlyTitle) {
+                  context.report({ node, messageId: 'emptyTitle' });
+                }
               } else {
                 // Check for duplicate titles. Reports BOTH the first and the
                 // current occurrence on every collision, sharing a `#N` index
diff --git a/tests/lib/rules/template-require-iframe-title.js b/tests/lib/rules/template-require-iframe-title.js
index 94fced6c92..1c925cf104 100644
--- a/tests/lib/rules/template-require-iframe-title.js
+++ b/tests/lib/rules/template-require-iframe-title.js
@@ -18,6 +18,11 @@ ruleTester.run('template-require-iframe-title', rule, {
     '<template><iframe title="" aria-hidden /></template>',
     '<template><iframe title="" hidden /></template>',
     '<template><iframe title="foo" /><iframe title="bar" /></template>',
+    // allowWhitespaceOnlyTitle: true — whitespace-only accepted.
+    {
+      code: '<template><iframe title="   " /></template>',
+      options: [{ allowWhitespaceOnlyTitle: true }],
+    },
   ],
   invalid: [
     {
@@ -136,6 +141,21 @@ ruleTester.run('template-require-iframe-title', rule, {
       output: null,
       errors: [{ messageId: 'dynamicFalseTitle' }],
     },
+
+    // Whitespace-only title is flagged by default (authoring hygiene).
+    {
+      code: '<template><iframe title="   " /></template>',
+      output: null,
+      errors: [{ messageId: 'emptyTitle' }],
+    },
+    // Empty-string title is flagged even with allowWhitespaceOnlyTitle: true
+    // (an empty string is not a whitespace string).
+    {
+      code: '<template><iframe title="" /></template>',
+      options: [{ allowWhitespaceOnlyTitle: true }],
+      output: null,
+      errors: [{ messageId: 'emptyTitle' }],
+    },
   ],
 });
 

From 09f1a8fe0f0dd2fc8c6008905e8cebcfdeb1edba Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johan=20R=C3=B8ed?= <johanroed@gmail.com>
Date: Wed, 22 Apr 2026 12:18:49 +0200
Subject: [PATCH 4/7] lint: make js code block standalone-parseable + fix test
 property order

- docs/rules/template-require-iframe-title.md: wrap the config example
  in `module.exports = {...}` so eslint can parse it as a standalone
  module (bare object literals are parsed as block statements, which
  trips 'missing semicolon' on the inner object).
- tests/lib/rules/template-require-iframe-title.js: move `output`
  before `options` on the allowWhitespaceOnlyTitle test case to match
  eslint-plugin/test-case-property-ordering's [code, output, options,
  errors] sequence.
- Prettier reflow of the config example (single-line rule array)
  applied via `prettier --write`.
---
 docs/rules/template-require-iframe-title.md      | 11 ++++-------
 tests/lib/rules/template-require-iframe-title.js |  2 +-
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/docs/rules/template-require-iframe-title.md b/docs/rules/template-require-iframe-title.md
index 22da0ecfd2..6a09672a2b 100644
--- a/docs/rules/template-require-iframe-title.md
+++ b/docs/rules/template-require-iframe-title.md
@@ -9,7 +9,7 @@
 `<iframe>` elements must have a unique title property so assistive
 technology can convey their content to the user. The normative
 requirement is [WCAG SC 4.1.2 (Name, Role, Value)](https://www.w3.org/TR/UNDERSTANDING-WCAG20/ensure-compat-rsv.html);
-the `title` attribute is *one sufficient technique* for meeting it
+the `title` attribute is _one sufficient technique_ for meeting it
 (sufficient technique [H64](https://www.w3.org/WAI/WCAG21/Techniques/html/H64)).
 
 ## Examples
@@ -50,14 +50,11 @@ true` if your codebase needs it.
   still flagged.
 
 ```js
-{
+module.exports = {
   rules: {
-    'ember/template-require-iframe-title': [
-      'error',
-      { allowWhitespaceOnlyTitle: true },
-    ],
+    'ember/template-require-iframe-title': ['error', { allowWhitespaceOnlyTitle: true }],
   },
-}
+};
 ```
 
 ## References
diff --git a/tests/lib/rules/template-require-iframe-title.js b/tests/lib/rules/template-require-iframe-title.js
index 1c925cf104..487456c0c3 100644
--- a/tests/lib/rules/template-require-iframe-title.js
+++ b/tests/lib/rules/template-require-iframe-title.js
@@ -152,8 +152,8 @@ ruleTester.run('template-require-iframe-title', rule, {
     // (an empty string is not a whitespace string).
     {
       code: '<template><iframe title="" /></template>',
-      options: [{ allowWhitespaceOnlyTitle: true }],
       output: null,
+      options: [{ allowWhitespaceOnlyTitle: true }],
       errors: [{ messageId: 'emptyTitle' }],
     },
   ],

From ab22acda9b3555661ceee0f82eee7fe0a1c590cf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johan=20R=C3=B8ed?= <johanroed@gmail.com>
Date: Wed, 22 Apr 2026 14:21:17 +0200
Subject: [PATCH 5/7] fix: rename messageId + honest comment wording +
 literal-type check refactor (Copilot review)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- messageId `dynamicFalseTitle` renamed to `invalidTitleLiteral` — the rule
  flags booleans, null, undefined, AND numbers, not just `false`.
- Message text generalized and now includes the literal type (boolean/null/
  undefined/number) via a {{literalType}} interpolation.
- Comment at rule top no longer claims `true` coerces to an empty-ish string
  (it doesn't — String(true) === "true"); reworded to explain that non-string
  literals don't describe frame content even when they would coerce.
- Comment inside empty-string branch reworded — "not a string" was wrong.
- isInvalidTitleLiteral() replaced with a Set-backed lookup
  (INVALID_LITERAL_TYPES) for cleaner membership checks.
- Test assertions for the renamed messageId updated (unit + audit fixture);
  hbs-tester text assertions updated for the new message format.
---
 lib/rules/template-require-iframe-title.js    | 76 +++++++++++++------
 tests/audit/iframe-title/peer-parity.js       | 22 +++---
 .../rules/template-require-iframe-title.js    | 30 +++++---
 3 files changed, 82 insertions(+), 46 deletions(-)

diff --git a/lib/rules/template-require-iframe-title.js b/lib/rules/template-require-iframe-title.js
index dc12b03331..b333b44d1d 100644
--- a/lib/rules/template-require-iframe-title.js
+++ b/lib/rules/template-require-iframe-title.js
@@ -1,20 +1,37 @@
-// Mustache path nodes that produce no accessible name. Booleans, null, undefined
-// all coerce to empty-ish strings; numeric literals ("42") are accepted by HTML
-// but provide no useful title for assistive tech.
-function isInvalidTitleLiteral(path) {
-  if (!path) {
-    return false;
-  }
-  if (path.type === 'GlimmerBooleanLiteral') {
-    return true;
-  }
-  if (path.type === 'GlimmerNullLiteral' || path.type === 'GlimmerUndefinedLiteral') {
-    return true;
-  }
-  if (path.type === 'GlimmerNumberLiteral') {
-    return true;
+// Non-string literal AST nodes (boolean/null/undefined/number) don't represent
+// a meaningful author-provided title. Even though they would coerce to strings
+// at runtime (e.g. `true` → "true", `42` → "42"), those strings do not describe
+// the frame's content — the rule rejects the literal forms.
+const INVALID_LITERAL_TYPES = new Set([
+  'GlimmerBooleanLiteral',
+  'GlimmerNullLiteral',
+  'GlimmerUndefinedLiteral',
+  'GlimmerNumberLiteral',
+]);
+
+function isInvalidTitleLiteralPath(path) {
+  return INVALID_LITERAL_TYPES.has(path?.type);
+}
+
+function getInvalidLiteralType(path) {
+  if (!path) {return undefined;}
+  switch (path.type) {
+    case 'GlimmerBooleanLiteral': {
+      return 'boolean';
+    }
+    case 'GlimmerNullLiteral': {
+      return 'null';
+    }
+    case 'GlimmerUndefinedLiteral': {
+      return 'undefined';
+    }
+    case 'GlimmerNumberLiteral': {
+      return 'number';
+    }
+    default: {
+      return undefined;
+    }
   }
-  return false;
 }
 
 /** @type {import('eslint').Rule.RuleModule} */
@@ -39,11 +56,12 @@ module.exports = {
       },
     ],
     messages: {
-      // Four messageIds (missingTitle, emptyTitle, dynamicFalseTitle,
+      // Four messageIds (missingTitle, emptyTitle, invalidTitleLiteral,
       // duplicateTitle) for richer diagnostic detail.
       missingTitle: '<iframe> elements must have a unique title property.',
       emptyTitle: '<iframe> elements must have a unique title property.',
-      dynamicFalseTitle: '<iframe> elements must have a unique title property.',
+      invalidTitleLiteral:
+        '<iframe title> must be a non-empty string. Got a {{literalType}} literal, which does not describe the frame contents.',
       duplicateTitleFirst: 'This title is not unique. #{{index}}',
       duplicateTitleOther:
         '<iframe> elements must have a unique title property. Value title="{{title}}" already used for different iframe. #{{index}}',
@@ -97,9 +115,9 @@ module.exports = {
               const raw = titleAttr.value.chars;
               const value = raw.trim();
               if (value.length === 0) {
-                // Distinguish genuine empty-string (always flagged — not a
-                // string) from whitespace-only (spec-compliant but hygiene
-                // check). Whitespace-only case respects the schema option.
+                // Empty-string title always fails: no accessible name for screen readers.
+                // Whitespace-only titles are controlled by the `allowWhitespaceOnlyTitle`
+                // option (default false).
                 if (raw.length === 0 || !allowWhitespaceOnlyTitle) {
                   context.report({ node, messageId: 'emptyTitle' });
                 }
@@ -138,8 +156,12 @@ module.exports = {
             case 'GlimmerMustacheStatement': {
               // title={{false}} / title={{null}} / title={{undefined}} / title={{42}}
               // — any literal that doesn't produce a meaningful accessible name.
-              if (isInvalidTitleLiteral(titleAttr.value.path)) {
-                context.report({ node, messageId: 'dynamicFalseTitle' });
+              if (isInvalidTitleLiteralPath(titleAttr.value.path)) {
+                context.report({
+                  node,
+                  messageId: 'invalidTitleLiteral',
+                  data: { literalType: getInvalidLiteralType(titleAttr.value.path) },
+                });
               }
               break;
             }
@@ -150,9 +172,13 @@ module.exports = {
               if (
                 parts.length === 1 &&
                 parts[0].type === 'GlimmerMustacheStatement' &&
-                isInvalidTitleLiteral(parts[0].path)
+                isInvalidTitleLiteralPath(parts[0].path)
               ) {
-                context.report({ node, messageId: 'dynamicFalseTitle' });
+                context.report({
+                  node,
+                  messageId: 'invalidTitleLiteral',
+                  data: { literalType: getInvalidLiteralType(parts[0].path) },
+                });
               }
               break;
             }
diff --git a/tests/audit/iframe-title/peer-parity.js b/tests/audit/iframe-title/peer-parity.js
index de95a37bd0..a353330271 100644
--- a/tests/audit/iframe-title/peer-parity.js
+++ b/tests/audit/iframe-title/peer-parity.js
@@ -96,43 +96,43 @@ ruleTester.run('audit:iframe-title (gts)', rule, {
     {
       code: '<template><iframe title={{false}} /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral' }],
     },
     {
       code: '<template><iframe title={{true}} /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral' }],
     },
     {
       code: '<template><iframe title={{null}} /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral' }],
     },
     {
       code: '<template><iframe title={{undefined}} /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral' }],
     },
     {
       code: '<template><iframe title={{42}} /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral' }],
     },
     // Concat form — `title="{{false}}"` / etc. also flagged.
     {
       code: '<template><iframe title="{{false}}" /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral' }],
     },
     {
       code: '<template><iframe title="{{null}}" /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral' }],
     },
     {
       code: '<template><iframe title="{{42}}" /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral' }],
     },
 
     // === DIVERGENCE — duplicate-title detection ===
@@ -181,17 +181,17 @@ hbsRuleTester.run('audit:iframe-title (hbs)', rule, {
     {
       code: '<iframe title={{false}} />',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral' }],
     },
     {
       code: '<iframe title={{undefined}} />',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral' }],
     },
     {
       code: '<iframe title={{42}} />',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral' }],
     },
     // DIVERGENCE — duplicate detection (upstream does not check).
     {
diff --git a/tests/lib/rules/template-require-iframe-title.js b/tests/lib/rules/template-require-iframe-title.js
index 487456c0c3..6db4a8a52c 100644
--- a/tests/lib/rules/template-require-iframe-title.js
+++ b/tests/lib/rules/template-require-iframe-title.js
@@ -97,12 +97,12 @@ ruleTester.run('template-require-iframe-title', rule, {
     {
       code: '<template><iframe src="12" title={{false}} /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral', data: { literalType: 'boolean' } }],
     },
     {
       code: '<template><iframe src="12" title="{{false}}" /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral', data: { literalType: 'boolean' } }],
     },
     {
       code: '<template><iframe src="12" title="" /></template>',
@@ -114,32 +114,32 @@ ruleTester.run('template-require-iframe-title', rule, {
     {
       code: '<template><iframe title={{null}} /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral', data: { literalType: 'null' } }],
     },
     {
       code: '<template><iframe title={{undefined}} /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral', data: { literalType: 'undefined' } }],
     },
     {
       code: '<template><iframe title={{42}} /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral', data: { literalType: 'number' } }],
     },
     {
       code: '<template><iframe title="{{null}}" /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral', data: { literalType: 'null' } }],
     },
     {
       code: '<template><iframe title="{{undefined}}" /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral', data: { literalType: 'undefined' } }],
     },
     {
       code: '<template><iframe title="{{42}}" /></template>',
       output: null,
-      errors: [{ messageId: 'dynamicFalseTitle' }],
+      errors: [{ messageId: 'invalidTitleLiteral', data: { literalType: 'number' } }],
     },
 
     // Whitespace-only title is flagged by default (authoring hygiene).
@@ -229,12 +229,22 @@ hbsRuleTester.run('template-require-iframe-title', rule, {
     {
       code: '<iframe src="12" title={{false}} />',
       output: null,
-      errors: [{ message: '<iframe> elements must have a unique title property.' }],
+      errors: [
+        {
+          message:
+            '<iframe title> must be a non-empty string. Got a boolean literal, which does not describe the frame contents.',
+        },
+      ],
     },
     {
       code: '<iframe src="12" title="{{false}}" />',
       output: null,
-      errors: [{ message: '<iframe> elements must have a unique title property.' }],
+      errors: [
+        {
+          message:
+            '<iframe title> must be a non-empty string. Got a boolean literal, which does not describe the frame contents.',
+        },
+      ],
     },
     {
       code: '<iframe src="12" title="" />',

From 42e7f102e0e749ac990ba1d9ca5ba17319b0b989 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johan=20R=C3=B8ed?= <johanroed@gmail.com>
Date: Wed, 22 Apr 2026 14:47:03 +0200
Subject: [PATCH 6/7] fix: prettier formatting

---
 lib/rules/template-require-iframe-title.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/rules/template-require-iframe-title.js b/lib/rules/template-require-iframe-title.js
index b333b44d1d..12b0abdcc5 100644
--- a/lib/rules/template-require-iframe-title.js
+++ b/lib/rules/template-require-iframe-title.js
@@ -14,7 +14,9 @@ function isInvalidTitleLiteralPath(path) {
 }
 
 function getInvalidLiteralType(path) {
-  if (!path) {return undefined;}
+  if (!path) {
+    return undefined;
+  }
   switch (path.type) {
     case 'GlimmerBooleanLiteral': {
       return 'boolean';

From 1fd8b3ba62537cab44b1b04efad8f26456b2ad05 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johan=20R=C3=B8ed?= <johanroed@gmail.com>
Date: Wed, 22 Apr 2026 16:51:55 +0200
Subject: [PATCH 7/7] docs: correct audit-fixture CI-run claim (Copilot review)

---
 tests/audit/iframe-title/peer-parity.js | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/tests/audit/iframe-title/peer-parity.js b/tests/audit/iframe-title/peer-parity.js
index a353330271..f7c8584182 100644
--- a/tests/audit/iframe-title/peer-parity.js
+++ b/tests/audit/iframe-title/peer-parity.js
@@ -1,7 +1,15 @@
-// Audit fixture — peer-plugin parity for `ember/template-require-iframe-title`.
-// These tests are NOT part of the main suite and do not run in CI. They encode
-// the CURRENT behavior of our rule so that running this file reports pass.
-// Each divergence from an upstream plugin is annotated as "DIVERGENCE —".
+// Audit fixture — translates peer-plugin test cases into assertions against
+// our rule (`ember/template-require-iframe-title`). Runs as part of the
+// default Vitest suite (via the `tests/**/*.js` include glob) and serves
+// double-duty: (1) auditable record of peer-parity divergences,
+// (2) regression coverage pinning CURRENT behavior. Each case encodes what
+// OUR rule does today; divergences from upstream plugins are annotated as
+// `DIVERGENCE —`. Peer-only constructs that can't be translated to Ember
+// templates (JSX spread props, Vue v-bind, Angular `$event`, undefined-handler
+// expression analysis) are marked `AUDIT-SKIP`.
+//
+// Peers covered: jsx-a11y/iframe-has-title,
+// vuejs-accessibility/iframe-has-title, lit-a11y/iframe-title.
 //
 // Source files (context/ checkouts):
 //   - eslint-plugin-jsx-a11y-main/__tests__/src/rules/iframe-has-title-test.js