feat: add template-valid-autocomplete

README.md

@@ -491,14 +491,15 @@ To disable a rule for an entire `.gjs`/`.gts` file, use a regular ESLint file-le
 
 ### Possible Errors
 
-| Name                                                                                                                       | Description                                                       | 💼 | 🔧 | 💡 |
-| :------------------------------------------------------------------------------------------------------------------------- | :---------------------------------------------------------------- | :- | :- | :- |
-| [template-no-extra-mut-helper-argument](docs/rules/template-no-extra-mut-helper-argument.md)                               | disallow passing more than one argument to the mut helper         | 📋 |    |    |
-| [template-no-jsx-attributes](docs/rules/template-no-jsx-attributes.md)                                                     | disallow JSX-style camelCase attributes                           |    | 🔧 |    |
-| [template-no-scope-outside-table-headings](docs/rules/template-no-scope-outside-table-headings.md)                         | disallow scope attribute outside th elements                      | 📋 |    |    |
-| [template-no-shadowed-elements](docs/rules/template-no-shadowed-elements.md)                                               | disallow ambiguity with block param names shadowing HTML elements | 📋 |    |    |
-| [template-no-unbalanced-curlies](docs/rules/template-no-unbalanced-curlies.md)                                             | disallow unbalanced mustache curlies                              | 📋 |    |    |
-| [template-no-unknown-arguments-for-builtin-components](docs/rules/template-no-unknown-arguments-for-builtin-components.md) | disallow unknown arguments for built-in components                | 📋 | 🔧 |    |
+| Name                                                                                                                       | Description                                                              | 💼 | 🔧 | 💡 |
+| :------------------------------------------------------------------------------------------------------------------------- | :----------------------------------------------------------------------- | :- | :- | :- |
+| [template-no-extra-mut-helper-argument](docs/rules/template-no-extra-mut-helper-argument.md)                               | disallow passing more than one argument to the mut helper                | 📋 |    |    |
+| [template-no-jsx-attributes](docs/rules/template-no-jsx-attributes.md)                                                     | disallow JSX-style camelCase attributes                                  |    | 🔧 |    |
+| [template-no-scope-outside-table-headings](docs/rules/template-no-scope-outside-table-headings.md)                         | disallow scope attribute outside th elements                             | 📋 |    |    |
+| [template-no-shadowed-elements](docs/rules/template-no-shadowed-elements.md)                                               | disallow ambiguity with block param names shadowing HTML elements        | 📋 |    |    |
+| [template-no-unbalanced-curlies](docs/rules/template-no-unbalanced-curlies.md)                                             | disallow unbalanced mustache curlies                                     | 📋 |    |    |
+| [template-no-unknown-arguments-for-builtin-components](docs/rules/template-no-unknown-arguments-for-builtin-components.md) | disallow unknown arguments for built-in components                       | 📋 | 🔧 |    |
+| [template-valid-autocomplete](docs/rules/template-valid-autocomplete.md)                                                   | require autocomplete attribute values to match the HTML autofill grammar |    |    |    |
 
 ### Routes
 

docs/rules/template-valid-autocomplete.md

@@ -0,0 +1,71 @@
+# ember/template-valid-autocomplete
+
+<!-- end auto-generated rule header -->
+
+This rule validates the `autocomplete` attribute against the HTML living
+standard. Browsers ignore unknown tokens and mismatched combinations
+silently, so authoring mistakes become invisible at runtime — the user
+just doesn't get the suggestions they expect.
+
+The rule handles:
+
+- `<form autocomplete>` must be `"on"` or `"off"`.
+- `<input type="hidden">` cannot use the bare values `"on"` / `"off"`.
+- `<input type="checkbox | radio | file | submit | image | reset | button">`
+  cannot use `autocomplete` at all.
+- Token grammar: tokens must be a valid combination from the section / hint /
+  contact / field-name / webauthn set, in the right order.
+
+Dynamic values (`autocomplete={{this.acValue}}`) are skipped. Static empty
+(`autocomplete=""`) and whitespace-only values are flagged: on `<form>` as
+an invalid non-on/off value, on controls as a missing field name.
+
+**Not checked**: whether a field name's control group matches the input type
+(e.g. `"current-password"` on `<input type="text">`). The HTML spec describes
+these field-name-to-control-group mappings descriptively — it does not
+prohibit mismatched pairings with a MUST/MUST NOT. UA and password-manager
+behavior varies, so such a pairing is a grammar-valid author choice whose
+UA-visibility is a UX question, not a spec violation. `html-validate` flags
+it; we don't. `eslint-plugin-jsx-a11y` and `eslint-plugin-lit-a11y` also
+don't (they delegate to axe-core's `autocomplete-valid`, which omits the
+check) — that corroborates but does not drive the decision.
+
+## Token order
+
+An autocomplete attribute value can contain these tokens, in this order:
+
+1. Optional section name (`section-*` prefix).
+2. Optional `shipping` or `billing`.
+3. Optional contact modifier: `home`, `work`, `mobile`, `fax`, `pager`
+   (only for `tel-*` / `email` / `impp` field names).
+4. Exactly one field name.
+5. Optional `webauthn`.
+
+## Examples
+
+This rule **forbids** the following:
+
+```hbs
+<form autocomplete='yes'>
+  <input autocomplete='first-name' type='text' />
+  <input autocomplete='off street-address' type='text' />
+  <input autocomplete='home email family-name' type='text' />
+  <input autocomplete='section-a' type='text' />
+</form>
+```
+
+This rule **allows** the following:
+
+```hbs
+<form autocomplete='off'>
+  <input autocomplete='email' type='email' />
+  <input autocomplete='section-ship shipping street-address' type='text' />
+  <input autocomplete='work email' type='email' />
+  <input autocomplete='new-password webauthn' type='password' />
+</form>
+```
+
+## References
+
+- [HTML spec: autofill](https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#autofill)
+- Adapted from [`html-validate`'s `valid-autocomplete`](https://html-validate.org/rules/valid-autocomplete.html) (MIT).