Rails form_with accessibility attributes and landmark role need version-specific diagnosis

Direct Answer

Do not manually add role="form" to Rails 6 forms to match Rails 7. The HTML5 specification states that a <form> with an accessible name (via aria-label, aria-labelledby, or title) is a native form landmark; adding role="form" redundantly can cause duplicate announcements in some screen readers. Instead, adopt a custom FormBuilder that normalizes landmark semantics, required/invalid attributes, and error associations across Rails 6 and 7.

Version-Specific Behavior (Confirmed)

• Rails 6.0–6.1: form_with emits no role="form". The <form> becomes a landmark only when it has an accessible name.
• Rails 7.0+: form_with adds role="form" by default. This is harmless but unnecessary on a named form.
• Both versions: Rails does not automatically add aria-required or aria-invalid based on model validations. It only adds the boolean required attribute when a presence validator exists.
• Error wrapping: The default field_error_proc wraps the input in <div class="field_with_errors">. This wrapper has no ARIA semantics; screen readers will not announce it unless the error message is linked via aria-describedby.

Recommended Normalization: Custom FormBuilder

Create ApplicationFormBuilder < ActionView::Helpers::FormBuilder and configure it as the default in config/application.rb:

# config/application.rb
config.action_view.default_form_builder = "ApplicationFormBuilder"

Override the methods that affect accessibility:

1. form_with / form_for – ensure the <form> receives an accessible name (aria-label or aria-labelledby) and omit role="form".
2. Field helpers (text_field, email_field, etc.) – add aria-required="true" when the model attribute has a presence validator; add aria-invalid="true" and aria-describedby="#{field_name}_error" when object.errors[field_name].any?.
3. Error rendering – instead of relying on field_error_proc, render an error <span id="#{field_name}_error" class="error-message" aria-live="polite"> containing the error text, and inject the aria-describedby reference on the input.

This single builder insulates the application from framework defaults (including future Rails 7.1+ changes) and guarantees identical markup across versions.

Reliable Error–Input Association

For every invalid field, the generated HTML must satisfy:

• Input has aria-invalid="true" and aria-describedby="field_error_id".
• Error element exists with id="field_error_id", role="alert" or aria-live="polite", and visible error text.
• Focus management: after a failed Turbo/HTML submit, move focus to the first invalid input (or its error message) so the announcement is immediate.

If you use Turbo Drive/Frames, ensure the error region persists across visits (e.g., render errors inside a Turbo Frame that is not replaced, or use a global aria-live region).

Verification Checklist

Check	Tool / Method	Pass Criteria
Form landmark	Chrome DevTools → Accessibility pane / Firefox Accessibility Inspector	<form> exposes as "form" landmark with non-empty accessible name
Required fields	axe-core (CI) + manual inspection	Each required input has required or aria-required="true" (not both)
Invalid fields	axe-core + manual inspection	Each invalid input has aria-invalid="true" and aria-describedby pointing to a live error element
Screen-reader announcement	NVDA (Windows) / VoiceOver (macOS)	Form landmark announced; submitting empty required fields speaks errors and moves focus
Regression guard	Custom test helper instantiating ApplicationFormBuilder	Generated markup matches expected attribute set for both Rails 6 and 7 test matrices

One Diagnostic Detail Needed

Does your application use Turbo Drive or Turbo Frames for form submissions? If yes, the error aria-live region must survive Turbo navigation (e.g., place it outside the replaced frame or use a persistent global live region). This changes the error-rendering strategy in the custom FormBuilder.