Missing grouping for related form fields

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<html lang="en">
<head>
    <meta charset="utf-8">
    <title>Form heuristics: true positives (#643)</title>
<meta name="viewport" content="width=device-width, initial-scale=1"><style>
  /* #783: page shell, so the case only reports what it is about */
  .skip, nav a { display: inline-block; padding: 12px; min-height: 44px; min-width: 44px; box-sizing: border-box; }
  button, input, select, textarea { min-height: 44px; min-width: 44px; box-sizing: border-box; }
  input[type="checkbox"], input[type="radio"] { width: 44px; height: 44px; }
</style>
</head>
<body>
    <a class="skip" href="#main">Skip to main content</a>
<header><p>Example Shop</p><nav aria-label="Main"><a href="/" aria-current="page">Home</a> <a href="/help">Help</a></nav></header>
<main id="main">
        <h1>Registration form</h1>
        <form>
            <!-- Date field without any instruction: still reported, but as
                 needs review (the format requirement is guessed from the
                 label), never as a confirmed violation -->
            <label for="dob">Date of birth</label>
            <input type="text" id="dob" name="dob">

            <!-- Two related checkboxes (same name) without fieldset/legend -->
            <p>Interests</p>
            <label><input type="checkbox" name="interests" value="news"> News</label>
            <label><input type="checkbox" name="interests" value="events"> Events</label>

            <button type="submit">Register</button>
        </form>
    </main>
<footer><p>Example Shop, 2026</p></footer>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <title>Form heuristics: true negatives (#643)</title>
<meta name="viewport" content="width=device-width, initial-scale=1"><style>
  /* #783: page shell, so the case only reports what it is about */
  .skip, nav a { display: inline-block; padding: 12px; min-height: 44px; min-width: 44px; box-sizing: border-box; }
  button, input, select, textarea { min-height: 44px; min-width: 44px; box-sizing: border-box; }
  input[type="checkbox"], input[type="radio"] { width: 44px; height: 44px; }
</style>
</head>
<body>
    <a class="skip" href="#main">Skip to main content</a>
<header><p>Example Shop</p><nav aria-label="Main"><a href="/" aria-current="page">Home</a> <a href="/help">Help</a></nav></header>
<main id="main">
        <h1>Booking form</h1>
        <form>
            <!-- Mode switch: radios correctly grouped -->
            <fieldset>
                <legend>Mode</legend>
                <label><input type="radio" name="mode" value="broken" checked> Broken</label>
                <label><input type="radio" name="mode" value="fixed"> Fixed</label>
            </fieldset>

            <!-- Date field with instructions via aria-describedby: the
                 description counts as the format instruction -->
            <label for="booking-date">Date</label>
            <input type="text" id="booking-date" name="date" inputmode="numeric" aria-describedby="booking-date-hint">
            <p id="booking-date-hint">Day of travel</p>

            <!-- "passiert" contains "pass" but is no passport field -->
            <label for="report-what">Was ist passiert?</label>
            <textarea id="report-what" name="what" rows="4" aria-describedby="report-what-hint"></textarea>
            <span id="report-what-hint">Was Sie erwartet haben und was stattdessen passiert ist</span>

            <!-- A single checkbox, and a second one with a different name:
                 neither is a group -->
            <label><input type="checkbox" class="bill-sr"> Screen reader view</label>
            <label><input type="checkbox" name="newsletter"> Send me the newsletter</label>

            <button type="submit">Search</button>
        </form>
    </main>
<footer><p>Example Shop, 2026</p></footer>
</body>
</html>