msynk · Oct 11, 2026 · Oct 11, 2026 · Oct 11, 2026 · Oct 11, 2026 · Oct 11, 2026
@@ -139,7 +139,7 @@ $rte-rule-color: var(--bit-RichTextEditor-table-border-color, #{$clr-brd-pri});
     display: block;
     color: inherit;
     font-size: $tg-fs-sm;
-    font-weight: $tg-fw-semibold;
+    font-weight: $tg-field-label-font-weight;
     letter-spacing: $tg-ctrl-letter-spacing;
     padding: spacing(0.75) spacing(1) spacing(0.5);
 }

@@ -23,7 +23,7 @@
 //   --bit-Rating-active-scale       how much the pressed item dips                 (default: 0.9; 1 turns it off)
 //   --bit-Rating-label-color        text color of the label                        (default: $clr-fg-pri)
 //   --bit-Rating-label-font-size    text size of the label                         (default: $tg-fs-sm)
-//   --bit-Rating-label-font-weight  text weight of the label                       (default: $tg-fw-semibold)
+//   --bit-Rating-label-font-weight  text weight of the label                       (default: $tg-field-label-font-weight)
 //   --bit-Rating-label-gap          room between the label and the items, and
 //                                   between the items and the description         (default: spacing(1))
 //   --bit-Rating-description-color  text color of the description                  (default: $clr-fg-sec)
@@ -161,7 +161,7 @@ $rtg-private-properties: clr, clr-hover, clr-active, clr-focus, size, lbl-size,
     letter-spacing: $tg-ctrl-letter-spacing;
     color: var(--bit-Rating-label-color, #{$clr-fg-pri});
     font-size: var(--bit-rtg-lbl-size, var(--bit-Rating-label-font-size, #{$tg-fs-sm}));
-    font-weight: var(--bit-Rating-label-font-weight, #{$tg-fw-semibold});
+    font-weight: var(--bit-Rating-label-font-weight, #{$tg-field-label-font-weight});
 }
 
 // The hint that sits under the items, pointed at by aria-describedby rather than read as part of the

@@ -48,7 +48,7 @@
 //   --bit-Toggle-content-padding             inset of the track content from the ends of
 //                                            the track                                     (default: spacing(0.375))
 //   --bit-Toggle-label-font-size             the label                                     (default: $tg-fs-sm)
-//   --bit-Toggle-label-font-weight           the label                                     (default: $tg-fw-semibold)
+//   --bit-Toggle-label-font-weight           the label                                     (default: $tg-field-label-font-weight)
 //   --bit-Toggle-text-font-size              the state text                                (default: inherited from the page)
 //   --bit-Toggle-description-font-size       the description                               (default: $tg-fs-xs)
 //   --bit-Toggle-error-font-size             the error message line                        (default: $tg-fs-xs)

@@ -554,7 +554,7 @@ public partial class BitRatingDemo
         new()
         {
             Name = "--bit-Rating-label-font-weight",
-            DefaultValue = "--bit-tpg-fw-semibold",
+            DefaultValue = "--bit-tpg-field-label-font-weight",
             Description = "Text weight of the label.",
         },
         new()

@@ -0,0 +1,254 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Text.RegularExpressions;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace Bit.BlazorUI.Tests.Utils.Theme;
+
+/// <summary>
+/// Pins that every caption naming a form field takes its weight from the theme's field-label token
+/// (<c>$tg-field-label-font-weight</c>), the one BitLabel reads too, and nothing else.
+/// </summary>
+/// <remarks>
+/// Fluent captions a field semibold, while Fluent 2, Material and Cupertino caption it regular, so a caption that
+/// reads any weight of its own - the semibold step, another step, <c>$tg-font-weight</c> or a literal - stays that
+/// weight under those presets beside every other input and BitLabel. Reading the token through the theme also keeps
+/// a caption following a <c>FontWeights</c> override of a BitThemeProvider, since the alias is re-declared for the
+/// overlay (the <c>typography</c> group).
+/// <para>
+/// Every class a component stylesheet names like a caption (a part ending in <c>-lbl</c>, <c>-rlb</c> or
+/// <c>-label</c>) is classified below, either as a field's caption or as a label that is not one (a button's text, a
+/// tag's, a pager's), so a new input's caption cannot slip past the contract unlisted. Every rule that
+/// targets a field caption is read - a grouped selector, a nested one, one inside <c>@media</c> - and each of its
+/// <c>font-weight</c> declarations has to read the token.
+/// </para>
+/// </remarks>
+[TestClass]
+public sealed class BitFieldLabelFontWeightContractTests
+{
+    private const string FieldLabelToken = "$tg-field-label-font-weight";
+
+    // The captions that name a form field, with the stylesheet each is styled in.
+    private static readonly (string Caption, string Path)[] FieldCaptions =
+    [
+        (".bit-chg-lbl", "Bit.BlazorUI/Components/Inputs/ChoiceGroup/BitChoiceGroup.scss"),
+        (".bit-ctp-lbl", "Bit.BlazorUI/Components/Inputs/CircularTimePicker/BitCircularTimePicker.scss"),
+        (".bit-clp-lbl", "Bit.BlazorUI/Components/Inputs/ColorPicker/BitColorPicker.scss"),
+        (".bit-dtp-lbl", "Bit.BlazorUI/Components/Inputs/DatePicker/BitDatePicker.scss"),
+        (".bit-dtrp-lbl", "Bit.BlazorUI/Components/Inputs/DateRangePicker/BitDateRangePicker.scss"),
+        (".bit-drp-lbl", "Bit.BlazorUI/Components/Inputs/Dropdown/BitDropdown.scss"),
+        (".bit-nfl-lbl", "Bit.BlazorUI/Components/Inputs/NumberField/BitNumberField.scss"),
+        (".bit-otp-lbl", "Bit.BlazorUI/Components/Inputs/OtpInput/BitOtpInput.scss"),
+        (".bit-rtg-lbl", "Bit.BlazorUI/Components/Inputs/Rating/BitRating.scss"),
+        (".bit-srb-lbl", "Bit.BlazorUI/Components/Inputs/SearchBox/BitSearchBox.scss"),
+        (".bit-sld-lbl", "Bit.BlazorUI/Components/Inputs/Slider/BitSlider.scss"),
+        (".bit-tgi-lbl", "Bit.BlazorUI/Components/Inputs/TagsInput/BitTagsInput.scss"),
+        (".bit-tfl-lbl", "Bit.BlazorUI/Components/Inputs/TextField/BitTextField.scss"),
+        (".bit-tpc-lbl", "Bit.BlazorUI/Components/Inputs/TimePicker/BitTimePicker.scss"),
+        (".bit-tgl-lbl", "Bit.BlazorUI/Components/Inputs/Toggle/BitToggle.scss"),
+        (".bit-bfc-field-label", "Bit.BlazorUI.Extras/Components/FullCalendar/BitFullCalendar.scss"),
+        (".bit-mde-lbl", "Bit.BlazorUI.Extras/Components/MarkdownEditor/BitMarkdownEditor.scss"),
+        (".bit-phi-lbl", "Bit.BlazorUI.Extras/Components/PhoneInput/BitPhoneInput.scss"),
+        (".bit-phi-rlb", "Bit.BlazorUI.Extras/Components/PhoneInput/BitPhoneInput.scss"),
+        (".bit-rte-lbl", "Bit.BlazorUI.Extras/Components/RichTextEditor/BitRichTextEditor.scss"),
+    ];
+
+    // The classes named like a caption that caption no field, so their weight is their own component's decision.
+    private static readonly HashSet<string> OtherLabels =
+    [
+        ".bit-acb-lbl", // the text of an action button
+        ".bit-btn-lbl", // the loading text of a button
+        ".bit-tgb-lbl", // the loading text of a toggle button
+        ".bit-chb-lbl", // the clickable row of a checkbox: the box and its text, read at the body weight
+        ".bit-fin-lbl", // the browse button of a file input
+        ".bit-upl-lbl", // the browse button / drop area of a file upload
+        ".bit-ldn-lbl", // the text under a loading indicator
+        ".bit-prb-lbl", // the text of a progress bar
+        ".bit-pgn-lbl", // the page text of a pagination
+        ".bit-tag-lbl", // the text of a tag
+        ".bit-dtg-chooser-label", // a checkbox row of a data grid's column chooser
+        ".bit-pdv-page-label", // the page number of a pdf viewer
+        ".bit-pdv-thumb-label", // the number under a pdf viewer's thumbnail
+        ".bit-bfc-bg-event-label", // the title of a full calendar's background event
+        ".bit-bfc-dropdown-label", // the heading of a section of a full calendar's settings menu
+        ".bit-bfc-dtp-month-label", // the month a full calendar's date picker shows
+        ".bit-bfc-event-detail-label", // the term of a row of a full calendar's event details
+        ".bit-bfc-repeat-dates-label", // the heading of the skipped / added dates of a repeating event
+        ".bit-bfc-time-slot-label", // the time of a full calendar's slot
+        ".bit-bfc-timeline-label", // the time on a full calendar's timeline
+        ".bit-bfc-tl-time-cell-label", // the time of a full calendar's timeline cell
+    ];
+
+    // A class named like a caption: a part of a component whose name ends in lbl, rlb or label. The name must end
+    // there: --bit-btn-lbl-fontsize is no class, .bit-tfl-lbl-x is another part.
+    private static readonly Regex CaptionClass = new(
+        @"\.bit-[a-z0-9]+(?:-[a-z0-9]+)*-(?:lbl|rlb|label)(?![-\w])",
+        RegexOptions.Compiled);
+
+    // The font-weight property itself - never a custom property whose name ends in font-weight - with its value,
+    // interpolations (#{...}) included.
+    private static readonly Regex FontWeight = new(
+        @"(?<![-\w])font-weight\s*:\s*(?<value>(?:#\{[^}]*\}|[^;{}])+)",
+        RegexOptions.Compiled);
+
+    // A weight of its own, once the token is taken out of the value: a typography step or the base weight, a number
+    // or a keyword.
+    private static readonly Regex OtherWeight = new(
+        @"\$tg-(?:fw-|font-weight)|(?<![-\w])[1-9]00(?![-\w])|(?<![-\w])(?:normal|bold|bolder|lighter|inherit)(?![-\w])",
+        RegexOptions.Compiled);
+
+    [TestMethod]
+    public void EveryCaptionClassShouldBeClassified()
+    {
+        var fieldCaptions = FieldCaptions.Select(c => c.Caption).ToHashSet();
+        var found = new Dictionary<string, string>();
+
+        foreach (var file in EnumerateComponentStylesheets())
+        {
+            var stylesheet = SourceFiles.StripScssComments(SourceFiles.ReadFullPath(file));
+
+            foreach (var rule in SourceFiles.GetScssRules(stylesheet))
+            {
+                foreach (Match match in CaptionClass.Matches(rule.Header))
+                {
+                    found.TryAdd(match.Value, Path.GetRelativePath(SourceFiles.Root, file));
+                }
+            }
+        }
+
+        var unclassified = found.Where(c => fieldCaptions.Contains(c.Key) is false && OtherLabels.Contains(c.Key) is false)
+                                .Select(c => $"{c.Value}: {c.Key}")
+                                .ToList();
+
+        Assert.AreEqual(0, unclassified.Count,
+            "These classes are named like a caption but are in neither list of this test - a field's caption goes in " +
+            "FieldCaptions, any other label in OtherLabels:\n" + string.Join("\n", unclassified));
+
+        var stale = fieldCaptions.Concat(OtherLabels).Where(c => found.ContainsKey(c) is false).ToList();
+
+        Assert.AreEqual(0, stale.Count, "No component stylesheet styles these listed classes any more:\n" + string.Join("\n", stale));
+    }
+
+    [TestMethod]
+    public void FieldCaptionShouldTakeItsWeightFromTheFieldLabelToken()
+    {
+        var offenders = new List<string>();
+
+        foreach (var (caption, path) in FieldCaptions)
+        {
+            var stylesheet = SourceFiles.StripScssComments(SourceFiles.Read(path.Split('/')));
+            var weighted = 0;
+
+            foreach (var rule in SourceFiles.GetScssRules(stylesheet))
+            {
+                if (ResolveSelectors(rule).Any(selector => Targets(selector, caption)) is false) continue;
+
+                var declarations = SourceFiles.GetScssDeclarations(stylesheet[rule.Index..], rule.Header);
+
+                foreach (Match weight in FontWeight.Matches(declarations))
+                {
+                    weighted++;
+
+                    var value = weight.Groups["value"].Value.Trim();
+
+                    if (value.Contains(FieldLabelToken) is false || OtherWeight.IsMatch(value.Replace(FieldLabelToken, "")))
+                    {
+                        offenders.Add($"{path}: {caption} in \"{rule.Header}\" has font-weight: {value}");
+                    }
+                }
+            }
+
+            if (weighted == 0)
+            {
+                offenders.Add($"{path}: no rule sets the font-weight of {caption}");
+            }
+        }
+
+        Assert.AreEqual(0, offenders.Count,
+            $"Every font-weight of a field caption reads {FieldLabelToken} and nothing else:\n" + string.Join("\n", offenders));
+    }
+
+    // Whether the selector's subject - its last compound, less any :not() - carries the caption class. A rule whose
+    // subject is a descendant of the caption (.bit-chb-lbl .bit-chb-box) or its pseudo-element (the required
+    // asterisk of ::after) styles something else.
+    private static bool Targets(string selector, string caption)
+    {
+        var subject = LastCompound(selector);
+
+        if (subject.Contains("::")) return false;
+
+        subject = Regex.Replace(subject, @":not\([^()]*\)", "");
+
+        return Regex.IsMatch(subject, Regex.Escape(caption) + @"(?![-\w])");
+    }
+
+    // The selectors a rule matches, its ancestors' folded in the way Sass nests them: & stands for the parent, and a
+    // selector without one is a descendant of it. An at-rule (@media, @supports, @include, @mixin) adds no selector.
+    private static IEnumerable<string> ResolveSelectors(SourceFiles.ScssRule rule)
+    {
+        if (rule.Header.StartsWith('@')) return [];
+
+        IEnumerable<string> resolved = [""];
+
+        foreach (var header in rule.Ancestors.Append(rule.Header))
+        {
+            if (header.StartsWith('@')) continue;
+
+            var parents = resolved.ToList();
+
+            resolved = SplitSelectorList(header).SelectMany(child => parents.Select(parent =>
+                parent.Length == 0 ? child.Replace("&", "")
+                : child.Contains('&') ? child.Replace("&", parent)
+                : $"{parent} {child}")).ToList();
+        }
+
+        return resolved;
+    }
+
+    private static IEnumerable<string> SplitSelectorList(string header)
+    {
+        var depth = 0;
+        var current = new StringBuilder();
+
+        foreach (var c in header)
+        {
+            if (c is '(' or '[') depth++;
+            else if (c is ')' or ']') depth--;
+
+            if (c == ',' && depth == 0)
+            {
+                yield return current.ToString().Trim();
+                current.Clear();
+            }
+            else
+            {
+                current.Append(c);
+            }
+        }
+
+        yield return current.ToString().Trim();
+    }
+
+    private static string LastCompound(string selector)
+    {
+        var depth = 0;
+        var start = 0;
+
+        for (var i = 0; i < selector.Length; i++)
+        {
+            var c = selector[i];
+
+            if (c is '(' or '[') depth++;
+            else if (c is ')' or ']') depth--;
+            else if (depth == 0 && (char.IsWhiteSpace(c) || c is '>' or '~' or '+')) start = i + 1;
+        }
+
+        return selector[start..];
+    }
+
+    private static IEnumerable<string> EnumerateComponentStylesheets()
+        => new[] { "Bit.BlazorUI", "Bit.BlazorUI.Extras" }
+            .SelectMany(project => Directory.EnumerateFiles(SourceFiles.GetDirectory(project, "Components"), "*.scss", SearchOption.AllDirectories));
+}