Retire the single-font rule

One family with weight and size contrast carrying the hierarchy is a
legitimate type system, and in practice the rule mostly punished
minimal pages: it was the loudest cross-rule noise on the fixture
corpus's should-pass columns. Removed from the registry, both engine
paths, the regex page analyzers, and the devtools category map; the
negative assertions stay as resurrection guards, and the text-content
analyzer index base shifts down one with the removal.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

cli/engine/detect-antipatterns-browser.js

@@ -139,16 +139,6 @@ const ANTIPATTERNS = [
     skillSection: 'Typography',
     skillGuideline: 'overused fonts like Inter',
   },
-  {
-    id: 'single-font',
-    category: 'slop',
-    scopes: ['type'],
-    name: 'Single font without hierarchy',
-    description:
-      'Only one font family is used for the entire page. A single family can work when weight and size contrast carry the hierarchy; otherwise pair a distinctive display font with a refined body font.',
-    skillSection: 'Typography',
-    skillGuideline: 'only one font family for the entire page',
-  },
   {
     id: 'flat-type-hierarchy',
     category: 'slop',
@@ -4712,12 +4702,6 @@ function checkTypography() {
       if (isBrandFontOnOwnDomain(font)) continue;
       findings.push({ type: 'overused-font', detail: `Primary font: ${font} (${Math.round(share * 100)}% of text)` });
     }
-
-    // Single-font check: only one distinct primary font across all text
-    if (fontUsage.size === 1) {
-      const only = [...fontUsage.keys()][0];
-      findings.push({ type: 'single-font', detail: `only font used is ${only}` });
-    }
   }
 
   const sizes = new Set();
@@ -4979,14 +4963,6 @@ function checkPageTypography(doc, win) {
     findings.push({ id: 'overused-font', snippet: `Primary font: ${font}` });
   }
 
-  // Single font
-  if (fonts.size === 1) {
-    const els = doc.querySelectorAll('*');
-    if (els.length >= 20) {
-      findings.push({ id: 'single-font', snippet: `only font used is ${[...fonts][0]}` });
-    }
-  }
-
   // Flat type hierarchy
   const sizes = new Set();
   const textEls = doc.querySelectorAll('h1, h2, h3, h4, h5, h6, p, span, a, li, td, th, label, button, div');

cli/engine/engines/regex/detect-text.mjs

@@ -241,24 +241,6 @@ const REGEX_MATCHERS = [
 ];
 
 const REGEX_ANALYZERS = [
-  // Single font
-  (content, filePath) => {
-    const fontFamilyRe = /font-family\s*:\s*([^;}]+)/gi;
-    const fonts = new Set();
-    let m;
-    while ((m = fontFamilyRe.exec(content)) !== null) {
-      for (const f of m[1].split(',').map(f => f.trim().replace(/^['"]|['"]$/g, '').toLowerCase())) {
-        if (f && !GENERIC_FONTS.has(f)) fonts.add(f);
-      }
-    }
-    for (const f of extractGoogleFontFamilies(content)) fonts.add(f);
-    if (fonts.size !== 1 || content.split('\n').length < 20) return [];
-    const name = [...fonts][0];
-    const lines = content.split('\n');
-    let line = 1;
-    for (let i = 0; i < lines.length; i++) { if (lines[i].toLowerCase().includes(name)) { line = i + 1; break; } }
-    return [finding('single-font', filePath, `only font used is ${name}`, line)];
-  },
   // Flat type hierarchy
   (content, filePath) => {
     const sizes = new Set();
@@ -626,10 +608,11 @@ const TEXT_CONTENT_ANALYZER_IDS = [
 function runTextContentAnalyzers(content, filePath, options = {}) {
   const profile = options?.profile;
   if (!shouldRunPageAnalyzers(content, filePath)) return [];
-  // The 3 text-content analyzers are at indices 3-5 in REGEX_ANALYZERS.
+  // The 3 text-content analyzers are at indices 2-4 in REGEX_ANALYZERS
+  // (single-font's removal on 2026-07-29 shifted every index down one).
   const findings = [];
   for (let i = 0; i < TEXT_CONTENT_ANALYZER_IDS.length; i++) {
-    const analyzer = REGEX_ANALYZERS[3 + i];
+    const analyzer = REGEX_ANALYZERS[2 + i];
     const ruleId = TEXT_CONTENT_ANALYZER_IDS[i];
     findings.push(...profileFindings(profile, {
       engine: 'regex',
@@ -750,7 +733,6 @@ function detectText(content, filePath, options = {}) {
   // Page-level analyzers only run on full pages
   if (shouldRunPageAnalyzers(content, filePath)) {
     const analyzerIds = [
-      'single-font',
       'flat-type-hierarchy',
       'monotonous-spacing',
       'em-dash-overuse',

cli/engine/engines/static-html/detect-html.mjs

@@ -60,9 +60,6 @@ function checkStaticPageTypography(document, window) {
   for (const font of overusedFound) {
     findings.push({ id: 'overused-font', snippet: `Primary font: ${font}` });
   }
-  if (fonts.size === 1 && document.querySelectorAll('*').length >= 20) {
-    findings.push({ id: 'single-font', snippet: `only font used is ${[...fonts][0]}` });
-  }
   const sizes = new Set();
   for (const el of document.querySelectorAll('h1, h2, h3, h4, h5, h6, p, span, a, li, td, th, label, button, div')) {
     const fontSize = parseFloat(window.getComputedStyle(el).fontSize);

cli/engine/registry/antipatterns.mjs

@@ -28,16 +28,6 @@ const ANTIPATTERNS = [
     skillSection: 'Typography',
     skillGuideline: 'overused fonts like Inter',
   },
-  {
-    id: 'single-font',
-    category: 'slop',
-    scopes: ['type'],
-    name: 'Single font without hierarchy',
-    description:
-      'Only one font family is used for the entire page. A single family can work when weight and size contrast carry the hierarchy; otherwise pair a distinctive display font with a refined body font.',
-    skillSection: 'Typography',
-    skillGuideline: 'only one font family for the entire page',
-  },
   {
     id: 'flat-type-hierarchy',
     category: 'slop',

cli/engine/rules/checks.mjs

@@ -3911,12 +3911,6 @@ function checkTypography() {
       if (isBrandFontOnOwnDomain(font)) continue;
       findings.push({ type: 'overused-font', detail: `Primary font: ${font} (${Math.round(share * 100)}% of text)` });
     }
-
-    // Single-font check: only one distinct primary font across all text
-    if (fontUsage.size === 1) {
-      const only = [...fontUsage.keys()][0];
-      findings.push({ type: 'single-font', detail: `only font used is ${only}` });
-    }
   }
 
   const sizes = new Set();
@@ -4178,14 +4172,6 @@ function checkPageTypography(doc, win) {
     findings.push({ id: 'overused-font', snippet: `Primary font: ${font}` });
   }
 
-  // Single font
-  if (fonts.size === 1) {
-    const els = doc.querySelectorAll('*');
-    if (els.length >= 20) {
-      findings.push({ id: 'single-font', snippet: `only font used is ${[...fonts][0]}` });
-    }
-  }
-
   // Flat type hierarchy
   const sizes = new Set();
   const textEls = doc.querySelectorAll('h1, h2, h3, h4, h5, h6, p, span, a, li, td, th, label, button, div');

extension/devtools/panel.js

@@ -228,7 +228,6 @@ const FIX_SKILLS = {
   'side-tab':                'distill, polish',
   'border-accent-on-rounded':'distill, polish',
   'overused-font':           'typeset',
-  'single-font':             'typeset',
   'flat-type-hierarchy':     'typeset',
   'gradient-text':           'typeset, distill',
   'ai-color-palette':        'colorize, distill',

tests/detect-antipatterns-fixtures.test.mjs

@@ -497,10 +497,12 @@ describe('detectHtml — static HTML/CSS fixtures', () => {
     assert.match(sideTabs[0].snippet, /border-left: 2px solid oklch/);
   });
 
-  it('typography-should-flag: detects all three issues', async () => {
+  it('typography-should-flag: detects both issues', async () => {
     const f = await detectHtml(path.join(FIXTURES, 'typography-should-flag.html'));
     assert.ok(f.some(r => r.antipattern === 'overused-font'));
-    assert.ok(f.some(r => r.antipattern === 'single-font'));
+    // single-font retired 2026-07-29: one family with weight/size contrast is
+    // a legitimate system, and the rule mostly punished minimal test pages.
+    assert.ok(!f.some(r => r.antipattern === 'single-font'), 'retired rule single-font should not resurface');
     assert.ok(f.some(r => r.antipattern === 'flat-type-hierarchy'));
     assert.equal(
       f.some(r => r.antipattern === 'low-contrast'),