refactor(preview): remove the unused column count detection

electron/preload/frameGuide.ts

@@ -24,13 +24,6 @@ const GUIDE_VARIABLES = {
   gutter: '--site-gutter',
   widthMax: '--max-width-main',
 } as const;
-// A site-wide column count on :root, tried in this order. The app's parser
-// accepts exactly these names (guideModel.ts).
-const SITE_COLUMN_COUNT_VARIABLES = ['--site-column-count', '--site-columns'] as const;
-// Lumos keeps its column count on its auto grid rather than on :root, so a
-// page with no site-wide count is asked through an element of that class.
-const GRID_CLASS = 'grid-autofit';
-const GRID_COLUMN_COUNT_VARIABLE = '--_column-count';
 const COLUMN_COUNT_PATTERN = /^\d{1,3}$/;
 // The names the app may ask about: one per menu value (margin, gutter, maximum
 // width and column count), each a custom property name within the app's own
@@ -143,7 +136,6 @@ function measureGuide(body: HTMLElement) {
     counts: Object.fromEntries(
       menuVariables.map((name) => [name, countOf(rootStyle.getPropertyValue(name))]),
     ),
-    ...columnCountOf(body, rootStyle),
   };
 }
 
@@ -166,27 +158,6 @@ function lengthOf(
   }
 }
 
-// The site-wide count when the page declares one, else Lumos's grid count.
-function columnCountOf(body: HTMLElement, rootStyle: CSSStyleDeclaration) {
-  for (const variable of SITE_COLUMN_COUNT_VARIABLES) {
-    const site = countOf(rootStyle.getPropertyValue(variable));
-    if (site !== undefined) {
-      return { columnCount: site, columnVariable: variable };
-    }
-  }
-  const probe = appendProbe(body, '');
-  probe.className = GRID_CLASS;
-  try {
-    const grid = countOf(getComputedStyle(probe).getPropertyValue(GRID_COLUMN_COUNT_VARIABLE));
-    if (grid !== undefined) {
-      return { columnCount: grid, columnVariable: GRID_COLUMN_COUNT_VARIABLE };
-    }
-    return { columnCount: undefined, columnVariable: undefined };
-  } finally {
-    probe.remove();
-  }
-}
-
 // An invisible, zero-height element the canvas owns: its own writes never
 // start a page walk (mutationKind in frameReports.ts).
 function appendProbe(body: HTMLElement, style: string): HTMLElement {

src/features/preview/guideModel.ts

@@ -39,14 +39,6 @@ export const GUIDE_COLUMN_VARIABLE_DEFAULT = '--site-columns';
 /** The numbers are the column colour, this much more opaque than the column. */
 export const GUIDE_NUMBER_OPACITY = 0.5;
 
-/** The variables a project count is read from, in the order they are tried. */
-export const GUIDE_COLUMN_VARIABLES = [
-  '--site-column-count',
-  '--site-columns',
-  '--_column-count',
-] as const;
-export type GuideColumnVariable = (typeof GUIDE_COLUMN_VARIABLES)[number];
-
 export type GuideLengthUnit = 'px' | 'rem';
 export interface GuideLength {
   readonly amount: number;
@@ -85,7 +77,6 @@ export interface GuideMetrics {
   readonly marginPx: number | undefined;
   readonly gutterPx: number | undefined;
   readonly widthMaxPx: number | undefined;
-  readonly columns: { readonly count: number; readonly variable: GuideColumnVariable } | undefined;
   /** The menu's own variables, by name; a name the page does not declare is absent. */
   readonly variablesPx: Readonly<Record<string, number | undefined>>;
   /** The same names read as column counts; absent unless a whole number. */

src/features/preview/previewMessages.ts

@@ -12,13 +12,7 @@ import {
 } from '../../../shared/core/boundary';
 import type { Digest } from '../../../shared/core/brand';
 import { parsePreviewRender, type PreviewRender } from '../../../shared/page/previewToken';
-import {
-  GUIDE_COLUMN_VARIABLES,
-  GUIDE_LIMITS,
-  parseGuideVariableName,
-  type GuideColumnVariable,
-  type GuideMetrics,
-} from './guideModel';
+import { GUIDE_LIMITS, parseGuideVariableName, type GuideMetrics } from './guideModel';
 
 export type PreviewMessage =
   | {
@@ -209,7 +203,6 @@ function parseGuideMetrics(value: Readonly<Record<string, unknown>>): GuideMetri
     marginPx: optional(guideLength)(value['margin']),
     gutterPx: optional(guideLength)(value['gutter']),
     widthMaxPx: optional(guideLength)(value['widthMax']),
-    columns: parseGuideColumns(value['columnCount'], value['columnVariable']),
     variablesPx: Object.fromEntries(
       guideVariableEntries(value['variables']).map(([name, px]) => [
         name,
@@ -245,31 +238,12 @@ function guideLength(input: unknown): number {
   return value;
 }
 
-// The count the page found and the variable it came from; undefined when the
-// page declares none.
-function parseGuideColumns(countInput: unknown, variableInput: unknown): GuideMetrics['columns'] {
-  if (countInput === undefined) {
-    return undefined;
-  }
-  const variable = parseGuideColumnVariable(variableInput);
-  const columnCount = declaredCount(countInput);
-  return columnCount === undefined ? undefined : { count: columnCount, variable };
-}
-
 // A whole number as the page read it. Whether the guide can use it is the
 // model's to decide, so invalid variable values remain distinguishable from counts.
 function declaredCount(input: unknown): number | undefined {
   return optional(count)(input);
 }
 
-function parseGuideColumnVariable(input: unknown): GuideColumnVariable {
-  const variable = GUIDE_COLUMN_VARIABLES.find((name) => name === input);
-  if (variable === undefined) {
-    throw new Error('Preview guide: unknown column variable');
-  }
-  return variable;
-}
-
 function parseReloadReason(input: unknown): PreviewReloadReason {
   const found = PREVIEW_RELOAD_REASONS.find((reason) => reason === input);
   if (found === undefined) {

test/renderer/preview/guideModel.test.js

@@ -33,7 +33,6 @@ const LUMOS_WIDE = {
   marginPx: 48,
   gutterPx: 32,
   widthMaxPx: 1440,
-  columns: { count: 12, variable: '--_column-count' },
   variablesPx: {},
   variableCounts: {},
 };
@@ -43,7 +42,6 @@ const NOTHING_DECLARED = {
   marginPx: undefined,
   gutterPx: undefined,
   widthMaxPx: undefined,
-  columns: undefined,
   variablesPx: {},
   variableCounts: {},
 };
@@ -167,11 +165,7 @@ test('automatic columns follow site-columns as it changes and show the binding',
 test('automatic columns fall back to 12 for missing or unusable site-columns', () => {
   assert.equal(guideColumnText(GUIDE_DEFAULTS.columns), '12');
   for (const count of [undefined, 0, 3, 25, 4.5, Number.NaN, Infinity]) {
-    const metrics = {
-      ...LUMOS_WIDE,
-      columns: { count: 8, variable: '--site-column-count' },
-      variableCounts: { '--site-columns': count },
-    };
+    const metrics = { ...LUMOS_WIDE, variableCounts: { '--site-columns': count } };
     const guide = resolveGuide(metrics, GUIDE_DEFAULTS);
     assert.equal(guide.columnCount, 12);
     assert.equal(guide.columnSource, 'stacki');
@@ -194,11 +188,7 @@ test('a connected column variable follows the page and updates with its value',
 test('unusable column variables fall back to 12, never another project variable', () => {
   const settings = { ...GUIDE_DEFAULTS, columns: variable('--cols') };
   for (const count of [undefined, 0, 3, 25, 4.5, Number.NaN, Infinity]) {
-    const metrics = {
-      ...LUMOS_WIDE,
-      columns: { count: 8, variable: '--site-columns' },
-      variableCounts: { '--cols': count },
-    };
+    const metrics = { ...LUMOS_WIDE, variableCounts: { '--cols': count, '--site-columns': 8 } };
     assert.equal(resolveGuide(metrics, settings).columnCount, 12);
     assert.equal(resolveGuide(metrics, settings).columnSource, 'stacki');
   }

test/renderer/preview/previewMessages.test.js

@@ -183,8 +183,6 @@ test('guide measurements parse, absent values stay absent, and bounds hold', ()
     margin: 48,
     gutter: 32,
     widthMax: undefined,
-    columnCount: 12,
-    columnVariable: '--_column-count',
     variables: { '--pad': 40, '--missing': undefined },
     counts: { '--cols': 10, '--pad': undefined },
   };
@@ -196,7 +194,6 @@ test('guide measurements parse, absent values stay absent, and bounds hold', ()
       marginPx: 48,
       gutterPx: 32,
       widthMaxPx: undefined,
-      columns: { count: 12, variable: '--_column-count' },
       variablesPx: { '--pad': 40, '--missing': undefined },
       variableCounts: { '--cols': 10, '--pad': undefined },
     },
@@ -205,26 +202,14 @@ test('guide measurements parse, absent values stay absent, and bounds hold', ()
   for (const count of [0, 49, 140, 999]) {
     const counts = { '--cols': count };
     assert.equal(parsePreviewMessage({ ...guide, counts }).metrics.variableCounts['--cols'], count);
-    const site = { ...guide, columnCount: count };
-    assert.equal(parsePreviewMessage(site).metrics.columns.count, count);
   }
-  for (const variable of ['--site-column-count', '--site-columns', '--_column-count']) {
-    const site = { ...guide, columnCount: 10, columnVariable: variable };
-    assert.deepEqual(parsePreviewMessage(site).metrics.columns, { count: 10, variable });
-  }
-  assert.equal(
-    parsePreviewMessage({ ...guide, columnCount: undefined }).metrics.columns,
-    undefined,
-  );
   for (const bad of [
     { margin: -1 },
     { gutter: Number.NaN },
     { widthMax: 100_001 },
     { viewportWidth: '1440' },
     { rootFontSize: 0 },
     { rootFontSize: 1_001 },
-    { columnCount: 2.5 },
-    { columnVariable: '--anything' },
     { margin: PLATFORM_NULL },
     { variables: undefined },
     { variables: { '--pad': -1 } },