@@ -0,0 +1,16 @@
+---
+'@objectstack/driver-memory': patch
+'@objectstack/core': patch
+'@objectstack/service-analytics': patch
+---
+
+fix(driver-memory): a preset `dateRange` on a `date` field counts the reference time zone's calendar days on the in-memory analytics face
+
+Clause-②: yes (widening)
+Metadata-protocol: none
+
+An analytics query on the in-memory driver with a preset `dateRange` (`this_quarter`, `this_month`, …) on a dimension whose field is declared `type: 'date'` counted the wrong calendar days from UTC westward. The face compared the preset's resolved instants (the zone's midnight, `2026-07-01T07:00:00.000Z` in `America/Los_Angeles`) against the stored bare day as text, so `this_quarter` (Q3 2026) dropped 2026-07-01 and counted 2026-10-01, in `America/Los_Angeles` and in `UTC` alike.
+
+Now a `date` field compares the calendar days the period covers in the reference zone (Q3 is 2026-07-01 through 2026-09-30 in any zone), and a `datetime` field keeps comparing instants: the same rule service-analytics' faces apply. An explicit `[a, b]` window is unchanged, and so is a field whose type the driver was never told through `syncSchema`.
+
+The rule now has one home, `@objectstack/core`: `dateRangeWindowBounds` and `inclusiveCalendarDayWindow` are exported from it, and `@objectstack/service-analytics` calls them instead of its own copy (no behaviour change there). `InMemoryDriver` gains `isDeclaredDateField(object, field)`, which answers from the declared schema.
@@ -42,6 +42,7 @@ import {
   resolveAnalyticsDateRangePreset,
   resolveAnalyticsDateRangeString,
   analyticsDateRangeUnrecognizedError,
+  dateRangeWindowBounds,
 } from './analytics-date-range.js';
 
 /** A frozen reference instant, deliberately mid-week, mid-month, mid-quarter. */
@@ -369,3 +370,27 @@ describe('#17341 — the END of every window is one CALENDAR day after the presc
         expect(end - lastDayStart).not.toBe(24 * 60 * 60 * 1000);
     });
 });
+
+describe('dateRangeWindowBounds — ADR-0053\'s one window rule (#27172, #27272)', () => {
+    const now = new Date('2026-09-09T12:00:00Z');
+
+    for (const timezone of ['America/Los_Angeles', 'UTC', 'Asia/Shanghai']) {
+        it(`${timezone}: this_quarter on a date column is Jul 1 through Sep 30`, () => {
+            const window = resolveAnalyticsDateRangePreset('this_quarter', { now, timezone });
+            expect(dateRangeWindowBounds(window, timezone, true)).toEqual({ $gte: '2026-07-01', $lte: '2026-09-30' });
+        });
+    }
+
+    it('a preset on any other column keeps its instants and stops before its end', () => {
+        const window = resolveAnalyticsDateRangePreset('this_quarter', { now, timezone: 'America/Los_Angeles' });
+        expect(dateRangeWindowBounds(window, 'America/Los_Angeles', false)).toEqual({
+            $gte: '2026-07-01T07:00:00.000Z',
+            $lt: '2026-10-01T07:00:00.000Z',
+        });
+    });
+
+    it('a caller\'s explicit window is handed back bound for bound, inclusive', () => {
+        const window = { start: '2026-07-01', end: '2026-09-30', endExclusive: false };
+        expect(dateRangeWindowBounds(window, 'America/Los_Angeles', true)).toEqual({ $gte: '2026-07-01', $lte: '2026-09-30' });
+    });
+});
@@ -83,7 +83,8 @@ import {
   analyticsDateRangeRefusalMessage,
   type DateRangePreset,
 } from '@objectstack/spec/data';
-import { zonedDateStartToUtcMs } from './datetime.js';
+import type { LoweredDateRangeWindow } from './analytics-date-range-conformance.js';
+import { bucketDateKey, zonedDateStartToUtcMs } from './datetime.js';
 import { resolveFilterToken } from './filter-tokens.js';
 
 /**
@@ -280,3 +281,90 @@ export function resolveAnalyticsDateRangeString(
   if (!isDateRangePresetName(range)) throw analyticsDateRangeUnrecognizedError(range);
   return resolveAnalyticsDateRangePreset(range, options);
 }
+
+/**
+ * [#17973] The calendar days a resolved window covers in `timezone`, as the
+ * INCLUSIVE `[first, last]` pair.
+ *
+ * ⚠️ `endExclusive` is load-bearing: every preset reports the first instant
+ * AFTER the window (`this_month` ends at the next month's start), so the last
+ * day it covers is the one holding the instant before that bound. Reading that
+ * bound as inclusive makes every preset one day too long.
+ *
+ * [#18245] ⭐ `timezone` decides WHICH calendar. The bounds are INSTANTS, and
+ * every preset opens and closes at the reference zone's midnight
+ * ({@link tokenDayStart}), so reading them on the UTC calendar moves a boundary
+ * in opposite directions either side of the meridian. ⛔ That is a day-boundary
+ * projection, not an off-by-one: no constant makes both sides right.
+ *
+ * A bare `YYYY-MM-DD` bound is a calendar day already and is carried on the
+ * UTC proxy {@link zonedDateStartToUtcMs} yields for an unset zone.
+ *
+ * [#27272] Here, beside the lowering, for the reason the lowering is: the
+ * analytics faces of `driver-memory` and `@objectstack/service-analytics` both
+ * filter by it and cannot import each other.
+ */
+export function inclusiveCalendarDayWindow(
+  window: LoweredDateRangeWindow,
+  timezone?: string,
+): [string, string] {
+  const endMs = windowBoundMs(window.end);
+  return [
+    calendarDayOf(windowBoundMs(window.start), timezone),
+    calendarDayOf(window.endExclusive ? endMs - 1 : endMs, timezone),
+  ];
+}
+
+/**
+ * [#27172] The bound pair a lowered `dateRange` window filters one column by —
+ * the ONE spelling every analytics face shares (#27272: `driver-memory`'s cube
+ * face, and service-analytics' two strategies, drill and draft preview).
+ *
+ * ADR-0053's one rule: a `datetime` column compares INSTANTS and a `date`
+ * column compares CALENDAR DAYS in the reference zone.
+ *
+ * - A resolved preset (`endExclusive`) on a `date` column is the calendar days
+ *   it covers in `timezone` ({@link inclusiveCalendarDayWindow}), as the
+ *   inclusive `{ $gte, $lte }` day pair. Q3 is 2026-07-01 through 2026-09-30
+ *   in any zone.
+ * - A resolved preset on any other column stays the instant pair it resolved
+ *   to, stopping before its end: `{ $gte, $lt }`.
+ * - A caller's explicit `[a, b]` is handed back bound for bound, with its
+ *   inclusive upper reading (#16179); each face gives a bare-day end its
+ *   whole-day reading where the column needs one.
+ *
+ * ⛔ The preset's instants used to reach a `date` column as they are. A SQL
+ * `date` column reads an instant by its leading UTC day, so east of UTC the
+ * window slid one day early (#27172); `driver-memory` compared the instant to
+ * the stored bare day as TEXT, so from UTC westward it dropped the first day
+ * and counted the day after the last (#27272).
+ *
+ * @param dateColumn - Is the window's column declared `date`? A column whose
+ *   type the caller cannot name answers `false` and keeps the instants.
+ */
+export function dateRangeWindowBounds(
+  window: LoweredDateRangeWindow,
+  timezone: string | undefined,
+  dateColumn: boolean,
+): Record<string, string> {
+  if (!window.endExclusive) return { $gte: window.start, $lte: window.end };
+  if (!dateColumn) return { $gte: window.start, $lt: window.end };
+  const [first, last] = inclusiveCalendarDayWindow(window, timezone);
+  return { $gte: first, $lte: last };
+}
+
+/** The epoch ms one window bound denotes: a bare day on its UTC proxy, else the instant. */
+function windowBoundMs(bound: string): number {
+  const ms = bound.length === 10 ? zonedDateStartToUtcMs(bound) : Date.parse(bound);
+  if (Number.isNaN(ms)) {
+    throw new TypeError(`[analytics-date-range] invalid date in a dateRange window: "${bound}"`);
+  }
+  return ms;
+}
+
+/** The calendar day the instant at `ms` falls on in `timezone`: {@link bucketDateKey} at `'day'`. */
+function calendarDayOf(ms: number, timezone?: string): string {
+  // `ms` is always a finite epoch {@link windowBoundMs} just checked, so the
+  // labeller answers a key; `String` only narrows its `null` arm away.
+  return String(bucketDateKey(ms, 'day', timezone));
+}
@@ -0,0 +1,138 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * #27272 — a preset `dateRange` on a `date` field counts the calendar days the
+ * period covers in the reference zone, on this driver's cube face too.
+ *
+ * ADR-0053's one window rule: a `date` field compares CALENDAR DAYS and a
+ * `datetime` field compares INSTANTS. Q3 is 2026-07-01 through 2026-09-30 in
+ * any zone. The rule is `@objectstack/core`'s `dateRangeWindowBounds`, the one
+ * spelling service-analytics' faces share (#27172).
+ *
+ * ⛔ Before the repair the face compared the preset's resolved instants (the
+ * zone's midnight, `2026-07-01T07:00:00.000Z` in Los Angeles) against the
+ * stored bare day as TEXT. West of UTC `'2026-07-01' < '2026-07-01T07:…'`, so
+ * `this_quarter` dropped Jul 1 and counted Oct 1. East of UTC the same text
+ * order happened to land on the right days.
+ *
+ * The declaration decides, as everywhere in this driver: a field declared
+ * `date` through `syncSchema` takes the calendar-day rule; a field whose type
+ * the driver was never told keeps the instant pair (`dateColumn: false`), as
+ * `dateRangeWindowBounds` does for a column whose type the caller cannot name.
+ */
+
+import { afterEach, describe, it, expect, vi } from 'vitest';
+import { InMemoryDriver } from './memory-driver.js';
+import { MemoryAnalyticsService } from './memory-analytics.js';
+import { AnalyticsQuerySchema } from '@objectstack/spec/data';
+import type { AnalyticsDateRange, AnalyticsQuery, Cube } from '@objectstack/spec/data';
+
+const CUBE: Cube = {
+    name: 'deals',
+    title: 'Deals',
+    sql: 'deals',
+    measures: {
+        count: { label: 'Count', type: 'count', sql: 'id' },
+    },
+    dimensions: {
+        probe: { label: 'Probe', type: 'string', sql: 'probe' },
+        closeDate: { label: 'Close Date', type: 'time', sql: 'close_date' },
+        closedAt: { label: 'Closed At', type: 'time', sql: 'closed_at' },
+    },
+    public: true,
+};
+
+/** The card's four rows: one day either side of Q3, and Q3's own first and last day. */
+const DAYS = ['2026-06-30', '2026-07-01', '2026-09-30', '2026-10-01'];
+const Q3 = ['2026-07-01', '2026-09-30'];
+
+afterEach(() => {
+    vi.useRealTimers();
+});
+
+async function serviceOver(declare: boolean, rows: Record<string, unknown>[]): Promise<MemoryAnalyticsService> {
+    const driver = new InMemoryDriver({ initialData: { deals: rows } });
+    await driver.connect();
+    if (declare) {
+        await driver.syncSchema('deals', {
+            name: 'deals',
+            fields: {
+                probe: { type: 'text' },
+                close_date: { type: 'date' },
+                closed_at: { type: 'datetime' },
+            },
+        });
+    }
+    return new MemoryAnalyticsService({ driver, cubes: [CUBE] });
+}
+
+async function probes(
+    service: MemoryAnalyticsService,
+    dimension: 'deals.closeDate' | 'deals.closedAt',
+    timezone: string,
+    dateRange: AnalyticsDateRange = 'this_quarter',
+): Promise<string[]> {
+    vi.useFakeTimers({ toFake: ['Date'] });
+    vi.setSystemTime(new Date('2026-09-09T12:00:00Z'));
+    const query: AnalyticsQuery = AnalyticsQuerySchema.parse({
+        cube: 'deals',
+        measures: ['deals.count'],
+        dimensions: ['deals.probe'],
+        timeDimensions: [{ dimension, dateRange }],
+        timezone,
+    });
+    const result = await service.query(query);
+    return result.rows.map((row) => String(row['deals.probe'])).sort();
+}
+
+describe('#27272 — a preset dateRange on a declared date field counts calendar days', () => {
+    const dateRows = DAYS.map((day, i) => ({ id: i + 1, probe: day, close_date: day }));
+
+    for (const zone of ['America/Los_Angeles', 'Asia/Shanghai', 'UTC']) {
+        it(`${zone}: this_quarter selects Jul 1 through Sep 30`, async () => {
+            const service = await serviceOver(true, dateRows);
+            expect(await probes(service, 'deals.closeDate', zone)).toEqual(Q3);
+        });
+    }
+
+    it('Los Angeles: this_month on Sep 9 selects Sep 30 and not Oct 1', async () => {
+        const service = await serviceOver(true, dateRows);
+        expect(await probes(service, 'deals.closeDate', 'America/Los_Angeles', 'this_month')).toEqual(['2026-09-30']);
+    });
+
+    it('an explicit window keeps its inclusive bare-day reading, untouched', async () => {
+        const service = await serviceOver(true, dateRows);
+        expect(await probes(service, 'deals.closeDate', 'America/Los_Angeles', ['2026-07-01', '2026-09-30'])).toEqual(Q3);
+    });
+});
+
+describe('#27272 — a datetime field keeps comparing instants', () => {
+    // Los Angeles' Q3 opens at 2026-07-01T07:00Z and closes before 2026-10-01T07:00Z.
+    const instants = [
+        '2026-07-01T06:59:59.000Z', // Jun 30, 23:59:59 local — outside
+        '2026-07-01T07:00:00.000Z', // Jul 1, 00:00 local — inside
+        '2026-10-01T06:59:59.000Z', // Sep 30, 23:59:59 local — inside
+        '2026-10-01T07:00:00.000Z', // Oct 1, 00:00 local — outside
+    ];
+    const rows = instants.map((iso, i) => ({ id: i + 1, probe: iso, closed_at: iso }));
+
+    it('Los Angeles: this_quarter on a declared datetime is the zone-midnight instant pair', async () => {
+        const service = await serviceOver(true, rows);
+        expect(await probes(service, 'deals.closedAt', 'America/Los_Angeles')).toEqual([
+            '2026-07-01T07:00:00.000Z',
+            '2026-10-01T06:59:59.000Z',
+        ]);
+    });
+});
+
+describe('#27272 — a field whose type was never declared keeps the instant pair', () => {
+    it('Los Angeles: an undeclared column is compared as the instants the preset resolved to', async () => {
+        const rows = ['2026-07-01T06:59:59.000Z', '2026-07-01T07:00:00.000Z'].map((iso, i) => ({
+            id: i + 1,
+            probe: iso,
+            close_date: iso,
+        }));
+        const service = await serviceOver(false, rows);
+        expect(await probes(service, 'deals.closeDate', 'America/Los_Angeles')).toEqual(['2026-07-01T07:00:00.000Z']);
+    });
+});
@@ -30,6 +30,10 @@ import {
   // the ONE refusal for a string outside it, shared with the SQL analytics
   // path so the two backends cannot answer one input differently again.
   resolveAnalyticsDateRangeString,
+  // [#27272] ADR-0053's one window rule — a `date` column compares the
+  // calendar days the period covers in the reference zone — shared with
+  // service-analytics' faces (#27172) for the same reason as the lowering.
+  dateRangeWindowBounds,
   // [#17596] The ONE constructor for that envelope, reused for the ARRAY arm's
   // own refusal: the shared conformance kit reads `code` + `status`, so the
   // pair must have a single origin across every face. ⛔ Only the SENTENCE is
@@ -1196,7 +1200,11 @@ export class MemoryAnalyticsService implements IAnalyticsService {
           // the aggregation with NO time predicate emitted at all.
           const resolved: ResolvedDateRange = Array.isArray(timeDim.dateRange)
             ? { bounds: explicitDateRangeWindow(timeDim.dateRange), endExclusive: false }
-            : this.parseDateRangeString(timeDim.dateRange, query.timezone);
+            : this.parseDateRangeString(
+              timeDim.dateRange,
+              query.timezone,
+              this.driver.isDeclaredDateField(this.extractTableName(cube.sql), fieldPath),
+            );
           const range = resolved.bounds;
 
           // The window matches BOTH stored forms of a datetime value — the
@@ -2243,13 +2251,26 @@ export class MemoryAnalyticsService implements IAnalyticsService {
    * explicit `[a, b]` array arm never arrives here at all: it is discriminated
    * at the call site and keeps its published `$lte` reading.
    *
+   * [#27272] On a column the driver holds as declared `date` (`dateColumn`)
+   * the window is instead the calendar days it covers, with an inclusive end.
+   *
    * @throws the ADR-0112 `400 ANALYTICS_DATE_RANGE_UNRECOGNIZED` envelope for
    *   a string outside `DATE_RANGE_PRESETS` — the same code, status and
    *   wording the schema door and the SQL analytics path answer with, since
    *   all three call one constructor.
    */
-  private parseDateRangeString(range: string, timezone?: string): ResolvedDateRange {
+  private parseDateRangeString(range: string, timezone: string | undefined, dateColumn: boolean): ResolvedDateRange {
     const window = resolveAnalyticsDateRangeString(range, { timezone });
+    if (dateColumn) {
+      // [#27272] A declared `date` column holds bare days, and the preset's
+      // instants (the zone's midnight) compared to them as TEXT dropped the
+      // first day and counted the day after the last from UTC westward. ADR-0053's
+      // one rule, through its one spelling: the calendar days the period covers
+      // in the reference zone, as the inclusive day pair — which the bound
+      // construction then reads exactly as a caller's bare-day `[a, b]`.
+      const days = dateRangeWindowBounds(window, timezone, true);
+      return { bounds: [days.$gte, days.$lte], endExclusive: false };
+    }
     return { bounds: [window.start, window.end], endExclusive: window.endExclusive };
   }
 
 
@@ -2359,6 +2359,20 @@ export class InMemoryDriver implements IDataDriver {
     return this.toStorageForm(object, field, value);
   }
 
+  /**
+   * [#27272] Is `field` on `object` declared `date`? For the analytics (cube)
+   * face's `dateRange` window, which compares a `date` column by CALENDAR DAYS
+   * and every other column by instants (ADR-0053, `dateRangeWindowBounds`).
+   *
+   * Keyed on the DECLARED kind ({@link temporalFields}, populated by
+   * {@link syncSchema}) for the reason {@link filterComparandStorageForm} is:
+   * only the driver holds it. An object never declared answers `false` — the
+   * driver does not guess types from values.
+   */
+  isDeclaredDateField(object: string | undefined, field: string): boolean {
+    return this.temporalKind(object, field) === 'date';
+  }
+
   /**
    * [#5374] The pattern a `$contains` / `$notContains` comparand becomes — the
    * substring rule itself, for the analytics (cube) face.