@@ -0,0 +1,96 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * [#20203] An epoch-millisecond NUMBER compared against a `date` field is read
+ * as the UTC calendar day of its instant — by `@objectstack/core`'s
+ * `temporalStorageForm`, the rule `coerceTemporalValue` calls — the reading a
+ * `Date` of the same value already had here.
+ *
+ * Measured on the base through this driver's `find()`, and through the engine
+ * and `POST /api/v1/data/:object/query` over it (which reach the same
+ * coercion): `where: { placed_on: { $gt: 1769940000000 } }` answered 0 of 6,
+ * because the number reached mingo unchanged and mingo never matches a number
+ * against the `YYYY-MM-DD` text the column holds. Every operator answered that
+ * way — 0, or all 6 for `$ne` / `$nin` — while `driver-sql` answered 6 on
+ * SQLite and a 500 on PostgreSQL (its suite pins it), and the same number on a
+ * `datetime` field (the control) was read as its instant everywhere.
+ *
+ * Each row asserts three things: the number's answer, the `Date` twin's answer
+ * (identical), and the `datetime` control.
+ */
+
+import { beforeAll, describe, expect, it } from 'vitest';
+import { InMemoryDriver } from './memory-driver.js';
+
+const OBJECT = 'ledger_order';
+const EMPTY = 'ledger_order_empty';
+const WRITES = 'ledger_order_writes';
+const FIELDS = { placed_on: { type: 'date' }, opened_at: { type: 'datetime' } };
+
+const ROWS = [
+  { id: 'o1', placed_on: '2026-01-10', opened_at: '2026-01-01T10:00:00.000Z' },
+  { id: 'o2', placed_on: '2026-01-02', opened_at: '2026-01-02T10:00:00.000Z' },
+  { id: 'o3', placed_on: '2026-03-01', opened_at: '2026-02-01T10:00:00.000Z' },
+  { id: 'o4', placed_on: '2026-02-01', opened_at: '2026-02-05T10:00:00.000Z' },
+  { id: 'o5', placed_on: '2026-01-15', opened_at: '2026-02-06T10:00:00.000Z' },
+  { id: 'o6', placed_on: '2026-02-01', opened_at: '2026-03-01T10:00:00.000Z' },
+];
+
+const N = 1769940000000; //          2026-02-01T10:00:00.000Z — a time of day, not a UTC midnight
+const N_JAN10 = 1768057200000; //    2026-01-10T15:00:00.000Z
+const N_JAN02 = 1767394800000; //    2026-01-02T23:00:00.000Z — late in its UTC day
+const N_MIDNIGHT = 1769904000000; // 2026-02-01T00:00:00.000Z
+
+type As = (ms: number) => unknown;
+const asNumber: As = (ms) => ms;
+const asDate: As = (ms) => new Date(ms);
+
+/** operator · the comparand, built from a number or its `Date` · `date` ids · `datetime` control ids */
+const OPERATORS: ReadonlyArray<readonly [string, (v: As) => unknown, string[], string[]]> = [
+  ['$gt', (v) => ({ $gt: v(N) }), ['o3'], ['o4', 'o5', 'o6']],
+  ['$lt', (v) => ({ $lt: v(N) }), ['o1', 'o2', 'o5'], ['o1', 'o2']],
+  ['$eq', (v) => ({ $eq: v(N) }), ['o4', 'o6'], ['o3']],
+  ['$in', (v) => ({ $in: [v(N), v(N_JAN10)] }), ['o1', 'o4', 'o6'], ['o3']],
+  ['$between', (v) => ({ $between: [v(N_JAN02), v(N)] }), ['o1', 'o2', 'o4', 'o5', 'o6'], ['o3']],
+  ['$gte', (v) => ({ $gte: v(N) }), ['o3', 'o4', 'o6'], ['o3', 'o4', 'o5', 'o6']],
+  ['$lte', (v) => ({ $lte: v(N) }), ['o1', 'o2', 'o4', 'o5', 'o6'], ['o1', 'o2', 'o3']],
+  ['$ne', (v) => ({ $ne: v(N) }), ['o1', 'o2', 'o3', 'o5'], ['o1', 'o2', 'o4', 'o5', 'o6']],
+  ['$nin', (v) => ({ $nin: [v(N), v(N_JAN10)] }), ['o2', 'o3', 'o5'], ['o1', 'o2', 'o4', 'o5', 'o6']],
+  ['implicit equality', (v) => v(N), ['o4', 'o6'], ['o3']],
+  ['$eq on a UTC midnight', (v) => ({ $eq: v(N_MIDNIGHT) }), ['o4', 'o6'], []],
+];
+
+describe('[#20203] an epoch-ms number on a date field reads as the UTC calendar day of its instant', () => {
+  let driver: InMemoryDriver;
+  const ids = async (object: string, where: Record<string, unknown>) =>
+    ((await driver.find(object, { where } as any)) as any[]).map((r) => r.id).sort();
+
+  beforeAll(async () => {
+    driver = new InMemoryDriver({});
+    await driver.connect();
+    for (const name of [OBJECT, EMPTY, WRITES]) await driver.syncSchema(name, { name, fields: FIELDS });
+    for (const row of ROWS) await driver.create(OBJECT, { ...row });
+  });
+
+  for (const [op, comparand, onDate, onDatetime] of OPERATORS) {
+    it(`${op}: ${onDate.join(', ')}; its Date agrees; the datetime control reads the instant`, async () => {
+      expect(await ids(OBJECT, { placed_on: comparand(asNumber) }), 'number on date').toEqual(onDate);
+      expect(await ids(OBJECT, { placed_on: comparand(asDate) }), 'the Date twin on date').toEqual(onDate);
+      expect(await ids(OBJECT, { opened_at: comparand(asNumber) }), 'datetime control').toEqual(onDatetime);
+    });
+
+    it(`${op}: an empty object answers no row`, async () => {
+      expect(await ids(EMPTY, { placed_on: comparand(asNumber) })).toEqual([]);
+    });
+  }
+
+  it('the write path stores the same UTC calendar day — create and update', async () => {
+    await driver.create(WRITES, { id: 'w1', placed_on: N });
+    await driver.create(WRITES, { id: 'w2', placed_on: -1 }); // one ms before the epoch
+    const read = async (id: string) => ((await driver.findOne(WRITES, { where: { id } } as any)) as any)?.placed_on;
+    expect(await read('w1')).toBe('2026-02-01');
+    expect(await read('w2')).toBe('1969-12-31');
+    await driver.update(WRITES, 'w1', { placed_on: N_JAN10 });
+    expect(await read('w1')).toBe('2026-01-10');
+  });
+});
@@ -0,0 +1,119 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * [#20203] An epoch-millisecond NUMBER compared against a `date` field is read
+ * as the UTC calendar day of its instant — by `@objectstack/core`'s
+ * `temporalStorageForm`, the rule `toDateOnly` / `temporalFilterValue` call —
+ * on every dialect this driver speaks.
+ *
+ * Measured on the base through `find()` (and through the engine and
+ * `POST /api/v1/data/:object/query`, which reach the same coercion), on this
+ * file's fixture, with `where: { placed_on: { $gt: 1769940000000 } }`
+ * (2026-02-01T10:00:00.000Z):
+ *
+ * | dialect | base | why |
+ * |:--|:--|:--|
+ * | SQLite | 6 of 6 | the number was bound as INTEGER, and SQLite orders every INTEGER below every TEXT |
+ * | PostgreSQL | `DATABASE_ERROR` (500 at REST) | the server's date input parser refused the bind, `22008` "date/time field value out of range" |
+ *
+ * and every other operator split the same way (SQLite: `$gte` / `$ne` / `$nin`
+ * 6, the rest 0; PostgreSQL: a refusal on each, on an empty table too), while
+ * the same number on a `datetime` field — the control — was read as its
+ * instant on both. `driver-memory` answered 0 (its own suite pins it).
+ *
+ * The number now names the same day a `Date` of the same value names, so each
+ * row below asserts three things on one cell: the number's answer, the `Date`
+ * twin's answer (identical), and the `datetime` control.
+ */
+
+import { afterAll, beforeAll, describe, expect, it } from 'vitest';
+import { SqlDriver } from './sql-driver.js';
+import { DIALECT_CELLS, declareDialectCell, type DialectCell } from './live-dialect-matrix.testkit.js';
+
+const TABLE = 'os20203_ledger';
+const EMPTY = 'os20203_ledger_empty';
+const WRITES = 'os20203_ledger_writes';
+
+const shape = (name: string) => ({
+  name,
+  fields: { placed_on: { type: 'date' }, opened_at: { type: 'datetime' } },
+}) as any;
+
+const ROWS = [
+  { id: 'o1', placed_on: '2026-01-10', opened_at: '2026-01-01T10:00:00.000Z' },
+  { id: 'o2', placed_on: '2026-01-02', opened_at: '2026-01-02T10:00:00.000Z' },
+  { id: 'o3', placed_on: '2026-03-01', opened_at: '2026-02-01T10:00:00.000Z' },
+  { id: 'o4', placed_on: '2026-02-01', opened_at: '2026-02-05T10:00:00.000Z' },
+  { id: 'o5', placed_on: '2026-01-15', opened_at: '2026-02-06T10:00:00.000Z' },
+  { id: 'o6', placed_on: '2026-02-01', opened_at: '2026-03-01T10:00:00.000Z' },
+];
+
+const N = 1769940000000; //          2026-02-01T10:00:00.000Z — a time of day, not a UTC midnight
+const N_JAN10 = 1768057200000; //    2026-01-10T15:00:00.000Z
+const N_JAN02 = 1767394800000; //    2026-01-02T23:00:00.000Z — late in its UTC day
+const N_MIDNIGHT = 1769904000000; // 2026-02-01T00:00:00.000Z
+
+type As = (ms: number) => unknown;
+const asNumber: As = (ms) => ms;
+const asDate: As = (ms) => new Date(ms);
+
+/** operator · the comparand, built from a number or its `Date` · `date` ids · `datetime` control ids */
+const OPERATORS: ReadonlyArray<readonly [string, (v: As) => unknown, string[], string[]]> = [
+  ['$gt', (v) => ({ $gt: v(N) }), ['o3'], ['o4', 'o5', 'o6']],
+  ['$lt', (v) => ({ $lt: v(N) }), ['o1', 'o2', 'o5'], ['o1', 'o2']],
+  ['$eq', (v) => ({ $eq: v(N) }), ['o4', 'o6'], ['o3']],
+  ['$in', (v) => ({ $in: [v(N), v(N_JAN10)] }), ['o1', 'o4', 'o6'], ['o3']],
+  ['$between', (v) => ({ $between: [v(N_JAN02), v(N)] }), ['o1', 'o2', 'o4', 'o5', 'o6'], ['o3']],
+  ['$gte', (v) => ({ $gte: v(N) }), ['o3', 'o4', 'o6'], ['o3', 'o4', 'o5', 'o6']],
+  ['$lte', (v) => ({ $lte: v(N) }), ['o1', 'o2', 'o4', 'o5', 'o6'], ['o1', 'o2', 'o3']],
+  ['$ne', (v) => ({ $ne: v(N) }), ['o1', 'o2', 'o3', 'o5'], ['o1', 'o2', 'o4', 'o5', 'o6']],
+  ['$nin', (v) => ({ $nin: [v(N), v(N_JAN10)] }), ['o2', 'o3', 'o5'], ['o1', 'o2', 'o4', 'o5', 'o6']],
+  ['implicit equality', (v) => v(N), ['o4', 'o6'], ['o3']],
+  ['$eq on a UTC midnight', (v) => ({ $eq: v(N_MIDNIGHT) }), ['o4', 'o6'], []],
+];
+
+const NO_AUDIT = { bypassTenantAudit: true } as any;
+
+function measure(cell: DialectCell): void {
+  describe(`[#20203] an epoch-ms number on a date field — ${cell.label}`, () => {
+    let driver: SqlDriver;
+    const ids = async (table: string, where: Record<string, unknown>) =>
+      ((await driver.find(table, { where }, NO_AUDIT)) as any[]).map((r) => r.id).sort();
+
+    beforeAll(async () => {
+      driver = new SqlDriver(cell.config());
+      for (const t of [TABLE, EMPTY, WRITES]) await driver.execute(`drop table if exists ${t}`).catch(() => {});
+      await driver.initObjects([shape(TABLE), shape(EMPTY), shape(WRITES)]);
+      for (const row of ROWS) await driver.create(TABLE, { ...row }, NO_AUDIT);
+    });
+
+    afterAll(async () => {
+      for (const t of [TABLE, EMPTY, WRITES]) await driver.execute(`drop table if exists ${t}`).catch(() => {});
+      await driver.disconnect();
+    });
+
+    for (const [op, comparand, onDate, onDatetime] of OPERATORS) {
+      it(`${op}: the UTC calendar day of the instant — ${onDate.join(', ')}; its Date agrees; the datetime control reads the instant`, async () => {
+        expect(await ids(TABLE, { placed_on: comparand(asNumber) }), 'number on date').toEqual(onDate);
+        expect(await ids(TABLE, { placed_on: comparand(asDate) }), 'the Date twin on date').toEqual(onDate);
+        expect(await ids(TABLE, { opened_at: comparand(asNumber) }), 'datetime control').toEqual(onDatetime);
+      });
+
+      it(`${op}: an empty table answers no row, not a refusal`, async () => {
+        expect(await ids(EMPTY, { placed_on: comparand(asNumber) })).toEqual([]);
+      });
+    }
+
+    it('the write path stores the same UTC calendar day — create and update', async () => {
+      await driver.create(WRITES, { id: 'w1', placed_on: N }, NO_AUDIT);
+      await driver.create(WRITES, { id: 'w2', placed_on: -1 }, NO_AUDIT); // one ms before the epoch
+      const read = async (id: string) => ((await driver.findOne(WRITES, { where: { id } }, NO_AUDIT)) as any)?.placed_on;
+      expect(await read('w1')).toBe('2026-02-01');
+      expect(await read('w2')).toBe('1969-12-31');
+      await driver.update(WRITES, 'w1', { placed_on: N_JAN10 }, NO_AUDIT);
+      expect(await read('w1')).toBe('2026-01-10');
+    });
+  });
+}
+
+for (const cell of DIALECT_CELLS) declareDialectCell(cell, 'epoch-ms date comparand', measure);