diff --git a/examples/app-showcase/src/data/objects/expense-report.object.ts b/examples/app-showcase/src/data/objects/expense-report.object.ts
index c24e7e489c2..227f6c8f634 100644
--- a/examples/app-showcase/src/data/objects/expense-report.object.ts
+++ b/examples/app-showcase/src/data/objects/expense-report.object.ts
@@ -69,15 +69,22 @@ export const ExpenseReport = ObjectSchema.create({
     // ── Filtered roll-ups (the point of this object) ─────────────────────────
     // Child FK is auto-detected (showcase_expense_line.expense_report), so none
     // of these need `relationshipField`.
+    //
+    // The three money roll-ups declare `scale: 2`. A summary has no currency
+    // of its own, and with no `scale` a sum renders at the natural precision of
+    // its value, so one column read `225.75`, `917` and `1,500.5`. Two
+    // decimals match the line `amount` they add up.
 
     /** Baseline: unfiltered — the grand total of every line. */
     total_amount: Field.summary({
       label: 'Total',
+      scale: 2,
       summaryOperations: { object: 'showcase_expense_line', field: 'amount', function: 'sum' },
     }),
     /** Filtered SUM (equality) — only lines a manager has approved. */
     approved_amount: Field.summary({
       label: 'Approved',
+      scale: 2,
       summaryOperations: {
         object: 'showcase_expense_line',
         field: 'amount',
@@ -88,6 +95,7 @@ export const ExpenseReport = ObjectSchema.create({
     /** Filtered SUM (boolean) — only lines billable back to a client. */
     reimbursable_amount: Field.summary({
       label: 'Reimbursable',
+      scale: 2,
       summaryOperations: {
         object: 'showcase_expense_line',
         field: 'amount',
diff --git a/examples/app-showcase/src/data/objects/project.object.ts b/examples/app-showcase/src/data/objects/project.object.ts
index 6a42b0bd62b..fdc0b0126f0 100644
--- a/examples/app-showcase/src/data/objects/project.object.ts
+++ b/examples/app-showcase/src/data/objects/project.object.ts
@@ -60,11 +60,33 @@ export const Project = ObjectSchema.create({
         { label: 'Red', value: 'red', color: '#EF4444' },
       ],
     }),
-    budget: Field.currency({ label: 'Budget', min: 0 }),
-    spent: Field.currency({ label: 'Spent', min: 0, defaultValue: 0 }),
+    // Money in one fixed currency, as on `showcase_account.annual_revenue`: with
+    // no currency code a currency field reads as a bare number (`200,000.00`)
+    // beside that column's `US$12,000,000.00`. `spent` declares the same
+    // currency as `budget`, so `budget_remaining` subtracts two amounts in one
+    // currency.
+    budget: Field.currency({
+      label: 'Budget',
+      min: 0,
+      currencyConfig: { currencyMode: 'fixed', defaultCurrency: 'USD' },
+    }),
+    spent: Field.currency({
+      label: 'Spent',
+      min: 0,
+      defaultValue: 0,
+      currencyConfig: { currencyMode: 'fixed', defaultCurrency: 'USD' },
+    }),
+    // A money result (#22727): `returnType: 'currency'` with the formula's own
+    // `currencyConfig` renders it as its sources render, not as a plain number
+    // (`200,000`). This pair is what `inferFormulaReturn` stamps for this
+    // expression over two USD amounts. `scale: 2` rounds the computed result
+    // to cents, so a float subtraction never returns a long fraction.
     budget_remaining: Field.formula({
       label: 'Budget Remaining',
       expression: cel`(record.budget == null ? 0 : record.budget) - (record.spent == null ? 0 : record.spent)`,
+      returnType: 'currency',
+      currencyConfig: { currencyMode: 'fixed', defaultCurrency: 'USD' },
+      scale: 2,
     }),
     start_date: Field.date({ label: 'Start Date' }),
     end_date: Field.date({ label: 'Target End Date' }),
diff --git a/examples/app-showcase/src/ui/datasets/chart-gallery.dataset.ts b/examples/app-showcase/src/ui/datasets/chart-gallery.dataset.ts
index cdd2d48ac0b..b245c4df467 100644
--- a/examples/app-showcase/src/ui/datasets/chart-gallery.dataset.ts
+++ b/examples/app-showcase/src/ui/datasets/chart-gallery.dataset.ts
@@ -55,15 +55,17 @@ export const ShowcaseProjectDataset = defineDataset({
   ],
   measures: [
     { name: 'project_count', label: 'Projects', aggregate: 'count' },
-    // `budget`/`spent` are currency fields with NO fixed currency (no
-    // `currencyConfig`, so no currency of their own). The column's currency
-    // resolves through the measure's own `currency` → the field's
-    // `currencyConfig.defaultCurrency`, read only under `currencyMode: 'fixed'`
-    // → the tenant `localization.currency` default; with none set it shows a
-    // plain grouped number (never a hardcoded "$"). To pin a symbol, set a
-    // measure `currency`, or give the field a fixed currency:
-    // `currencyConfig: { currencyMode: 'fixed', defaultCurrency: 'USD' }`.
-    { name: 'budget_sum', label: 'Total Budget', aggregate: 'sum', field: 'budget', format: '0,0' },
-    { name: 'spent_sum', label: 'Total Spent', aggregate: 'sum', field: 'spent', format: '0,0' },
+    // `budget`/`spent` are currency fields with a FIXED currency
+    // (`currencyConfig: { currencyMode: 'fixed', defaultCurrency: 'USD' }`).
+    // The column's currency resolves through the measure's own `currency` →
+    // the field's `currencyConfig.defaultCurrency`, read only under
+    // `currencyMode: 'fixed'` → the tenant `localization.currency` default, so
+    // these measures need no `currency` of their own (never a hardcoded "$"
+    // in `format`). `0,0.00` writes a total the way the Projects list writes
+    // an amount, with two decimals. The Command Center's `cc_k6` tile, which
+    // aggregates `budget` without this dataset, declares the same pattern and
+    // currency, so both dashboards read one total budget alike.
+    { name: 'budget_sum', label: 'Total Budget', aggregate: 'sum', field: 'budget', format: '0,0.00' },
+    { name: 'spent_sum', label: 'Total Spent', aggregate: 'sum', field: 'spent', format: '0,0.00' },
   ],
 });
diff --git a/examples/app-showcase/src/ui/pages/command-center.page.ts b/examples/app-showcase/src/ui/pages/command-center.page.ts
index a98af74d611..42df4e0db65 100644
--- a/examples/app-showcase/src/ui/pages/command-center.page.ts
+++ b/examples/app-showcase/src/ui/pages/command-center.page.ts
@@ -76,14 +76,23 @@ function band(id: string, cols: number, children: any[], gap = '16px'): any {
 }
 
 /** A LIVE KPI — object-metric in the new `bare` variant (big tinted number + label). */
-function kpi(id: string, object: string, label: string, colorVariant: string, aggregate: any, filter?: any, format?: string): any {
+function kpi(id: string, object: string, label: string, colorVariant: string, aggregate: any, filter?: any, format?: string, currency?: string): any {
   return {
     id, type: 'object-metric',
     responsiveStyles: { large: { minWidth: '0' } },
-    properties: { objectName: object, label, colorVariant, variant: 'bare', aggregate, ...(filter ? { filter } : {}), ...(format ? { format } : {}) },
+    properties: { objectName: object, label, colorVariant, variant: 'bare', aggregate, ...(filter ? { filter } : {}), ...(format ? { format } : {}), ...(currency ? { currency } : {}) },
   };
 }
 
+/**
+ * How a total budget is written: the pattern and currency of the
+ * `showcase_project_metrics` dataset's `budget_sum` measure, which the
+ * Delivery Operations "Total Budget" tile reads. `object-metric` takes no
+ * currency from the field, so `cc_k6` names it.
+ */
+const BUDGET_FORMAT = '0,0.00';
+const BUDGET_CURRENCY = 'USD';
+
 /**
  * A dataset-bound chart with the shared brand palette. `integerYAxis` pins the
  * tick step to 1 — without it, count aggregates (small integers like 0-5)
@@ -159,7 +168,7 @@ export const CommandCenterPage = definePage({
                   kpi('cc_k3', 'showcase_task', '待复审 Review', 'purple', { field: 'id', function: 'count' }, IN_REVIEW),
                   kpi('cc_k4', 'showcase_project', '风险项目 At-Risk', 'danger', { field: 'id', function: 'count' }, [{ field: 'health', operator: 'equals', value: 'red' }]),
                   kpi('cc_k5', 'showcase_account', '客户 Accounts', 'orange', { field: 'id', function: 'count' }),
-                  kpi('cc_k6', 'showcase_project', '总预算 Budget', 'success', { field: 'budget', function: 'sum' }, undefined, '0.0a'),
+                  kpi('cc_k6', 'showcase_project', '总预算 Budget', 'success', { field: 'budget', function: 'sum' }, undefined, BUDGET_FORMAT, BUDGET_CURRENCY),
                 ], '10px'),
               }),
 
diff --git a/examples/app-showcase/test/money-format-declarations.test.ts b/examples/app-showcase/test/money-format-declarations.test.ts
new file mode 100644
index 00000000000..aed79d996a4
--- /dev/null
+++ b/examples/app-showcase/test/money-format-declarations.test.ts
@@ -0,0 +1,112 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+import { describe, it, expect } from 'vitest';
+import { inferFormulaReturn } from '@objectstack/formula';
+
+import { Account, ExpenseReport, Project } from '../src/data/objects/index.js';
+import { ShowcaseProjectDataset } from '../src/ui/datasets/index.js';
+import { CommandCenterPage } from '../src/ui/pages/index.js';
+import { OpsDashboard } from '../src/ui/dashboards/index.js';
+
+/**
+ * The showcase writes money one way.
+ *
+ * Every declaration this pins is display metadata the renderer already reads,
+ * so leaving one out raises nothing at `os validate` or at boot: the column
+ * just reads differently from the one beside it. The four readings it guards
+ * against:
+ *
+ *  - the expense report roll-ups summed at their natural precision, so one
+ *    column read `225.75`, `917` and `1,500.5` — they declare `scale: 2`;
+ *  - `showcase_project.budget` had no currency and read `200,000.00` beside
+ *    Accounts' `US$12,000,000.00` — it declares the same fixed currency;
+ *  - `budget_remaining`, a formula over two amounts, read as a plain number
+ *    (`200,000`) — it declares a currency result;
+ *  - the Command Center KPI wrote the total budget as `109万` and Delivery
+ *    Operations wrote the same sum as `1,090,000` — both write it with one
+ *    pattern and one currency.
+ */
+
+type AnyRec = Record<string, unknown>;
+const isRec = (v: unknown): v is AnyRec => !!v && typeof v === 'object' && !Array.isArray(v);
+
+const fields = (o: unknown): Record<string, AnyRec> => (o as { fields: Record<string, AnyRec> }).fields;
+
+const USD_FIXED = { currencyMode: 'fixed', defaultCurrency: 'USD' };
+
+/** The node with this `id`, at any depth. */
+function nodeById(root: unknown, id: string): AnyRec | undefined {
+  let found: AnyRec | undefined;
+  const visit = (v: unknown): void => {
+    if (found) return;
+    if (Array.isArray(v)) {
+      for (const item of v) visit(item);
+      return;
+    }
+    if (!isRec(v)) return;
+    if (v.id === id) {
+      found = v;
+      return;
+    }
+    for (const child of Object.values(v)) visit(child);
+  };
+  visit(root);
+  return found;
+}
+
+describe('showcase money declarations', () => {
+  it('the expense report money roll-ups declare two decimals', () => {
+    const f = fields(ExpenseReport);
+    for (const name of ['total_amount', 'approved_amount', 'reimbursable_amount']) {
+      expect(f[name]?.type, name).toBe('summary');
+      expect(f[name]?.scale, `${name}.scale`).toBe(2);
+    }
+  });
+
+  it('project budget and spent carry the fixed currency Accounts uses', () => {
+    const revenue = fields(Account).annual_revenue?.currencyConfig;
+    expect(revenue).toEqual(USD_FIXED);
+    const f = fields(Project);
+    expect(f.budget?.currencyConfig).toEqual(revenue);
+    expect(f.spent?.currencyConfig).toEqual(revenue);
+  });
+
+  it('budget_remaining declares a currency result, rounded to cents', () => {
+    const remaining = fields(Project).budget_remaining;
+    expect(remaining?.type).toBe('formula');
+    expect(remaining?.returnType).toBe('currency');
+    expect(remaining?.currencyConfig).toEqual(USD_FIXED);
+    expect(remaining?.scale).toBe(2);
+  });
+
+  it('the currency result is the one authoring would stamp for its expression', () => {
+    const f = fields(Project);
+    const remaining = f.budget_remaining!;
+    expect(inferFormulaReturn(remaining.expression as never, f as never)).toEqual({
+      returnType: remaining.returnType,
+      currencyConfig: remaining.currencyConfig,
+    });
+  });
+
+  it('both dashboards write the total budget with one format and one currency', () => {
+    const tile = nodeById(CommandCenterPage.regions, 'cc_k6');
+    const props = (tile?.properties ?? {}) as AnyRec;
+    expect(tile?.type).toBe('object-metric');
+    expect(props.aggregate).toEqual({ field: 'budget', function: 'sum' });
+
+    const widget = (OpsDashboard.widgets as AnyRec[]).find((w) => w.id === 'kpi_total_budget');
+    expect(widget?.values).toEqual(['budget_sum']);
+    const measure = ShowcaseProjectDataset.measures.find((m) => m.name === 'budget_sum');
+    expect(measure).toMatchObject({ aggregate: 'sum', field: 'budget' });
+
+    // The dataset-bound tile takes its currency from the measure, else from
+    // the aggregated field's fixed currency; the object-metric tile from its
+    // own `currency` only.
+    const datasetCurrency = measure?.currency ?? (fields(Project).budget?.currencyConfig as AnyRec | undefined)?.defaultCurrency;
+
+    expect(props.format).toBeDefined();
+    expect(props.format).toBe(measure?.format);
+    expect(props.currency).toBeDefined();
+    expect(props.currency).toBe(datasetCurrency);
+  });
+});