fix: localize decimal separator

cypress/component/TableCellNumber.cy.js

@@ -0,0 +1,51 @@
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+import { setLocale } from '@nextcloud/l10n'
+
+import TableCellNumber from '../../src/shared/components/ncTable/partials/TableCellNumber.vue'
+
+describe('TableCellNumber', () => {
+	beforeEach(() => {
+		setLocale('en_US')
+	})
+
+	it('displays decimals with the current locale separator', () => {
+		setLocale('de_DE')
+
+		mountNumberCell(1.234, { numberDecimals: 3 })
+
+		cy.get('.number-display').should('contain.text', '1,234')
+	})
+
+	it('keeps the configured amount of decimal places', () => {
+		mountNumberCell(1.2, { numberDecimals: 2 })
+
+		cy.get('.number-display').should('contain.text', '1.20')
+	})
+
+	it('clamps out-of-range decimal counts for Intl.NumberFormat', () => {
+		mountNumberCell(1.234567, { numberDecimals: 50 })
+
+		cy.get('.number-display').should('contain.text', '1.234567')
+	})
+})
+
+function mountNumberCell(value, columnOverrides = {}) {
+	cy.mount(TableCellNumber, {
+		props: {
+			column: {
+				id: 1,
+				numberDecimals: 0,
+				numberMax: null,
+				numberMin: null,
+				numberPrefix: '',
+				numberSuffix: '',
+				...columnOverrides,
+			},
+			rowId: 1,
+			value,
+		},
+	})
+}

src/shared/components/ncTable/partials/TableCellNumber.vue

@@ -23,6 +23,7 @@
 </template>
 
 <script>
+import { getCanonicalLocale } from '@nextcloud/l10n'
 import cellEditMixin from '../mixins/cellEditMixin.js'
 
 export default {
@@ -42,7 +43,16 @@ export default {
 			if (this.value === null) {
 				return null
 			}
-			return this.value.toFixed(this.column?.numberDecimals)
+			// Intl.NumberFormat only accepts 0..20 fraction digits
+			const raw = Number(this.column?.numberDecimals ?? 0)
+			const fractionDigits = Number.isFinite(raw)
+				? Math.min(20, Math.max(0, Math.trunc(raw)))
+				: 0
+			return new Intl.NumberFormat(getCanonicalLocale(), {
+				maximumFractionDigits: fractionDigits,
+				minimumFractionDigits: fractionDigits,
+				useGrouping: false,
+			}).format(this.value)
 		},
 
 		getStep() {