diff --git a/packages/jsonforms-renderers/src/renderers/SpreadsheetControl.tsx b/packages/jsonforms-renderers/src/renderers/SpreadsheetControl.tsx
index c736bb5..83fb133 100644
--- a/packages/jsonforms-renderers/src/renderers/SpreadsheetControl.tsx
+++ b/packages/jsonforms-renderers/src/renderers/SpreadsheetControl.tsx
@@ -9,11 +9,11 @@ import { formatBytes, formatAccept } from '../utils/format'
 import {
   parseWorkbookToMatrix,
   columnLetter,
-  evaluateExpressions,
+  processMatrix,
   SheetParseError,
   type CellValue,
   type FormulaConfigEntry,
-  type FormulaResult,
+  type SpreadsheetValue,
 } from '../utils/spreadsheet'
 
 interface XSpreadsheetOptions {
@@ -37,13 +37,6 @@ type SpreadsheetControlProps = ControlProps & {
   schema: JsonSchema & { 'x-spreadsheet'?: XSpreadsheetOptions; 'x-evaluate'?: FormulaConfigEntry[] }
 }
 
-// Persisted value shape — the field's data is an object, not a string key.
-// No `fileName`: there's no storage service to name a retrievable file for.
-interface SpreadsheetValue {
-  sheet?: CellValue[][]
-  derivations: FormulaResult[]
-}
-
 type Status = 'empty' | 'parsing' | 'ready' | 'error'
 
 const DEFAULT_ACCEPT =
@@ -150,11 +143,8 @@ const SpreadsheetControl = ({
       }
 
       setLocalMatrix(parsedMatrix)
-      const newDerivations = await evaluateExpressions(parsedMatrix, xEvaluate)
-      handleChange(
-        path,
-        persistSheet ? { sheet: parsedMatrix, derivations: newDerivations } : { derivations: newDerivations },
-      )
+      const value = await processMatrix(parsedMatrix, xEvaluate, { persistSheet })
+      handleChange(path, value)
       setStatus('ready')
     },
     [accept, maxSize, persistSheet, sheetName, xEvaluate, path, handleChange],
diff --git a/packages/jsonforms-renderers/src/utils/spreadsheet/index.ts b/packages/jsonforms-renderers/src/utils/spreadsheet/index.ts
index 8826444..4309101 100644
--- a/packages/jsonforms-renderers/src/utils/spreadsheet/index.ts
+++ b/packages/jsonforms-renderers/src/utils/spreadsheet/index.ts
@@ -1,3 +1,13 @@
 export { parseWorkbookToMatrix, columnLetter, SheetParseError } from './parse'
 export { evaluateExpression, evaluateExpressions } from './expression'
-export type { CellValue, Matrix, ParsedSheet, FormulaConfigEntry, FormulaResult, FormulaErrorCode } from './types'
+export { processMatrix } from './process'
+export type { ProcessMatrixOptions } from './process'
+export type {
+  CellValue,
+  Matrix,
+  ParsedSheet,
+  FormulaConfigEntry,
+  FormulaResult,
+  FormulaErrorCode,
+  SpreadsheetValue,
+} from './types'
diff --git a/packages/jsonforms-renderers/src/utils/spreadsheet/process.test.ts b/packages/jsonforms-renderers/src/utils/spreadsheet/process.test.ts
new file mode 100644
index 0000000..f77cc43
--- /dev/null
+++ b/packages/jsonforms-renderers/src/utils/spreadsheet/process.test.ts
@@ -0,0 +1,47 @@
+import { describe, expect, it } from 'vitest'
+import { processMatrix } from './process'
+import type { CellValue } from './types'
+
+const matrix: CellValue[][] = [
+  ['Item', 'Qty'],
+  ['Widget', 10],
+  ['Gadget', 20],
+]
+
+describe('processMatrix', () => {
+  it('includes the raw sheet by default (persistSheet omitted)', async () => {
+    const result = await processMatrix(matrix, [{ label: 'Total', expression: '=SUM(B2:B3)' }])
+    expect(result).toEqual({ sheet: matrix, derivations: [{ label: 'Total', value: 30 }] })
+  })
+
+  it('includes the raw sheet when persistSheet is explicitly true', async () => {
+    const result = await processMatrix(matrix, [{ label: 'Total', expression: '=SUM(B2:B3)' }], {
+      persistSheet: true,
+    })
+    expect(result).toEqual({ sheet: matrix, derivations: [{ label: 'Total', value: 30 }] })
+  })
+
+  it('omits the raw sheet when persistSheet is false', async () => {
+    const result = await processMatrix(matrix, [{ label: 'Total', expression: '=SUM(B2:B3)' }], {
+      persistSheet: false,
+    })
+    expect(result).toEqual({ derivations: [{ label: 'Total', value: 30 }] })
+    expect(result).not.toHaveProperty('sheet')
+  })
+
+  it('yields an empty derivations array for an empty formulas config', async () => {
+    const result = await processMatrix(matrix, [])
+    expect(result).toEqual({ sheet: matrix, derivations: [] })
+  })
+
+  it('surfaces an evaluateExpressions error entry unchanged, alongside a good one', async () => {
+    const result = await processMatrix(matrix, [
+      { label: 'Good', expression: '=SUM(B2:B3)' },
+      { label: 'Bad', expression: '=FOO(B2)' },
+    ])
+    expect(result.derivations).toEqual([
+      { label: 'Good', value: 30 },
+      { label: 'Bad', value: null, error: '#NAME?' },
+    ])
+  })
+})
diff --git a/packages/jsonforms-renderers/src/utils/spreadsheet/process.ts b/packages/jsonforms-renderers/src/utils/spreadsheet/process.ts
new file mode 100644
index 0000000..9f9fc27
--- /dev/null
+++ b/packages/jsonforms-renderers/src/utils/spreadsheet/process.ts
@@ -0,0 +1,18 @@
+import { evaluateExpressions } from './expression'
+import type { CellValue, FormulaConfigEntry, SpreadsheetValue } from './types'
+
+export interface ProcessMatrixOptions {
+  persistSheet?: boolean
+}
+
+// Matrix-in, persisted-value-out. Deliberately format-agnostic: doesn't care
+// whether the matrix came from an xlsx/csv upload or (in the future) an XML
+// one — this is the reusable seam for both.
+export async function processMatrix(
+  matrix: CellValue[][],
+  formulas: FormulaConfigEntry[],
+  options: ProcessMatrixOptions = {},
+): Promise<SpreadsheetValue> {
+  const derivations = await evaluateExpressions(matrix, formulas)
+  return options.persistSheet !== false ? { sheet: matrix, derivations } : { derivations }
+}
diff --git a/packages/jsonforms-renderers/src/utils/spreadsheet/types.ts b/packages/jsonforms-renderers/src/utils/spreadsheet/types.ts
index f2757d3..1e17a44 100644
--- a/packages/jsonforms-renderers/src/utils/spreadsheet/types.ts
+++ b/packages/jsonforms-renderers/src/utils/spreadsheet/types.ts
@@ -28,3 +28,13 @@ export interface FormulaResult {
 // class; ERROR is our own catch-all for anything that doesn't map cleanly
 // (a syntax error, or a wrapped cause we don't otherwise recognize).
 export type FormulaErrorCode = 'REF' | 'VALUE' | 'DIV0' | 'NAME' | 'ERROR' | 'NA' | 'NUM' | 'NULL'
+
+// Persisted value shape for SpreadsheetControl — the field's data is an
+// object, not a string key. No `fileName`: there's no storage service to
+// name a retrievable file for. Shared here (rather than kept private to
+// SpreadsheetControl.tsx) so sibling renderers, like ComputedControl, can
+// read a SpreadsheetControl's persisted `derivations` with the same type.
+export interface SpreadsheetValue {
+  sheet?: CellValue[][]
+  derivations: FormulaResult[]
+}