refactor: simplify file size estimate and drop unused param

Author: BilgeGates

src/components/features/Export/ExportProgress.tsx

@@ -70,6 +70,15 @@ export const ExportProgress = memo(function ExportProgress({
     exportInfo = null;
   }
 
+  const estimatedSize = exportInfo
+    ? exportInfo.fileSizeEstimates[format] ||
+      exportInfo.fileSizeEstimates['png']
+    : '';
+  const fileSizeText =
+    actualBytes != null
+      ? `File size: ${formatFileSize(actualBytes)}`
+      : `File size estimate: ~${estimatedSize}`;
+
   return (
     <ModalShell
       isOpen={isExporting}
@@ -89,17 +98,7 @@ export const ExportProgress = memo(function ExportProgress({
         {exportInfo && (
           <div className="text-xs text-text-muted bg-surface-elevated border border-border rounded-lg px-3 py-2 space-y-1">
             <div>Resolution: {exportInfo.displaySize}</div>
-            <div>
-              {actualBytes != null ? (
-                <>File size: {formatFileSize(actualBytes)}</>
-              ) : (
-                <>
-                  File size estimate: ~
-                  {exportInfo.fileSizeEstimates[format] ||
-                    exportInfo.fileSizeEstimates['png']}
-                </>
-              )}
-            </div>
+            <div>{fileSizeText}</div>
             {exportInfo.isLargeExport && (
               <div className="text-warning mt-1">
                 Large export (RAM: {exportInfo.memoryEstimateMB} MB). May take

src/shared/utils/exportState.ts

@@ -100,8 +100,7 @@ export function getExportInfo(config: ExportConfig): ExportInfo {
   const mode = getExportMode(exportQuality);
   const fileSizes = estimateFileSizes(
     exportSize.canvasWidth,
-    exportSize.canvasHeight,
-    exportQuality
+    exportSize.canvasHeight
   );
 
   return {

src/shared/utils/imageOptimizer.test.ts

@@ -10,8 +10,8 @@ test('formatFileSize scales unit with magnitude', () => {
 });
 
 test('estimateFileSizes stays positive and grows with resolution', () => {
-  const small = estimateFileSizes(1000, 1000, 1);
-  const large = estimateFileSizes(4000, 4000, 1);
+  const small = estimateFileSizes(1000, 1000);
+  const large = estimateFileSizes(4000, 4000);
 
   assert.ok(small.pngBytes > 0);
   assert.ok(small.jpegBytes > 0);
@@ -20,8 +20,8 @@ test('estimateFileSizes stays positive and grows with resolution', () => {
 });
 
 test('estimateFileSizes bytes-per-pixel falls as the image grows', () => {
-  const small = estimateFileSizes(1000, 1000, 1);
-  const large = estimateFileSizes(4000, 4000, 1);
+  const small = estimateFileSizes(1000, 1000);
+  const large = estimateFileSizes(4000, 4000);
 
   const smallBpp = small.pngBytes / (1000 * 1000);
   const largeBpp = large.pngBytes / (4000 * 4000);

src/shared/utils/imageOptimizer.ts

@@ -166,16 +166,9 @@ export interface FileSizeEstimates {
 
 export function estimateFileSizes(
   width: number,
-  height: number,
-  _exportQuality: number
+  height: number
 ): FileSizeEstimates {
-  const pixels = width * height;
-  // A chess diagram is mostly flat colour, so bytes-per-pixel falls as the
-  // image grows (larger flat runs compress better). Modelling the encoded
-  // size as proportional to sqrt(pixels) tracks that far more closely than a
-  // fixed bytes-per-pixel factor. Coefficients fitted against real PNG/JPEG
-  // (q=0.92) exports of coordinate boards across export sizes.
-  const scale = Math.sqrt(pixels);
+  const scale = Math.sqrt(width * height);
   const pngBytes = Math.round(scale * 90);
   const jpegBytes = Math.round(scale * 55);
   return {