Reduce cost display precision to 2 decimal places

formatCost now uses 2 decimal places (was 4) everywhere: webview
details panel, status-bar tooltip, and the related test.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: rajbos

vscode-extension/src/extension.ts

@@ -1332,8 +1332,8 @@ class CopilotTokenTracker implements vscode.Disposable {
 			tooltip.appendMarkdown(`📅 Today  \n`);
 			tooltip.appendMarkdown(`|                 |  |\n|-----------------------|-------|\n`);
 			tooltip.appendMarkdown(`| Tokens :                | ${detailedStats.today.tokens.toLocaleString()} |\n`);
-			tooltip.appendMarkdown(`| Estimated cost (est.) :      | $ ${detailedStats.today.estimatedCost.toFixed(4)} |\n`);
-			tooltip.appendMarkdown(`| Estimated cost (TBB) :       | $ ${(detailedStats.today.estimatedCostCopilot ?? 0).toFixed(4)} |\n`);
+			tooltip.appendMarkdown(`| Estimated cost (est.) :      | $ ${detailedStats.today.estimatedCost.toFixed(2)} |\n`);
+			tooltip.appendMarkdown(`| Estimated cost (TBB) :       | $ ${(detailedStats.today.estimatedCostCopilot ?? 0).toFixed(2)} |\n`);
 			tooltip.appendMarkdown(`| CO₂ estimated :              | ${detailedStats.today.co2.toFixed(2)} grams |\n`);
 			tooltip.appendMarkdown(`| Water estimated :           | ${detailedStats.today.waterUsage.toFixed(3)} liters |\n`);
 			tooltip.appendMarkdown(`| Sessions :             | ${detailedStats.today.sessions} |\n`);
@@ -1346,8 +1346,8 @@ class CopilotTokenTracker implements vscode.Disposable {
 			tooltip.appendMarkdown(`📊 Last 30 Days  \n`);
 			tooltip.appendMarkdown(`|                 |  |\n|-----------------------|-------|\n`);
 			tooltip.appendMarkdown(`| Tokens :                | ${detailedStats.last30Days.tokens.toLocaleString()} |\n`);
-			tooltip.appendMarkdown(`| Estimated cost (est.) :      | $ ${detailedStats.last30Days.estimatedCost.toFixed(4)} |\n`);
-			tooltip.appendMarkdown(`| Estimated cost (TBB) :       | $ ${(detailedStats.last30Days.estimatedCostCopilot ?? 0).toFixed(4)} |\n`);
+			tooltip.appendMarkdown(`| Estimated cost (est.) :      | $ ${detailedStats.last30Days.estimatedCost.toFixed(2)} |\n`);
+			tooltip.appendMarkdown(`| Estimated cost (TBB) :       | $ ${(detailedStats.last30Days.estimatedCostCopilot ?? 0).toFixed(2)} |\n`);
 			tooltip.appendMarkdown(`| CO₂ estimated :              | ${detailedStats.last30Days.co2.toFixed(2)} grams |\n`);
 			tooltip.appendMarkdown(`| Water estimated :           | ${detailedStats.last30Days.waterUsage.toFixed(3)} liters |\n`);
 			tooltip.appendMarkdown(`| Sessions :             | ${detailedStats.last30Days.sessions} |\n`);

vscode-extension/src/webview/shared/formatUtils.ts

@@ -92,13 +92,13 @@ export function formatCompact(value: number): string {
 }
 
 /**
- * Formats a number as a USD cost with 4 decimal places.
+ * Formats a number as a USD cost with 2 decimal places.
  */
 export function formatCost(value: number): string {
 	return new Intl.NumberFormat(currentLocale, {
 		style: 'currency',
 		currency: 'USD',
-		minimumFractionDigits: 4,
-		maximumFractionDigits: 4
+		minimumFractionDigits: 2,
+		maximumFractionDigits: 2
 	}).format(value);
 }

vscode-extension/test/unit/webview-utils.test.ts

@@ -82,16 +82,16 @@ test('formatNumber: adds thousand separators', () => {
 
 // ── formatCost ──────────────────────────────────────────────────────────
 
-test('formatCost: formats as USD with 4 decimal places', () => {
+test('formatCost: formats as USD with 2 decimal places', () => {
 	setFormatLocale('en-US');
 	const result = formatCost(1.23456789);
 	assert.ok(result.includes('$'), 'should contain dollar sign');
-	assert.ok(result.includes('1.2346'), 'should round to 4 decimal places');
+	assert.ok(result.includes('1.23'), 'should round to 2 decimal places');
 });
 
 test('formatCost: zero cost', () => {
 	setFormatLocale('en-US');
 	const result = formatCost(0);
 	assert.ok(result.includes('$'), 'should contain dollar sign');
-	assert.ok(result.includes('0.0000'), 'should show four decimal zeros');
+	assert.ok(result.includes('0.00'), 'should show two decimal zeros');
 });