Set aria label and include split number/total

Fixes #122332

src/vs/workbench/contrib/terminal/browser/terminalTabsWidget.ts

@@ -228,16 +228,34 @@ class TerminalTabsRenderer implements ITreeRenderer<ITerminalInstance, never, IT
 		const hasText = !this.shouldHideText();
 		template.element.classList.toggle('has-text', hasText);
 
+		let ariaLabel: string = '';
 		let prefix: string = '';
 		if (tab.terminalInstances.length > 1) {
-			const terminalIndex = tab?.terminalInstances.indexOf(instance);
+			const terminalIndex = tab.terminalInstances.indexOf(instance);
+			ariaLabel = localize({
+				key: 'splitTerminalAriaLabel',
+				comment: [
+					`The terminal's ID`,
+					`The terminal's title`,
+					`The terminal's split number`,
+					`The terminal group's total split number`
+				]
+			}, "Terminal {0} {1}, split {2} of {3}", instance.instanceId, instance.title, terminalIndex + 1, tab.terminalInstances.length);
 			if (terminalIndex === 0) {
 				prefix = `┌ `;
 			} else if (terminalIndex === tab!.terminalInstances.length - 1) {
 				prefix = `└ `;
 			} else {
 				prefix = `├ `;
 			}
+		} else {
+			ariaLabel = localize({
+				key: 'terminalAriaLabel',
+				comment: [
+					`The terminal's ID`,
+					`The terminal's title`
+				]
+			}, "Terminal {0} {1}", instance.instanceId, instance.title);
 		}
 
 		let title = instance.title;
@@ -256,6 +274,7 @@ class TerminalTabsRenderer implements ITreeRenderer<ITerminalInstance, never, IT
 			const primaryStatus = instance.statusList.primary;
 			if (primaryStatus && primaryStatus.severity >= Severity.Warning) {
 				label = `${prefix}$(${primaryStatus.icon?.id || instance.icon?.id})`;
+				ariaLabel = '';
 			} else {
 				label = `${prefix}$(${instance.icon?.id})`;
 			}
@@ -279,6 +298,10 @@ class TerminalTabsRenderer implements ITreeRenderer<ITerminalInstance, never, IT
 				instance.dispose();
 			}
 		}));
+
+		// Set aria lable to expose split information to screen reader
+		template.label.element.querySelector('.label-name')?.setAttribute('aria-label', ariaLabel);
+
 		template.label.setResource({
 			resource: instance.resource,
 			name: label,