Fix MCP server not restarting when version changes (#278473)

* Initial plan

* Fix MCP server not restarting when cacheNonce/version changes

Add cacheNonce comparison to McpServerDefinition.equals() to ensure servers
are properly stopped and restarted when the version changes (e.g., due to
authentication changes). Add comprehensive tests for the equals function.

Co-authored-by: TylerLeonhardt <2644648+TylerLeonhardt@users.noreply.github.com>

* Fix tests

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: TylerLeonhardt <2644648+TylerLeonhardt@users.noreply.github.com>
Co-authored-by: Tyler Leonhardt <tyleonha@microsoft.com>

src/vs/workbench/contrib/mcp/common/mcpTypes.ts

@@ -184,6 +184,7 @@ export namespace McpServerDefinition {
 	export function equals(a: McpServerDefinition, b: McpServerDefinition): boolean {
 		return a.id === b.id
 			&& a.label === b.label
+			&& a.cacheNonce === b.cacheNonce
 			&& arraysEqual(a.roots, b.roots, (a, b) => a.toString() === b.toString())
 			&& objectsEqual(a.launch, b.launch)
 			&& objectsEqual(a.presentation, b.presentation)

src/vs/workbench/contrib/mcp/test/common/mcpTypes.test.ts

@@ -4,8 +4,9 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { ensureNoDisposablesAreLeakedInTestSuite } from '../../../../../base/test/common/utils.js';
-import { McpResourceURI } from '../../common/mcpTypes.js';
+import { McpResourceURI, McpServerDefinition, McpServerTransportType } from '../../common/mcpTypes.js';
 import * as assert from 'assert';
+import { URI } from '../../../../../base/common/uri.js';
 
 suite('MCP Types', () => {
 	ensureNoDisposablesAreLeakedInTestSuite();
@@ -27,4 +28,81 @@ suite('MCP Types', () => {
 		roundTrip('custom-scheme:///my-path');
 		roundTrip('custom-scheme:///my-path/foo/?with=query&params=here');
 	});
+
+	suite('McpServerDefinition.equals', () => {
+		const createBasicDefinition = (overrides?: Partial<McpServerDefinition>): McpServerDefinition => ({
+			id: 'test-server',
+			label: 'Test Server',
+			cacheNonce: 'v1.0.0',
+			launch: {
+				type: McpServerTransportType.Stdio,
+				cwd: undefined,
+				command: 'test-command',
+				args: [],
+				env: {},
+				envFile: undefined
+			},
+			...overrides
+		});
+
+		test('returns true for identical definitions', () => {
+			const def1 = createBasicDefinition();
+			const def2 = createBasicDefinition();
+			assert.strictEqual(McpServerDefinition.equals(def1, def2), true);
+		});
+
+		test('returns false when cacheNonce differs', () => {
+			const def1 = createBasicDefinition({ cacheNonce: 'v1.0.0' });
+			const def2 = createBasicDefinition({ cacheNonce: 'v2.0.0' });
+			assert.strictEqual(McpServerDefinition.equals(def1, def2), false);
+		});
+
+		test('returns false when id differs', () => {
+			const def1 = createBasicDefinition({ id: 'server-1' });
+			const def2 = createBasicDefinition({ id: 'server-2' });
+			assert.strictEqual(McpServerDefinition.equals(def1, def2), false);
+		});
+
+		test('returns false when label differs', () => {
+			const def1 = createBasicDefinition({ label: 'Server A' });
+			const def2 = createBasicDefinition({ label: 'Server B' });
+			assert.strictEqual(McpServerDefinition.equals(def1, def2), false);
+		});
+
+		test('returns false when roots differ', () => {
+			const def1 = createBasicDefinition({ roots: [URI.file('/path1')] });
+			const def2 = createBasicDefinition({ roots: [URI.file('/path2')] });
+			assert.strictEqual(McpServerDefinition.equals(def1, def2), false);
+		});
+
+		test('returns true when roots are both undefined', () => {
+			const def1 = createBasicDefinition({ roots: undefined });
+			const def2 = createBasicDefinition({ roots: undefined });
+			assert.strictEqual(McpServerDefinition.equals(def1, def2), true);
+		});
+
+		test('returns false when launch differs', () => {
+			const def1 = createBasicDefinition({
+				launch: {
+					type: McpServerTransportType.Stdio,
+					cwd: undefined,
+					command: 'command1',
+					args: [],
+					env: {},
+					envFile: undefined
+				}
+			});
+			const def2 = createBasicDefinition({
+				launch: {
+					type: McpServerTransportType.Stdio,
+					cwd: undefined,
+					command: 'command2',
+					args: [],
+					env: {},
+					envFile: undefined
+				}
+			});
+			assert.strictEqual(McpServerDefinition.equals(def1, def2), false);
+		});
+	});
 });