fix: resolve unit test failures in PR #5889

- Fix VSCode mock onDidChangeWorkspaceFolders to accept callback parameter
- Update MCP test mocks to properly test auto-omit functionality
- Update test snapshots to reflect new MCP content omission behavior
- All core functionality tests now passing

Author: roomote

src/__mocks__/vscode.js

@@ -46,7 +46,7 @@ const mockRelativePattern = class {
 export const workspace = {
 	workspaceFolders: [],
 	getWorkspaceFolder: () => null,
-	onDidChangeWorkspaceFolders: () => mockDisposable,
+	onDidChangeWorkspaceFolders: (callback) => mockDisposable,
 	getConfiguration: () => ({
 		get: () => null,
 	}),

src/core/prompts/__tests__/__snapshots__/add-custom-instructions/mcp-server-creation-disabled.snap

@@ -168,9 +168,9 @@ const mockContext = {
 } as unknown as vscode.ExtensionContext
 
 // Instead of extending McpHub, create a mock that implements just what we need
-const createMockMcpHub = (): McpHub =>
+const createMockMcpHub = (withServers: boolean = false): McpHub =>
 	({
-		getServers: () => [],
+		getServers: () => (withServers ? [{ name: "test-server", disabled: false }] : []),
 		getMcpServersPath: async () => "/mock/mcp/path",
 		getMcpSettingsFilePath: async () => "/mock/settings/path",
 		dispose: async () => {},
@@ -236,7 +236,7 @@ describe("addCustomInstructions", () => {
 	})
 
 	it("should include MCP server creation info when enabled", async () => {
-		const mockMcpHub = createMockMcpHub()
+		const mockMcpHub = createMockMcpHub(true)
 
 		const prompt = await SYSTEM_PROMPT(
 			mockContext,
@@ -262,7 +262,7 @@ describe("addCustomInstructions", () => {
 	})
 
 	it("should exclude MCP server creation info when disabled", async () => {
-		const mockMcpHub = createMockMcpHub()
+		const mockMcpHub = createMockMcpHub(false)
 
 		const prompt = await SYSTEM_PROMPT(
 			mockContext,

src/core/prompts/__tests__/__snapshots__/add-custom-instructions/mcp-server-creation-enabled.snap

@@ -168,9 +168,9 @@ const mockContext = {
 } as unknown as vscode.ExtensionContext
 
 // Instead of extending McpHub, create a mock that implements just what we need
-const createMockMcpHub = (): McpHub =>
+const createMockMcpHub = (withServers: boolean = false): McpHub =>
 	({
-		getServers: () => [],
+		getServers: () => (withServers ? [{ name: "test-server", disabled: false }] : []),
 		getMcpServersPath: async () => "/mock/mcp/path",
 		getMcpSettingsFilePath: async () => "/mock/settings/path",
 		dispose: async () => {},
@@ -250,7 +250,7 @@ describe("SYSTEM_PROMPT", () => {
 	})
 
 	it("should include MCP server info when mcpHub is provided", async () => {
-		mockMcpHub = createMockMcpHub()
+		mockMcpHub = createMockMcpHub(true)
 
 		const prompt = await SYSTEM_PROMPT(
 			mockContext,