refactor: replace JSON.stringify with safeWriteJson for file operations

Replace all non-test instances of JSON.stringify used for writing to JSON files with safeWriteJson to ensure safer file operations with proper locking, error handling, and atomic writes.

- Updated src/services/mcp/McpHub.ts
- Updated src/services/code-index/cache-manager.ts
- Updated src/api/providers/fetchers/modelEndpointCache.ts
- Updated src/api/providers/fetchers/modelCache.ts
- Updated tests to match the new implementation

Signed-off-by: Eric Wheeler <[email protected]>

Author: Eric Wheeler

src/api/providers/fetchers/modelCache.ts

@@ -2,6 +2,7 @@ import * as path from "path"
 import fs from "fs/promises"
 
 import NodeCache from "node-cache"
+import { safeWriteJson } from "../../../utils/safeWriteJson"
 
 import { ContextProxy } from "../../../core/config/ContextProxy"
 import { getCacheDirectoryPath } from "../../../utils/storage"
@@ -19,7 +20,7 @@ const memoryCache = new NodeCache({ stdTTL: 5 * 60, checkperiod: 5 * 60 })
 async function writeModels(router: RouterName, data: ModelRecord) {
 	const filename = `${router}_models.json`
 	const cacheDir = await getCacheDirectoryPath(ContextProxy.instance.globalStorageUri.fsPath)
-	await fs.writeFile(path.join(cacheDir, filename), JSON.stringify(data))
+	await safeWriteJson(path.join(cacheDir, filename), data)
 }
 
 async function readModels(router: RouterName): Promise<ModelRecord | undefined> {

src/api/providers/fetchers/modelEndpointCache.ts

@@ -2,6 +2,7 @@ import * as path from "path"
 import fs from "fs/promises"
 
 import NodeCache from "node-cache"
+import { safeWriteJson } from "../../../utils/safeWriteJson"
 import sanitize from "sanitize-filename"
 
 import { ContextProxy } from "../../../core/config/ContextProxy"
@@ -18,7 +19,7 @@ const getCacheKey = (router: RouterName, modelId: string) => sanitize(`${router}
 async function writeModelEndpoints(key: string, data: ModelRecord) {
 	const filename = `${key}_endpoints.json`
 	const cacheDir = await getCacheDirectoryPath(ContextProxy.instance.globalStorageUri.fsPath)
-	await fs.writeFile(path.join(cacheDir, filename), JSON.stringify(data, null, 2))
+	await safeWriteJson(path.join(cacheDir, filename), data)
 }
 
 async function readModelEndpoints(key: string): Promise<ModelRecord | undefined> {

src/services/code-index/__tests__/cache-manager.test.ts

@@ -2,6 +2,7 @@ import * as vscode from "vscode"
 import { createHash } from "crypto"
 import debounce from "lodash.debounce"
 import { CacheManager } from "../cache-manager"
+import { safeWriteJson } from "../../../utils/safeWriteJson"
 
 // Mock vscode
 jest.mock("vscode", () => ({
@@ -11,12 +12,16 @@ jest.mock("vscode", () => ({
 	workspace: {
 		fs: {
 			readFile: jest.fn(),
-			writeFile: jest.fn(),
 			delete: jest.fn(),
 		},
 	},
 }))
 
+// Mock safeWriteJson
+jest.mock("../../../utils/safeWriteJson", () => ({
+	safeWriteJson: jest.fn(),
+}))
+
 // Mock debounce to execute immediately
 jest.mock("lodash.debounce", () => jest.fn((fn) => fn))
 
@@ -88,7 +93,7 @@ describe("CacheManager", () => {
 			cacheManager.updateHash(filePath, hash)
 
 			expect(cacheManager.getHash(filePath)).toBe(hash)
-			expect(vscode.workspace.fs.writeFile).toHaveBeenCalled()
+			expect(safeWriteJson).toHaveBeenCalled()
 		})
 
 		it("should delete hash and trigger save", () => {
@@ -99,7 +104,7 @@ describe("CacheManager", () => {
 			cacheManager.deleteHash(filePath)
 
 			expect(cacheManager.getHash(filePath)).toBeUndefined()
-			expect(vscode.workspace.fs.writeFile).toHaveBeenCalled()
+			expect(safeWriteJson).toHaveBeenCalled()
 		})
 
 		it("should return shallow copy of hashes", () => {
@@ -124,18 +129,14 @@ describe("CacheManager", () => {
 
 			cacheManager.updateHash(filePath, hash)
 
-			expect(vscode.workspace.fs.writeFile).toHaveBeenCalledWith(mockCachePath, expect.any(Uint8Array))
+			expect(safeWriteJson).toHaveBeenCalledWith(mockCachePath.fsPath, { [filePath]: hash })
 
-			// Verify the saved data
-			const savedData = JSON.parse(
-				Buffer.from((vscode.workspace.fs.writeFile as jest.Mock).mock.calls[0][1]).toString(),
-			)
-			expect(savedData).toEqual({ [filePath]: hash })
+			// No need to parse the data since safeWriteJson receives the object directly
 		})
 
 		it("should handle save errors gracefully", async () => {
 			const consoleErrorSpy = jest.spyOn(console, "error").mockImplementation()
-			;(vscode.workspace.fs.writeFile as jest.Mock).mockRejectedValue(new Error("Save failed"))
+			;(safeWriteJson as jest.Mock).mockRejectedValue(new Error("Save failed"))
 
 			cacheManager.updateHash("test.ts", "hash")
 
@@ -152,19 +153,19 @@ describe("CacheManager", () => {
 		it("should clear cache file and reset state", async () => {
 			cacheManager.updateHash("test.ts", "hash")
 
-			// Reset the mock to ensure writeFile succeeds for clearCacheFile
-			;(vscode.workspace.fs.writeFile as jest.Mock).mockClear()
-			;(vscode.workspace.fs.writeFile as jest.Mock).mockResolvedValue(undefined)
+			// Reset the mock to ensure safeWriteJson succeeds for clearCacheFile
+			;(safeWriteJson as jest.Mock).mockClear()
+			;(safeWriteJson as jest.Mock).mockResolvedValue(undefined)
 
 			await cacheManager.clearCacheFile()
 
-			expect(vscode.workspace.fs.writeFile).toHaveBeenCalledWith(mockCachePath, Buffer.from("{}"))
+			expect(safeWriteJson).toHaveBeenCalledWith(mockCachePath.fsPath, {})
 			expect(cacheManager.getAllHashes()).toEqual({})
 		})
 
 		it("should handle clear errors gracefully", async () => {
 			const consoleErrorSpy = jest.spyOn(console, "error").mockImplementation()
-			;(vscode.workspace.fs.writeFile as jest.Mock).mockRejectedValue(new Error("Save failed"))
+			;(safeWriteJson as jest.Mock).mockRejectedValue(new Error("Save failed"))
 
 			await cacheManager.clearCacheFile()
 

src/services/code-index/cache-manager.ts

@@ -2,6 +2,7 @@ import * as vscode from "vscode"
 import { createHash } from "crypto"
 import { ICacheManager } from "./interfaces/cache"
 import debounce from "lodash.debounce"
+import { safeWriteJson } from "../../utils/safeWriteJson"
 
 /**
  * Manages the cache for code indexing
@@ -46,7 +47,7 @@ export class CacheManager implements ICacheManager {
 	 */
 	private async _performSave(): Promise<void> {
 		try {
-			await vscode.workspace.fs.writeFile(this.cachePath, Buffer.from(JSON.stringify(this.fileHashes, null, 2)))
+			await safeWriteJson(this.cachePath.fsPath, this.fileHashes)
 		} catch (error) {
 			console.error("Failed to save cache:", error)
 		}
@@ -57,7 +58,7 @@ export class CacheManager implements ICacheManager {
 	 */
 	async clearCacheFile(): Promise<void> {
 		try {
-			await vscode.workspace.fs.writeFile(this.cachePath, Buffer.from("{}"))
+			await safeWriteJson(this.cachePath.fsPath, {})
 			this.fileHashes = {}
 		} catch (error) {
 			console.error("Failed to clear cache file:", error, this.cachePath)

src/services/mcp/McpHub.ts

@@ -1135,7 +1135,7 @@ export class McpHub {
 			mcpServers: config.mcpServers,
 		}
 
-		await fs.writeFile(configPath, JSON.stringify(updatedConfig, null, 2))
+		await safeWriteJson(configPath, updatedConfig)
 	}
 
 	public async updateServerTimeout(