TanStack
diff --git a/.changeset/quiet-files-travel.md b/.changeset/quiet-files-travel.md
@@ -0,0 +1,5 @@
+---
+'@tanstack/create': patch
+---
+
+Remove `memfs` from the published runtime dependencies by reusing the internal in-memory environment.
diff --git a/packages/create/package.json b/packages/create/package.json
@@ -73,7 +73,6 @@
     "ejs": "^3.1.10",
     "execa": "^9.5.2",
     "ignore": "^7.0.3",
-    "memfs": "^4.17.0",
     "parse-gitignore": "^2.0.0",
     "prettier": "^3.5.0",
     "rimraf": "^6.0.1",
@@ -85,6 +84,7 @@
     "@types/parse-gitignore": "^1.0.2",
     "@vitest/coverage-v8": "4.1.5",
     "eslint": "^9.20.0",
+    "memfs": "4.17.0",
     "typescript": "^6.0.2",
     "vitest": "^4.1.5",
     "vitest-fetch-mock": "^0.4.5"

diff --git a/packages/create/src/environment.ts b/packages/create/src/environment.ts
@@ -8,24 +8,16 @@ import {
   writeFile,
 } from 'node:fs/promises'
 import { existsSync, statSync } from 'node:fs'
-import { dirname } from 'node:path'
+import { dirname, resolve } from 'node:path'
 import { execa } from 'execa'
-import { memfs } from 'memfs'
 import { rimraf } from 'rimraf'
 
-import {
-  cleanUpFileArray,
-  cleanUpFiles,
-  getBinaryFile,
-} from './file-helpers.js'
+import { createMemoryEnvironment as createEdgeMemoryEnvironment } from './edge-environment.js'
+import { getBinaryFile } from './file-helpers.js'
 
 import type { Environment } from './types.js'
 
-export interface MemoryEnvironmentOutput {
-  files: Record<string, string>
-  deletedFiles: Array<string>
-  commands: Array<{ command: string; args: Array<string> }>
-}
+export type { MemoryEnvironmentOutput } from './edge-environment.js'
 
 export function createDefaultEnvironment(): Environment {
   let errors: Array<string> = []
@@ -115,79 +107,43 @@ export function createDefaultEnvironment(): Environment {
 }
 
 export function createMemoryEnvironment(returnPathsRelativeTo: string = '') {
-  const environment = createDefaultEnvironment()
+  const { environment, output } =
+    createEdgeMemoryEnvironment(returnPathsRelativeTo)
+  const resolvePath = (path: string) => resolve(process.cwd(), path)
 
-  const output: MemoryEnvironmentOutput = {
-    files: {},
-    commands: [],
-    deletedFiles: [],
-  }
+  const appendFile = environment.appendFile
+  environment.appendFile = (path, contents) =>
+    appendFile(resolvePath(path), contents)
 
-  const { fs, vol } = memfs({})
+  const copyFile = environment.copyFile
+  environment.copyFile = (from, to) =>
+    copyFile(resolvePath(from), resolvePath(to))
 
-  environment.appendFile = async (path: string, contents: string) => {
-    fs.mkdirSync(dirname(path), { recursive: true })
-    await fs.appendFileSync(path, contents)
-  }
-  environment.copyFile = async (from: string, to: string) => {
-    fs.mkdirSync(dirname(to), { recursive: true })
-    fs.copyFileSync(from, to)
-    return Promise.resolve()
-  }
-  environment.execute = async (command: string, args: Array<string>) => {
-    output.commands.push({
-      command,
-      args,
-    })
-    return Promise.resolve({ stdout: '' })
-  }
-  environment.readFile = async (path: string) => {
-    return Promise.resolve(fs.readFileSync(path, 'utf-8').toString())
-  }
-  environment.writeFile = async (path: string, contents: string) => {
-    fs.mkdirSync(dirname(path), { recursive: true })
-    await fs.writeFileSync(path, contents)
-  }
-  environment.writeFileBase64 = async (path: string, contents: string) => {
-    // For the in-memory file system, we are not converting the base64 to binary
-    // because it's not needed.
-    fs.mkdirSync(dirname(path), { recursive: true })
-    await fs.writeFileSync(path, contents)
-  }
-  environment.deleteFile = async (path: string) => {
-    output.deletedFiles.push(path)
-    if (fs.existsSync(path)) {
-      await fs.unlinkSync(path)
-    }
-  }
-  environment.finishRun = () => {
-    output.files = vol.toJSON() as Record<string, string>
-    for (const file of Object.keys(output.files)) {
-      if (fs.statSync(file).isDirectory()) {
-        delete output.files[file]
-      }
-    }
-    if (returnPathsRelativeTo.length) {
-      output.files = cleanUpFiles(output.files, returnPathsRelativeTo)
-      output.deletedFiles = cleanUpFileArray(
-        output.deletedFiles,
-        returnPathsRelativeTo,
-      )
-    }
-  }
-  environment.exists = (path: string) => {
-    return fs.existsSync(path)
-  }
-  environment.isDirectory = (path: string) => {
-    return fs.statSync(path).isDirectory()
-  }
-  environment.readdir = async (path: string) => {
-    return Promise.resolve(fs.readdirSync(path).map((d) => d.toString()))
-  }
-  environment.rimraf = async () => {}
+  const writeFile = environment.writeFile
+  environment.writeFile = (path, contents) =>
+    writeFile(resolvePath(path), contents)
 
-  return {
-    environment,
-    output,
-  }
+  const writeFileBase64 = environment.writeFileBase64
+  environment.writeFileBase64 = (path, contents) =>
+    writeFileBase64(resolvePath(path), contents)
+
+  const deleteFile = environment.deleteFile
+  environment.deleteFile = (path) => deleteFile(resolvePath(path))
+
+  const readFile = environment.readFile
+  environment.readFile = (path) => readFile(resolvePath(path))
+
+  const exists = environment.exists
+  environment.exists = (path) => exists(resolvePath(path))
+
+  const isDirectory = environment.isDirectory
+  environment.isDirectory = (path) => isDirectory(resolvePath(path))
+
+  const readdir = environment.readdir
+  environment.readdir = (path) => readdir(resolvePath(path))
+
+  const rimraf = environment.rimraf
+  environment.rimraf = (path) => rimraf(resolvePath(path))
+
+  return { environment, output }
 }
diff --git a/packages/create/src/file-helpers.ts b/packages/create/src/file-helpers.ts
@@ -48,7 +48,7 @@ export function toCleanPath(absolutePath: string, baseDir: string): string {
   if (normalizedPath.startsWith(normalizedBase)) {
     cleanPath = normalizedPath.slice(normalizedBase.length)
   } else if (hasDrive(normalizedPath) !== hasDrive(normalizedBase)) {
-    // Handle paths that are missing the Windows drive letter (e.g. memfs on Windows)
+    // Handle paths that are missing the Windows drive letter in memory.
     const pathNoDrive = stripDrive(normalizedPath)
     const baseNoDrive = stripDrive(normalizedBase)
     if (pathNoDrive.startsWith(baseNoDrive)) {

diff --git a/packages/create/tests/index.test.ts b/packages/create/tests/index.test.ts
@@ -1,9 +1,35 @@
-import { describe, expect, it } from 'vitest'
+import { readFile } from 'node:fs/promises'
+import { afterEach, describe, expect, it, vi } from 'vitest'
 
-import { createApp } from '../src/index.js'
+afterEach(() => {
+  vi.doUnmock('memfs')
+  vi.resetModules()
+})
 
 describe('index', () => {
-  it('should be a test', () => {
+  it('exports createApp', async () => {
+    const { createApp } = await import('../src/index.js')
+
+    expect(createApp).toBeDefined()
+  })
+
+  it('does not import the test-only memory filesystem', async () => {
+    vi.resetModules()
+    vi.doMock('memfs', () => {
+      throw new Error('memfs is unavailable')
+    })
+
+    const { createApp } = await import('../src/index.js')
+
     expect(createApp).toBeDefined()
   })
+
+  it('does not publish the test-only memory filesystem', async () => {
+    const packageJSON = JSON.parse(
+      await readFile(new URL('../package.json', import.meta.url), 'utf8'),
+    )
+
+    expect(packageJSON.dependencies).not.toHaveProperty('memfs')
+    expect(packageJSON.devDependencies).toHaveProperty('memfs')
+  })
 })
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml