fix(desktop): Harden local file tree paths (#43618)

* fix(desktop): Harden local file tree paths

Normalize Electron local path handling across file tree, preview, media, and git-root flows. Reject malformed and Windows device paths, recheck sensitive files after realpath resolution, and preserve external symlink traversal with stable renderer errors.

* fix(desktop): Address file tree review feedback

apps/desktop/electron/fs-read-dir.cjs

@@ -0,0 +1,109 @@
+'use strict'
+
+const fs = require('node:fs')
+const path = require('node:path')
+const { resolveDirectoryForIpc } = require('./hardening.cjs')
+
+const FS_READDIR_STAT_CONCURRENCY = 16
+
+// Always-hidden noise (covers non-git projects too; gitignore catches many of
+// these, but the project tree should keep the same hygiene without one).
+const FS_READDIR_HIDDEN = new Set([
+  '.git',
+  '.hg',
+  '.svn',
+  '.cache',
+  '.next',
+  '.turbo',
+  '.venv',
+  '__pycache__',
+  'build',
+  'dist',
+  'node_modules',
+  'target',
+  'venv'
+])
+
+function direntIsDirectory(dirent) {
+  return typeof dirent.isDirectory === 'function' && dirent.isDirectory()
+}
+
+function direntIsFile(dirent) {
+  return typeof dirent.isFile === 'function' && dirent.isFile()
+}
+
+function direntIsSymbolicLink(dirent) {
+  return typeof dirent.isSymbolicLink === 'function' && dirent.isSymbolicLink()
+}
+
+function shouldStatDirent(dirent) {
+  if (direntIsDirectory(dirent)) return false
+
+  return direntIsSymbolicLink(dirent) || !direntIsFile(dirent)
+}
+
+async function entryForDirent(dirent, resolved, fsImpl) {
+  const fullPath = path.join(resolved, dirent.name)
+  let isDirectory = direntIsDirectory(dirent)
+
+  if (!isDirectory && shouldStatDirent(dirent)) {
+    try {
+      isDirectory = (await fsImpl.promises.stat(fullPath)).isDirectory()
+    } catch {
+      isDirectory = false
+    }
+  }
+
+  return { name: dirent.name, path: fullPath, isDirectory }
+}
+
+async function mapWithStatConcurrency(items, mapper) {
+  const results = new Array(items.length)
+  let nextIndex = 0
+
+  async function runWorker() {
+    while (nextIndex < items.length) {
+      const index = nextIndex
+      nextIndex += 1
+      results[index] = await mapper(items[index])
+    }
+  }
+
+  const workerCount = Math.min(FS_READDIR_STAT_CONCURRENCY, items.length)
+  const workers = Array.from({ length: workerCount }, () => runWorker())
+  await Promise.all(workers)
+
+  return results
+}
+
+async function readDirForIpc(dirPath, options = {}) {
+  const fsImpl = options.fs || fs
+  let resolved
+
+  try {
+    ;({ resolvedPath: resolved } = await resolveDirectoryForIpc(dirPath, {
+      fs: fsImpl,
+      purpose: 'Directory read'
+    }))
+  } catch (error) {
+    return { entries: [], error: error?.code || 'read-error' }
+  }
+
+  try {
+    const dirents = await fsImpl.promises.readdir(resolved, { withFileTypes: true })
+    const visibleDirents = dirents.filter(dirent => !FS_READDIR_HIDDEN.has(dirent.name))
+    const entries = await mapWithStatConcurrency(visibleDirents, dirent =>
+      entryForDirent(dirent, resolved, fsImpl)
+    )
+
+    entries.sort((a, b) => Number(b.isDirectory) - Number(a.isDirectory) || a.name.localeCompare(b.name))
+
+    return { entries }
+  } catch (error) {
+    return { entries: [], error: error?.code || 'read-error' }
+  }
+}
+
+module.exports = {
+  readDirForIpc
+}

apps/desktop/electron/fs-read-dir.test.cjs

@@ -0,0 +1,364 @@
+'use strict'
+
+const assert = require('node:assert/strict')
+const fs = require('node:fs')
+const os = require('node:os')
+const path = require('node:path')
+const test = require('node:test')
+const { pathToFileURL } = require('node:url')
+
+const { readDirForIpc } = require('./fs-read-dir.cjs')
+
+function mkTmpDir() {
+  return fs.mkdtempSync(path.join(os.tmpdir(), 'hermes-fs-read-dir-'))
+}
+
+function fakeDirent(name, flags = {}) {
+  return {
+    name,
+    isDirectory: () => Boolean(flags.directory),
+    isFile: () => Boolean(flags.file),
+    isSymbolicLink: () => Boolean(flags.symlink)
+  }
+}
+
+test('readDirForIpc hides noisy directories and files from the project tree', async () => {
+  const root = mkTmpDir()
+
+  try {
+    fs.mkdirSync(path.join(root, 'node_modules'))
+    fs.mkdirSync(path.join(root, 'src'))
+    fs.writeFileSync(path.join(root, 'target'), 'hidden file')
+    fs.writeFileSync(path.join(root, 'README.md'), 'visible file')
+
+    const result = await readDirForIpc(root)
+
+    assert.equal(result.error, undefined)
+    assert.deepEqual(
+      result.entries.map(entry => entry.name),
+      ['src', 'README.md']
+    )
+  } finally {
+    fs.rmSync(root, { recursive: true, force: true })
+  }
+})
+
+test('readDirForIpc filters a hidden basename whether it is a file or directory', async () => {
+  const dirRoot = mkTmpDir()
+  const fileRoot = mkTmpDir()
+
+  try {
+    fs.mkdirSync(path.join(dirRoot, 'node_modules'))
+    fs.writeFileSync(path.join(dirRoot, 'visible.txt'), 'visible')
+    fs.writeFileSync(path.join(fileRoot, 'node_modules'), 'hidden file')
+    fs.writeFileSync(path.join(fileRoot, 'visible.txt'), 'visible')
+
+    assert.deepEqual(
+      (await readDirForIpc(dirRoot)).entries.map(entry => entry.name),
+      ['visible.txt']
+    )
+    assert.deepEqual(
+      (await readDirForIpc(fileRoot)).entries.map(entry => entry.name),
+      ['visible.txt']
+    )
+  } finally {
+    fs.rmSync(dirRoot, { recursive: true, force: true })
+    fs.rmSync(fileRoot, { recursive: true, force: true })
+  }
+})
+
+test('readDirForIpc returns directories before files and sorts by name within groups', async () => {
+  const root = mkTmpDir()
+
+  try {
+    fs.writeFileSync(path.join(root, 'z.txt'), 'z')
+    fs.mkdirSync(path.join(root, 'src'))
+    fs.writeFileSync(path.join(root, 'a.txt'), 'a')
+    fs.mkdirSync(path.join(root, 'lib'))
+
+    const result = await readDirForIpc(root)
+
+    assert.equal(result.error, undefined)
+    assert.deepEqual(
+      result.entries.map(entry => entry.name),
+      ['lib', 'src', 'a.txt', 'z.txt']
+    )
+  } finally {
+    fs.rmSync(root, { recursive: true, force: true })
+  }
+})
+
+test('readDirForIpc accepts file URLs for directories', async () => {
+  const root = mkTmpDir()
+
+  try {
+    fs.mkdirSync(path.join(root, 'src'))
+    fs.writeFileSync(path.join(root, 'README.md'), 'visible file')
+
+    const result = await readDirForIpc(pathToFileURL(root).toString())
+
+    assert.equal(result.error, undefined)
+    assert.deepEqual(
+      result.entries.map(entry => entry.name),
+      ['src', 'README.md']
+    )
+  } finally {
+    fs.rmSync(root, { recursive: true, force: true })
+  }
+})
+
+test('readDirForIpc returns invalid-path for blank or non-string input', async () => {
+  let readdirCalls = 0
+  const fsImpl = {
+    promises: {
+      readdir: async () => {
+        readdirCalls += 1
+        return []
+      }
+    }
+  }
+
+  assert.deepEqual(await readDirForIpc('', { fs: fsImpl }), { entries: [], error: 'invalid-path' })
+  assert.deepEqual(await readDirForIpc('   ', { fs: fsImpl }), { entries: [], error: 'invalid-path' })
+  assert.deepEqual(await readDirForIpc(null, { fs: fsImpl }), { entries: [], error: 'invalid-path' })
+  assert.equal(readdirCalls, 0)
+})
+
+test('readDirForIpc rejects Windows device paths before readdir', async () => {
+  let readdirCalls = 0
+  const fsImpl = {
+    promises: {
+      readdir: async () => {
+        readdirCalls += 1
+        return []
+      }
+    }
+  }
+
+  assert.deepEqual(await readDirForIpc('\\\\?\\C:\\secret', { fs: fsImpl }), {
+    entries: [],
+    error: 'device-path'
+  })
+  assert.equal(readdirCalls, 0)
+})
+
+test('readDirForIpc returns filesystem error codes instead of throwing', async () => {
+  const root = mkTmpDir()
+
+  try {
+    const result = await readDirForIpc(path.join(root, 'missing'))
+
+    assert.deepEqual(result, { entries: [], error: 'ENOENT' })
+  } finally {
+    fs.rmSync(root, { recursive: true, force: true })
+  }
+})
+
+test('readDirForIpc marks a symlink to a directory as a directory', async t => {
+  const root = mkTmpDir()
+
+  try {
+    fs.mkdirSync(path.join(root, 'actual-dir'))
+
+    try {
+      fs.symlinkSync(path.join(root, 'actual-dir'), path.join(root, 'linked-dir'), 'dir')
+    } catch (error) {
+      if (error?.code === 'EPERM' || error?.code === 'EACCES') {
+        t.skip(`symlink creation is not permitted on this platform (${error.code})`)
+
+        return
+      }
+
+      throw error
+    }
+
+    const result = await readDirForIpc(root)
+    const linked = result.entries.find(entry => entry.name === 'linked-dir')
+
+    assert.equal(result.error, undefined)
+    assert.equal(linked?.isDirectory, true)
+  } finally {
+    fs.rmSync(root, { recursive: true, force: true })
+  }
+})
+
+test('readDirForIpc marks a Windows junction to a directory as a directory', async t => {
+  if (process.platform !== 'win32') {
+    t.skip('junctions are a Windows-specific symlink type')
+
+    return
+  }
+
+  const root = mkTmpDir()
+
+  try {
+    fs.mkdirSync(path.join(root, 'actual-dir'))
+
+    try {
+      fs.symlinkSync(path.join(root, 'actual-dir'), path.join(root, 'junction-dir'), 'junction')
+    } catch (error) {
+      if (error?.code === 'EPERM' || error?.code === 'EACCES') {
+        t.skip(`junction creation is not permitted on this platform (${error.code})`)
+
+        return
+      }
+
+      throw error
+    }
+
+    const result = await readDirForIpc(root)
+    const junction = result.entries.find(entry => entry.name === 'junction-dir')
+
+    assert.equal(result.error, undefined)
+    assert.equal(junction?.isDirectory, true)
+  } finally {
+    fs.rmSync(root, { recursive: true, force: true })
+  }
+})
+
+test('readDirForIpc allows expanding symlink or junction directories outside the project root', async t => {
+  const root = mkTmpDir()
+  const outside = mkTmpDir()
+
+  try {
+    fs.writeFileSync(path.join(outside, 'outside.txt'), 'ok')
+
+    const linkPath = path.join(root, 'outside-link')
+    try {
+      fs.symlinkSync(outside, linkPath, process.platform === 'win32' ? 'junction' : 'dir')
+    } catch (error) {
+      if (error?.code === 'EPERM' || error?.code === 'EACCES') {
+        t.skip(`directory symlink creation is not permitted on this platform (${error.code})`)
+
+        return
+      }
+
+      throw error
+    }
+
+    const result = await readDirForIpc(linkPath)
+
+    assert.equal(result.error, undefined)
+    assert.deepEqual(result.entries, [
+      { name: 'outside.txt', path: path.join(linkPath, 'outside.txt'), isDirectory: false }
+    ])
+  } finally {
+    fs.rmSync(root, { recursive: true, force: true })
+    fs.rmSync(outside, { recursive: true, force: true })
+  }
+})
+
+test('readDirForIpc stats symbolic links and unknown entries without dropping the whole listing', async () => {
+  const input = path.join('virtual-root')
+  const resolved = path.resolve(input)
+  const statCalls = []
+  const fsImpl = {
+    promises: {
+      readdir: async () => [
+        fakeDirent('unknown-entry'),
+        fakeDirent('linked-dir', { symlink: true }),
+        fakeDirent('broken-link', { symlink: true }),
+        fakeDirent('plain.txt', { file: true })
+      ],
+      stat: async fullPath => {
+        if (fullPath === resolved) {
+          return { isDirectory: () => true }
+        }
+
+        statCalls.push(fullPath)
+        if (fullPath.endsWith(`${path.sep}linked-dir`)) {
+          return { isDirectory: () => true }
+        }
+        throw Object.assign(new Error('gone'), { code: 'ENOENT' })
+      }
+    }
+  }
+
+  const result = await readDirForIpc(input, { fs: fsImpl })
+
+  assert.equal(result.error, undefined)
+  assert.deepEqual(
+    statCalls.sort(),
+    [path.join(resolved, 'broken-link'), path.join(resolved, 'linked-dir'), path.join(resolved, 'unknown-entry')].sort()
+  )
+  assert.deepEqual(result.entries, [
+    { name: 'linked-dir', path: path.join(resolved, 'linked-dir'), isDirectory: true },
+    { name: 'broken-link', path: path.join(resolved, 'broken-link'), isDirectory: false },
+    { name: 'plain.txt', path: path.join(resolved, 'plain.txt'), isDirectory: false },
+    { name: 'unknown-entry', path: path.join(resolved, 'unknown-entry'), isDirectory: false }
+  ])
+})
+
+test('readDirForIpc bounds concurrent stats while preserving complete sorted output', async () => {
+  const input = path.join('virtual-root')
+  const resolved = path.resolve(input)
+  const names = Array.from({ length: 105 }, (_, index) => `entry-${String(104 - index).padStart(3, '0')}`)
+  const failedName = 'entry-100'
+  const directoryNames = new Set(names.filter((_, index) => index % 10 === 4))
+  const successfulDirectoryNames = new Set([...directoryNames].filter(name => name !== failedName))
+  const statCalls = []
+  let active = 0
+  let peak = 0
+  let releaseStats
+  let markFirstStatStarted
+  const statsReleased = new Promise(resolve => {
+    releaseStats = resolve
+  })
+  const firstStatStarted = new Promise(resolve => {
+    markFirstStatStarted = resolve
+  })
+  const fsImpl = {
+    promises: {
+      readdir: async () => [
+        fakeDirent('node_modules', { symlink: true }),
+        ...names.map((name, index) => fakeDirent(name, { symlink: index % 2 === 0 }))
+      ],
+      stat: async fullPath => {
+        if (fullPath === resolved) {
+          return { isDirectory: () => true }
+        }
+
+        statCalls.push(fullPath)
+        active += 1
+        peak = Math.max(peak, active)
+        markFirstStatStarted()
+        await statsReleased
+        active -= 1
+
+        const name = path.basename(fullPath)
+        if (name === failedName) {
+          throw Object.assign(new Error('gone'), { code: 'ENOENT' })
+        }
+
+        return { isDirectory: () => successfulDirectoryNames.has(name) }
+      }
+    }
+  }
+
+  const resultPromise = readDirForIpc(input, { fs: fsImpl })
+  await firstStatStarted
+  await new Promise(resolve => setImmediate(resolve))
+  releaseStats()
+  const result = await resultPromise
+
+  const expectedNames = [
+    ...names.filter(name => successfulDirectoryNames.has(name)).sort(),
+    ...names.filter(name => !successfulDirectoryNames.has(name)).sort()
+  ]
+
+  assert.equal(result.error, undefined)
+  assert.equal(result.entries.length, names.length)
+  assert.equal(statCalls.length, names.length)
+  assert.equal(statCalls.some(fullPath => fullPath.endsWith(`${path.sep}node_modules`)), false)
+  assert.ok(peak > 1, `expected concurrent stats, observed peak ${peak}`)
+  assert.ok(peak <= 16, `expected at most 16 concurrent stats, observed peak ${peak}`)
+  assert.deepEqual(
+    result.entries.map(entry => entry.name),
+    expectedNames
+  )
+  assert.equal(result.entries.find(entry => entry.name === failedName)?.isDirectory, false)
+  assert.equal(
+    result.entries.filter(entry => entry.isDirectory).length,
+    successfulDirectoryNames.size
+  )
+})

apps/desktop/electron/git-root.cjs

@@ -0,0 +1,54 @@
+'use strict'
+
+const fs = require('node:fs')
+const path = require('node:path')
+const { resolveRequestedPathForIpc } = require('./hardening.cjs')
+
+function findGitRoot(start, fsImpl = fs) {
+  let dir = start
+
+  for (let i = 0; i < 50; i += 1) {
+    try {
+      if (fsImpl.existsSync(path.join(dir, '.git'))) {
+        return dir
+      }
+    } catch {
+      return null
+    }
+
+    const parent = path.dirname(dir)
+
+    if (parent === dir) {
+      return null
+    }
+
+    dir = parent
+  }
+
+  return null
+}
+
+async function gitRootForIpc(startPath, options = {}) {
+  const fsImpl = options.fs || fs
+  let resolved
+
+  try {
+    resolved = resolveRequestedPathForIpc(startPath, { purpose: 'Git root' })
+  } catch {
+    return null
+  }
+
+  try {
+    const stat = await fsImpl.promises.stat(resolved)
+    const start = stat.isDirectory() ? resolved : path.dirname(resolved)
+
+    return findGitRoot(start, fsImpl)
+  } catch {
+    return findGitRoot(resolved, fsImpl)
+  }
+}
+
+module.exports = {
+  findGitRoot,
+  gitRootForIpc
+}

apps/desktop/electron/git-root.test.cjs

@@ -0,0 +1,40 @@
+'use strict'
+
+const assert = require('node:assert/strict')
+const fs = require('node:fs')
+const os = require('node:os')
+const path = require('node:path')
+const test = require('node:test')
+const { pathToFileURL } = require('node:url')
+
+const { gitRootForIpc } = require('./git-root.cjs')
+
+function mkTmpDir() {
+  return fs.mkdtempSync(path.join(os.tmpdir(), 'hermes-git-root-'))
+}
+
+test('gitRootForIpc returns null for invalid and device paths', async () => {
+  assert.equal(await gitRootForIpc(''), null)
+  assert.equal(await gitRootForIpc('   '), null)
+  assert.equal(await gitRootForIpc(null), null)
+  assert.equal(await gitRootForIpc('\\\\?\\C:\\secret'), null)
+  assert.equal(await gitRootForIpc('file:///%E0%A4%A'), null)
+})
+
+test('gitRootForIpc resolves directories files missing descendants and file URLs', async t => {
+  const root = mkTmpDir()
+  t.after(() => fs.rmSync(root, { recursive: true, force: true }))
+
+  const gitDir = path.join(root, '.git')
+  const srcDir = path.join(root, 'src')
+  const filePath = path.join(srcDir, 'index.ts')
+  fs.mkdirSync(gitDir)
+  fs.mkdirSync(srcDir)
+  fs.writeFileSync(filePath, 'export {}\n', 'utf8')
+
+  assert.equal(await gitRootForIpc(root), root)
+  assert.equal(await gitRootForIpc(srcDir), root)
+  assert.equal(await gitRootForIpc(filePath), root)
+  assert.equal(await gitRootForIpc(pathToFileURL(filePath).toString()), root)
+  assert.equal(await gitRootForIpc(path.join(srcDir, 'missing.ts')), root)
+})

apps/desktop/electron/hardening.cjs

@@ -106,71 +106,155 @@ function sensitiveFileBlockReason(filePath) {
   return null
 }
 
-function resolveRequestedFilePath(filePath, baseDir = process.cwd(), purpose = 'File read') {
-  const raw = String(filePath || '').trim()
+function ipcPathError(code, message) {
+  const error = new Error(message)
+  error.code = code
+  return error
+}
+
+function rejectUnsafePathSyntax(filePath, purpose = 'File read') {
+  if (typeof filePath !== 'string') {
+    throw ipcPathError('invalid-path', `${purpose} failed: file path is required.`)
+  }
+
+  const raw = filePath.trim()
 
   if (!raw) {
-    throw new Error(`${purpose} failed: file path is required.`)
+    throw ipcPathError('invalid-path', `${purpose} failed: file path is required.`)
   }
 
   if (raw.includes('\0')) {
-    throw new Error(`${purpose} failed: file path is invalid.`)
+    throw ipcPathError('invalid-path', `${purpose} failed: file path is invalid.`)
   }
 
+  const normalized = raw.replace(/\\/g, '/').toLowerCase()
+  if (
+    normalized.startsWith('//?/') ||
+    normalized.startsWith('//./') ||
+    normalized.startsWith('globalroot/device/') ||
+    normalized.includes('/globalroot/device/')
+  ) {
+    throw ipcPathError('device-path', `${purpose} blocked: Windows device paths are not allowed.`)
+  }
+
+  return raw
+}
+
+function resolveRequestedPathForIpc(filePath, options = {}) {
+  const purpose = String(options.purpose || 'File read')
+  const raw = rejectUnsafePathSyntax(filePath, purpose)
+
   if (/^file:/i.test(raw)) {
+    let resolvedPath
     try {
-      return fileURLToPath(raw)
+      const parsed = new URL(raw)
+      if (parsed.protocol !== 'file:') {
+        throw new Error('not a file URL')
+      }
+      resolvedPath = fileURLToPath(parsed)
     } catch {
-      throw new Error(`${purpose} failed: file URL is invalid.`)
+      throw ipcPathError('invalid-path', `${purpose} failed: file URL is invalid.`)
     }
+
+    rejectUnsafePathSyntax(resolvedPath, purpose)
+    return path.resolve(resolvedPath)
   }
 
-  const resolvedBase = path.resolve(String(baseDir || process.cwd()))
-  return path.resolve(resolvedBase, raw)
+  const baseInput = typeof options.baseDir === 'string' && options.baseDir.trim() ? options.baseDir : process.cwd()
+  const safeBaseInput = rejectUnsafePathSyntax(baseInput, purpose)
+  const resolvedBase = path.resolve(safeBaseInput)
+  rejectUnsafePathSyntax(resolvedBase, purpose)
+  const resolvedPath = path.resolve(resolvedBase, raw)
+  rejectUnsafePathSyntax(resolvedPath, purpose)
+
+  return resolvedPath
+}
+
+async function statForIpc(fsImpl, resolvedPath, purpose, typeLabel) {
+  try {
+    return await fsImpl.promises.stat(resolvedPath)
+  } catch (error) {
+    const code = error && typeof error === 'object' ? error.code : ''
+    if (code === 'ENOENT' || code === 'ENOTDIR') {
+      throw ipcPathError(code || 'ENOENT', `${purpose} failed: ${typeLabel} does not exist.`)
+    }
+    throw ipcPathError(code || 'read-error', `${purpose} failed: ${error instanceof Error ? error.message : String(error)}`)
+  }
+}
+
+async function realpathForIpc(fsImpl, resolvedPath, purpose) {
+  if (typeof fsImpl.promises.realpath !== 'function') {
+    return resolvedPath
+  }
+
+  try {
+    const realPath = await fsImpl.promises.realpath(resolvedPath)
+    rejectUnsafePathSyntax(realPath, purpose)
+    return realPath
+  } catch (error) {
+    const code = error && typeof error === 'object' ? error.code : ''
+    throw ipcPathError(code || 'read-error', `${purpose} failed: ${error instanceof Error ? error.message : String(error)}`)
+  }
+}
+
+function rejectSensitiveFilePath(filePath, purpose) {
+  const blockReason = sensitiveFileBlockReason(filePath)
+  if (blockReason) {
+    throw ipcPathError('sensitive-file', `${purpose} blocked for sensitive file: ${blockReason}`)
+  }
+}
+
+async function resolveDirectoryForIpc(dirPath, options = {}) {
+  const purpose = String(options.purpose || 'Directory read')
+  const fsImpl = options.fs || fs
+  const resolvedPath = resolveRequestedPathForIpc(dirPath, { baseDir: options.baseDir, purpose })
+  const stat = await statForIpc(fsImpl, resolvedPath, purpose, 'directory')
+
+  if (!stat.isDirectory()) {
+    throw ipcPathError('ENOTDIR', `${purpose} failed: path is not a directory.`)
+  }
+
+  const realPath = await realpathForIpc(fsImpl, resolvedPath, purpose)
+
+  return { realPath, resolvedPath, stat }
 }
 
 async function resolveReadableFileForIpc(filePath, options = {}) {
   const purpose = String(options.purpose || 'File read')
-  const resolvedPath = resolveRequestedFilePath(filePath, options.baseDir, purpose)
+  const fsImpl = options.fs || fs
+  const resolvedPath = resolveRequestedPathForIpc(filePath, { baseDir: options.baseDir, purpose })
 
   if (options.blockSensitive !== false) {
-    const blockReason = sensitiveFileBlockReason(resolvedPath)
-    if (blockReason) {
-      throw new Error(`${purpose} blocked for sensitive file: ${blockReason}`)
-    }
+    rejectSensitiveFilePath(resolvedPath, purpose)
   }
 
-  let stat
-  try {
-    stat = await fs.promises.stat(resolvedPath)
-  } catch (error) {
-    const code = error && typeof error === 'object' ? error.code : ''
-    if (code === 'ENOENT' || code === 'ENOTDIR') {
-      throw new Error(`${purpose} failed: file does not exist.`)
-    }
-    throw new Error(`${purpose} failed: ${error instanceof Error ? error.message : String(error)}`)
-  }
+  const stat = await statForIpc(fsImpl, resolvedPath, purpose, 'file')
 
   if (stat.isDirectory()) {
-    throw new Error(`${purpose} failed: path points to a directory.`)
+    throw ipcPathError('EISDIR', `${purpose} failed: path points to a directory.`)
   }
 
   if (!stat.isFile()) {
-    throw new Error(`${purpose} failed: only regular files can be read.`)
+    throw ipcPathError('EINVAL', `${purpose} failed: only regular files can be read.`)
+  }
+
+  const realPath = await realpathForIpc(fsImpl, resolvedPath, purpose)
+  if (options.blockSensitive !== false) {
+    rejectSensitiveFilePath(realPath, purpose)
   }
 
   const maxBytes = Number.isFinite(options.maxBytes) && Number(options.maxBytes) > 0 ? Number(options.maxBytes) : null
   if (maxBytes && stat.size > maxBytes) {
-    throw new Error(`${purpose} failed: file is too large (${stat.size} bytes; limit ${maxBytes} bytes).`)
+    throw ipcPathError('EFBIG', `${purpose} failed: file is too large (${stat.size} bytes; limit ${maxBytes} bytes).`)
   }
 
   try {
-    await fs.promises.access(resolvedPath, fs.constants.R_OK)
+    await fsImpl.promises.access(resolvedPath, fs.constants.R_OK)
   } catch {
-    throw new Error(`${purpose} failed: file is not readable.`)
+    throw ipcPathError('EACCES', `${purpose} failed: file is not readable.`)
   }
 
-  return { resolvedPath, stat }
+  return { realPath, resolvedPath, stat }
 }
 
 module.exports = {
@@ -178,7 +262,10 @@ module.exports = {
   DEFAULT_FETCH_TIMEOUT_MS,
   TEXT_PREVIEW_SOURCE_MAX_BYTES,
   encryptDesktopSecret,
+  rejectUnsafePathSyntax,
+  resolveDirectoryForIpc,
   resolveReadableFileForIpc,
+  resolveRequestedPathForIpc,
   resolveTimeoutMs,
   sensitiveFileBlockReason
 }

apps/desktop/electron/hardening.test.cjs

@@ -8,11 +8,20 @@ const { pathToFileURL } = require('node:url')
 const {
   DEFAULT_FETCH_TIMEOUT_MS,
   encryptDesktopSecret,
+  resolveDirectoryForIpc,
   resolveReadableFileForIpc,
+  resolveRequestedPathForIpc,
   resolveTimeoutMs,
   sensitiveFileBlockReason
 } = require('./hardening.cjs')
 
+async function rejectsWithCode(promise, code) {
+  await assert.rejects(promise, error => {
+    assert.equal(error?.code, code)
+    return true
+  })
+}
+
 test('resolveTimeoutMs falls back to defaults and accepts overrides', () => {
   assert.equal(resolveTimeoutMs(undefined), DEFAULT_FETCH_TIMEOUT_MS)
   assert.equal(resolveTimeoutMs(0), DEFAULT_FETCH_TIMEOUT_MS)
@@ -51,6 +60,52 @@ test('sensitiveFileBlockReason blocks obvious secret file patterns', () => {
   assert.match(String(sensitiveFileBlockReason('/tmp/server-cert.pem')), /\.pem/)
 })
 
+test('path helpers reject blank non-string NUL and Windows device syntax', async () => {
+  await rejectsWithCode(resolveReadableFileForIpc('', { purpose: 'File preview' }), 'invalid-path')
+  await rejectsWithCode(resolveReadableFileForIpc('   ', { purpose: 'File preview' }), 'invalid-path')
+  await rejectsWithCode(resolveReadableFileForIpc(null, { purpose: 'File preview' }), 'invalid-path')
+  await rejectsWithCode(resolveReadableFileForIpc(`safe${String.fromCharCode(0)}name.txt`), 'invalid-path')
+
+  const devicePaths = [
+    '\\\\?\\C:\\secret.txt',
+    '\\\\.\\C:\\secret.txt',
+    '\\\\?\\UNC\\server\\share\\secret.txt',
+    'GLOBALROOT/Device/HarddiskVolumeShadowCopy1/secret.txt'
+  ]
+
+  for (const devicePath of devicePaths) {
+    assert.throws(
+      () => resolveRequestedPathForIpc(devicePath, { purpose: 'File preview' }),
+      error => {
+        assert.equal(error?.code, 'device-path')
+        return true
+      }
+    )
+    await rejectsWithCode(resolveReadableFileForIpc(devicePath, { purpose: 'File preview' }), 'device-path')
+  }
+
+  assert.throws(
+    () => resolveRequestedPathForIpc('file:///%E0%A4%A', { purpose: 'File preview' }),
+    error => {
+      assert.equal(error?.code, 'invalid-path')
+      return true
+    }
+  )
+  await rejectsWithCode(resolveReadableFileForIpc('file:///%E0%A4%A', { purpose: 'File preview' }), 'invalid-path')
+})
+
+test('resolveRequestedPathForIpc resolves relative paths from the trimmed base directory', () => {
+  const baseDir = path.join(os.tmpdir(), 'hermes-desktop-base')
+
+  assert.equal(
+    resolveRequestedPathForIpc('notes.txt', {
+      baseDir: `  ${baseDir}  `,
+      purpose: 'File preview'
+    }),
+    path.resolve(baseDir, 'notes.txt')
+  )
+})
+
 test('resolveReadableFileForIpc validates existence type size and sensitivity', async t => {
   const tempDir = fs.mkdtempSync(path.join(os.tmpdir(), 'hermes-desktop-hardening-'))
   t.after(() => fs.rmSync(tempDir, { recursive: true, force: true }))
@@ -71,6 +126,13 @@ test('resolveReadableFileForIpc validates existence type size and sensitivity',
   })
   assert.equal(fromFileUrl.resolvedPath, textPath)
 
+  const spacedPath = path.join(tempDir, 'notes with spaces.txt')
+  fs.writeFileSync(spacedPath, 'space ok', 'utf8')
+  const fromSpacedFileUrl = await resolveReadableFileForIpc(pathToFileURL(spacedPath).toString(), {
+    purpose: 'File preview'
+  })
+  assert.equal(fromSpacedFileUrl.resolvedPath, spacedPath)
+
   await assert.rejects(
     resolveReadableFileForIpc('missing.txt', {
       baseDir: tempDir,
@@ -114,3 +176,91 @@ test('resolveReadableFileForIpc validates existence type size and sensitivity',
   })
   assert.equal(envTemplate.resolvedPath, envTemplatePath)
 })
+
+test('resolveReadableFileForIpc blocks common sensitive files', async t => {
+  const tempDir = fs.mkdtempSync(path.join(os.tmpdir(), 'hermes-desktop-sensitive-'))
+  t.after(() => fs.rmSync(tempDir, { recursive: true, force: true }))
+
+  const sshDir = path.join(tempDir, '.ssh')
+  fs.mkdirSync(sshDir)
+
+  const blockedFiles = [
+    path.join(tempDir, '.env'),
+    path.join(tempDir, '.npmrc'),
+    path.join(sshDir, 'id_ed25519'),
+    path.join(tempDir, 'cert.pem'),
+    path.join(tempDir, 'cert.p12'),
+    path.join(tempDir, 'cert.pfx')
+  ]
+
+  for (const filePath of blockedFiles) {
+    fs.writeFileSync(filePath, 'secret', 'utf8')
+    await rejectsWithCode(resolveReadableFileForIpc(filePath, { purpose: 'File preview' }), 'sensitive-file')
+  }
+
+  const allowed = path.join(tempDir, '.env.example')
+  fs.writeFileSync(allowed, 'EXAMPLE_TOKEN=value', 'utf8')
+  assert.equal((await resolveReadableFileForIpc(allowed, { purpose: 'File preview' })).resolvedPath, allowed)
+})
+
+test('resolveReadableFileForIpc blocks symlinks whose realpath is sensitive', async t => {
+  const tempDir = fs.mkdtempSync(path.join(os.tmpdir(), 'hermes-desktop-realpath-'))
+  t.after(() => fs.rmSync(tempDir, { recursive: true, force: true }))
+
+  const envPath = path.join(tempDir, '.env')
+  const linkPath = path.join(tempDir, 'safe-name.txt')
+  fs.writeFileSync(envPath, 'SECRET_TOKEN=123', 'utf8')
+
+  try {
+    fs.symlinkSync(envPath, linkPath, 'file')
+  } catch (error) {
+    if (error?.code === 'EPERM' || error?.code === 'EACCES') {
+      t.skip(`symlink creation is not permitted on this platform (${error.code})`)
+      return
+    }
+    throw error
+  }
+
+  await rejectsWithCode(resolveReadableFileForIpc(linkPath, { purpose: 'File preview' }), 'sensitive-file')
+})
+
+test('resolveDirectoryForIpc accepts directories and rejects invalid directory targets', async t => {
+  const tempDir = fs.mkdtempSync(path.join(os.tmpdir(), 'hermes-desktop-dir-'))
+  t.after(() => fs.rmSync(tempDir, { recursive: true, force: true }))
+
+  const directory = path.join(tempDir, 'project')
+  const filePath = path.join(tempDir, 'file.txt')
+  fs.mkdirSync(directory)
+  fs.writeFileSync(filePath, 'not a directory', 'utf8')
+
+  const resolved = await resolveDirectoryForIpc(directory)
+  assert.equal(resolved.resolvedPath, directory)
+  assert.equal(resolved.stat.isDirectory(), true)
+
+  await rejectsWithCode(resolveDirectoryForIpc(filePath), 'ENOTDIR')
+  await rejectsWithCode(resolveDirectoryForIpc(path.join(tempDir, 'missing')), 'ENOENT')
+  await rejectsWithCode(resolveDirectoryForIpc('\\\\?\\C:\\secret'), 'device-path')
+})
+
+test('resolveDirectoryForIpc accepts directory symlinks or junctions', async t => {
+  const tempDir = fs.mkdtempSync(path.join(os.tmpdir(), 'hermes-desktop-dir-link-'))
+  t.after(() => fs.rmSync(tempDir, { recursive: true, force: true }))
+
+  const directory = path.join(tempDir, 'actual-project')
+  const linkPath = path.join(tempDir, 'linked-project')
+  fs.mkdirSync(directory)
+
+  try {
+    fs.symlinkSync(directory, linkPath, process.platform === 'win32' ? 'junction' : 'dir')
+  } catch (error) {
+    if (error?.code === 'EPERM' || error?.code === 'EACCES') {
+      t.skip(`directory symlink creation is not permitted on this platform (${error.code})`)
+      return
+    }
+    throw error
+  }
+
+  const resolved = await resolveDirectoryForIpc(linkPath)
+  assert.equal(resolved.resolvedPath, linkPath)
+  assert.equal(resolved.stat.isDirectory(), true)
+})

apps/desktop/electron/main.cjs

@@ -22,7 +22,7 @@ const http = require('node:http')
 const https = require('node:https')
 const net = require('node:net')
 const path = require('node:path')
-const { fileURLToPath, pathToFileURL } = require('node:url')
+const { pathToFileURL } = require('node:url')
 const { execFileSync, spawn } = require('node:child_process')
 const { detectRemoteDisplay, isWindowsBinaryPathInWsl, isWslEnvironment } = require('./bootstrap-platform.cjs')
 const { runBootstrap } = require('./bootstrap-runner.cjs')
@@ -31,6 +31,8 @@ const { canImportHermesCli, verifyHermesCli } = require('./backend-probes.cjs')
 const { probeGatewayWebSocket } = require('./gateway-ws-probe.cjs')
 const { serializeJsonBody, setJsonRequestHeaders } = require('./oauth-net-request.cjs')
 const { fetchMarketplaceThemes, searchMarketplaceThemes } = require('./vscode-marketplace.cjs')
+const { readDirForIpc } = require('./fs-read-dir.cjs')
+const { gitRootForIpc } = require('./git-root.cjs')
 const {
   OFFICIAL_REPO_HTTPS_URL,
   isOfficialSshRemote
@@ -65,6 +67,7 @@ const {
   TEXT_PREVIEW_SOURCE_MAX_BYTES,
   encryptDesktopSecret: encryptDesktopSecretStrict,
   resolveReadableFileForIpc,
+  resolveRequestedPathForIpc,
   resolveTimeoutMs
 } = require('./hardening.cjs')
 
@@ -730,7 +733,7 @@ function openExternalUrl(rawUrl) {
   if (parsed.protocol === 'file:') {
     let localPath
     try {
-      localPath = fileURLToPath(parsed.toString())
+      localPath = resolveRequestedPathForIpc(parsed.toString(), { purpose: 'Open external file' })
     } catch {
       return false
     }
@@ -2878,10 +2881,10 @@ async function resourceBufferFromUrl(rawUrl) {
     const buffer = match[2] ? Buffer.from(encoded, 'base64') : Buffer.from(decodeURIComponent(encoded), 'utf8')
     return { buffer, mimeType }
   }
-  if (rawUrl.startsWith('file:')) {
-    const filePath = fileURLToPath(rawUrl)
-    const buffer = await fs.promises.readFile(filePath)
-    return { buffer, mimeType: mimeTypeForPath(filePath) }
+  if (/^file:/i.test(rawUrl)) {
+    const { resolvedPath } = await resolveReadableFileForIpc(rawUrl, { purpose: 'Image file' })
+    const buffer = await fs.promises.readFile(resolvedPath)
+    return { buffer, mimeType: mimeTypeForPath(resolvedPath) }
   }
 
   const parsed = new URL(rawUrl)
@@ -2959,11 +2962,13 @@ function expandUserPath(filePath) {
   return value
 }
 
-function previewFileTarget(rawTarget, baseDir) {
+async function previewFileTarget(rawTarget, baseDir) {
   const raw = String(rawTarget || '').trim()
   const base = baseDir ? path.resolve(expandUserPath(baseDir)) : resolveHermesCwd()
-  const filePath = raw.startsWith('file:') ? fileURLToPath(raw) : path.resolve(base, expandUserPath(raw))
-  let resolved = filePath
+  let resolved = resolveRequestedPathForIpc(/^file:/i.test(raw) ? raw : expandUserPath(raw), {
+    baseDir: base,
+    purpose: 'Preview target'
+  })
 
   if (directoryExists(resolved)) {
     resolved = path.join(resolved, 'index.html')
@@ -2974,6 +2979,8 @@ function previewFileTarget(rawTarget, baseDir) {
     return null
   }
 
+  ;({ resolvedPath: resolved } = await resolveReadableFileForIpc(resolved, { purpose: 'Preview target' }))
+
   const mimeType = mimeTypeForPath(resolved)
   const metadata = previewFileMetadata(resolved, mimeType)
   const isHtml = PREVIEW_HTML_EXTENSIONS.has(ext)
@@ -3019,7 +3026,7 @@ function previewUrlTarget(rawTarget) {
   }
 }
 
-function normalizePreviewTarget(rawTarget, baseDir) {
+async function normalizePreviewTarget(rawTarget, baseDir) {
   const raw = String(rawTarget || '').trim()
 
   if (!raw) {
@@ -3031,20 +3038,15 @@ function normalizePreviewTarget(rawTarget, baseDir) {
       return previewUrlTarget(raw)
     }
 
-    return previewFileTarget(raw, baseDir)
+    return await previewFileTarget(raw, baseDir)
   } catch {
     return null
   }
 }
 
-function filePathFromPreviewUrl(rawUrl) {
-  const filePath = fileURLToPath(String(rawUrl || ''))
-
-  if (!fileExists(filePath)) {
-    throw new Error('Preview file is not readable')
-  }
-
-  return filePath
+async function filePathFromPreviewUrl(rawUrl) {
+  const { resolvedPath } = await resolveReadableFileForIpc(String(rawUrl || ''), { purpose: 'Preview file' })
+  return resolvedPath
 }
 
 function sendPreviewFileChanged(payload) {
@@ -3054,8 +3056,8 @@ function sendPreviewFileChanged(payload) {
   webContents.send('hermes:preview-file-changed', payload)
 }
 
-function watchPreviewFile(rawUrl) {
-  const filePath = filePathFromPreviewUrl(rawUrl)
+async function watchPreviewFile(rawUrl) {
+  const filePath = await filePathFromPreviewUrl(rawUrl)
   const watchDir = path.dirname(filePath)
   const targetName = path.basename(filePath)
   const id = crypto.randomBytes(12).toString('base64url')
@@ -5587,48 +5589,6 @@ ipcMain.handle('hermes:logs:reveal', async () => {
 
 ipcMain.handle('hermes:logs:recent', async () => ({ path: DESKTOP_LOG_PATH, lines: hermesLog.slice(-200) }))
 
-// Always-hidden noise (covers non-git projects too — gitignore would catch
-// these anyway when present, but we want the same hygiene without one).
-const FS_READDIR_HIDDEN = new Set([
-  '.git',
-  '.hg',
-  '.svn',
-  '.cache',
-  '.next',
-  '.turbo',
-  '.venv',
-  '__pycache__',
-  'build',
-  'dist',
-  'node_modules',
-  'target',
-  'venv'
-])
-
-function findGitRoot(start) {
-  let dir = start
-
-  for (let i = 0; i < 50; i += 1) {
-    try {
-      if (fs.existsSync(path.join(dir, '.git'))) {
-        return dir
-      }
-    } catch {
-      return null
-    }
-
-    const parent = path.dirname(dir)
-
-    if (parent === dir) {
-      return null
-    }
-
-    dir = parent
-  }
-
-  return null
-}
-
 function isExecutableFile(filePath) {
   if (!filePath || !path.isAbsolute(filePath)) {
     return false
@@ -5811,46 +5771,9 @@ function disposeTerminalSession(id) {
   return true
 }
 
-ipcMain.handle('hermes:fs:readDir', async (_event, dirPath) => {
-  const resolved = path.resolve(String(dirPath || ''))
+ipcMain.handle('hermes:fs:readDir', async (_event, dirPath) => readDirForIpc(dirPath))
 
-  if (!resolved) {
-    return { entries: [], error: 'invalid-path' }
-  }
-
-  try {
-    const dirents = await fs.promises.readdir(resolved, { withFileTypes: true })
-
-    const entries = dirents
-      .filter(d => {
-        if (FS_READDIR_HIDDEN.has(d.name)) {
-          return false
-        }
-
-        return true
-      })
-      .map(d => ({ name: d.name, path: path.join(resolved, d.name), isDirectory: d.isDirectory() }))
-      .sort((a, b) => Number(b.isDirectory) - Number(a.isDirectory) || a.name.localeCompare(b.name))
-
-    return { entries }
-  } catch (error) {
-    return { entries: [], error: error?.code || 'read-error' }
-  }
-})
-
-ipcMain.handle('hermes:fs:gitRoot', async (_event, startPath) => {
-  const input = String(startPath || '')
-  const resolved = input.startsWith('file:') ? fileURLToPath(input) : path.resolve(input)
-
-  try {
-    const stat = await fs.promises.stat(resolved)
-    const start = stat.isDirectory() ? resolved : path.dirname(resolved)
-
-    return findGitRoot(start)
-  } catch {
-    return findGitRoot(resolved)
-  }
-})
+ipcMain.handle('hermes:fs:gitRoot', async (_event, startPath) => gitRootForIpc(startPath))
 
 ipcMain.handle('hermes:terminal:start', async (event, payload = {}) => {
   if (!nodePty) {