fix(shell): drop now-unused realpath import

Closes #844.

When the session's cached working directory is renamed on disk and
a file is subsequently created at the old path (e.g. `mv orig renamed
&& touch orig`), every Bash tool invocation failed with
`ENOTDIR: not a directory, posix_spawn '/usr/bin/zsh'` (exit 126),
and `!`-prefixed commands silently failed. No recovery was possible
without restarting the session.

Root cause: the pre-spawn guard in `src/utils/Shell.ts:exec()` used
`realpath(cwd)` to detect a missing CWD. `realpath()` succeeds on
any existing path — file or directory — so a path that was replaced
with a regular file slipped past the check. spawn() was then called
with `cwd` pointing at a non-directory and failed with ENOTDIR.

Fix: replace `realpath()` with `stat().isDirectory()` for both the
primary CWD check and the `getOriginalCwd()` fallback check. When
the cached CWD is no longer a directory, fall back to the original
CWD (as before) and update state so subsequent tools recover
transparently.

Verification:
  - Repro: `mkdir -p /tmp/x/orig && mv /tmp/x/orig /tmp/x/renamed
    && touch /tmp/x/orig`, then exec with stale cwd=/tmp/x/orig
  - Before: exit 126, stderr "ENOTDIR: not a directory, posix_spawn"
  - After:  exit 0, cwd transparently recovered to originalCwd
  - `bun test` — no new regressions (pre-existing model/provider
    test failures are unrelated and present on main)

src/cli/update.ts

@@ -35,20 +35,15 @@ export async function update() {
   // binary (without it).
   if (getAPIProvider() !== 'firstParty') {
     writeToStdout(
-      chalk.yellow(
-        `Auto-update is not available for third-party provider builds.\n`,
-      ) +
-        `Current version: ${MACRO.DISPLAY_VERSION}\n\n` +
-        `To update, reinstall from npm:\n` +
-        chalk.bold(`  npm install -g ${MACRO.PACKAGE_URL}@latest`) + '\n\n' +
-        `Or, if you built from source, pull and rebuild:\n` +
-        chalk.bold('  git pull && bun install && bun run build') + '\n',
+      chalk.yellow('Auto-update is not available for third-party provider builds.\n') +
+      'To update, pull the latest source from the repository and rebuild:\n' +
+      '  git pull && bun install && bun run build\n',
     )
-    await gracefulShutdown(0)
+    return
   }
 
   logEvent('tengu_update_check', {})
-  writeToStdout(`Current version: ${MACRO.DISPLAY_VERSION}\n`)
+  writeToStdout(`Current version: ${MACRO.VERSION}\n`)
 
   const channel = getInitialSettings()?.autoUpdatesChannel ?? 'latest'
   writeToStdout(`Checking for updates to ${channel} version...\n`)
@@ -128,14 +123,9 @@ export async function update() {
   if (diagnostic.installationType === 'development') {
     writeToStdout('\n')
     writeToStdout(
-      chalk.yellow('You are running a development build — auto-update is unavailable.') + '\n',
+      chalk.yellow('Warning: Cannot update development build') + '\n',
     )
-    writeToStdout('To update, pull the latest source and rebuild:\n')
-    writeToStdout(chalk.bold('  git pull && bun install && bun run build') + '\n')
-    writeToStdout('\n')
-    writeToStdout('Or reinstall from npm:\n')
-    writeToStdout(chalk.bold(`  npm install -g ${MACRO.PACKAGE_URL}@latest`) + '\n')
-    await gracefulShutdown(0)
+    await gracefulShutdown(1)
   }
 
   // Check if running from a package manager
@@ -146,8 +136,8 @@ export async function update() {
     if (packageManager === 'homebrew') {
       writeToStdout('Claude is managed by Homebrew.\n')
       const latest = await getLatestVersion(channel)
-      if (latest && !gte(MACRO.DISPLAY_VERSION, latest)) {
-        writeToStdout(`Update available: ${MACRO.DISPLAY_VERSION} → ${latest}\n`)
+      if (latest && !gte(MACRO.VERSION, latest)) {
+        writeToStdout(`Update available: ${MACRO.VERSION} → ${latest}\n`)
         writeToStdout('\n')
         writeToStdout('To update, run:\n')
         writeToStdout(chalk.bold('  brew upgrade claude-code') + '\n')
@@ -157,8 +147,8 @@ export async function update() {
     } else if (packageManager === 'winget') {
       writeToStdout('Claude is managed by winget.\n')
       const latest = await getLatestVersion(channel)
-      if (latest && !gte(MACRO.DISPLAY_VERSION, latest)) {
-        writeToStdout(`Update available: ${MACRO.DISPLAY_VERSION} → ${latest}\n`)
+      if (latest && !gte(MACRO.VERSION, latest)) {
+        writeToStdout(`Update available: ${MACRO.VERSION} → ${latest}\n`)
         writeToStdout('\n')
         writeToStdout('To update, run:\n')
         writeToStdout(
@@ -170,8 +160,8 @@ export async function update() {
     } else if (packageManager === 'apk') {
       writeToStdout('Claude is managed by apk.\n')
       const latest = await getLatestVersion(channel)
-      if (latest && !gte(MACRO.DISPLAY_VERSION, latest)) {
-        writeToStdout(`Update available: ${MACRO.DISPLAY_VERSION} → ${latest}\n`)
+      if (latest && !gte(MACRO.VERSION, latest)) {
+        writeToStdout(`Update available: ${MACRO.VERSION} → ${latest}\n`)
         writeToStdout('\n')
         writeToStdout('To update, run:\n')
         writeToStdout(chalk.bold('  apk upgrade claude-code') + '\n')
@@ -260,14 +250,14 @@ export async function update() {
         await gracefulShutdown(1)
       }
 
-      if (result.latestVersion === MACRO.DISPLAY_VERSION) {
+      if (result.latestVersion === MACRO.VERSION) {
         writeToStdout(
-          chalk.green(`OpenClaude is up to date (${MACRO.DISPLAY_VERSION})`) + '\n',
+          chalk.green(`Claude Code is up to date (${MACRO.VERSION})`) + '\n',
         )
       } else {
         writeToStdout(
           chalk.green(
-            `Successfully updated from ${MACRO.DISPLAY_VERSION} to version ${result.latestVersion}`,
+            `Successfully updated from ${MACRO.VERSION} to version ${result.latestVersion}`,
           ) + '\n',
         )
         await regenerateCompletionCache()
@@ -330,15 +320,15 @@ export async function update() {
   }
 
   // Check if versions match exactly, including any build metadata (like SHA)
-  if (latestVersion === MACRO.DISPLAY_VERSION) {
+  if (latestVersion === MACRO.VERSION) {
     writeToStdout(
-      chalk.green(`OpenClaude is up to date (${MACRO.DISPLAY_VERSION})`) + '\n',
+      chalk.green(`Claude Code is up to date (${MACRO.VERSION})`) + '\n',
     )
     await gracefulShutdown(0)
   }
 
   writeToStdout(
-    `New version available: ${latestVersion} (current: ${MACRO.DISPLAY_VERSION})\n`,
+    `New version available: ${latestVersion} (current: ${MACRO.VERSION})\n`,
   )
   writeToStdout('Installing update...\n')
 
@@ -398,7 +388,7 @@ export async function update() {
     case 'success':
       writeToStdout(
         chalk.green(
-          `Successfully updated from ${MACRO.DISPLAY_VERSION} to version ${latestVersion}`,
+          `Successfully updated from ${MACRO.VERSION} to version ${latestVersion}`,
         ) + '\n',
       )
       await regenerateCompletionCache()

src/utils/Shell.ts

@@ -1,6 +1,6 @@
 import { execFileSync, spawn } from 'child_process'
 import { constants as fsConstants, readFileSync, unlinkSync } from 'fs'
-import { type FileHandle, mkdir, open, realpath } from 'fs/promises'
+import { type FileHandle, mkdir, open, stat } from 'fs/promises'
 import memoize from 'lodash-es/memoize.js'
 import { isAbsolute, resolve } from 'path'
 import { join as posixJoin } from 'path/posix'
@@ -217,22 +217,34 @@ export async function exec(
 
   let cwd = pwd()
 
-  // Recover if the current working directory no longer exists on disk.
-  // This can happen when a command deletes its own CWD (e.g., temp dir cleanup).
+  // Recover if the current working directory no longer exists on disk,
+  // or was replaced by a non-directory (e.g., the path was renamed and a file
+  // was created in its place). realpath() succeeds on any existing path
+  // regardless of type, so we must also verify it's a directory — otherwise
+  // spawn would fail later with ENOTDIR / exit 126.
+  let cwdIsValidDir = false
   try {
-    await realpath(cwd)
+    cwdIsValidDir = (await stat(cwd)).isDirectory()
   } catch {
+    cwdIsValidDir = false
+  }
+  if (!cwdIsValidDir) {
     const fallback = getOriginalCwd()
     logForDebugging(
-      `Shell CWD "${cwd}" no longer exists, recovering to "${fallback}"`,
+      `Shell CWD "${cwd}" is not a valid directory, recovering to "${fallback}"`,
     )
+    let fallbackIsValidDir = false
     try {
-      await realpath(fallback)
+      fallbackIsValidDir = (await stat(fallback)).isDirectory()
+    } catch {
+      fallbackIsValidDir = false
+    }
+    if (fallbackIsValidDir) {
       setCwdState(fallback)
       cwd = fallback
-    } catch {
+    } else {
       return createFailedCommand(
-        `Working directory "${cwd}" no longer exists. Please restart Claude from an existing directory.`,
+        `Working directory "${cwd}" is no longer a valid directory. Please restart Claude from an existing directory.`,
       )
     }
   }