fix(desktop): avoid incompatible startup shells

packages/electron-app/electron/main/user-shell.test.ts

@@ -0,0 +1,18 @@
+import assert from "node:assert/strict"
+import { describe, it } from "node:test"
+
+import { getDefaultShellPath } from "./user-shell"
+
+describe("desktop POSIX shell selection", () => {
+  it("falls back from incompatible user shells", () => {
+    assert.equal(getDefaultShellPath("darwin", "/opt/homebrew/bin/nu"), "/bin/zsh")
+    assert.equal(getDefaultShellPath("linux", "/usr/bin/fish"), "/bin/bash")
+    assert.equal(getDefaultShellPath("darwin", "/tmp/not-bash"), "/bin/zsh")
+    assert.equal(getDefaultShellPath("darwin", "  "), "/bin/zsh")
+  })
+
+  it("preserves configured bash and zsh paths", () => {
+    assert.equal(getDefaultShellPath("darwin", "/opt/homebrew/bin/bash"), "/opt/homebrew/bin/bash")
+    assert.equal(getDefaultShellPath("linux", " /usr/local/bin/zsh "), "/usr/local/bin/zsh")
+  })
+})

packages/electron-app/electron/main/user-shell.ts

@@ -8,18 +8,29 @@ interface ShellCommand {
 
 const isWindows = process.platform === "win32"
 
-function getDefaultShellPath(): string {
-  if (process.env.SHELL && process.env.SHELL.trim().length > 0) {
-    return process.env.SHELL
+export function getDefaultShellPath(
+  platform: NodeJS.Platform = process.platform,
+  configuredShell = process.env.SHELL,
+): string {
+  const shellPath = configuredShell?.trim()
+  if (shellPath && isSupportedPosixShell(shellPath)) {
+    return shellPath
   }
 
-  if (process.platform === "darwin") {
+  // The launch script uses POSIX syntax. Never pass it to arbitrary user shells
+  // such as Nushell or Fish even when they are configured through $SHELL.
+  if (platform === "darwin") {
     return "/bin/zsh"
   }
 
   return "/bin/bash"
 }
 
+function isSupportedPosixShell(shellPath: string): boolean {
+  const shellName = path.basename(shellPath).toLowerCase()
+  return shellName === "bash" || shellName === "zsh"
+}
+
 function wrapCommandForShell(command: string, shellPath: string): string {
   const shellName = path.basename(shellPath)
 

packages/electron-app/package.json

@@ -24,7 +24,7 @@
     "prebuild": "npm run prepare:resources",
     "build": "electron-vite build",
     "typecheck": "tsc --noEmit -p tsconfig.json",
-    "test:native": "node --import tsx --test electron/main/client-state-cross-host.test.ts electron/main/client-state-process.test.ts electron/main/client-state.test.ts electron/main/client-state-ipc.test.ts electron/main/client-state-navigation.test.ts electron/main/developer-mode.test.ts electron/main/local-window-registry.test.ts electron/main/menu-target.test.ts electron/main/multiwindow-lifecycle.test.ts electron/main/native-request.test.ts electron/main/navigation-security.test.ts electron/main/preferences-ipc.test.ts electron/main/preferences-window.test.ts electron/main/process-exit.test.ts electron/main/process-output.test.ts electron/main/process-stop.test.ts electron/main/remote-window-registry.test.ts electron/main/renderer-client-state-flush.test.ts electron/main/renderer-origin.test.ts electron/main/serialized-lifecycle.test.ts electron/main/startup.test.ts electron/main/window-state.test.ts electron/main/workspace-open.test.ts electron/preload/index.test.ts",
+    "test:native": "node --import tsx --test electron/main/client-state-cross-host.test.ts electron/main/client-state-process.test.ts electron/main/client-state.test.ts electron/main/client-state-ipc.test.ts electron/main/client-state-navigation.test.ts electron/main/developer-mode.test.ts electron/main/local-window-registry.test.ts electron/main/menu-target.test.ts electron/main/multiwindow-lifecycle.test.ts electron/main/native-request.test.ts electron/main/navigation-security.test.ts electron/main/preferences-ipc.test.ts electron/main/preferences-window.test.ts electron/main/process-exit.test.ts electron/main/process-output.test.ts electron/main/process-stop.test.ts electron/main/remote-window-registry.test.ts electron/main/renderer-client-state-flush.test.ts electron/main/renderer-origin.test.ts electron/main/serialized-lifecycle.test.ts electron/main/startup.test.ts electron/main/user-shell.test.ts electron/main/window-state.test.ts electron/main/workspace-open.test.ts electron/preload/index.test.ts",
     "preview": "electron-vite preview",
     "build:binaries": "node scripts/build.js",
     "build:mac": "node scripts/build.js mac",

packages/tauri-app/src-tauri/src/cli_manager.rs

@@ -1128,7 +1128,7 @@ impl CliProcessManager {
         }
 
         let command_info = if use_user_shell {
-            log_line("spawning via user shell");
+            log_line("spawning via POSIX-compatible shell");
             ShellCommandType::UserShell(build_shell_command_string(&resolution, &args)?)
         } else {
             log_line(if resolution.runner == Runner::Tsx {
@@ -1872,17 +1872,32 @@ fn build_shell_command_string(
     );
     let wrapped_command = wrap_command_for_shell(&command, &shell);
     let args = build_shell_args(&shell, &wrapped_command);
-    log_line(&format!("user shell command: {} {:?}", shell, args));
+    log_line(&format!("POSIX shell command: {} {:?}", shell, args));
     Ok(ShellCommand { shell, args })
 }
 
 fn default_shell() -> String {
-    if let Ok(shell) = std::env::var("SHELL") {
-        if !shell.trim().is_empty() {
-            return shell;
-        }
-    }
-    if cfg!(target_os = "macos") {
+    select_posix_shell(
+        std::env::var("SHELL").ok().as_deref(),
+        cfg!(target_os = "macos"),
+    )
+}
+
+fn select_posix_shell(configured_shell: Option<&str>, macos: bool) -> String {
+    if let Some(shell) = configured_shell.map(str::trim).filter(|shell| {
+        let name = std::path::Path::new(shell)
+            .file_name()
+            .and_then(OsStr::to_str)
+            .unwrap_or("")
+            .to_lowercase();
+        matches!(name.as_str(), "bash" | "zsh")
+    }) {
+        return shell.to_string();
+    }
+
+    // The launch script uses POSIX syntax. Never pass it to arbitrary user shells
+    // such as Nushell or Fish even when they are configured through $SHELL.
+    if macos {
         "/bin/zsh".to_string()
     } else {
         "/bin/bash".to_string()
@@ -2025,6 +2040,32 @@ mod tests {
         );
     }
 
+    #[test]
+    fn posix_shell_selection_rejects_incompatible_user_shells() {
+        assert_eq!(
+            select_posix_shell(Some("/opt/homebrew/bin/nu"), true),
+            "/bin/zsh"
+        );
+        assert_eq!(
+            select_posix_shell(Some("/usr/bin/fish"), false),
+            "/bin/bash"
+        );
+        assert_eq!(select_posix_shell(Some("/tmp/not-bash"), true), "/bin/zsh");
+        assert_eq!(select_posix_shell(Some("  "), true), "/bin/zsh");
+    }
+
+    #[test]
+    fn posix_shell_selection_preserves_bash_and_zsh() {
+        assert_eq!(
+            select_posix_shell(Some("/opt/homebrew/bin/bash"), true),
+            "/opt/homebrew/bin/bash"
+        );
+        assert_eq!(
+            select_posix_shell(Some(" /usr/local/bin/zsh "), false),
+            "/usr/local/bin/zsh"
+        );
+    }
+
     #[test]
     fn augment_launch_url_trims_leading_fragment_marker() {
         let _guard = ENV_LOCK.lock().expect("env lock poisoned");