docs: clarify Nushell XDG startup requirements and recovery

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_self_setup_nushell/assert.nu

@@ -0,0 +1,87 @@
+def main [mode: string] {
+  if $mode not-in ["config", "parent"] {
+    error make {msg: "Expected config or parent mode"}
+  }
+  $env.HOME = ($env.PWD | path join "user")
+  $env.XDG_CONFIG_HOME = ($env.HOME | path join "config")
+  $env.XDG_DATA_DIRS = ($env.HOME | path join "system-data")
+  $env.VP_HOME = ($env.PWD | path join "installation")
+  $env.VP_SKIP_DEPS_INSTALL = "1"
+  $env.VP_VERSION = "nushell-test"
+  $env.VP_NODE_MANAGER = "no"
+  $env.VP_PM_MANAGER = "no"
+  $env.CI = "true"
+  hide-env -i XDG_DATA_HOME
+
+  let config_dir = ($env.XDG_CONFIG_HOME | path join "nushell")
+  let custom_data = ($env.HOME | path join "custom-data")
+  # Use a non-default directory on both Linux and macOS so the mismatch is observable.
+  mkdir $config_dir
+  '' | save ($config_dir | path join "env.nu")
+  if $mode == "config" {
+    '$env.XDG_DATA_HOME = ($env.HOME | path join "custom-data")'
+      | save ($config_dir | path join "config.nu")
+  } else {
+    $env.XDG_DATA_HOME = $custom_data
+    '' | save ($config_dir | path join "config.nu")
+  }
+
+  # Real interactive startup loads config.nu before invoking the standalone installer.
+  let install = (^$nu.current-exe --no-history --execute 'try { source install.nu } catch { |err| print -e $err; exit 1 }; exit 0' | complete)
+  if $install.exit_code != 0 {
+    error make {msg: $"Installer session failed: ($install.stdout) ($install.stderr)"}
+  }
+  let installed = ($install.stdout | from json)
+  let session_dir = $installed.directory
+  if $installed.data_home != $custom_data {
+    error make {msg: "The installer session did not inherit the configured XDG_DATA_HOME"}
+  }
+  let snippet = ($custom_data | path join "nushell/vendor/autoload/vite-plus.nu")
+  if not ($snippet | path exists) {
+    error make {msg: "Installer did not write vite-plus.nu into the child-resolved directory"}
+  }
+  if not ($env.VP_HOME | path join "current/bin/.vp-setup-complete" | path exists) {
+    error make {msg: "Installer did not complete setup"}
+  }
+
+  # Launch from the original parent environment, not from the modified interactive session.
+  let fresh = (^$nu.current-exe --no-history --execute 'try { source probe.nu } catch { |err| print -e $err; exit 1 }; exit 0' | complete)
+  if $fresh.exit_code != 0 {
+    error make {msg: $"Fresh session failed: ($fresh.stdout) ($fresh.stderr)"}
+  }
+  let state = ($fresh.stdout | from json)
+  if $state.data_home != $custom_data {
+    error make {msg: "The fresh session did not load the configured XDG_DATA_HOME"}
+  }
+  let expected_loaded = ($mode == "parent")
+  if $state.directory != $session_dir {
+    error make {msg: "Fresh session did not resolve the original session's autoload directory"}
+  }
+  if (($snippet | path dirname) == $session_dir) != $expected_loaded {
+    error make {msg: "Unexpected agreement between installer and session autoload directories"}
+  }
+  if $state.loaded != $expected_loaded {
+    error make {msg: $"Unexpected Vite+ autoload state: ($state.loaded)"}
+  }
+  print "Standalone setup completed and wrote vite-plus.nu"
+  print "Both sessions have the configured XDG_DATA_HOME after startup: true"
+  print $"Installer and session directories match: ($expected_loaded)"
+  print $"Fresh session loaded Vite+ environment: ($state.loaded)"
+
+  if $mode == "config" {
+    # Apply the documented workaround without changing the XDG settings.
+    # source requires a parse-time path, so write a quoted literal into config.nu.
+    let env_file = ($env.VP_HOME | path join "env.nu" | to nuon)
+    $"\nsource ($env_file)\n" | save --append ($config_dir | path join "config.nu")
+    let repaired = (^$nu.current-exe --no-history --execute 'try { let help = (^vp help | complete); if $help.exit_code != 0 { error make {msg: $help.stderr} }; source probe.nu } catch { |err| print -e $err; exit 1 }; exit 0' | complete)
+    if $repaired.exit_code != 0 {
+      error make {msg: $"Session with the documented source line failed: ($repaired.stdout) ($repaired.stderr)"}
+    }
+    let repaired_state = ($repaired.stdout | from json)
+    if not $repaired_state.loaded or $repaired_state.directory != $session_dir or $repaired_state.data_home != $custom_data {
+      error make {msg: "The source workaround did not load Vite+ with the original XDG configuration"}
+    }
+    print "After adding source to config.nu, a fresh session loaded Vite+: true"
+    print "vp help succeeded in the fresh session"
+  }
+}

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_self_setup_nushell/install.nu

@@ -0,0 +1,8 @@
+let result = (^./external/vp | complete)
+if $result.exit_code != 0 or ($result.stderr | str contains "Could not configure shell profiles") {
+  error make {msg: $"Standalone setup failed: ($result.stdout) ($result.stderr)"}
+}
+{
+  directory: ($nu.vendor-autoload-dirs | last)
+  data_home: $env.XDG_DATA_HOME
+} | to json --raw | print

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_self_setup_nushell/probe.nu

@@ -0,0 +1,5 @@
+{
+  directory: ($nu.vendor-autoload-dirs | last)
+  data_home: $env.XDG_DATA_HOME
+  loaded: (($env.VP_HOME | path join "bin") in $env.PATH)
+} | to json --raw | print

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_self_setup_nushell/snapshots.toml

@@ -0,0 +1,27 @@
+[[case]]
+name = "command_self_setup_nushell_config_xdg_mismatch"
+vp = "global"
+requires = ["nu"]
+skip-platforms = ["windows"]
+seed-runtime = false
+comment = "Issue #2491: with XDG_DATA_HOME unset in the parent and set in config.nu, installation succeeds but a fresh session does not load Vite+."
+steps = [
+  { argv = ["vpt", "mkdir", "external"], snapshot = false },
+  { argv = ["vpt", "cp", "$VP_HOME/bin/vp", "external/vp"], snapshot = false },
+  { argv = ["vpt", "chmod", "+x", "external/vp"], snapshot = false },
+  ["nu", "--no-config-file", "assert.nu", "config"],
+]
+
+[[case]]
+name = "command_self_setup_nushell_parent_xdg"
+vp = "global"
+requires = ["nu"]
+skip-platforms = ["windows"]
+seed-runtime = false
+comment = "Setting XDG_DATA_HOME before Nushell starts lets new sessions load the installed snippet."
+steps = [
+  { argv = ["vpt", "mkdir", "external"], snapshot = false },
+  { argv = ["vpt", "cp", "$VP_HOME/bin/vp", "external/vp"], snapshot = false },
+  { argv = ["vpt", "chmod", "+x", "external/vp"], snapshot = false },
+  ["nu", "--no-config-file", "assert.nu", "parent"],
+]

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_self_setup_nushell/snapshots/command_self_setup_nushell_config_xdg_mismatch.md

@@ -0,0 +1,23 @@
+# command_self_setup_nushell_config_xdg_mismatch
+
+Issue #2491: with XDG_DATA_HOME unset in the parent and set in config.nu, installation succeeds but a fresh session does not load Vite+.
+
+## `vpt mkdir external`
+
+
+## `vpt cp $VP_HOME/bin/vp external/vp`
+
+
+## `vpt chmod +x external/vp`
+
+
+## `nu --no-config-file assert.nu config`
+
+```
+Standalone setup completed and wrote vite-plus.nu
+Both sessions have the configured XDG_DATA_HOME after startup: true
+Installer and session directories match: false
+Fresh session loaded Vite+ environment: false
+After adding source to config.nu, a fresh session loaded Vite+: true
+vp help succeeded in the fresh session
+```

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_self_setup_nushell/snapshots/command_self_setup_nushell_parent_xdg.md

@@ -0,0 +1,21 @@
+# command_self_setup_nushell_parent_xdg
+
+Setting XDG_DATA_HOME before Nushell starts lets new sessions load the installed snippet.
+
+## `vpt mkdir external`
+
+
+## `vpt cp $VP_HOME/bin/vp external/vp`
+
+
+## `vpt chmod +x external/vp`
+
+
+## `nu --no-config-file assert.nu parent`
+
+```
+Standalone setup completed and wrote vite-plus.nu
+Both sessions have the configured XDG_DATA_HOME after startup: true
+Installer and session directories match: true
+Fresh session loaded Vite+ environment: true
+```

docs/guide/global-cli.md

@@ -265,6 +265,20 @@ Vite+ sets additional `VP_*` variables during shim dispatch and shell integratio
 
 Vite+ also respects these standard environment variables:
 
+#### Nushell and XDG directories
+
+If you customize `XDG_DATA_HOME` or `XDG_CONFIG_HOME`, set them **before starting Nushell**, through your terminal application, operating system, or parent shell. This is a [Nushell startup requirement](https://www.nushell.sh/book/configuration.html#changing-default-directories); setting them only in `config.nu` or `env.nu` does not configure the running session's startup directories.
+
+Assignments in those files still affect child processes. The Vite+ installer starts a child Nushell to locate its vendor autoload directory, so it can write `vite-plus.nu` to a directory that normal new sessions do not read. Installation can succeed while `vp` remains unavailable in those sessions.
+
+If this happens, open your Nushell configuration with `config nu` and add a `source` line pointing to the installed Vite+ `env.nu` file. For a default fresh macOS or Linux installation without a custom `XDG_CONFIG_HOME`, use:
+
+```nu
+source ~/.config/vite-plus/env.nu
+```
+
+For a custom `XDG_CONFIG_HOME`, use the absolute path to `<XDG_CONFIG_HOME>/vite-plus/env.nu` as resolved during installation. For an installation under `VP_HOME` or an existing `~/.vite-plus` installation, use `<VP_HOME>/env.nu` or `~/.vite-plus/env.nu` instead. Replace placeholders with actual paths and quote paths containing spaces. Open a new Nushell session and run `vp help` to verify the configuration.
+
 #### `CI`
 
 - **Purpose**: Indicates running in CI environment

docs/guide/index.md

@@ -36,6 +36,8 @@ The `vp-setup.exe` is not yet code-signed. Your browser may show a warning when
 
 The installer scripts and `vp-setup.exe` read [environment variables](/guide/global-cli#installation-variables) such as `VP_VERSION` and `VP_HOME`.
 
+If you use Nushell with custom XDG directories, read the [Nushell startup requirements](/guide/global-cli#nushell-and-xdg-directories) before installing.
+
 After installation, open a new shell and run:
 
 ```bash