Update config directly at assignment (#13332)

# Description

Allows `Stack` to have a modified local `Config`, which is updated
immediately when `$env.config` is assigned to. This means that even
within a script, commands that come after `$env.config` changes will
always see those changes in `Stack::get_config()`.

Also fixed a lot of cases where `engine_state.get_config()` was used
even when `Stack` was available.

Closes #13324.

# User-Facing Changes
- Config changes apply immediately after the assignment is executed,
rather than whenever config is read by a command that needs it.
- Potentially slower performance when executing a lot of lines that
change `$env.config` one after another. Recommended to get `$env.config`
into a `mut` variable first and do modifications, then assign it back.
- Much faster performance when executing a script that made
modifications to `$env.config`, as the changes are only parsed once.

# Tests + Formatting
All passing.

# After Submitting
- [ ] release notes

Cargo.lock

@@ -3257,6 +3257,7 @@ dependencies = [
  "nu-plugin-core",
  "nu-plugin-protocol",
  "nu-protocol",
+ "nu-utils",
  "serde",
  "thiserror",
  "typetag",
@@ -3286,6 +3287,7 @@ dependencies = [
  "nu-plugin-protocol",
  "nu-protocol",
  "nu-system",
+ "nu-utils",
  "serde",
  "typetag",
  "windows 0.54.0",

crates/nu-cli/src/eval_cmds.rs

@@ -53,9 +53,8 @@ pub fn evaluate_commands(
     // Parse the source code
     let (block, delta) = {
         if let Some(ref t_mode) = table_mode {
-            let mut config = engine_state.get_config().clone();
+            Arc::make_mut(&mut engine_state.config).table_mode =
-            config.table_mode = t_mode.coerce_str()?.parse().unwrap_or_default();
+                t_mode.coerce_str()?.parse().unwrap_or_default();
-            engine_state.set_config(config);
         }
 
         let mut working_set = StateWorkingSet::new(engine_state);

crates/nu-cli/src/menus/help_completions.rs

@@ -1,25 +1,31 @@
 use nu_engine::documentation::get_flags_section;
-use nu_protocol::{engine::EngineState, levenshtein_distance};
+use nu_protocol::{engine::EngineState, levenshtein_distance, Config};
 use nu_utils::IgnoreCaseExt;
 use reedline::{Completer, Suggestion};
 use std::{fmt::Write, sync::Arc};
 
-pub struct NuHelpCompleter(Arc<EngineState>);
+pub struct NuHelpCompleter {
+    engine_state: Arc<EngineState>,
+    config: Arc<Config>,
+}
 
 impl NuHelpCompleter {
-    pub fn new(engine_state: Arc<EngineState>) -> Self {
+    pub fn new(engine_state: Arc<EngineState>, config: Arc<Config>) -> Self {
-        Self(engine_state)
+        Self {
+            engine_state,
+            config,
+        }
     }
 
     fn completion_helper(&self, line: &str, pos: usize) -> Vec<Suggestion> {
         let folded_line = line.to_folded_case();
 
         let mut commands = self
-            .0
+            .engine_state
             .get_decls_sorted(false)
             .into_iter()
             .filter_map(|(_, decl_id)| {
-                let decl = self.0.get_decl(decl_id);
+                let decl = self.engine_state.get_decl(decl_id);
                 (decl.name().to_folded_case().contains(&folded_line)
                     || decl.usage().to_folded_case().contains(&folded_line)
                     || decl
@@ -54,9 +60,12 @@ impl NuHelpCompleter {
                 let _ = write!(long_desc, "Usage:\r\n  > {}\r\n", sig.call_signature());
 
                 if !sig.named.is_empty() {
-                    long_desc.push_str(&get_flags_section(Some(&*self.0.clone()), &sig, |v| {
+                    long_desc.push_str(&get_flags_section(
-                        v.to_parsable_string(", ", &self.0.config)
+                        Some(&self.engine_state),
-                    }))
+                        Some(&self.config),
+                        &sig,
+                        |v| v.to_parsable_string(", ", &self.config),
+                    ))
                 }
 
                 if !sig.required_positional.is_empty()
@@ -71,7 +80,7 @@ impl NuHelpCompleter {
                         let opt_suffix = if let Some(value) = &positional.default_value {
                             format!(
                                 " (optional, default: {})",
-                                &value.to_parsable_string(", ", &self.0.config),
+                                &value.to_parsable_string(", ", &self.config),
                             )
                         } else {
                             (" (optional)").to_string()
@@ -138,7 +147,8 @@ mod test {
     ) {
         let engine_state =
             nu_command::add_shell_command_context(nu_cmd_lang::create_default_context());
-        let mut completer = NuHelpCompleter::new(engine_state.into());
+        let config = engine_state.get_config().clone();
+        let mut completer = NuHelpCompleter::new(engine_state.into(), config);
         let suggestions = completer.complete(line, end);
 
         assert_eq!(

crates/nu-cli/src/nu_highlight.rs

@@ -1,3 +1,5 @@
+use std::sync::Arc;
+
 use nu_engine::command_prelude::*;
 use reedline::{Highlighter, StyledText};
 
@@ -33,13 +35,10 @@ impl Command for NuHighlight {
         let head = call.head;
 
         let signals = engine_state.signals();
-        let engine_state = std::sync::Arc::new(engine_state.clone());
-        let config = engine_state.get_config().clone();
 
         let highlighter = crate::NuHighlighter {
-            engine_state,
+            engine_state: Arc::new(engine_state.clone()),
-            stack: std::sync::Arc::new(stack.clone()),
+            stack: Arc::new(stack.clone()),
-            config,
         };
 
         input.map(

crates/nu-cli/src/reedline_config.rs

@@ -77,13 +77,19 @@ pub(crate) fn add_menus(
     mut line_editor: Reedline,
     engine_state_ref: Arc<EngineState>,
     stack: &Stack,
-    config: &Config,
+    config: Arc<Config>,
 ) -> Result<Reedline, ShellError> {
     //log::trace!("add_menus: config: {:#?}", &config);
     line_editor = line_editor.clear_menus();
 
     for menu in &config.menus {
-        line_editor = add_menu(line_editor, menu, engine_state_ref.clone(), stack, config)?
+        line_editor = add_menu(
+            line_editor,
+            menu,
+            engine_state_ref.clone(),
+            stack,
+            config.clone(),
+        )?
     }
 
     // Checking if the default menus have been added from the config file
@@ -100,7 +106,7 @@ pub(crate) fn add_menus(
         if !config
             .menus
             .iter()
-            .any(|menu| menu.name.to_expanded_string("", config) == name)
+            .any(|menu| menu.name.to_expanded_string("", &config) == name)
         {
             let (block, delta) = {
                 let mut working_set = StateWorkingSet::new(&engine_state);
@@ -137,7 +143,7 @@ pub(crate) fn add_menus(
                     &menu,
                     new_engine_state_ref.clone(),
                     stack,
-                    config,
+                    config.clone(),
                 )?;
             }
         }
@@ -151,27 +157,27 @@ fn add_menu(
     menu: &ParsedMenu,
     engine_state: Arc<EngineState>,
     stack: &Stack,
-    config: &Config,
+    config: Arc<Config>,
 ) -> Result<Reedline, ShellError> {
     let span = menu.menu_type.span();
     if let Value::Record { val, .. } = &menu.menu_type {
-        let layout = extract_value("layout", val, span)?.to_expanded_string("", config);
+        let layout = extract_value("layout", val, span)?.to_expanded_string("", &config);
 
         match layout.as_str() {
-            "columnar" => add_columnar_menu(line_editor, menu, engine_state, stack, config),
+            "columnar" => add_columnar_menu(line_editor, menu, engine_state, stack, &config),
             "list" => add_list_menu(line_editor, menu, engine_state, stack, config),
             "ide" => add_ide_menu(line_editor, menu, engine_state, stack, config),
             "description" => add_description_menu(line_editor, menu, engine_state, stack, config),
             _ => Err(ShellError::UnsupportedConfigValue {
                 expected: "columnar, list, ide or description".to_string(),
-                value: menu.menu_type.to_abbreviated_string(config),
+                value: menu.menu_type.to_abbreviated_string(&config),
                 span: menu.menu_type.span(),
             }),
         }
     } else {
         Err(ShellError::UnsupportedConfigValue {
             expected: "only record type".to_string(),
-            value: menu.menu_type.to_abbreviated_string(config),
+            value: menu.menu_type.to_abbreviated_string(&config),
             span: menu.menu_type.span(),
         })
     }
@@ -282,9 +288,9 @@ pub(crate) fn add_list_menu(
     menu: &ParsedMenu,
     engine_state: Arc<EngineState>,
     stack: &Stack,
-    config: &Config,
+    config: Arc<Config>,
 ) -> Result<Reedline, ShellError> {
-    let name = menu.name.to_expanded_string("", config);
+    let name = menu.name.to_expanded_string("", &config);
     let mut list_menu = ListMenu::default().with_name(&name);
 
     let span = menu.menu_type.span();
@@ -311,7 +317,7 @@ pub(crate) fn add_list_menu(
         }
     }
 
-    let marker = menu.marker.to_expanded_string("", config);
+    let marker = menu.marker.to_expanded_string("", &config);
     list_menu = list_menu.with_marker(&marker);
 
     let only_buffer_difference = menu.only_buffer_difference.as_bool()?;
@@ -337,7 +343,7 @@ pub(crate) fn add_list_menu(
         }
         _ => Err(ShellError::UnsupportedConfigValue {
             expected: "block or omitted value".to_string(),
-            value: menu.source.to_abbreviated_string(config),
+            value: menu.source.to_abbreviated_string(&config),
             span: menu.source.span(),
         }),
     }
@@ -349,10 +355,10 @@ pub(crate) fn add_ide_menu(
     menu: &ParsedMenu,
     engine_state: Arc<EngineState>,
     stack: &Stack,
-    config: &Config,
+    config: Arc<Config>,
 ) -> Result<Reedline, ShellError> {
     let span = menu.menu_type.span();
-    let name = menu.name.to_expanded_string("", config);
+    let name = menu.name.to_expanded_string("", &config);
     let mut ide_menu = IdeMenu::default().with_name(&name);
 
     if let Value::Record { val, .. } = &menu.menu_type {
@@ -417,7 +423,7 @@ pub(crate) fn add_ide_menu(
                 } else {
                     return Err(ShellError::UnsupportedConfigValue {
                         expected: "bool or record".to_string(),
-                        value: border.to_abbreviated_string(config),
+                        value: border.to_abbreviated_string(&config),
                         span: border.span(),
                     });
                 }
@@ -441,7 +447,7 @@ pub(crate) fn add_ide_menu(
                 _ => {
                     return Err(ShellError::UnsupportedConfigValue {
                         expected: "\"left\", \"right\" or \"prefer_right\"".to_string(),
-                        value: description_mode.to_abbreviated_string(config),
+                        value: description_mode.to_abbreviated_string(&config),
                         span: description_mode.span(),
                     });
                 }
@@ -509,7 +515,7 @@ pub(crate) fn add_ide_menu(
         }
     }
 
-    let marker = menu.marker.to_expanded_string("", config);
+    let marker = menu.marker.to_expanded_string("", &config);
     ide_menu = ide_menu.with_marker(&marker);
 
     let only_buffer_difference = menu.only_buffer_difference.as_bool()?;
@@ -535,7 +541,7 @@ pub(crate) fn add_ide_menu(
         }
         _ => Err(ShellError::UnsupportedConfigValue {
             expected: "block or omitted value".to_string(),
-            value: menu.source.to_abbreviated_string(config),
+            value: menu.source.to_abbreviated_string(&config),
             span,
         }),
     }
@@ -547,9 +553,9 @@ pub(crate) fn add_description_menu(
     menu: &ParsedMenu,
     engine_state: Arc<EngineState>,
     stack: &Stack,
-    config: &Config,
+    config: Arc<Config>,
 ) -> Result<Reedline, ShellError> {
-    let name = menu.name.to_expanded_string("", config);
+    let name = menu.name.to_expanded_string("", &config);
     let mut description_menu = DescriptionMenu::default().with_name(&name);
 
     let span = menu.menu_type.span();
@@ -608,7 +614,7 @@ pub(crate) fn add_description_menu(
         }
     }
 
-    let marker = menu.marker.to_expanded_string("", config);
+    let marker = menu.marker.to_expanded_string("", &config);
     description_menu = description_menu.with_marker(&marker);
 
     let only_buffer_difference = menu.only_buffer_difference.as_bool()?;
@@ -617,7 +623,7 @@ pub(crate) fn add_description_menu(
     let span = menu.source.span();
     match &menu.source {
         Value::Nothing { .. } => {
-            let completer = Box::new(NuHelpCompleter::new(engine_state));
+            let completer = Box::new(NuHelpCompleter::new(engine_state, config));
             Ok(line_editor.with_menu(ReedlineMenu::WithCompleter {
                 menu: Box::new(description_menu),
                 completer,
@@ -638,7 +644,7 @@ pub(crate) fn add_description_menu(
         }
         _ => Err(ShellError::UnsupportedConfigValue {
             expected: "closure or omitted value".to_string(),
-            value: menu.source.to_abbreviated_string(config),
+            value: menu.source.to_abbreviated_string(&config),
             span: menu.source.span(),
         }),
     }

crates/nu-cli/src/repl.rs

@@ -297,7 +297,7 @@ fn loop_iteration(ctx: LoopContext) -> (bool, Stack, Reedline) {
     perf!("env-change hook", start_time, use_color);
 
     let engine_reference = Arc::new(engine_state.clone());
-    let config = engine_state.get_config();
+    let config = stack.get_config(engine_state);
 
     start_time = std::time::Instant::now();
     // Find the configured cursor shapes for each mode
@@ -323,7 +323,6 @@ fn loop_iteration(ctx: LoopContext) -> (bool, Stack, Reedline) {
             engine_state: engine_reference.clone(),
             // STACK-REFERENCE 1
             stack: stack_arc.clone(),
-            config: config.clone(),
         }))
         .with_validator(Box::new(NuValidator {
             engine_state: engine_reference.clone(),

crates/nu-cli/src/syntax_highlight.rs

@@ -6,7 +6,7 @@ use nu_parser::{flatten_block, parse, FlatShape};
 use nu_protocol::{
     ast::{Block, Expr, Expression, PipelineRedirection, RecordItem},
     engine::{EngineState, Stack, StateWorkingSet},
-    Config, Span,
+    Span,
 };
 use reedline::{Highlighter, StyledText};
 use std::sync::Arc;
@@ -14,15 +14,14 @@ use std::sync::Arc;
 pub struct NuHighlighter {
     pub engine_state: Arc<EngineState>,
     pub stack: Arc<Stack>,
-    pub config: Config,
 }
 
 impl Highlighter for NuHighlighter {
     fn highlight(&self, line: &str, _cursor: usize) -> StyledText {
         trace!("highlighting: {}", line);
 
-        let highlight_resolved_externals =
+        let config = self.stack.get_config(&self.engine_state);
-            self.engine_state.get_config().highlight_resolved_externals;
+        let highlight_resolved_externals = config.highlight_resolved_externals;
         let mut working_set = StateWorkingSet::new(&self.engine_state);
         let block = parse(&mut working_set, None, line.as_bytes(), false);
         let (shapes, global_span_offset) = {
@@ -88,7 +87,7 @@ impl Highlighter for NuHighlighter {
                 .to_string();
 
             let mut add_colored_token = |shape: &FlatShape, text: String| {
-                output.push((get_shape_color(shape.as_str(), &self.config), text));
+                output.push((get_shape_color(shape.as_str(), &config), text));
             };
 
             match shape.1 {
@@ -128,9 +127,9 @@ impl Highlighter for NuHighlighter {
                         let start = part.start - span.start;
                         let end = part.end - span.start;
                         let text = next_token[start..end].to_string();
-                        let mut style = get_shape_color(shape.as_str(), &self.config);
+                        let mut style = get_shape_color(shape.as_str(), &config);
                         if highlight {
-                            style = get_matching_brackets_style(style, &self.config);
+                            style = get_matching_brackets_style(style, &config);
                         }
                         output.push((style, text));
                     }

crates/nu-cmd-extra/src/extra/formats/to/html.rs

@@ -239,7 +239,7 @@ fn to_html(
     let partial = call.has_flag(engine_state, stack, "partial")?;
     let list = call.has_flag(engine_state, stack, "list")?;
     let theme: Option<Spanned<String>> = call.get_flag(engine_state, stack, "theme")?;
-    let config = engine_state.get_config();
+    let config = &stack.get_config(engine_state);
 
     let vec_of_values = input.into_iter().collect::<Vec<Value>>();
     let headers = merge_descriptors(&vec_of_values);

crates/nu-cmd-extra/src/extra/strings/format/command.rs

@@ -1,5 +1,5 @@
 use nu_engine::command_prelude::*;
-use nu_protocol::{ast::PathMember, engine::StateWorkingSet, ListStream};
+use nu_protocol::{ast::PathMember, engine::StateWorkingSet, Config, ListStream};
 
 #[derive(Clone)]
 pub struct FormatPattern;
@@ -43,6 +43,8 @@ impl Command for FormatPattern {
         let it_id = working_set.add_variable(b"$it".to_vec(), call.head, Type::Any, false);
         stack.add_var(it_id, input_val.clone());
 
+        let config = stack.get_config(engine_state);
+
         match specified_pattern {
             Err(e) => Err(e),
             Ok(pattern) => {
@@ -56,7 +58,7 @@ impl Command for FormatPattern {
                     string_span.start + 1,
                 )?;
 
-                format(input_val, &ops, engine_state, call.head)
+                format(input_val, &ops, engine_state, &config, call.head)
             }
         }
     }
@@ -181,33 +183,30 @@ fn format(
     input_data: Value,
     format_operations: &[FormatOperation],
     engine_state: &EngineState,
+    config: &Config,
     head_span: Span,
 ) -> Result<PipelineData, ShellError> {
     let data_as_value = input_data;
 
     //  We can only handle a Record or a List of Records
     match data_as_value {
-        Value::Record { .. } => {
+        Value::Record { .. } => match format_record(format_operations, &data_as_value, config) {
-            match format_record(format_operations, &data_as_value, engine_state) {
             Ok(value) => Ok(PipelineData::Value(Value::string(value, head_span), None)),
             Err(value) => Err(value),
-            }
+        },
-        }
 
         Value::List { vals, .. } => {
             let mut list = vec![];
             for val in vals.iter() {
                 match val {
-                    Value::Record { .. } => {
+                    Value::Record { .. } => match format_record(format_operations, val, config) {
-                        match format_record(format_operations, val, engine_state) {
                         Ok(value) => {
                             list.push(Value::string(value, head_span));
                         }
                         Err(value) => {
                             return Err(value);
                         }
-                        }
+                    },
-                    }
                     Value::Error { error, .. } => return Err(*error.clone()),
                     _ => {
                         return Err(ShellError::OnlySupportsThisInputType {
@@ -237,9 +236,8 @@ fn format(
 fn format_record(
     format_operations: &[FormatOperation],
     data_as_value: &Value,
-    engine_state: &EngineState,
+    config: &Config,
 ) -> Result<String, ShellError> {
-    let config = engine_state.get_config();
     let mut output = String::new();
 
     for op in format_operations {

crates/nu-color-config/src/style_computer.rs

@@ -1,6 +1,6 @@
 use crate::{color_record_to_nustyle, lookup_ansi_color_style, text_style::Alignment, TextStyle};
 use nu_ansi_term::{Color, Style};
-use nu_engine::{env::get_config, ClosureEvalOnce};
+use nu_engine::ClosureEvalOnce;
 use nu_protocol::{
     cli_error::CliError,
     engine::{Closure, EngineState, Stack, StateWorkingSet},
@@ -114,7 +114,7 @@ impl<'a> StyleComputer<'a> {
 
     // The main constructor.
     pub fn from_config(engine_state: &'a EngineState, stack: &'a Stack) -> StyleComputer<'a> {
-        let config = get_config(engine_state, stack);
+        let config = stack.get_config(engine_state);
 
         // Create the hashmap
         #[rustfmt::skip]

crates/nu-command/src/conversions/into/string.rs

@@ -1,3 +1,5 @@
+use std::sync::Arc;
+
 use nu_cmd_base::input_handler::{operate, CmdArgument};
 use nu_engine::command_prelude::*;
 use nu_protocol::{into_code, Config};
@@ -7,7 +9,7 @@ use num_format::ToFormattedString;
 struct Arguments {
     decimals_value: Option<i64>,
     cell_paths: Option<Vec<CellPath>>,
-    config: Config,
+    config: Arc<Config>,
 }
 
 impl CmdArgument for Arguments {
@@ -174,7 +176,7 @@ fn string_helper(
             })
         }
     } else {
-        let config = engine_state.get_config().clone();
+        let config = stack.get_config(engine_state);
         let args = Arguments {
             decimals_value,
             cell_paths,

crates/nu-command/src/debug/debug_.rs

@@ -33,7 +33,7 @@ impl Command for Debug {
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
         let head = call.head;
-        let config = engine_state.get_config().clone();
+        let config = stack.get_config(engine_state);
         let raw = call.has_flag(engine_state, stack, "raw")?;
 
         // Should PipelineData::Empty result in an error here?

crates/nu-command/src/filesystem/rm.rs

@@ -170,7 +170,7 @@ fn rm(
     }
 
     let span = call.head;
-    let rm_always_trash = engine_state.get_config().rm_always_trash;
+    let rm_always_trash = stack.get_config(engine_state).rm_always_trash;
 
     if !TRASH_SUPPORTED {
         if rm_always_trash {

crates/nu-command/src/filters/find.rs

@@ -213,7 +213,7 @@ fn find_with_regex(
     input: PipelineData,
 ) -> Result<PipelineData, ShellError> {
     let span = call.head;
-    let config = engine_state.get_config().clone();
+    let config = stack.get_config(engine_state);
 
     let insensitive = call.has_flag(engine_state, stack, "ignore-case")?;
     let multiline = call.has_flag(engine_state, stack, "multiline")?;
@@ -348,8 +348,8 @@ fn find_with_rest_and_highlight(
     input: PipelineData,
 ) -> Result<PipelineData, ShellError> {
     let span = call.head;
-    let config = engine_state.get_config().clone();
+    let config = stack.get_config(engine_state);
-    let filter_config = engine_state.get_config().clone();
+    let filter_config = config.clone();
     let invert = call.has_flag(engine_state, stack, "invert")?;
     let terms = call.rest::<Value>(engine_state, stack, 0)?;
     let lower_terms = terms

crates/nu-command/src/formats/to/md.rs

@@ -70,8 +70,8 @@ impl Command for ToMd {
         let head = call.head;
         let pretty = call.has_flag(engine_state, stack, "pretty")?;
         let per_element = call.has_flag(engine_state, stack, "per-element")?;
-        let config = engine_state.get_config();
+        let config = stack.get_config(engine_state);
-        to_md(input, pretty, per_element, config, head)
+        to_md(input, pretty, per_element, &config, head)
     }
 }
 

crates/nu-command/src/formats/to/text.rs

@@ -31,18 +31,19 @@ impl Command for ToText {
     fn run(
         &self,
         engine_state: &EngineState,
-        _stack: &mut Stack,
+        stack: &mut Stack,
         call: &Call,
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
         let span = call.head;
         let input = input.try_expand_range()?;
+        let config = stack.get_config(engine_state);
 
         match input {
             PipelineData::Empty => Ok(Value::string(String::new(), span)
                 .into_pipeline_data_with_metadata(update_metadata(None))),
             PipelineData::Value(value, ..) => {
-                let str = local_into_string(value, LINE_ENDING, engine_state.get_config());
+                let str = local_into_string(value, LINE_ENDING, &config);
                 Ok(
                     Value::string(str, span)
                         .into_pipeline_data_with_metadata(update_metadata(None)),
@@ -50,7 +51,6 @@ impl Command for ToText {
             }
             PipelineData::ListStream(stream, meta) => {
                 let span = stream.span();
-                let config = engine_state.get_config().clone();
                 let iter = stream.into_inner().map(move |value| {
                     let mut str = local_into_string(value, LINE_ENDING, &config);
                     str.push_str(LINE_ENDING);

crates/nu-command/src/help/help_aliases.rs

@@ -143,7 +143,7 @@ pub fn help_aliases(
         long_desc.push_str("\n\n");
         long_desc.push_str(&format!("{G}Expansion{RESET}:\n  {alias_expansion}"));
 
-        let config = engine_state.get_config();
+        let config = stack.get_config(engine_state);
         if !config.use_ansi_coloring {
             long_desc = nu_utils::strip_ansi_string_likely(long_desc);
         }

crates/nu-command/src/help/help_modules.rs

@@ -230,7 +230,7 @@ pub fn help_modules(
             ));
         }
 
-        let config = engine_state.get_config();
+        let config = stack.get_config(engine_state);
         if !config.use_ansi_coloring {
             long_desc = nu_utils::strip_ansi_string_likely(long_desc);
         }

crates/nu-command/src/network/url/parse.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::Config;
 use url::Url;
 
 #[derive(Clone)]
@@ -38,11 +39,15 @@ impl Command for SubCommand {
     fn run(
         &self,
         engine_state: &EngineState,
-        _: &mut Stack,
+        stack: &mut Stack,
         call: &Call,
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        parse(input.into_value(call.head)?, call.head, engine_state)
+        parse(
+            input.into_value(call.head)?,
+            call.head,
+            &stack.get_config(engine_state),
+        )
     }
 
     fn examples(&self) -> Vec<Example> {
@@ -68,12 +73,12 @@ impl Command for SubCommand {
     }
 }
 
-fn get_url_string(value: &Value, engine_state: &EngineState) -> String {
+fn get_url_string(value: &Value, config: &Config) -> String {
-    value.to_expanded_string("", engine_state.get_config())
+    value.to_expanded_string("", config)
 }
 
-fn parse(value: Value, head: Span, engine_state: &EngineState) -> Result<PipelineData, ShellError> {
+fn parse(value: Value, head: Span, config: &Config) -> Result<PipelineData, ShellError> {
-    let url_string = get_url_string(&value, engine_state);
+    let url_string = get_url_string(&value, config);
 
     let result_url = Url::parse(url_string.as_str());
 

crates/nu-command/src/platform/ansi/ansi_.rs

@@ -653,7 +653,7 @@ Operating system commands:
         let list: bool = call.has_flag(engine_state, stack, "list")?;
         let escape: bool = call.has_flag(engine_state, stack, "escape")?;
         let osc: bool = call.has_flag(engine_state, stack, "osc")?;
-        let use_ansi_coloring = engine_state.get_config().use_ansi_coloring;
+        let use_ansi_coloring = stack.get_config(engine_state).use_ansi_coloring;
 
         if list {
             return Ok(generate_ansi_code_list(

crates/nu-command/src/platform/ansi/strip.rs

@@ -1,10 +1,12 @@
+use std::sync::Arc;
+
 use nu_cmd_base::input_handler::{operate, CmdArgument};
 use nu_engine::command_prelude::*;
 use nu_protocol::Config;
 
 pub struct Arguments {
     cell_paths: Option<Vec<CellPath>>,
-    config: Config,
+    config: Arc<Config>,
 }
 
 impl CmdArgument for Arguments {
@@ -51,11 +53,8 @@ impl Command for SubCommand {
     ) -> Result<PipelineData, ShellError> {
         let cell_paths: Vec<CellPath> = call.rest(engine_state, stack, 1)?;
         let cell_paths = (!cell_paths.is_empty()).then_some(cell_paths);
-        let config = engine_state.get_config();
+        let config = stack.get_config(engine_state);
-        let args = Arguments {
+        let args = Arguments { cell_paths, config };
-            cell_paths,
-            config: config.clone(),
-        };
         operate(action, args, input, call.head, engine_state.signals())
     }
 

crates/nu-command/src/platform/input/list.rs

@@ -79,6 +79,7 @@ impl Command for InputList {
         let fuzzy = call.has_flag(engine_state, stack, "fuzzy")?;
         let index = call.has_flag(engine_state, stack, "index")?;
         let display_path: Option<CellPath> = call.get_flag(engine_state, stack, "display")?;
+        let config = stack.get_config(engine_state);
 
         let options: Vec<Options> = match input {
             PipelineData::Value(Value::Range { .. }, ..)
@@ -89,9 +90,9 @@ impl Command for InputList {
                     let display_value = if let Some(ref cellpath) = display_path {
                         val.clone()
                             .follow_cell_path(&cellpath.members, false)?
-                            .to_expanded_string(", ", engine_state.get_config())
+                            .to_expanded_string(", ", &config)
                     } else {
-                        val.to_expanded_string(", ", engine_state.get_config())
+                        val.to_expanded_string(", ", &config)
                     };
                     Ok(Options {
                         name: display_value,

crates/nu-command/src/stor/insert.rs

@@ -65,7 +65,7 @@ impl Command for StorInsert {
         let span = call.head;
         let table_name: Option<String> = call.get_flag(engine_state, stack, "table-name")?;
         let data_record: Option<Record> = call.get_flag(engine_state, stack, "data-record")?;
-        // let config = engine_state.get_config();
+        // let config = stack.get_config(engine_state);
         let db = Box::new(SQLiteDatabase::new(
             std::path::Path::new(MEMORY_DB),
             Signals::empty(),

crates/nu-command/src/strings/detect_columns.rs

@@ -1,7 +1,7 @@
 use itertools::Itertools;
 use nu_engine::command_prelude::*;
-use nu_protocol::Range;
+use nu_protocol::{Config, Range};
-use std::{io::Cursor, iter::Peekable, str::CharIndices};
+use std::{io::Cursor, iter::Peekable, str::CharIndices, sync::Arc};
 
 type Input<'t> = Peekable<CharIndices<'t>>;
 
@@ -110,11 +110,13 @@ none             8150224         4   8150220   1% /mnt/c' | detect columns --gue
         let num_rows_to_skip: Option<usize> = call.get_flag(engine_state, stack, "skip")?;
         let noheader = call.has_flag(engine_state, stack, "no-headers")?;
         let range: Option<Range> = call.get_flag(engine_state, stack, "combine-columns")?;
+        let config = stack.get_config(engine_state);
 
         let args = Arguments {
             noheader,
             num_rows_to_skip,
             range,
+            config,
         };
 
         if call.has_flag(engine_state, stack, "guess")? {
@@ -133,11 +135,13 @@ none             8150224         4   8150220   1% /mnt/c' | detect columns --gue
         let num_rows_to_skip: Option<usize> = call.get_flag_const(working_set, "skip")?;
         let noheader = call.has_flag_const(working_set, "no-headers")?;
         let range: Option<Range> = call.get_flag_const(working_set, "combine-columns")?;
+        let config = working_set.get_config().clone();
 
         let args = Arguments {
             noheader,
             num_rows_to_skip,
             range,
+            config,
         };
 
         if call.has_flag_const(working_set, "guess")? {
@@ -152,6 +156,7 @@ struct Arguments {
     num_rows_to_skip: Option<usize>,
     noheader: bool,
     range: Option<Range>,
+    config: Arc<Config>,
 }
 
 fn guess_width(
@@ -163,7 +168,7 @@ fn guess_width(
     use super::guess_width::GuessWidth;
     let input_span = input.span().unwrap_or(call.head);
 
-    let mut input = input.collect_string("", engine_state.get_config())?;
+    let mut input = input.collect_string("", &args.config)?;
     if let Some(rows) = args.num_rows_to_skip {
         input = input.lines().skip(rows).map(|x| x.to_string()).join("\n");
     }
@@ -235,8 +240,7 @@ fn detect_columns(
     args: Arguments,
 ) -> Result<PipelineData, ShellError> {
     let name_span = call.head;
-    let config = engine_state.get_config();
+    let input = input.collect_string("", &args.config)?;
-    let input = input.collect_string("", config)?;
 
     let input: Vec<_> = input
         .lines()

crates/nu-command/src/system/nu_check.rs

@@ -1,4 +1,4 @@
-use nu_engine::{command_prelude::*, env::get_config, find_in_dirs_env, get_dirs_var_from_call};
+use nu_engine::{command_prelude::*, find_in_dirs_env, get_dirs_var_from_call};
 use nu_parser::{parse, parse_module_block, parse_module_file_or_dir, unescape_unquote_string};
 use nu_protocol::engine::{FileStack, StateWorkingSet};
 use std::path::Path;
@@ -59,7 +59,7 @@ impl Command for NuCheck {
                 }
             }
             PipelineData::ListStream(stream, ..) => {
-                let config = get_config(engine_state, stack);
+                let config = stack.get_config(engine_state);
                 let list_stream = stream.into_string("\n", &config);
                 let contents = Vec::from(list_stream);
 

crates/nu-command/src/system/run_external.rs

@@ -366,7 +366,7 @@ pub fn command_not_found(
     stack: &mut Stack,
 ) -> ShellError {
     // Run the `command_not_found` hook if there is one.
-    if let Some(hook) = &engine_state.config.hooks.command_not_found {
+    if let Some(hook) = &stack.get_config(engine_state).hooks.command_not_found {
         let mut stack = stack.start_capture();
         // Set a special environment variable to avoid infinite loops when the
         // `command_not_found` hook triggers itself.

crates/nu-command/src/viewers/griddle.rs

@@ -61,7 +61,7 @@ prints out the list properly."#
         let width_param: Option<i64> = call.get_flag(engine_state, stack, "width")?;
         let color_param: bool = call.has_flag(engine_state, stack, "color")?;
         let separator_param: Option<String> = call.get_flag(engine_state, stack, "separator")?;
-        let config = engine_state.get_config();
+        let config = &stack.get_config(engine_state);
         let env_str = match stack.get_env_var(engine_state, "LS_COLORS") {
             Some(v) => Some(env_to_string("LS_COLORS", &v, engine_state, stack)?),
             None => None,

crates/nu-command/src/viewers/table.rs

@@ -4,7 +4,7 @@
 
 use lscolors::{LsColors, Style};
 use nu_color_config::{color_from_hex, StyleComputer, TextStyle};
-use nu_engine::{command_prelude::*, env::get_config, env_to_string};
+use nu_engine::{command_prelude::*, env_to_string};
 use nu_pretty_hex::HexConfig;
 use nu_protocol::{
     ByteStream, Config, DataSource, ListStream, PipelineMetadata, Signals, TableMode, ValueIterator,
@@ -258,7 +258,7 @@ fn parse_table_config(
     let flatten_separator: Option<String> = call.get_flag(state, stack, "flatten-separator")?;
     let abbrivation: Option<usize> = call
         .get_flag(state, stack, "abbreviated")?
-        .or_else(|| get_config(state, stack).table_abbreviation_threshold);
+        .or_else(|| stack.get_config(state).table_abbreviation_threshold);
     let table_view = match (expand, collapse) {
         (false, false) => TableView::General,
         (_, true) => TableView::Collapsed,
@@ -269,7 +269,7 @@ fn parse_table_config(
         },
     };
     let theme =
-        get_theme_flag(call, state, stack)?.unwrap_or_else(|| get_config(state, stack).table_mode);
+        get_theme_flag(call, state, stack)?.unwrap_or_else(|| stack.get_config(state).table_mode);
     let index = get_index_flag(call, state, stack)?;
 
     let term_width = get_width_param(width_param);
@@ -493,7 +493,11 @@ fn handle_record(
     cfg: TableConfig,
     mut record: Record,
 ) -> Result<PipelineData, ShellError> {
-    let config = get_config(input.engine_state, input.stack);
+    let config = {
+        let state = input.engine_state;
+        let stack: &Stack = input.stack;
+        stack.get_config(state)
+    };
     let span = input.data.span().unwrap_or(input.call.head);
     let styles = &StyleComputer::from_config(input.engine_state, input.stack);
 
@@ -608,7 +612,11 @@ fn handle_row_stream(
             data_source: DataSource::Ls,
             ..
         }) => {
-            let config = get_config(input.engine_state, input.stack);
+            let config = {
+                let state = input.engine_state;
+                let stack: &Stack = input.stack;
+                stack.get_config(state)
+            };
             let ls_colors_env_str = match input.stack.get_env_var(input.engine_state, "LS_COLORS") {
                 Some(v) => Some(env_to_string(
                     "LS_COLORS",
@@ -758,7 +766,11 @@ impl PagingTableCreator {
             return Ok(None);
         }
 
-        let cfg = get_config(&self.engine_state, &self.stack);
+        let cfg = {
+            let state = &self.engine_state;
+            let stack = &self.stack;
+            stack.get_config(state)
+        };
         let style_comp = StyleComputer::from_config(&self.engine_state, &self.stack);
         let opts = self.create_table_opts(&cfg, &style_comp);
         let view = TableView::Expanded {
@@ -775,7 +787,11 @@ impl PagingTableCreator {
             return Ok(None);
         }
 
-        let cfg = get_config(&self.engine_state, &self.stack);
+        let cfg = {
+            let state = &self.engine_state;
+            let stack = &self.stack;
+            stack.get_config(state)
+        };
         let style_comp = StyleComputer::from_config(&self.engine_state, &self.stack);
         let opts = self.create_table_opts(&cfg, &style_comp);
 
@@ -783,7 +799,11 @@ impl PagingTableCreator {
     }
 
     fn build_general(&mut self, batch: Vec<Value>) -> StringResult {
-        let cfg = get_config(&self.engine_state, &self.stack);
+        let cfg = {
+            let state = &self.engine_state;
+            let stack = &self.stack;
+            stack.get_config(state)
+        };
         let style_comp = StyleComputer::from_config(&self.engine_state, &self.stack);
         let opts = self.create_table_opts(&cfg, &style_comp);
 
@@ -872,7 +892,11 @@ impl Iterator for PagingTableCreator {
 
         self.row_offset += batch_size;
 
-        let config = get_config(&self.engine_state, &self.stack);
+        let config = {
+            let state = &self.engine_state;
+            let stack = &self.stack;
+            stack.get_config(state)
+        };
         convert_table_to_output(
             table,
             &config,
@@ -1049,7 +1073,7 @@ fn create_empty_placeholder(
     engine_state: &EngineState,
     stack: &Stack,
 ) -> String {
-    let config = get_config(engine_state, stack);
+    let config = stack.get_config(engine_state);
     if !config.table_show_empty {
         return String::new();
     }

crates/nu-engine/src/documentation.rs

@@ -3,8 +3,8 @@ use nu_protocol::{
     ast::{Argument, Call, Expr, Expression, RecordItem},
     debugger::WithoutDebug,
     engine::{Command, EngineState, Stack, UNKNOWN_SPAN_ID},
-    record, Category, Example, IntoPipelineData, PipelineData, Signature, Span, SpanId, Spanned,
+    record, Category, Config, Example, IntoPipelineData, PipelineData, Signature, Span, SpanId,
-    SyntaxShape, Type, Value,
+    Spanned, SyntaxShape, Type, Value,
 };
 use std::{collections::HashMap, fmt::Write};
 
@@ -13,7 +13,7 @@ pub fn get_full_help(
     engine_state: &EngineState,
     stack: &mut Stack,
 ) -> String {
-    let config = engine_state.get_config();
+    let config = stack.get_config(engine_state);
     let doc_config = DocumentationConfig {
         no_subcommands: false,
         no_color: !config.use_ansi_coloring,
@@ -70,16 +70,30 @@ fn get_documentation(
     config: &DocumentationConfig,
     is_parser_keyword: bool,
 ) -> String {
+    let nu_config = stack.get_config(engine_state);
+
     // Create ansi colors
     //todo make these configurable -- pull from enginestate.config
-    let help_section_name: String =
+    let help_section_name: String = get_ansi_color_for_component_or_default(
-        get_ansi_color_for_component_or_default(engine_state, "shape_string", "\x1b[32m"); // default: green
+        engine_state,
+        &nu_config,
+        "shape_string",
+        "\x1b[32m",
+    ); // default: green
 
-    let help_subcolor_one: String =
+    let help_subcolor_one: String = get_ansi_color_for_component_or_default(
-        get_ansi_color_for_component_or_default(engine_state, "shape_external", "\x1b[36m"); // default: cyan
+        engine_state,
+        &nu_config,
+        "shape_external",
+        "\x1b[36m",
+    ); // default: cyan
        // was const bb: &str = "\x1b[1;34m"; // bold blue
-    let help_subcolor_two: String =
+    let help_subcolor_two: String = get_ansi_color_for_component_or_default(
-        get_ansi_color_for_component_or_default(engine_state, "shape_block", "\x1b[94m"); // default: light blue (nobold, should be bolding the *names*)
+        engine_state,
+        &nu_config,
+        "shape_block",
+        "\x1b[94m",
+    ); // default: light blue (nobold, should be bolding the *names*)
 
     const RESET: &str = "\x1b[0m"; // reset
 
@@ -139,13 +153,12 @@ fn get_documentation(
     }
 
     if !sig.named.is_empty() {
-        long_desc.push_str(&get_flags_section(Some(engine_state), sig, |v| {
+        long_desc.push_str(&get_flags_section(
-            nu_highlight_string(
+            Some(engine_state),
-                &v.to_parsable_string(", ", &engine_state.config),
+            Some(&nu_config),
-                engine_state,
+            sig,
-                stack,
+            |v| nu_highlight_string(&v.to_parsable_string(", ", &nu_config), engine_state, stack),
-            )
+        ))
-        }))
     }
 
     if !sig.required_positional.is_empty()
@@ -189,7 +202,7 @@ fn get_documentation(
                         format!(
                             " (optional, default: {})",
                             nu_highlight_string(
-                                &value.to_parsable_string(", ", &engine_state.config),
+                                &value.to_parsable_string(", ", &nu_config),
                                 engine_state,
                                 stack
                             )
@@ -339,7 +352,7 @@ fn get_documentation(
                 let _ = writeln!(
                     long_desc,
                     "  {}",
-                    item.to_expanded_string("", engine_state.get_config())
+                    item.to_expanded_string("", &nu_config)
                         .replace('\n', "\n  ")
                         .trim()
                 );
@@ -358,15 +371,16 @@ fn get_documentation(
 
 fn get_ansi_color_for_component_or_default(
     engine_state: &EngineState,
+    nu_config: &Config,
     theme_component: &str,
     default: &str,
 ) -> String {
-    if let Some(color) = &engine_state.get_config().color_config.get(theme_component) {
+    if let Some(color) = &nu_config.color_config.get(theme_component) {
         let caller_stack = &mut Stack::new().capture();
         let span = Span::unknown();
         let span_id = UNKNOWN_SPAN_ID;
 
-        let argument_opt = get_argument_for_color_value(engine_state, color, span, span_id);
+        let argument_opt = get_argument_for_color_value(nu_config, color, span, span_id);
 
         // Call ansi command using argument
         if let Some(argument) = argument_opt {
@@ -394,8 +408,8 @@ fn get_ansi_color_for_component_or_default(
 }
 
 fn get_argument_for_color_value(
-    engine_state: &EngineState,
+    nu_config: &Config,
-    color: &&Value,
+    color: &Value,
     span: Span,
     span_id: SpanId,
 ) -> Option<Argument> {
@@ -412,9 +426,7 @@ fn get_argument_for_color_value(
                             Type::String,
                         ),
                         Expression::new_existing(
-                            Expr::String(
+                            Expr::String(v.clone().to_expanded_string("", nu_config)),
-                                v.clone().to_expanded_string("", engine_state.get_config()),
-                            ),
                             span,
                             span_id,
                             Type::String,
@@ -456,6 +468,7 @@ pub fn document_shape(shape: SyntaxShape) -> SyntaxShape {
 
 pub fn get_flags_section<F>(
     engine_state_opt: Option<&EngineState>,
+    nu_config_opt: Option<&Config>,
     signature: &Signature,
     mut value_formatter: F, // format default Value (because some calls cant access config or nu-highlight)
 ) -> String
@@ -470,13 +483,26 @@ where
     // Sometimes we want to get the flags without engine_state
     // For example, in nu-plugin. In that case, we fall back on default values
     if let Some(engine_state) = engine_state_opt {
-        help_section_name =
+        let nu_config = nu_config_opt.unwrap_or_else(|| engine_state.get_config());
-            get_ansi_color_for_component_or_default(engine_state, "shape_string", "\x1b[32m"); // default: green
+        help_section_name = get_ansi_color_for_component_or_default(
-        help_subcolor_one =
+            engine_state,
-            get_ansi_color_for_component_or_default(engine_state, "shape_external", "\x1b[36m"); // default: cyan
+            nu_config,
+            "shape_string",
+            "\x1b[32m",
+        ); // default: green
+        help_subcolor_one = get_ansi_color_for_component_or_default(
+            engine_state,
+            nu_config,
+            "shape_external",
+            "\x1b[36m",
+        ); // default: cyan
            // was const bb: &str = "\x1b[1;34m"; // bold blue
-        help_subcolor_two =
+        help_subcolor_two = get_ansi_color_for_component_or_default(
-            get_ansi_color_for_component_or_default(engine_state, "shape_block", "\x1b[94m");
+            engine_state,
+            nu_config,
+            "shape_block",
+            "\x1b[94m",
+        );
     // default: light blue (nobold, should be bolding the *names*)
     } else {
         help_section_name = "\x1b[32m".to_string();

crates/nu-engine/src/env.rs

@@ -3,7 +3,7 @@ use nu_path::canonicalize_with;
 use nu_protocol::{
     ast::Expr,
     engine::{Call, EngineState, Stack, StateWorkingSet},
-    Config, ShellError, Span, Value, VarId,
+    ShellError, Span, Value, VarId,
 };
 use std::{
     collections::HashMap,
@@ -323,18 +323,6 @@ pub fn find_in_dirs_env(
     Ok(check_dir(lib_dirs).or_else(|| check_dir(lib_dirs_fallback)))
 }
 
-/// Get config
-///
-/// This combines config stored in permanent state and any runtime updates to the environment. This
-/// is the canonical way to fetch config at runtime when you have Stack available.
-pub fn get_config(engine_state: &EngineState, stack: &Stack) -> Config {
-    if let Some(mut config_record) = stack.get_env_var(engine_state, "config") {
-        config_record.parse_as_config(engine_state.get_config()).0
-    } else {
-        engine_state.get_config().clone()
-    }
-}
-
 fn get_converted_value(
     engine_state: &EngineState,
     stack: &Stack,

crates/nu-engine/src/eval.rs

@@ -1,6 +1,6 @@
 use crate::eval_ir_block;
 #[allow(deprecated)]
-use crate::{current_dir, get_config, get_full_help};
+use crate::{current_dir, get_full_help};
 use nu_path::{expand_path_with, AbsolutePathBuf};
 use nu_protocol::{
     ast::{
@@ -14,7 +14,7 @@ use nu_protocol::{
     Spanned, Type, Value, VarId, ENV_VARIABLE_ID,
 };
 use nu_utils::IgnoreCaseExt;
-use std::{borrow::Cow, fs::OpenOptions, path::PathBuf};
+use std::{fs::OpenOptions, path::PathBuf, sync::Arc};
 
 pub fn eval_call<D: DebugContext>(
     engine_state: &EngineState,
@@ -196,6 +196,9 @@ pub fn redirect_env(engine_state: &EngineState, caller_stack: &mut Stack, callee
     for (var, value) in callee_stack.get_stack_env_vars() {
         caller_stack.add_env_var(var, value);
     }
+
+    // set config to callee config, to capture any updates to that
+    caller_stack.config = callee_stack.config.clone();
 }
 
 fn eval_external(
@@ -652,8 +655,8 @@ impl Eval for EvalRuntime {
 
     type MutState = Stack;
 
-    fn get_config<'a>(engine_state: Self::State<'a>, stack: &mut Stack) -> Cow<'a, Config> {
+    fn get_config(engine_state: Self::State<'_>, stack: &mut Stack) -> Arc<Config> {
-        Cow::Owned(get_config(engine_state, stack))
+        stack.get_config(engine_state)
     }
 
     fn eval_filepath(
@@ -843,7 +846,14 @@ impl Eval for EvalRuntime {
                                     });
                                 }
 
+                                let is_config = original_key == "config";
+
                                 stack.add_env_var(original_key, value);
+
+                                // Trigger the update to config, if we modified that.
+                                if is_config {
+                                    stack.update_config(engine_state)?;
+                                }
                             } else {
                                 lhs.upsert_data_at_cell_path(&cell_path.tail, rhs)?;
                                 stack.add_var(*var_id, lhs);

crates/nu-explore/src/commands/expand.rs

@@ -64,8 +64,8 @@ fn convert_value_to_string(
     let has_no_head = cols.is_empty() || (cols.len() == 1 && cols[0].is_empty());
     let has_single_value = vals.len() == 1 && vals[0].len() == 1;
     if !has_no_head && has_single_value {
-        let config = engine_state.get_config();
+        let config = stack.get_config(engine_state);
-        Ok(vals[0][0].to_abbreviated_string(config))
+        Ok(vals[0][0].to_abbreviated_string(&config))
     } else {
         let config = engine_state.get_config();
         let style_computer = StyleComputer::from_config(engine_state, stack);

crates/nu-explore/src/explore.rs

@@ -63,10 +63,10 @@ impl Command for Explore {
         let tail: bool = call.has_flag(engine_state, stack, "tail")?;
         let peek_value: bool = call.has_flag(engine_state, stack, "peek")?;
 
-        let nu_config = engine_state.get_config();
+        let nu_config = stack.get_config(engine_state);
         let style_computer = StyleComputer::from_config(engine_state, stack);
 
-        let mut explore_config = ExploreConfig::from_nu_config(nu_config);
+        let mut explore_config = ExploreConfig::from_nu_config(&nu_config);
         explore_config.table.show_header = show_head;
         explore_config.table.show_index = show_index;
         explore_config.table.separator_style = lookup_color(&style_computer, "separator");
@@ -74,7 +74,7 @@ impl Command for Explore {
         let lscolors = create_lscolors(engine_state, stack);
 
         let config = PagerConfig::new(
-            nu_config,
+            &nu_config,
             &explore_config,
             &style_computer,
             &lscolors,

crates/nu-plugin-engine/Cargo.toml

@@ -16,6 +16,7 @@ nu-protocol = { path = "../nu-protocol", version = "0.95.1" }
 nu-system = { path = "../nu-system", version = "0.95.1" }
 nu-plugin-protocol = { path = "../nu-plugin-protocol", version = "0.95.1" }
 nu-plugin-core = { path = "../nu-plugin-core", version = "0.95.1", default-features = false }
+nu-utils = { path = "../nu-utils", version = "0.95.1" }
 
 serde = { workspace = true }
 log = { workspace = true }

crates/nu-plugin-engine/src/context.rs

@@ -20,7 +20,7 @@ pub trait PluginExecutionContext: Send + Sync {
     /// The pipeline externals state, for tracking the foreground process group, if present
     fn pipeline_externals_state(&self) -> Option<&Arc<(AtomicU32, AtomicU32)>>;
     /// Get engine configuration
-    fn get_config(&self) -> Result<Config, ShellError>;
+    fn get_config(&self) -> Result<Arc<Config>, ShellError>;
     /// Get plugin configuration
     fn get_plugin_config(&self) -> Result<Option<Value>, ShellError>;
     /// Get an environment variable from `$env`
@@ -85,8 +85,8 @@ impl<'a> PluginExecutionContext for PluginExecutionCommandContext<'a> {
         Some(&self.engine_state.pipeline_externals_state)
     }
 
-    fn get_config(&self) -> Result<Config, ShellError> {
+    fn get_config(&self) -> Result<Arc<Config>, ShellError> {
-        Ok(nu_engine::get_config(&self.engine_state, &self.stack))
+        Ok(self.stack.get_config(&self.engine_state))
     }
 
     fn get_plugin_config(&self) -> Result<Option<Value>, ShellError> {
@@ -239,7 +239,7 @@ impl PluginExecutionContext for PluginExecutionBogusContext {
         None
     }
 
-    fn get_config(&self) -> Result<Config, ShellError> {
+    fn get_config(&self) -> Result<Arc<Config>, ShellError> {
         Err(ShellError::NushellFailed {
             msg: "get_config not implemented on bogus".into(),
         })

crates/nu-plugin-engine/src/declaration.rs

@@ -76,7 +76,7 @@ impl Command for PluginDeclaration {
             EvaluatedCall::try_from_call(call, engine_state, stack, eval_expression)?;
 
         // Get the engine config
-        let engine_config = nu_engine::get_config(engine_state, stack);
+        let engine_config = stack.get_config(engine_state);
 
         // Get, or start, the plugin.
         let plugin = self

crates/nu-plugin-engine/src/interface/mod.rs

@@ -14,6 +14,7 @@ use nu_protocol::{
     ast::Operator, CustomValue, IntoSpanned, PipelineData, PluginMetadata, PluginSignature,
     ShellError, Signals, Span, Spanned, Value,
 };
+use nu_utils::SharedCow;
 use std::{
     collections::{btree_map, BTreeMap},
     sync::{mpsc, Arc, OnceLock},
@@ -1260,7 +1261,7 @@ pub(crate) fn handle_engine_call(
 
     match call {
         EngineCall::GetConfig => {
-            let config = Box::new(context.get_config()?);
+            let config = SharedCow::from(context.get_config()?);
             Ok(EngineCallResponse::Config(config))
         }
         EngineCall::GetPluginConfig => {

crates/nu-plugin-protocol/src/lib.rs

@@ -25,6 +25,7 @@ use nu_protocol::{
     ast::Operator, engine::Closure, ByteStreamType, Config, LabeledError, PipelineData,
     PluginMetadata, PluginSignature, ShellError, Span, Spanned, Value,
 };
+use nu_utils::SharedCow;
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 
@@ -553,7 +554,7 @@ impl<D> EngineCall<D> {
 pub enum EngineCallResponse<D> {
     Error(ShellError),
     PipelineData(D),
-    Config(Box<Config>),
+    Config(SharedCow<Config>),
     ValueMap(HashMap<String, Value>),
 }
 

crates/nu-plugin/Cargo.toml

@@ -15,6 +15,7 @@ nu-engine = { path = "../nu-engine", version = "0.95.1" }
 nu-protocol = { path = "../nu-protocol", version = "0.95.1" }
 nu-plugin-protocol = { path = "../nu-plugin-protocol", version = "0.95.1" }
 nu-plugin-core = { path = "../nu-plugin-core", version = "0.95.1", default-features = false }
+nu-utils = { path = "../nu-utils", version = "0.95.1" }
 
 log = { workspace = true }
 thiserror = "1.0"

crates/nu-plugin/src/plugin/interface/mod.rs

@@ -14,6 +14,7 @@ use nu_protocol::{
     engine::Closure, Config, LabeledError, PipelineData, PluginMetadata, PluginSignature,
     ShellError, Signals, Span, Spanned, Value,
 };
+use nu_utils::SharedCow;
 use std::{
     collections::{btree_map, BTreeMap, HashMap},
     sync::{mpsc, Arc},
@@ -525,9 +526,9 @@ impl EngineInterface {
     /// # Ok(())
     /// # }
     /// ```
-    pub fn get_config(&self) -> Result<Box<Config>, ShellError> {
+    pub fn get_config(&self) -> Result<Arc<Config>, ShellError> {
         match self.engine_call(EngineCall::GetConfig)? {
-            EngineCallResponse::Config(config) => Ok(config),
+            EngineCallResponse::Config(config) => Ok(SharedCow::into_arc(config)),
             EngineCallResponse::Error(err) => Err(err),
             _ => Err(ShellError::PluginFailedToDecode {
                 msg: "Received unexpected response for EngineCall::GetConfig".into(),

crates/nu-plugin/src/plugin/mod.rs

@@ -670,7 +670,7 @@ fn print_help(plugin: &impl Plugin, encoder: impl PluginEncoder) {
                 }
             })
             .and_then(|_| {
-                let flags = get_flags_section(None, &signature, |v| format!("{:#?}", v));
+                let flags = get_flags_section(None, None, &signature, |v| format!("{:#?}", v));
                 write!(help, "{flags}")
             })
             .and_then(|_| writeln!(help, "\nParameters:"))

crates/nu-protocol/src/engine/engine_state.rs

@@ -301,28 +301,11 @@ impl EngineState {
         stack: &mut Stack,
         cwd: impl AsRef<Path>,
     ) -> Result<(), ShellError> {
-        let mut config_updated = false;
-
         for mut scope in stack.env_vars.drain(..) {
             for (overlay_name, mut env) in Arc::make_mut(&mut scope).drain() {
                 if let Some(env_vars) = Arc::make_mut(&mut self.env_vars).get_mut(&overlay_name) {
                     // Updating existing overlay
-                    for (k, v) in env.drain() {
+                    env_vars.extend(env.drain());
-                        if k == "config" {
-                            // Don't insert the record as the "config" env var as-is.
-                            // Instead, mutate a clone of it with into_config(), and put THAT in env_vars.
-                            let mut new_record = v.clone();
-                            let (config, error) = new_record.parse_as_config(&self.config);
-                            self.config = Arc::new(config);
-                            config_updated = true;
-                            env_vars.insert(k, new_record);
-                            if let Some(e) = error {
-                                return Err(e);
-                            }
-                        } else {
-                            env_vars.insert(k, v);
-                        }
-                    }
                 } else {
                     // Pushing a new overlay
                     Arc::make_mut(&mut self.env_vars).insert(overlay_name, env);
@@ -333,7 +316,10 @@ impl EngineState {
         // TODO: better error
         std::env::set_current_dir(cwd)?;
 
-        if config_updated {
+        if let Some(config) = stack.config.take() {
+            // If config was updated in the stack, replace it.
+            self.config = config;
+
             // Make plugin GC config changes take effect immediately.
             #[cfg(feature = "plugin")]
             self.update_plugin_gc_configs(&self.config.plugin_gc);
@@ -738,18 +724,24 @@ impl EngineState {
         &[0u8; 0]
     }
 
-    pub fn get_config(&self) -> &Config {
+    /// Get the global config from the engine state.
+    ///
+    /// Use [`Stack::get_config()`] instead whenever the `Stack` is available, as it takes into
+    /// account local changes to `$env.config`.
+    pub fn get_config(&self) -> &Arc<Config> {
         &self.config
     }
 
-    pub fn set_config(&mut self, conf: Config) {
+    pub fn set_config(&mut self, conf: impl Into<Arc<Config>>) {
+        let conf = conf.into();
+
         #[cfg(feature = "plugin")]
         if conf.plugin_gc != self.config.plugin_gc {
             // Make plugin GC config changes take effect immediately.
             self.update_plugin_gc_configs(&conf.plugin_gc);
         }
 
-        self.config = Arc::new(conf);
+        self.config = conf;
     }
 
     /// Fetch the configuration for a plugin
@@ -1137,7 +1129,7 @@ mod engine_state_tests {
         let mut plugins = HashMap::new();
         plugins.insert("example".into(), Value::string("value", Span::test_data()));
 
-        let mut config = engine_state.get_config().clone();
+        let mut config = Config::clone(engine_state.get_config());
         config.plugins = plugins;
 
         engine_state.set_config(config);

crates/nu-protocol/src/engine/stack.rs

@@ -3,7 +3,7 @@ use crate::{
         ArgumentStack, EngineState, ErrorHandlerStack, Redirection, StackCallArgGuard,
         StackCaptureGuard, StackIoGuard, StackOutDest, DEFAULT_OVERLAY_NAME,
     },
-    OutDest, ShellError, Span, Value, VarId, ENV_VARIABLE_ID, NU_VARIABLE_ID,
+    Config, OutDest, ShellError, Span, Value, VarId, ENV_VARIABLE_ID, NU_VARIABLE_ID,
 };
 use std::{
     collections::{HashMap, HashSet},
@@ -51,6 +51,8 @@ pub struct Stack {
     pub parent_stack: Option<Arc<Stack>>,
     /// Variables that have been deleted (this is used to hide values from parent stack lookups)
     pub parent_deletions: Vec<VarId>,
+    /// Locally updated config. Use [`.get_config()`] to access correctly.
+    pub config: Option<Arc<Config>>,
     pub(crate) out_dest: StackOutDest,
 }
 
@@ -80,6 +82,7 @@ impl Stack {
             recursion_count: 0,
             parent_stack: None,
             parent_deletions: vec![],
+            config: None,
             out_dest: StackOutDest::new(),
         }
     }
@@ -100,6 +103,7 @@ impl Stack {
             recursion_count: parent.recursion_count,
             vars: vec![],
             parent_deletions: vec![],
+            config: parent.config.clone(),
             out_dest: parent.out_dest.clone(),
             parent_stack: Some(parent),
         }
@@ -126,6 +130,7 @@ impl Stack {
         unique_stack.env_vars = child.env_vars;
         unique_stack.env_hidden = child.env_hidden;
         unique_stack.active_overlays = child.active_overlays;
+        unique_stack.config = child.config;
         unique_stack
     }
 
@@ -192,6 +197,36 @@ impl Stack {
         }
     }
 
+    /// Get the local config if set, otherwise the config from the engine state.
+    ///
+    /// This is the canonical way to get [`Config`] when [`Stack`] is available.
+    pub fn get_config(&self, engine_state: &EngineState) -> Arc<Config> {
+        self.config
+            .clone()
+            .unwrap_or_else(|| engine_state.config.clone())
+    }
+
+    /// Update the local config with the config stored in the `config` environment variable. Run
+    /// this after assigning to `$env.config`.
+    ///
+    /// The config will be updated with successfully parsed values even if an error occurs.
+    pub fn update_config(&mut self, engine_state: &EngineState) -> Result<(), ShellError> {
+        if let Some(mut config) = self.get_env_var(engine_state, "config") {
+            let existing_config = self.get_config(engine_state);
+            let (new_config, error) = config.parse_as_config(&existing_config);
+            self.config = Some(new_config.into());
+            // The config value is modified by the update, so we should add it again
+            self.add_env_var("config".into(), config);
+            match error {
+                None => Ok(()),
+                Some(err) => Err(err),
+            }
+        } else {
+            self.config = None;
+            Ok(())
+        }
+    }
+
     pub fn add_var(&mut self, var_id: VarId, value: Value) {
         //self.vars.insert(var_id, value);
         for (id, val) in &mut self.vars {
@@ -272,6 +307,7 @@ impl Stack {
             recursion_count: self.recursion_count,
             parent_stack: None,
             parent_deletions: vec![],
+            config: self.config.clone(),
             out_dest: self.out_dest.clone(),
         }
     }
@@ -305,6 +341,7 @@ impl Stack {
             recursion_count: self.recursion_count,
             parent_stack: None,
             parent_deletions: vec![],
+            config: self.config.clone(),
             out_dest: self.out_dest.clone(),
         }
     }

crates/nu-protocol/src/engine/state_working_set.rs

@@ -627,9 +627,9 @@ impl<'a> StateWorkingSet<'a> {
 
     /// Returns a reference to the config stored at permanent state
     ///
-    /// At runtime, you most likely want to call nu_engine::env::get_config because this method
+    /// At runtime, you most likely want to call [`Stack::get_config()`][super::Stack::get_config()]
-    /// does not capture environment updates during runtime.
+    /// because this method does not capture environment updates during runtime.
-    pub fn get_config(&self) -> &Config {
+    pub fn get_config(&self) -> &Arc<Config> {
         &self.permanent_state.config
     }
 

crates/nu-protocol/src/eval_base.rs

@@ -7,7 +7,7 @@ use crate::{
     debugger::DebugContext,
     Config, GetSpan, Range, Record, ShellError, Span, Value, VarId, ENV_VARIABLE_ID,
 };
-use std::{borrow::Cow, collections::HashMap};
+use std::{collections::HashMap, sync::Arc};
 
 /// To share implementations for regular eval and const eval
 pub trait Eval {
@@ -316,7 +316,7 @@ pub trait Eval {
         }
     }
 
-    fn get_config<'a>(state: Self::State<'a>, mut_state: &mut Self::MutState) -> Cow<'a, Config>;
+    fn get_config(state: Self::State<'_>, mut_state: &mut Self::MutState) -> Arc<Config>;
 
     fn eval_filepath(
         state: Self::State<'_>,

crates/nu-protocol/src/eval_const.rs

@@ -11,8 +11,8 @@ use crate::{
 };
 use nu_system::os_info::{get_kernel_version, get_os_arch, get_os_family, get_os_name};
 use std::{
-    borrow::Cow,
     path::{Path, PathBuf},
+    sync::Arc,
 };
 
 /// Create a Value for `$nu`.
@@ -364,8 +364,8 @@ impl Eval for EvalConst {
 
     type MutState = ();
 
-    fn get_config<'a>(state: Self::State<'a>, _: &mut ()) -> Cow<'a, Config> {
+    fn get_config(state: Self::State<'_>, _: &mut ()) -> Arc<Config> {
-        Cow::Borrowed(state.get_config())
+        state.get_config().clone()
     }
 
     fn eval_filepath(