Make `$env.config` access produce a record describing the full state of EngineState.config

[webbedspace]

Related problem

Breakoff of discussion here. $env.config access is currently a brittle way of querying the system configuration state (e.g. to check the state of always_trash for UX purposes), because you can put invalid values on $env.config like $env.config.rm_always_trash = 'foobarbaz' and have it actually stick on the record (even though doing so does not update EngineState for obvious reasons), and moreover you can write things like let-env config = "foobarbaz" that just blow the whole record away outright.

Describe the solution you'd like

My idea is that each $env.config access (that is to say, anything that reads from that value) causes Nushell to instead create and return a new record which always and only has values corresponding to those on the EngineState.config struct.

The struct looks like this:

pub struct Config {
    pub external_completer: Option<usize>,
    pub filesize_metric: bool,
    pub table_mode: String,
    pub use_ls_colors: bool,
    pub color_config: HashMap<String, Value>,
    pub use_grid_icons: bool,
    pub footer_mode: FooterMode,
    pub float_precision: i64,
    pub max_external_completion_results: i64,
    pub filesize_format: String,
    pub use_ansi_coloring: bool,
    pub quick_completions: bool,
    pub partial_completions: bool,
    pub completion_algorithm: String,
    pub edit_mode: String,
    pub max_history_size: i64,
    pub sync_history_on_enter: bool,
    pub history_file_format: HistoryFileFormat,
    pub log_level: String,
    pub keybindings: Vec<ParsedKeybinding>,
    pub menus: Vec<ParsedMenu>,
    pub hooks: Hooks,
    pub rm_always_trash: bool,
    pub shell_integration: bool,
    pub buffer_editor: String,
    pub table_index_mode: TableIndexMode,
    pub cd_with_abbreviations: bool,
    pub case_sensitive_completions: bool,
    pub enable_external_completion: bool,
    pub trim_strategy: TrimStrategy,
    pub show_banner: bool,
    pub show_clickable_links_in_ls: bool,
    pub render_right_prompt_on_last_line: bool,
}

$env.config access would thus produce a record holding external_completer, filesize_metric, table_mode, use_ls_colors, color_config, use_grid_icons, footer_mode, float_precision, max_external_completion_results, filesize_format, use_ansi_coloring, quick_completions, partial_completions, completion_algorithm, edit_mode, max_history_size, sync_history_on_enter, history_file_format, log_level, keybindings, menus, hooks, rm_always_trash, shell_integration, buffer_editor, table_index_mode, cd_with_abbreviations, case_sensitive_completions, enable_external_completion, trim_strategy, show_banner, show_clickable_links_in_ls, render_right_prompt_on_last_line keys.

Now, HistoryFileFormat, FooterMode, TrimStrategy and TableIndexMode can be translated back to Nuon values relatively easily. ParsedKeybinding and ParsedMenu might be a bit trickier (haven't examined them just yet).

Describe alternatives you've considered

No response

Additional context and details

No response

[fdncred]

Agreed that this is a good conversation to have.

It may also be good to have an official blessed command like config set key value/config get key with better error handling and config value enforcement.

We used to have a config command in version 44, pre engine-q. Here's a screenshot.