cmakefmt/spec/

registry.rs

// SPDX-FileCopyrightText: Copyright 2026 Puneet Matharu
//
// SPDX-License-Identifier: MIT OR Apache-2.0

//! Built-in and override-backed command registry.

#[cfg(all(not(target_arch = "wasm32"), feature = "cli"))]
use std::fs;
#[cfg(all(not(target_arch = "wasm32"), feature = "cli"))]
use std::path::Path;
use std::path::PathBuf;
use std::sync::OnceLock;

use indexmap::{IndexMap, IndexSet};

#[cfg(all(not(target_arch = "wasm32"), feature = "cli"))]
use crate::config::file::{detect_config_format, ConfigFileFormat};
use crate::error::{Error, Result};

use super::{
    has_ascii_uppercase, CommandForm, CommandFormOverride, CommandSpec, CommandSpecOverride,
    KwargSpec, KwargSpecOverride, LayoutOverrides, LayoutOverridesOverride, SpecFile, SpecMetadata,
    SpecOverrideFile,
};

// The embedded command spec is split across two YAML files:
//
// * `builtins.yaml` covers commands documented by `cmake --help-command-list`
//   — the CMake language itself (`if`, `add_executable`, `install`, etc.).
// * `modules.yaml` covers commands defined in CMake's bundled modules
//   (`FetchContent_Declare`, `ExternalProject_Add`, `find_dependency`, the
//   `Check<X>` family, etc.) which become available after
//   `include(<Module>)` or `find_package(<Module>)`.
//
// The two-file split mirrors the natural taxonomy users already use to
// think about CMake commands and keeps `builtins.yaml` focused on the
// language surface. The runtime loads both at startup and merges them
// into a single command table; spec consumers see no difference.
//
// The pre-deserialised MessagePack blobs come from `build.rs`. Decoding
// them with `rmp-serde` is roughly 20× faster than parsing YAML on every
// process startup. The human-readable sources remain
// `src/spec/builtins.yaml` and `src/spec/modules.yaml`.
//
// A future refactor could move modules to per-module YAML files under
// `src/spec/modules/<Name>.yaml` if/when the formatter becomes aware
// of which modules have actually been included earlier in the file
// being formatted. Until then the single-file form is simpler and
// equivalent.
const BUILTINS_PATH: &str = "src/spec/builtins.yaml";
const BUILTINS_MSGPACK: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/builtins.msgpack"));
const MODULES_PATH: &str = "src/spec/modules.yaml";
const MODULES_MSGPACK: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/modules.msgpack"));

/// Registry of known CMake command specifications used to guide formatting.
///
/// The registry describes the argument structure of each command — positional
/// slots, keyword sections, flags, and per-form layout hints — so the formatter
/// can group and wrap arguments correctly.
///
/// # Two-tier model
///
/// The built-in registry covers the full CMake standard library.  User override
/// files (TOML or YAML) can extend or modify any entry without replacing the
/// whole registry.
///
/// # Getting a registry
///
/// | Situation | Recommended call |
/// |-----------|-----------------|
/// | No customisation needed | [`CommandRegistry::builtins`] — lazily initialised singleton, cheapest |
/// | Fresh owned copy | [`CommandRegistry::load`] — allocates every call |
/// | Merge with user override file | [`CommandRegistry::from_builtins_and_overrides`] |
/// | Owned copy without overrides | [`CommandRegistry::from_builtins_and_overrides`] with `None::<&Path>` (equivalent to `load()`) |
#[derive(Debug, Clone)]
pub struct CommandRegistry {
    metadata: SpecMetadata,
    builtin_commands: IndexSet<String>,
    commands: IndexMap<String, CommandSpec>,
    fallback: CommandSpec,
}

impl CommandRegistry {
    /// Load the embedded built-in registry from `builtins.yaml`.
    ///
    /// Returns a fresh owned [`CommandRegistry`] on every call.  Prefer
    /// [`CommandRegistry::builtins`] when you only need a read-only reference —
    /// it initialises once and amortises the parse cost across all callers.
    pub fn load() -> Result<Self> {
        Self::load_builtins_impl()
    }

    /// Return the lazily initialised built-in registry singleton.
    ///
    /// The registry is parsed exactly once on first call; subsequent calls
    /// return a `&'static` reference at zero cost.  Use [`CommandRegistry::load`]
    /// if you need an owned, mutable copy.
    pub fn builtins() -> &'static Self {
        static BUILTINS: OnceLock<CommandRegistry> = OnceLock::new();
        BUILTINS.get_or_init(|| {
            Self::load_builtins_impl()
                .expect("embedded built-in command registry should deserialize")
        })
    }

    #[cfg(all(not(target_arch = "wasm32"), feature = "cli"))]
    fn load_builtins_impl() -> Result<Self> {
        Self::from_builtins_and_overrides(None::<&Path>)
    }

    #[cfg(any(target_arch = "wasm32", not(feature = "cli")))]
    fn load_builtins_impl() -> Result<Self> {
        Ok(Self::from_spec_file(parse_embedded_spec()?))
    }

    /// Load the embedded built-ins and optionally merge a user override file.
    #[cfg(all(not(target_arch = "wasm32"), feature = "cli"))]
    pub fn from_builtins_and_overrides(path: Option<impl AsRef<Path>>) -> Result<Self> {
        let mut registry = Self::from_spec_file(parse_embedded_spec()?);

        if let Some(path) = path {
            registry.merge_override_file(path.as_ref())?;
        }

        Ok(registry)
    }

    /// Build a registry directly from a deserialized [`SpecFile`].
    pub(crate) fn from_spec_file(mut spec_file: SpecFile) -> Self {
        normalize_spec_file(&mut spec_file);
        let builtin_commands = spec_file.commands.keys().cloned().collect();
        Self {
            metadata: spec_file.metadata,
            builtin_commands,
            commands: spec_file.commands,
            fallback: CommandSpec::Single(CommandForm::default()),
        }
    }

    /// Merge TOML-formatted command spec overrides from a string.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use cmakefmt::CommandRegistry;
    ///
    /// let mut registry = CommandRegistry::load().unwrap();
    /// registry.merge_toml_overrides(r#"
    ///     [commands.my_add_test]
    ///     pargs = 0
    ///     flags = ["VERBOSE"]
    ///
    ///     [commands.my_add_test.kwargs.NAME]
    ///     nargs = 1
    ///
    ///     [commands.my_add_test.kwargs.SOURCES]
    ///     nargs = "+"
    /// "#).unwrap();
    /// ```
    ///
    /// # Errors
    ///
    /// Returns [`Error::Formatter`] with an unstructured parse error
    /// string. For structured line/column diagnostics, use
    /// [`CommandRegistry::merge_override_str`] or
    /// [`CommandRegistry::merge_override_file`] which return
    /// [`Error::Spec`].
    pub fn merge_toml_overrides(&mut self, toml_source: &str) -> Result<()> {
        let mut overrides: SpecOverrideFile = toml::from_str(toml_source)
            .map_err(|e| Error::Formatter(format!("spec TOML error: {e}")))?;
        self.apply_overrides(&mut overrides);
        Ok(())
    }

    /// Merge YAML-formatted command spec overrides from a string.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use cmakefmt::CommandRegistry;
    ///
    /// let mut registry = CommandRegistry::load().unwrap();
    /// registry.merge_yaml_overrides("
    /// commands:
    ///   my_add_test:
    ///     pargs: 0
    ///     flags: [VERBOSE]
    ///     kwargs:
    ///       NAME:
    ///         nargs: 1
    ///       SOURCES:
    ///         nargs: \"+\"
    /// ").unwrap();
    /// ```
    ///
    /// # Errors
    ///
    /// Returns [`Error::Formatter`] with an unstructured parse error
    /// string. For structured line/column diagnostics, use
    /// [`CommandRegistry::merge_override_file`] which returns
    /// [`Error::Spec`].
    pub fn merge_yaml_overrides(&mut self, yaml_source: &str) -> Result<()> {
        let mut overrides: SpecOverrideFile = serde_yaml::from_str(yaml_source)
            .map_err(|e| Error::Formatter(format!("spec YAML error: {e}")))?;
        self.apply_overrides(&mut overrides);
        Ok(())
    }

    fn apply_overrides(&mut self, overrides: &mut SpecOverrideFile) {
        normalize_override_file(overrides);
        let commands = std::mem::take(&mut overrides.commands);
        for (name, override_spec) in commands {
            match self.commands.get_mut(&name) {
                Some(existing) => merge_command_spec(existing, override_spec),
                None => {
                    self.commands.insert(name, override_spec.into_full_spec());
                }
            }
        }
    }

    /// Merge a supported user override file from disk into the registry.
    ///
    /// # Errors
    ///
    /// Deserialisation failures are reported as [`Error::Spec`] with
    /// structured [`crate::error::FileParseError`] metadata
    /// including 1-based line and column numbers — suitable for
    /// surfacing to editors and IDE integrations. I/O failures are
    /// reported as [`Error::Io`].
    #[cfg(all(not(target_arch = "wasm32"), feature = "cli"))]
    #[cfg_attr(docsrs, doc(cfg(feature = "cli")))]
    pub fn merge_override_file(&mut self, path: &Path) -> Result<()> {
        let source = fs::read_to_string(path)?;
        self.merge_override_source(&source, path.to_path_buf(), detect_config_format(path)?)
    }

    /// Merge TOML override contents into the registry.
    ///
    /// # Errors
    ///
    /// Like [`merge_override_file`](Self::merge_override_file),
    /// parse failures are reported as [`Error::Spec`] with
    /// structured line/column metadata — unlike
    /// [`merge_toml_overrides`](Self::merge_toml_overrides), which
    /// returns an unstructured [`Error::Formatter`].
    #[cfg(all(not(target_arch = "wasm32"), feature = "cli"))]
    #[cfg_attr(docsrs, doc(cfg(feature = "cli")))]
    pub fn merge_override_str(&mut self, source: &str, path: impl Into<PathBuf>) -> Result<()> {
        self.merge_override_source(source, path.into(), ConfigFileFormat::Toml)
    }

    #[cfg(all(not(target_arch = "wasm32"), feature = "cli"))]
    fn merge_override_source(
        &mut self,
        source: &str,
        path: PathBuf,
        format: ConfigFileFormat,
    ) -> Result<()> {
        let mut overrides: SpecOverrideFile = match format {
            ConfigFileFormat::Toml => toml::from_str(source).map_err(|toml_err| {
                let (line, column) = crate::config::file::toml_line_col(
                    source,
                    toml_err.span().map(|span| span.start),
                );
                Error::Spec(crate::error::SpecError::new(
                    path.clone(),
                    format.as_str(),
                    toml_err.to_string(),
                    line,
                    column,
                ))
            })?,
            ConfigFileFormat::Yaml => serde_yaml::from_str(source).map_err(|yaml_err| {
                let location = yaml_err.location();
                Error::Spec(crate::error::SpecError::new(
                    path.clone(),
                    format.as_str(),
                    yaml_err.to_string(),
                    location.as_ref().map(|loc| loc.line()),
                    location.as_ref().map(|loc| loc.column()),
                ))
            })?,
        };
        normalize_override_file(&mut overrides);

        for (name, override_spec) in overrides.commands {
            match self.commands.get_mut(&name) {
                Some(existing) => merge_command_spec(existing, override_spec),
                None => {
                    self.commands.insert(name, override_spec.into_full_spec());
                }
            }
        }

        Ok(())
    }

    /// Get the command spec for `command_name`, falling back to a
    /// permissive default when the command is unknown.
    ///
    /// The fallback is a [`CommandSpec::Single`] with `pargs =
    /// ZeroOrMore`, no kwargs, and no flags — i.e. "format as
    /// generically as possible, treat every token as a positional
    /// argument". This lets user-defined commands format sensibly
    /// without requiring every project to author a spec override.
    pub fn get(&self, command_name: &str) -> &CommandSpec {
        if let Some(spec) = self.commands.get(command_name) {
            return spec;
        }

        if !has_ascii_uppercase(command_name) {
            return &self.fallback;
        }

        self.commands
            .get(&command_name.to_ascii_lowercase())
            .unwrap_or(&self.fallback)
    }

    /// Return `true` when the command has a known spec (built-in or
    /// user-defined).
    pub fn contains(&self, command_name: &str) -> bool {
        self.commands.contains_key(command_name)
            || (has_ascii_uppercase(command_name)
                && self
                    .commands
                    .contains_key(&command_name.to_ascii_lowercase()))
    }

    /// Return `true` when the command is present in the built-in registry.
    pub fn contains_builtin(&self, command_name: &str) -> bool {
        self.builtin_commands.contains(command_name)
            || (has_ascii_uppercase(command_name)
                && self
                    .builtin_commands
                    .contains(&command_name.to_ascii_lowercase()))
    }

    /// Report the upstream CMake version the built-in spec was last
    /// audited against. The return value is a SemVer-style string
    /// (e.g. `"4.3.1"`) sourced from the `[metadata]` block in
    /// `src/spec/builtins.yaml`. Useful for tooling that wants to
    /// surface "cmakefmt knows about CMake X.Y" to end users.
    pub fn audited_cmake_version(&self) -> &str {
        &self.metadata.cmake_version
    }

    /// Iterate over the names of every built-in command in the
    /// registry. Yields the lowercase canonical form; user-merged
    /// override commands are excluded. Intended for tooling that
    /// wants to introspect the spec surface (e.g.
    /// `cmakefmt dump spec-coverage`).
    pub fn builtin_command_names(&self) -> impl Iterator<Item = &str> {
        self.builtin_commands.iter().map(String::as_str)
    }
}

/// Decode the embedded `builtins.yaml` blob and merge in the embedded
/// `modules.yaml` blob, returning a single combined [`SpecFile`].
///
/// Metadata (e.g. the audited CMake version) is taken from the builtins
/// blob; `modules.yaml` is expected to contribute only command entries.
/// On a key collision between the two blobs, the modules entry wins —
/// in practice this should never happen, since CMake's
/// `--help-command-list` and `--help-module-list` are disjoint.
fn parse_embedded_spec() -> Result<SpecFile> {
    let mut spec = parse_msgpack_spec(BUILTINS_MSGPACK, BUILTINS_PATH)?;
    let modules = parse_msgpack_spec(MODULES_MSGPACK, MODULES_PATH)?;
    spec.commands.extend(modules.commands);
    Ok(spec)
}

fn parse_msgpack_spec(bytes: &[u8], path: &str) -> Result<SpecFile> {
    let mut spec: SpecFile = rmp_serde::from_slice(bytes).map_err(|source| {
        Error::Spec(crate::error::SpecError::new(
            PathBuf::from(path),
            "MessagePack",
            source.to_string(),
            None,
            None,
        ))
    })?;
    normalize_spec_file(&mut spec);
    Ok(spec)
}

fn normalize_spec_file(spec: &mut SpecFile) {
    spec.commands = std::mem::take(&mut spec.commands)
        .into_iter()
        .map(|(name, mut command)| {
            normalize_command_spec(&mut command);
            (name.to_ascii_lowercase(), command)
        })
        .collect();
}

fn normalize_override_file(spec: &mut SpecOverrideFile) {
    spec.commands = std::mem::take(&mut spec.commands)
        .into_iter()
        .map(|(name, mut command)| {
            normalize_command_override(&mut command);
            (name.to_ascii_lowercase(), command)
        })
        .collect();
}

fn normalize_command_spec(spec: &mut CommandSpec) {
    match spec {
        CommandSpec::Single(form) => normalize_form(form),
        CommandSpec::Discriminated { forms, fallback } => {
            *forms = std::mem::take(forms)
                .into_iter()
                .map(|(name, mut form)| {
                    normalize_form(&mut form);
                    (name.to_ascii_uppercase(), form)
                })
                .collect();

            if let Some(fallback) = fallback {
                normalize_form(fallback);
            }
        }
    }
}

fn normalize_command_override(spec: &mut CommandSpecOverride) {
    match spec {
        CommandSpecOverride::Single(form) => normalize_form_override(form),
        CommandSpecOverride::Discriminated { forms, fallback } => {
            *forms = std::mem::take(forms)
                .into_iter()
                .map(|(name, mut form)| {
                    normalize_form_override(&mut form);
                    (name.to_ascii_uppercase(), form)
                })
                .collect();

            if let Some(fallback) = fallback {
                normalize_form_override(fallback);
            }
        }
    }
}

fn normalize_form(form: &mut CommandForm) {
    form.kwargs = std::mem::take(&mut form.kwargs)
        .into_iter()
        .map(|(name, mut kwarg)| {
            normalize_kwarg(&mut kwarg);
            (name.to_ascii_uppercase(), kwarg)
        })
        .collect();

    form.flags = std::mem::take(&mut form.flags)
        .into_iter()
        .map(|flag| flag.to_ascii_uppercase())
        .collect();
}

fn normalize_form_override(form: &mut CommandFormOverride) {
    form.kwargs = std::mem::take(&mut form.kwargs)
        .into_iter()
        .map(|(name, mut kwarg)| {
            normalize_kwarg_override(&mut kwarg);
            (name.to_ascii_uppercase(), kwarg)
        })
        .collect();

    form.flags = std::mem::take(&mut form.flags)
        .into_iter()
        .map(|flag| flag.to_ascii_uppercase())
        .collect();
}

fn normalize_kwarg(spec: &mut KwargSpec) {
    spec.kwargs = std::mem::take(&mut spec.kwargs)
        .into_iter()
        .map(|(name, mut kwarg)| {
            normalize_kwarg(&mut kwarg);
            (name.to_ascii_uppercase(), kwarg)
        })
        .collect();

    spec.flags = std::mem::take(&mut spec.flags)
        .into_iter()
        .map(|flag| flag.to_ascii_uppercase())
        .collect();
}

fn normalize_kwarg_override(spec: &mut KwargSpecOverride) {
    spec.kwargs = std::mem::take(&mut spec.kwargs)
        .into_iter()
        .map(|(name, mut kwarg)| {
            normalize_kwarg_override(&mut kwarg);
            (name.to_ascii_uppercase(), kwarg)
        })
        .collect();

    spec.flags = std::mem::take(&mut spec.flags)
        .into_iter()
        .map(|flag| flag.to_ascii_uppercase())
        .collect();
}

fn merge_command_spec(base: &mut CommandSpec, override_spec: CommandSpecOverride) {
    match (base, override_spec) {
        (CommandSpec::Single(base_form), CommandSpecOverride::Single(override_form)) => {
            merge_form(base_form, override_form);
        }
        (
            CommandSpec::Discriminated {
                forms: base_forms,
                fallback: base_fallback,
            },
            CommandSpecOverride::Discriminated {
                forms: override_forms,
                fallback: override_fallback,
            },
        ) => {
            for (name, override_form) in override_forms {
                match base_forms.get_mut(&name) {
                    Some(base_form) => merge_form(base_form, override_form),
                    None => {
                        base_forms.insert(name, override_form.into_full_form());
                    }
                }
            }

            if let Some(override_fallback) = override_fallback {
                match base_fallback {
                    Some(base_fallback) => merge_form(base_fallback, override_fallback),
                    None => {
                        *base_fallback = Some(override_fallback.into_full_form());
                    }
                }
            }
        }
        (base_spec, override_spec) => {
            *base_spec = override_spec.into_full_spec();
        }
    }
}

fn merge_form(base: &mut CommandForm, override_form: CommandFormOverride) {
    if let Some(pargs) = override_form.pargs {
        base.pargs = pargs;
    }

    merge_flags(&mut base.flags, override_form.flags);

    for (name, override_kwarg) in override_form.kwargs {
        match base.kwargs.get_mut(&name) {
            Some(base_kwarg) => merge_kwarg(base_kwarg, override_kwarg),
            None => {
                base.kwargs.insert(name, override_kwarg.into_full_spec());
            }
        }
    }

    if let Some(layout) = override_form.layout {
        merge_layout(
            base.layout.get_or_insert_with(LayoutOverrides::default),
            layout,
        );
    }
}

fn merge_kwarg(base: &mut KwargSpec, override_kwarg: KwargSpecOverride) {
    if let Some(nargs) = override_kwarg.nargs {
        base.nargs = nargs;
    }

    merge_flags(&mut base.flags, override_kwarg.flags);

    for (name, nested_override) in override_kwarg.kwargs {
        match base.kwargs.get_mut(&name) {
            Some(base_nested) => merge_kwarg(base_nested, nested_override),
            None => {
                base.kwargs.insert(name, nested_override.into_full_spec());
            }
        }
    }
}

fn merge_layout(base: &mut LayoutOverrides, override_layout: LayoutOverridesOverride) {
    if let Some(value) = override_layout.line_width {
        base.line_width = Some(value);
    }
    if let Some(value) = override_layout.tab_size {
        base.tab_size = Some(value);
    }
    if let Some(value) = override_layout.dangle_parens {
        base.dangle_parens = Some(value);
    }
    if let Some(value) = override_layout.always_wrap {
        base.always_wrap = Some(value);
    }
    if let Some(value) = override_layout.max_pargs_hwrap {
        base.max_pargs_hwrap = Some(value);
    }
    if let Some(value) = override_layout.continuation_align {
        base.continuation_align = Some(value);
    }
}

fn merge_flags(base: &mut IndexSet<String>, override_flags: IndexSet<String>) {
    for flag in override_flags {
        base.insert(flag);
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::spec::NArgs;
    use std::fs;

    #[test]
    fn registry_has_target_link_libraries_keywords() {
        let registry = CommandRegistry::load().unwrap();
        let CommandSpec::Single(form) = registry.get("target_link_libraries") else {
            panic!()
        };
        assert!(form.kwargs.contains_key("PUBLIC"));
        assert!(form.kwargs.contains_key("PRIVATE"));
        assert!(form.kwargs.contains_key("INTERFACE"));
    }

    #[test]
    fn registry_has_install_forms() {
        let registry = CommandRegistry::load().unwrap();
        assert!(matches!(
            registry.get("install"),
            CommandSpec::Discriminated { .. }
        ));
    }

    #[test]
    fn registry_unknown_command_uses_fallback() {
        let registry = CommandRegistry::load().unwrap();
        let spec = registry.get("my_unknown_command");
        let CommandSpec::Single(form) = spec else {
            panic!()
        };
        assert_eq!(form.pargs, NArgs::ZeroOrMore);
        assert!(form.kwargs.is_empty());
        assert!(form.flags.is_empty());
    }

    #[test]
    fn registry_knows_builtin_surface() {
        let registry = CommandRegistry::load().unwrap();
        assert!(registry.contains_builtin("cmake_minimum_required"));
        assert!(registry.contains_builtin("target_sources"));
        assert!(registry.contains_builtin("while"));
        assert!(registry.contains_builtin("external_project_add"));
    }

    #[test]
    fn registry_reports_audited_cmake_version() {
        let registry = CommandRegistry::load().unwrap();
        assert_eq!(registry.audited_cmake_version(), "4.3.1");
    }

    #[test]
    fn registry_knows_project_43_keywords() {
        let registry = CommandRegistry::load().unwrap();
        let CommandSpec::Single(form) = registry.get("project") else {
            panic!()
        };
        assert!(form.flags.contains("COMPAT_VERSION"));
        assert!(form.flags.contains("SPDX_LICENSE"));
    }

    #[test]
    fn registry_knows_export_package_info_form() {
        let registry = CommandRegistry::load().unwrap();
        let CommandSpec::Discriminated { .. } = registry.get("export") else {
            panic!()
        };
        let form = registry.get("export").form_for(Some("PACKAGE_INFO"));
        assert_eq!(form.pargs, NArgs::Fixed(1));
        assert!(form.kwargs.contains_key("EXPORT"));
        assert!(form.kwargs.contains_key("CXX_MODULES_DIRECTORY"));
    }

    #[test]
    fn registry_knows_install_package_info_form() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("install").form_for(Some("PACKAGE_INFO"));
        assert_eq!(form.pargs, NArgs::Fixed(1));
        assert!(form.kwargs.contains_key("DESTINATION"));
        assert!(form.kwargs.contains_key("COMPAT_VERSION"));
    }

    #[test]
    fn registry_knows_install_export_namespace_keyword() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("install").form_for(Some("EXPORT"));
        assert!(form.kwargs.contains_key("DESTINATION"));
        assert!(form.kwargs.contains_key("NAMESPACE"));
        assert!(form.kwargs.contains_key("FILE"));
        assert!(form.flags.contains("EXCLUDE_FROM_ALL"));
    }

    #[test]
    fn registry_knows_install_targets_export_and_includes_sections() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("install").form_for(Some("TARGETS"));
        assert!(form.kwargs.contains_key("EXPORT"));
        assert!(form.kwargs.contains_key("INCLUDES"));
        assert!(form
            .kwargs
            .get("INCLUDES")
            .is_some_and(|spec| spec.kwargs.contains_key("DESTINATION")));
        assert!(form.kwargs.contains_key("RUNTIME_DEPENDENCY_SET"));
    }

    #[test]
    fn install_targets_artifact_kinds_are_kwargs_with_subgroups() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("install").form_for(Some("TARGETS"));

        for kind in [
            "ARCHIVE",
            "LIBRARY",
            "RUNTIME",
            "OBJECTS",
            "FRAMEWORK",
            "BUNDLE",
            "PRIVATE_HEADER",
            "PUBLIC_HEADER",
            "RESOURCE",
            "FILE_SET",
            "CXX_MODULES_BMI",
        ] {
            let spec = form
                .kwargs
                .get(kind)
                .unwrap_or_else(|| panic!("install(TARGETS) missing artifact kind {kind}"));
            for sub in [
                "DESTINATION",
                "PERMISSIONS",
                "CONFIGURATIONS",
                "COMPONENT",
                "NAMELINK_COMPONENT",
            ] {
                assert!(
                    spec.kwargs.contains_key(sub),
                    "{kind} missing subkwarg {sub}"
                );
            }
            for flag in [
                "OPTIONAL",
                "EXCLUDE_FROM_ALL",
                "NAMELINK_ONLY",
                "NAMELINK_SKIP",
            ] {
                assert!(spec.flags.contains(flag), "{kind} missing subflag {flag}");
            }
            assert!(
                !form.flags.contains(kind),
                "{kind} should not appear as an outer flag"
            );
        }
    }

    #[test]
    fn install_targets_file_set_takes_positional_set_name() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("install").form_for(Some("TARGETS"));
        let file_set = form.kwargs.get("FILE_SET").unwrap();
        assert_eq!(file_set.nargs, crate::spec::NArgs::Fixed(1));
    }

    #[test]
    fn install_targets_artifact_option_flags_are_not_outer_flags() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("install").form_for(Some("TARGETS"));
        for flag in [
            "OPTIONAL",
            "EXCLUDE_FROM_ALL",
            "NAMELINK_ONLY",
            "NAMELINK_SKIP",
        ] {
            assert!(
                !form.flags.contains(flag),
                "{flag} should not appear at the outer TARGETS level"
            );
        }
    }

    #[test]
    fn install_targets_runtime_dependencies_is_kwarg_group() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("install").form_for(Some("TARGETS"));
        let rd = form.kwargs.get("RUNTIME_DEPENDENCIES").unwrap();
        for sub in [
            "DIRECTORIES",
            "PRE_INCLUDE_REGEXES",
            "PRE_EXCLUDE_REGEXES",
            "POST_INCLUDE_REGEXES",
            "POST_EXCLUDE_REGEXES",
            "POST_INCLUDE_FILES",
            "POST_EXCLUDE_FILES",
        ] {
            assert!(
                rd.kwargs.contains_key(sub),
                "RUNTIME_DEPENDENCIES missing subkwarg {sub}"
            );
        }
    }

    #[test]
    fn install_imported_runtime_artifacts_artifact_kinds_are_kwargs() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry
            .get("install")
            .form_for(Some("IMPORTED_RUNTIME_ARTIFACTS"));

        for kind in ["LIBRARY", "RUNTIME", "FRAMEWORK", "BUNDLE"] {
            let spec = form
                .kwargs
                .get(kind)
                .unwrap_or_else(|| panic!("IMPORTED_RUNTIME_ARTIFACTS missing {kind}"));
            for sub in ["DESTINATION", "PERMISSIONS", "CONFIGURATIONS", "COMPONENT"] {
                assert!(
                    spec.kwargs.contains_key(sub),
                    "{kind} missing subkwarg {sub}"
                );
            }
            for flag in ["OPTIONAL", "EXCLUDE_FROM_ALL"] {
                assert!(spec.flags.contains(flag), "{kind} missing subflag {flag}");
            }
            assert!(!form.flags.contains(kind));
        }
    }

    #[test]
    fn install_files_has_type_rename_and_exclude_from_all() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("install").form_for(Some("FILES"));
        assert!(form.kwargs.contains_key("TYPE"));
        assert!(form.kwargs.contains_key("RENAME"));
        assert!(form.flags.contains("EXCLUDE_FROM_ALL"));
    }

    #[test]
    fn install_directory_has_full_option_coverage() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("install").form_for(Some("DIRECTORY"));
        for kw in [
            "TYPE",
            "DESTINATION",
            "FILE_PERMISSIONS",
            "DIRECTORY_PERMISSIONS",
            "CONFIGURATIONS",
            "COMPONENT",
            "PATTERN",
            "REGEX",
        ] {
            assert!(form.kwargs.contains_key(kw), "DIRECTORY missing kwarg {kw}");
        }
        // PERMISSIONS is not a top-level kwarg of install(DIRECTORY) per
        // CMake docs — it only appears nested under PATTERN/REGEX.
        assert!(
            !form.kwargs.contains_key("PERMISSIONS"),
            "PERMISSIONS must not be a top-level DIRECTORY kwarg"
        );
        for flag in [
            "OPTIONAL",
            "USE_SOURCE_PERMISSIONS",
            "MESSAGE_NEVER",
            "EXCLUDE_FROM_ALL",
            "FILES_MATCHING",
        ] {
            assert!(form.flags.contains(flag), "DIRECTORY missing flag {flag}");
        }
    }

    #[test]
    fn install_directory_pattern_and_regex_open_subgroup() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("install").form_for(Some("DIRECTORY"));
        for name in ["PATTERN", "REGEX"] {
            let spec = form.kwargs.get(name).unwrap();
            assert_eq!(spec.nargs, crate::spec::NArgs::Fixed(1));
            assert!(spec.flags.contains("EXCLUDE"), "{name} missing EXCLUDE");
            assert!(
                spec.kwargs.contains_key("PERMISSIONS"),
                "{name} missing PERMISSIONS subkwarg"
            );
        }
    }

    #[test]
    fn install_programs_mirrors_files_form() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("install").form_for(Some("PROGRAMS"));
        for kw in [
            "TYPE",
            "DESTINATION",
            "PERMISSIONS",
            "CONFIGURATIONS",
            "COMPONENT",
            "RENAME",
        ] {
            assert!(form.kwargs.contains_key(kw), "PROGRAMS missing kwarg {kw}");
        }
        assert!(form.flags.contains("OPTIONAL"));
        assert!(form.flags.contains("EXCLUDE_FROM_ALL"));
    }

    #[test]
    fn install_script_and_code_accept_component_and_flags() {
        let registry = CommandRegistry::load().unwrap();
        for disc in ["SCRIPT", "CODE"] {
            let form = registry.get("install").form_for(Some(disc));
            assert!(
                form.kwargs.contains_key("COMPONENT"),
                "{disc} missing COMPONENT"
            );
            assert!(
                form.flags.contains("ALL_COMPONENTS"),
                "{disc} missing ALL_COMPONENTS"
            );
            assert!(
                form.flags.contains("EXCLUDE_FROM_ALL"),
                "{disc} missing EXCLUDE_FROM_ALL"
            );
        }
    }

    #[test]
    fn install_runtime_dependency_set_has_filter_kwargs_and_artifact_kinds() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry
            .get("install")
            .form_for(Some("RUNTIME_DEPENDENCY_SET"));

        for sub in [
            "DIRECTORIES",
            "PRE_INCLUDE_REGEXES",
            "PRE_EXCLUDE_REGEXES",
            "POST_INCLUDE_REGEXES",
            "POST_EXCLUDE_REGEXES",
            "POST_INCLUDE_FILES",
            "POST_EXCLUDE_FILES",
        ] {
            assert!(
                form.kwargs.contains_key(sub),
                "RUNTIME_DEPENDENCY_SET missing {sub}"
            );
        }

        for kind in ["LIBRARY", "RUNTIME", "FRAMEWORK"] {
            let spec = form
                .kwargs
                .get(kind)
                .unwrap_or_else(|| panic!("RUNTIME_DEPENDENCY_SET missing {kind}"));
            for k in [
                "DESTINATION",
                "PERMISSIONS",
                "CONFIGURATIONS",
                "COMPONENT",
                "NAMELINK_COMPONENT",
            ] {
                assert!(spec.kwargs.contains_key(k), "{kind} missing subkwarg {k}");
            }
            for f in [
                "OPTIONAL",
                "EXCLUDE_FROM_ALL",
                "NAMELINK_ONLY",
                "NAMELINK_SKIP",
            ] {
                assert!(spec.flags.contains(f), "{kind} missing subflag {f}");
            }
        }
    }

    #[test]
    fn registry_knows_cmake_language_trace_form() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("cmake_language").form_for(Some("TRACE"));
        assert!(form.flags.contains("ON"));
        assert!(form.flags.contains("OFF"));
        assert!(form.flags.contains("EXPAND"));
    }

    #[test]
    fn registry_knows_cmake_pkg_config_import_keywords() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("cmake_pkg_config").form_for(Some("IMPORT"));
        assert!(form.kwargs.contains_key("NAME"));
        assert!(form.kwargs.contains_key("BIND_PC_REQUIRES"));
    }

    #[test]
    fn registry_knows_file_archive_create_threads() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("file").form_for(Some("ARCHIVE_CREATE"));
        assert!(form.kwargs.contains_key("THREADS"));
        assert!(form.kwargs.contains_key("COMPRESSION_LEVEL"));
    }

    #[test]
    fn registry_knows_file_strings_keywords() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("file").form_for(Some("STRINGS"));
        assert_eq!(form.pargs, NArgs::Fixed(2));
        assert!(form.kwargs.contains_key("REGEX"));
        assert!(form.kwargs.contains_key("LIMIT_COUNT"));
    }

    #[test]
    fn registry_knows_cmake_package_config_helpers_commands() {
        let registry = CommandRegistry::load().unwrap();
        let configure = registry.get("configure_package_config_file").form_for(None);
        assert!(configure.kwargs.contains_key("INSTALL_DESTINATION"));
        assert!(configure.kwargs.contains_key("PATH_VARS"));

        let version = registry
            .get("write_basic_package_version_file")
            .form_for(None);
        assert!(version.kwargs.contains_key("COMPATIBILITY"));
        assert!(version.kwargs.contains_key("VERSION"));
    }

    #[test]
    fn registry_knows_utility_module_commands() {
        let registry = CommandRegistry::load().unwrap();
        assert_eq!(
            registry.get("cmake_dependent_option").form_for(None).pargs,
            NArgs::Fixed(5)
        );
        assert_eq!(
            registry.get("check_language").form_for(None).pargs,
            NArgs::Fixed(1)
        );
        assert_eq!(
            registry.get("check_include_file").form_for(None).pargs,
            NArgs::AtLeast(2)
        );
        assert_eq!(
            registry.get("check_compiler_flag").form_for(None).pargs,
            NArgs::Fixed(3)
        );
        assert_eq!(
            registry
                .get("check_objc_compiler_flag")
                .form_for(None)
                .pargs,
            NArgs::Fixed(2)
        );
        assert_eq!(
            registry.get("check_cxx_symbol_exists").form_for(None).pargs,
            NArgs::Fixed(3)
        );
        assert!(registry
            .get("cmake_push_check_state")
            .form_for(None)
            .flags
            .contains("RESET"));
        let print_props = registry.get("cmake_print_properties").form_for(None);
        assert!(print_props.kwargs.contains_key("TARGETS"));
        assert!(print_props.kwargs.contains_key("PROPERTIES"));
        let pie = registry.get("check_pie_supported").form_for(None);
        assert!(pie.kwargs.contains_key("OUTPUT_VARIABLE"));
        assert!(pie.kwargs.contains_key("LANGUAGES"));
        let source_compiles = registry.get("check_source_compiles").form_for(None);
        assert!(source_compiles.kwargs.contains_key("SRC_EXT"));
        assert!(source_compiles.kwargs.contains_key("FAIL_REGEX"));
        let find_dependency = registry.get("find_dependency").form_for(None);
        assert!(find_dependency.flags.contains("REQUIRED"));
        assert!(find_dependency.kwargs.contains_key("COMPONENTS"));
    }

    #[test]
    fn registry_knows_supported_deprecated_module_commands() {
        let registry = CommandRegistry::load().unwrap();
        let version = registry
            .get("write_basic_config_version_file")
            .form_for(None);
        assert_eq!(version.pargs, NArgs::Fixed(1));
        assert!(version.kwargs.contains_key("COMPATIBILITY"));
        assert!(version.flags.contains("ARCH_INDEPENDENT"));
        assert_eq!(
            registry.get("check_cxx_accepts_flag").form_for(None).pargs,
            NArgs::Fixed(2)
        );
    }

    #[test]
    fn registry_knows_fetchcontent_commands() {
        let registry = CommandRegistry::load().unwrap();
        let declare = registry.get("fetchcontent_declare").form_for(None);
        assert_eq!(declare.pargs, NArgs::Fixed(1));
        assert!(declare.flags.contains("EXCLUDE_FROM_ALL"));
        assert!(declare.kwargs.contains_key("FIND_PACKAGE_ARGS"));

        let get_properties = registry.get("fetchcontent_getproperties").form_for(None);
        assert!(get_properties.kwargs.contains_key("SOURCE_DIR"));
        assert!(get_properties.kwargs.contains_key("BINARY_DIR"));
        assert!(get_properties.kwargs.contains_key("POPULATED"));

        let populate = registry.get("fetchcontent_populate").form_for(None);
        assert!(populate.flags.contains("QUIET"));
        assert!(populate.kwargs.contains_key("SUBBUILD_DIR"));
    }

    #[test]
    fn registry_knows_common_test_and_package_helper_modules() {
        let registry = CommandRegistry::load().unwrap();

        let google_add = registry.get("gtest_add_tests").form_for(None);
        assert!(google_add.kwargs.contains_key("TARGET"));
        assert!(google_add.kwargs.contains_key("SOURCES"));
        assert!(google_add.flags.contains("SKIP_DEPENDENCY"));

        let google_discover = registry.get("gtest_discover_tests").form_for(None);
        assert!(google_discover.kwargs.contains_key("DISCOVERY_MODE"));
        assert!(google_discover.kwargs.contains_key("XML_OUTPUT_DIR"));
        assert!(google_discover.flags.contains("NO_PRETTY_TYPES"));

        assert_eq!(
            registry.get("processorcount").form_for(None).pargs,
            NArgs::Fixed(1)
        );

        let fp_hsa = registry
            .get("find_package_handle_standard_args")
            .form_for(None);
        assert!(fp_hsa.flags.contains("DEFAULT_MSG"));
        assert!(fp_hsa.kwargs.contains_key("REQUIRED_VARS"));
        assert!(fp_hsa.kwargs.contains_key("VERSION_VAR"));

        let fp_check = registry.get("find_package_check_version").form_for(None);
        assert_eq!(fp_check.pargs, NArgs::Fixed(2));
        assert!(fp_check.flags.contains("HANDLE_VERSION_RANGE"));
    }

    #[test]
    fn registry_knows_externalproject_helper_commands() {
        let registry = CommandRegistry::load().unwrap();
        let step = registry.get("externalproject_add_step").form_for(None);
        assert_eq!(step.pargs, NArgs::Fixed(2));
        assert!(step.kwargs.contains_key("COMMAND"));
        assert!(step.kwargs.contains_key("DEPENDEES"));
        assert!(step.kwargs.contains_key("ENVIRONMENT_MODIFICATION"));

        let targets = registry
            .get("externalproject_add_steptargets")
            .form_for(None);
        assert_eq!(targets.pargs, NArgs::AtLeast(2));
        assert!(targets.flags.contains("NO_DEPENDS"));

        let deps = registry
            .get("externalproject_add_stepdependencies")
            .form_for(None);
        assert_eq!(deps.pargs, NArgs::AtLeast(3));

        let props = registry.get("externalproject_get_property").form_for(None);
        assert_eq!(props.pargs, NArgs::AtLeast(2));
    }

    #[test]
    fn registry_knows_packaging_and_find_helper_module_commands() {
        let registry = CommandRegistry::load().unwrap();

        assert_eq!(
            registry.get("find_package_message").form_for(None).pargs,
            NArgs::Fixed(3)
        );
        assert_eq!(
            registry
                .get("select_library_configurations")
                .form_for(None)
                .pargs,
            NArgs::Fixed(1)
        );

        let component = registry.get("cpack_add_component").form_for(None);
        assert!(component.flags.contains("HIDDEN"));
        assert!(component.kwargs.contains_key("DISPLAY_NAME"));
        assert!(component.kwargs.contains_key("DEPENDS"));

        let group = registry.get("cpack_add_component_group").form_for(None);
        assert!(group.flags.contains("EXPANDED"));
        assert!(group.kwargs.contains_key("PARENT_GROUP"));

        let downloads = registry.get("cpack_configure_downloads").form_for(None);
        assert_eq!(downloads.pargs, NArgs::Fixed(1));
        assert!(downloads.kwargs.contains_key("UPLOAD_DIRECTORY"));
    }

    #[test]
    fn registry_knows_export_header_module_commands() {
        let registry = CommandRegistry::load().unwrap();
        let export_header = registry.get("generate_export_header").form_for(None);
        assert_eq!(export_header.pargs, NArgs::Fixed(1));
        assert!(export_header.flags.contains("DEFINE_NO_DEPRECATED"));
        assert!(export_header.kwargs.contains_key("EXPORT_FILE_NAME"));
        assert!(export_header.kwargs.contains_key("PREFIX_NAME"));

        assert_eq!(
            registry
                .get("add_compiler_export_flags")
                .form_for(None)
                .pargs,
            NArgs::Optional
        );
    }

    #[test]
    fn registry_knows_remaining_utility_module_commands() {
        let registry = CommandRegistry::load().unwrap();

        for command in [
            "android_add_test_data",
            "add_file_dependencies",
            "cmake_add_fortran_subdirectory",
            "cmake_expand_imported_targets",
            "cmake_force_c_compiler",
            "cmake_force_cxx_compiler",
            "cmake_force_fortran_compiler",
            "ctest_coverage_collect_gcov",
            "copy_and_fixup_bundle",
            "fixup_bundle",
            "fixup_bundle_item",
            "verify_app",
            "verify_bundle_prerequisites",
            "verify_bundle_symlinks",
            "get_bundle_main_executable",
            "get_dotapp_dir",
            "get_bundle_and_executable",
            "get_bundle_all_executables",
            "get_bundle_keys",
            "get_item_key",
            "get_item_rpaths",
            "clear_bundle_keys",
            "set_bundle_key_values",
            "copy_resolved_framework_into_bundle",
            "copy_resolved_item_into_bundle",
            "cpack_ifw_add_package_resources",
            "cpack_ifw_add_repository",
            "cpack_ifw_configure_component",
            "cpack_ifw_configure_component_group",
            "cpack_ifw_update_repository",
            "cpack_ifw_configure_file",
            "csharp_set_windows_forms_properties",
            "csharp_set_designer_cs_properties",
            "csharp_set_xaml_cs_properties",
            "csharp_get_filename_keys",
            "csharp_get_filename_key_base",
            "csharp_get_dependentupon_name",
            "externaldata_expand_arguments",
            "externaldata_add_test",
            "externaldata_add_target",
            "fortrancinterface_header",
            "fortrancinterface_verify",
            "fetchcontent_setpopulated",
            "gnuinstalldirs_get_absolute_install_dir",
            "find_jar",
            "add_jar",
            "install_jar",
            "install_jar_exports",
            "export_jars",
            "create_javadoc",
            "create_javah",
            "install_jni_symlink",
            "swig_add_library",
            "swig_link_libraries",
            "print_enabled_features",
            "print_disabled_features",
            "set_feature_info",
            "set_package_info",
        ] {
            assert!(
                registry.contains_builtin(command),
                "missing built-in {command}"
            );
        }

        assert_eq!(
            registry
                .get("ctest_coverage_collect_gcov")
                .form_for(None)
                .pargs,
            NArgs::ZeroOrMore
        );
        assert_eq!(
            registry
                .get("fortrancinterface_verify")
                .form_for(None)
                .pargs,
            NArgs::ZeroOrMore
        );
        assert_eq!(
            registry.get("add_jar").form_for(None).pargs,
            NArgs::AtLeast(2)
        );
        assert_eq!(
            registry
                .get("cpack_ifw_configure_file")
                .form_for(None)
                .pargs,
            NArgs::Fixed(2)
        );
        assert_eq!(
            registry
                .get("gnuinstalldirs_get_absolute_install_dir")
                .form_for(None)
                .pargs,
            NArgs::AtLeast(3)
        );
    }

    #[test]
    fn registry_knows_string_json_43_modes() {
        let registry = CommandRegistry::load().unwrap();
        let form = registry.get("string").form_for(Some("JSON"));
        assert!(form.flags.contains("GET_RAW"));
        assert!(form.flags.contains("STRING_ENCODE"));
        assert!(form.kwargs.contains_key("ERROR_VARIABLE"));
    }

    #[test]
    fn user_override_entries_merge_with_builtins() {
        let mut registry = CommandRegistry::load().unwrap();
        let overrides = r#"
[commands.target_link_libraries.layout]
always_wrap = true

[commands.target_link_libraries.kwargs.LINKER_LANGUAGE]
nargs = 1
"#;

        registry
            .merge_override_str(overrides, PathBuf::from("test-overrides.toml"))
            .unwrap();

        let CommandSpec::Single(form) = registry.get("target_link_libraries") else {
            panic!()
        };
        assert_eq!(
            form.layout.as_ref().and_then(|layout| layout.always_wrap),
            Some(true)
        );
        assert!(form.kwargs.contains_key("PUBLIC"));
        assert_eq!(form.kwargs["LINKER_LANGUAGE"].nargs, NArgs::Fixed(1));
    }

    #[test]
    fn uppercase_lookup_uses_builtin_normalization() {
        let registry = CommandRegistry::load().unwrap();
        assert!(registry.contains_builtin("TARGET_LINK_LIBRARIES"));
        let CommandSpec::Single(form) = registry.get("TARGET_LINK_LIBRARIES") else {
            panic!()
        };
        assert!(form.kwargs.contains_key("PUBLIC"));
        assert!(form.kwargs.contains_key("PRIVATE"));
    }

    #[test]
    fn contains_builtin_excludes_user_added_commands_after_merge() {
        let mut registry = CommandRegistry::load().unwrap();
        registry
            .merge_toml_overrides(
                r#"
[commands.my_custom_command]
pargs = 1
"#,
            )
            .unwrap();

        assert!(!registry.contains_builtin("my_custom_command"));
        assert!(!registry.contains_builtin("MY_CUSTOM_COMMAND"));
        assert!(matches!(
            registry.get("my_custom_command"),
            CommandSpec::Single(_)
        ));
    }

    #[test]
    fn from_builtins_and_yaml_override_file_merges_entries() {
        let dir = tempfile::tempdir().unwrap();
        let overrides = dir.path().join("override.yaml");
        fs::write(
            &overrides,
            r#"
commands:
  target_link_libraries:
    kwargs:
      linker_language:
        nargs: 1
"#,
        )
        .unwrap();

        let registry = CommandRegistry::from_builtins_and_overrides(Some(&overrides)).unwrap();
        let CommandSpec::Single(form) = registry.get("target_link_libraries") else {
            panic!()
        };
        assert_eq!(form.kwargs["LINKER_LANGUAGE"].nargs, NArgs::Fixed(1));
    }

    #[test]
    fn merge_override_file_reports_structured_toml_parse_errors() {
        let mut registry = CommandRegistry::load().unwrap();
        let dir = tempfile::tempdir().unwrap();
        let path = dir.path().join("override.toml");
        fs::write(&path, "[commands.bad]\npargs = [\n").unwrap();

        let err = registry.merge_override_file(&path).unwrap_err();
        match err {
            Error::Spec(spec_err) => {
                let details = &spec_err.details;
                assert_eq!(details.format, "TOML");
                assert!(details.line.is_some());
                assert!(details.column.is_some());
            }
            other => panic!("expected spec parse error, got {other:?}"),
        }
    }

    #[test]
    fn merge_override_file_reports_structured_yaml_parse_errors() {
        let mut registry = CommandRegistry::load().unwrap();
        let dir = tempfile::tempdir().unwrap();
        let path = dir.path().join("override.yaml");
        fs::write(&path, "commands:\n  target_link_libraries: [\n").unwrap();

        let err = registry.merge_override_file(&path).unwrap_err();
        match err {
            Error::Spec(spec_err) => {
                let details = &spec_err.details;
                assert_eq!(details.format, "YAML");
                assert!(details.line.is_some());
                assert!(details.column.is_some());
            }
            other => panic!("expected spec parse error, got {other:?}"),
        }
    }

    #[test]
    fn override_with_mismatched_shape_replaces_base_command_spec() {
        let mut registry = CommandRegistry::load().unwrap();
        registry
            .merge_override_str(
                r#"
[commands.cmake_minimum_required.forms.VERSION]
pargs = 1
"#,
                PathBuf::from("override.toml"),
            )
            .unwrap();

        let CommandSpec::Discriminated { .. } = registry.get("cmake_minimum_required") else {
            panic!("expected discriminated command after mismatched override")
        };
        assert_eq!(
            registry
                .get("cmake_minimum_required")
                .form_for(Some("VERSION"))
                .pargs,
            NArgs::Fixed(1)
        );
    }
}