Stage bounded source8 typed resolution and expression lowering

crates/oa-core/src/language/analysis_source.rs

@@ -1,9 +1,10 @@
 //! Unresolved typed source8 syntax, staged for the complete source adapter.
-//! This module does not admit a Project, resolve references or enable source8.
+//! This module does not admit a Project or enable public source8.
 mod budget;
 mod cursor;
 mod declarations;
 mod lex;
+mod lower;
 mod syntax;
 
 use super::Span;

crates/oa-core/src/language/analysis_source/budget.rs

@@ -134,4 +134,21 @@ impl Budget {
     pub fn numeric_units(&self) -> u64 {
         self.numeric.usage().numeric_units
     }
+    /// Check phase allocation bounds without recharging parsed syntax or exact
+    /// work. S4 must also charge ordinary records through the inherited budget.
+    pub fn lowering_entries(&self, count: usize, span: Span) -> Result<(), Error> {
+        self.active()?;
+        if count > self.limits.entries {
+            return Err(error(span, "Source8 lowering entry limit exceeded."));
+        }
+        Ok(())
+    }
+    pub fn lowering_occurrences(&self, count: usize, span: Span) -> Result<(), Error> {
+        self.active()?;
+        // Parameter declarations are syntax entries, not reference uses.
+        if count > self.limits.references.saturating_add(self.limits.entries) {
+            return Err(error(span, "Source8 lowering occurrence limit exceeded."));
+        }
+        Ok(())
+    }
 }

crates/oa-core/src/language/analysis_source/lower.rs

@@ -0,0 +1,939 @@
+//! Staged typed resolution. The caller owns parsing, ID stabilization and the
+//! single complete-Project semantic admission after merging these additions.
+use super::declarations::{self as d, Declaration, DeclarationKind};
+use super::*;
+use crate::analysis as a;
+use crate::analysis_numeric::Dimension;
+use crate::{Element, ElementBody, Id, Kind, Layer, Project, SharedBody};
+use std::collections::{BTreeMap, BTreeSet};
+
+/// Caller-assigned file key; spans are original offsets within that file.
+pub(super) struct Unit {
+    pub file: usize,
+    pub declarations: Vec<Declaration>,
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub(super) struct Failure {
+    /// None denotes an invalid ordinary skeleton, before typed resolution.
+    pub file: Option<usize>,
+    pub error: Error,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(super) enum Category {
+    Project,
+    Element(Kind, Layer),
+    Relation,
+    Diagram,
+    Node,
+    Artifact,
+    Trace,
+    QuantityKind,
+    Unit,
+    Calculation,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(super) enum Target {
+    Global(Id),
+    Parameter {
+        calculation: Id,
+        parameter: a::ParameterId,
+    },
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(super) enum Field {
+    Algebra,
+    Kind,
+    Input(a::ParameterId),
+    Result,
+    Body,
+    Subject,
+    Type,
+    Base,
+    DisplayUnit,
+    DocumentedConstraint,
+    Predicate,
+    Override(Id),
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(super) enum Role {
+    Reference,
+    ParameterDeclaration,
+    ParameterUse,
+    CallTarget,
+    ArgumentLabel,
+    OverrideTarget,
+}
+
+/// Stable structural edges, independent of alias spelling and argument order.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(super) enum Child {
+    Item(usize),
+    Operand,
+    Left,
+    Right,
+    Condition,
+    WhenTrue,
+    WhenFalse,
+    Argument(a::ParameterId),
+    Values,
+    Initial,
+    Base,
+    Value,
+}
+
+/// An arena index is only local to this lowering result. Follow parent edges
+/// to obtain the owner/field/path identity for S3; never persist the index.
+#[derive(Debug, PartialEq, Eq)]
+pub(super) struct ExpressionSite {
+    pub file: usize,
+    pub owner: Id,
+    pub field: Field,
+    pub parent: Option<(usize, Child)>,
+    pub span: Span,
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub(super) struct Occurrence {
+    pub file: usize,
+    pub owner: Id,
+    pub field: Field,
+    pub expression: Option<usize>,
+    pub role: Role,
+    pub target: Target,
+    /// Alias/name token only, excluding @/$ and surrounding trivia.
+    pub span: Span,
+}
+
+#[derive(Debug)]
+pub(super) struct Lowered {
+    pub definitions: BTreeMap<Id, a::Definition>,
+    pub elements: BTreeMap<Id, Element>,
+    pub occurrences: Vec<Occurrence>,
+    pub expressions: Vec<ExpressionSite>,
+}
+
+#[derive(Clone, Copy)]
+struct Symbol {
+    id: Id,
+    category: Category,
+}
+
+#[derive(Default)]
+struct Tables {
+    aliases: BTreeMap<String, Symbol>,
+    ids: BTreeSet<Id>,
+    parameters: BTreeMap<Id, BTreeMap<String, a::ParameterId>>,
+    entries: usize,
+}
+
+fn category(kind: DeclarationKind) -> Category {
+    match kind {
+        DeclarationKind::QuantityKind => Category::QuantityKind,
+        DeclarationKind::Unit => Category::Unit,
+        DeclarationKind::Calculation => Category::Calculation,
+        DeclarationKind::Property(layer) => Category::Element(Kind::EngineeringProperty, layer),
+        DeclarationKind::Check(layer) => Category::Element(Kind::AnalysisCheck, layer),
+        DeclarationKind::Case(layer) => Category::Element(Kind::AnalysisCase, layer),
+    }
+}
+
+fn identity(identity: &d::IdentitySyntax, span: Span) -> Result<Id, Error> {
+    identity.value.ok_or_else(|| {
+        error(
+            span,
+            "Missing ID requires source stabilization before lowering.",
+        )
+    })
+}
+
+impl Tables {
+    fn reserve(&mut self, span: Span, budget: &Budget) -> Result<(), Error> {
+        budget.lowering_entries(self.entries + 1, span)?;
+        self.entries += 1;
+        Ok(())
+    }
+    fn insert(
+        &mut self,
+        id: Id,
+        alias: &str,
+        category: Category,
+        span: Span,
+        budget: &Budget,
+    ) -> Result<(), Error> {
+        // A phase allocation bound, not a second syntax charge. Ordinary
+        // records, typed headers and scoped parameters share this bound.
+        self.reserve(span, budget)?;
+        if self.ids.contains(&id) {
+            return Err(error(span, "Duplicate global identity."));
+        }
+        if self.aliases.contains_key(alias) {
+            return Err(error(span, format!("Duplicate global alias '{alias}'.")));
+        }
+        self.ids.insert(id);
+        self.aliases
+            .insert(alias.to_owned(), Symbol { id, category });
+        Ok(())
+    }
+
+    fn ordinary(&mut self, project: &Project, budget: &Budget) -> Result<(), Error> {
+        let at = Span::default();
+        self.insert(project.id, &project.alias, Category::Project, at, budget)?;
+        for value in project.definitions.values() {
+            let category = match &value.body {
+                a::DefinitionBody::QuantityKind(_) => Category::QuantityKind,
+                a::DefinitionBody::Unit(_) => Category::Unit,
+                a::DefinitionBody::Calculation(_) => Category::Calculation,
+            };
+            self.insert(value.id, &value.alias, category, at, budget)?;
+            if let a::DefinitionBody::Calculation(calculation) = &value.body {
+                let mut names = BTreeMap::new();
+                let mut ids = BTreeSet::new();
+                for parameter in &calculation.parameters {
+                    self.reserve(at, budget)?;
+                    if names.contains_key(&parameter.name) || !ids.insert(parameter.id) {
+                        return Err(error(
+                            at,
+                            "Duplicate parameter name or identity in ordinary catalog.",
+                        ));
+                    }
+                    names.insert(parameter.name.clone(), parameter.id);
+                }
+                self.parameters.insert(value.id, names);
+            }
+        }
+        for value in project.elements.values() {
+            self.insert(
+                value.id,
+                &value.alias,
+                Category::Element(value.kind(), value.layer()),
+                at,
+                budget,
+            )?;
+        }
+        for value in project.relations.values() {
+            self.insert(value.id, &value.alias, Category::Relation, at, budget)?;
+        }
+        for value in project.diagrams.values() {
+            self.insert(value.id, &value.alias, Category::Diagram, at, budget)?;
+            for node in value.nodes.values() {
+                self.insert(node.id, &node.alias, Category::Node, at, budget)?;
+            }
+        }
+        for value in project.artifact_links.values() {
+            self.insert(value.id, &value.alias, Category::Artifact, at, budget)?;
+        }
+        for value in project.traces.values() {
+            self.insert(value.id, &value.alias, Category::Trace, at, budget)?;
+        }
+        Ok(())
+    }
+
+    fn typed(&mut self, declaration: &Declaration, budget: &Budget) -> Result<(), Error> {
+        let header = &declaration.header;
+        let id = identity(&header.identity, header.alias.span)?;
+        self.insert(
+            id,
+            &header.alias.name,
+            category(header.kind),
+            header.alias.span,
+            budget,
+        )?;
+        if let d::Body::Calculation { parameters, .. } = &declaration.body {
+            let mut names = BTreeMap::new();
+            let mut ids = BTreeSet::new();
+            for parameter in parameters {
+                self.reserve(parameter.span, budget)?;
+                let id = a::ParameterId(identity(&parameter.identity, parameter.name.span)?);
+                if names.contains_key(&parameter.name.name) || !ids.insert(id) {
+                    return Err(error(
+                        parameter.name.span,
+                        "Duplicate parameter name or identity.",
+                    ));
+                }
+                names.insert(parameter.name.name.clone(), id);
+            }
+            self.parameters.insert(id, names);
+        }
+        Ok(())
+    }
+}
+
+/// Inputs must come from the same live Budget and stabilization pass. No scan,
+/// exact conversion or reference charge occurs here. The ordinary skeleton is
+/// not semantically admitted: its typed forward references may need additions.
+pub(super) fn lower(
+    ordinary: &Project,
+    units: &[Unit],
+    budget: &Budget,
+) -> Result<Lowered, Failure> {
+    budget
+        .active()
+        .map_err(|error| Failure { file: None, error })?;
+    let mut tables = Tables::default();
+    tables
+        .ordinary(ordinary, budget)
+        .map_err(|error| Failure { file: None, error })?;
+    let mut files = BTreeSet::new();
+    for unit in units {
+        budget
+            .lowering_entries(files.len() + 1, Span::default())
+            .map_err(|error| Failure {
+                file: Some(unit.file),
+                error,
+            })?;
+        if !files.insert(unit.file) {
+            return Err(Failure {
+                file: Some(unit.file),
+                error: error(Span::default(), "Duplicate source file key."),
+            });
+        }
+        for declaration in &unit.declarations {
+            tables.typed(declaration, budget).map_err(|error| Failure {
+                file: Some(unit.file),
+                error,
+            })?;
+        }
+    }
+    let mut output = Lowered {
+        definitions: BTreeMap::new(),
+        elements: BTreeMap::new(),
+        occurrences: Vec::new(),
+        expressions: Vec::new(),
+    };
+    for unit in units {
+        for declaration in &unit.declarations {
+            let owner = declaration
+                .header
+                .identity
+                .value
+                .expect("collected stable identity");
+            let mut resolver = Resolver {
+                tables: &tables,
+                output: &mut output,
+                budget,
+                file: unit.file,
+                owner,
+            };
+            resolver.declaration(declaration).map_err(|error| Failure {
+                file: Some(unit.file),
+                error,
+            })?;
+        }
+    }
+    Ok(output)
+}
+
+struct Resolver<'a> {
+    tables: &'a Tables,
+    output: &'a mut Lowered,
+    budget: &'a Budget,
+    file: usize,
+    owner: Id,
+}
+
+impl Resolver<'_> {
+    fn occurrence(
+        &mut self,
+        reference: &Reference,
+        field: Field,
+        expression: Option<usize>,
+        role: Role,
+        target: Target,
+    ) -> Result<(), Error> {
+        self.budget
+            .lowering_occurrences(self.output.occurrences.len() + 1, reference.span)?;
+        self.output.occurrences.push(Occurrence {
+            file: self.file,
+            owner: self.owner,
+            field,
+            expression,
+            role,
+            target,
+            span: reference.span,
+        });
+        Ok(())
+    }
+
+    fn global(
+        &mut self,
+        reference: &Reference,
+        field: Field,
+        expression: Option<usize>,
+        role: Role,
+        expected: impl FnOnce(Category) -> bool,
+    ) -> Result<Symbol, Error> {
+        let symbol = *self.tables.aliases.get(&reference.name).ok_or_else(|| {
+            error(
+                reference.span,
+                format!("Unknown global reference '@{}'.", reference.name),
+            )
+        })?;
+        if !expected(symbol.category) {
+            return Err(error(
+                reference.span,
+                format!(
+                    "Wrong reference domain for '@{}': {:?}.",
+                    reference.name, symbol.category
+                ),
+            ));
+        }
+        self.occurrence(
+            reference,
+            field,
+            expression,
+            role,
+            Target::Global(symbol.id),
+        )?;
+        Ok(symbol)
+    }
+
+    fn definition_ref(
+        &mut self,
+        reference: &Reference,
+        field: Field,
+        expression: Option<usize>,
+        expected: Category,
+    ) -> Result<a::DefinitionRef, Error> {
+        self.global(reference, field, expression, Role::Reference, |category| {
+            category == expected
+        })
+        .map(|symbol| a::DefinitionRef::Local(symbol.id))
+    }
+
+    fn value_type(
+        &mut self,
+        value: &d::TypeSyntax,
+        field: Field,
+    ) -> Result<a::AnalysisType, Error> {
+        let scalar =
+            match &value.scalar.kind {
+                d::ScalarKind::Boolean => a::ScalarType::Boolean,
+                d::ScalarKind::Number => a::ScalarType::Number,
+                d::ScalarKind::Quantity(reference) => a::ScalarType::Quantity(
+                    self.definition_ref(reference, field, None, Category::QuantityKind)?,
+                ),
+            };
+        Ok(if value.list {
+            a::AnalysisType::List(scalar)
+        } else {
+            a::AnalysisType::Scalar(scalar)
+        })
+    }
+
+    fn subject(&mut self, reference: &Reference) -> Result<a::AnalysisSubject, Error> {
+        let symbol = self.global(
+            reference,
+            Field::Subject,
+            None,
+            Role::Reference,
+            |category| matches!(category, Category::Element(..) | Category::Relation),
+        )?;
+        Ok(if symbol.category == Category::Relation {
+            a::AnalysisSubject::Relation(symbol.id)
+        } else {
+            a::AnalysisSubject::Element(symbol.id)
+        })
+    }
+
+    fn optional_subject(
+        &mut self,
+        subject: &Option<d::Field<Option<Reference>>>,
+    ) -> Result<Option<a::AnalysisSubject>, Error> {
+        subject
+            .as_ref()
+            .and_then(|field| field.value.as_ref())
+            .map(|reference| self.subject(reference))
+            .transpose()
+    }
+
+    fn declaration(&mut self, declaration: &Declaration) -> Result<(), Error> {
+        let header = &declaration.header;
+        let definition = match &declaration.body {
+            d::Body::QuantityKind { dimension, algebra } => {
+                Some(a::DefinitionBody::QuantityKind(a::QuantityKindDefinition {
+                    dimension: Dimension::new(dimension.value.exponents)
+                        .map_err(|cause| error(dimension.value_span, cause.to_string()))?,
+                    algebra: match &algebra.value {
+                        d::AlgebraSyntax::Linear => a::QuantityAlgebra::Linear,
+                        d::AlgebraSyntax::Affine(reference) => a::QuantityAlgebra::Affine {
+                            difference: self.definition_ref(
+                                reference,
+                                Field::Algebra,
+                                None,
+                                Category::QuantityKind,
+                            )?,
+                        },
+                    },
+                }))
+            }
+            d::Body::Unit {
+                kind,
+                scale,
+                offset,
+                symbol,
+            } => Some(a::DefinitionBody::Unit(a::UnitDefinition {
+                kind: self.definition_ref(
+                    &kind.value,
+                    Field::Kind,
+                    None,
+                    Category::QuantityKind,
+                )?,
+                scale: scale.value.value.clone(),
+                offset: offset.value.value.clone(),
+                symbol: symbol.value.clone(),
+            })),
+            d::Body::Calculation {
+                parameters,
+                result,
+                body,
+            } => {
+                let mut lowered = Vec::new();
+                for parameter in parameters {
+                    self.budget
+                        .lowering_entries(lowered.len() + 1, parameter.span)?;
+                    let id = self.tables.parameters[&self.owner][&parameter.name.name];
+                    self.occurrence(
+                        &parameter.name,
+                        Field::Input(id),
+                        None,
+                        Role::ParameterDeclaration,
+                        Target::Parameter {
+                            calculation: self.owner,
+                            parameter: id,
+                        },
+                    )?;
+                    lowered.push(a::Parameter {
+                        id,
+                        name: parameter.name.name.clone(),
+                        value_type: self.value_type(&parameter.value_type, Field::Input(id))?,
+                    });
+                }
+                Some(a::DefinitionBody::Calculation(a::CalculationDefinition {
+                    parameters: lowered,
+                    result: self.value_type(&result.value, Field::Result)?,
+                    body: self.binding(&body.value, Field::Body, Some(self.owner))?,
+                }))
+            }
+            _ => None,
+        };
+        let description = declaration
+            .description
+            .as_ref()
+            .map_or_else(String::new, |field| field.value.clone());
+        if let Some(body) = definition {
+            self.output.definitions.insert(
+                self.owner,
+                a::Definition {
+                    id: self.owner,
+                    alias: header.alias.name.clone(),
+                    name: header.name.clone(),
+                    description,
+                    body,
+                },
+            );
+            return Ok(());
+        }
+        let (layer, body) = match (&declaration.body, header.kind) {
+            (
+                d::Body::Property {
+                    subject,
+                    value_type,
+                    base,
+                    display_unit,
+                },
+                DeclarationKind::Property(layer),
+            ) => (
+                layer,
+                SharedBody::EngineeringProperty {
+                    subject: self.subject(&subject.value)?,
+                    value_type: self.value_type(&value_type.value, Field::Type)?,
+                    base: self.binding(&base.value, Field::Base, None)?,
+                    display_unit: display_unit
+                        .as_ref()
+                        .and_then(|field| field.value.as_ref())
+                        .map(|reference| {
+                            self.definition_ref(reference, Field::DisplayUnit, None, Category::Unit)
+                        })
+                        .transpose()?,
+                },
+            ),
+            (
+                d::Body::Check {
+                    subject,
+                    documented_constraint,
+                    predicate,
+                },
+                DeclarationKind::Check(layer),
+            ) => (
+                layer,
+                SharedBody::AnalysisCheck {
+                    subject: self.optional_subject(subject)?,
+                    documented_constraint: documented_constraint
+                        .as_ref()
+                        .and_then(|field| field.value.as_ref())
+                        .map(|reference| {
+                            self.global(
+                                reference,
+                                Field::DocumentedConstraint,
+                                None,
+                                Role::Reference,
+                                |category| {
+                                    matches!(category, Category::Element(Kind::Constraint, _))
+                                },
+                            )
+                            .map(|symbol| symbol.id)
+                        })
+                        .transpose()?,
+                    predicate: self.binding(&predicate.value, Field::Predicate, None)?,
+                },
+            ),
+            (
+                d::Body::Case {
+                    subject, overrides, ..
+                },
+                DeclarationKind::Case(layer),
+            ) => {
+                let subject = self.optional_subject(subject)?;
+                let mut lowered = BTreeMap::new();
+                for entry in &overrides.value {
+                    let property = self
+                        .global(
+                            &entry.target,
+                            Field::Base,
+                            None,
+                            Role::OverrideTarget,
+                            |category| {
+                                matches!(category, Category::Element(Kind::EngineeringProperty, _))
+                            },
+                        )?
+                        .id;
+                    // Replace the placeholder field after resolution so the key
+                    // and its binding share their stable override identity.
+                    self.output
+                        .occurrences
+                        .last_mut()
+                        .expect("override occurrence")
+                        .field = Field::Override(property);
+                    if lowered.contains_key(&property) {
+                        return Err(error(
+                            entry.target.span,
+                            "Duplicate resolved override target.",
+                        ));
+                    }
+                    self.budget
+                        .lowering_entries(lowered.len() + 1, entry.span)?;
+                    lowered.insert(
+                        property,
+                        self.binding(&entry.binding, Field::Override(property), None)?,
+                    );
+                }
+                (
+                    layer,
+                    SharedBody::AnalysisCase {
+                        subject,
+                        base: a::BaselineBase::ModelBaseline,
+                        overrides: lowered,
+                    },
+                )
+            }
+            _ => {
+                return Err(error(
+                    header.kind_span,
+                    "Typed declaration header/body mismatch.",
+                ));
+            }
+        };
+        self.output.elements.insert(
+            self.owner,
+            Element {
+                id: self.owner,
+                alias: header.alias.name.clone(),
+                name: header.name.clone(),
+                description,
+                parent: None,
+                body: ElementBody::shared_in(layer, body),
+            },
+        );
+        Ok(())
+    }
+
+    fn binding(
+        &mut self,
+        binding: &Binding,
+        field: Field,
+        calculation: Option<Id>,
+    ) -> Result<a::Binding, Error> {
+        match binding {
+            Binding::Unbound(_) => Ok(a::Binding::Unbound),
+            Binding::Expression(expression) => self
+                .expression(expression, field, calculation)
+                .map(a::Binding::Expression),
+        }
+    }
+
+    fn call(
+        &mut self,
+        definition: &Reference,
+        arguments: &[Argument],
+        field: Field,
+        site: usize,
+    ) -> Result<Call, Error> {
+        let calculation = self
+            .global(
+                definition,
+                field,
+                Some(site),
+                Role::CallTarget,
+                |category| category == Category::Calculation,
+            )?
+            .id;
+        let tables = self.tables;
+        let signature = &tables.parameters[&calculation];
+        let mut parameters = Vec::new();
+        let mut seen = BTreeSet::new();
+        for argument in arguments {
+            self.budget
+                .lowering_entries(parameters.len() + 1, argument.parameter.span)?;
+            let parameter = *signature.get(&argument.parameter.name).ok_or_else(|| {
+                error(
+                    argument.parameter.span,
+                    "Unknown argument name in called calculation.",
+                )
+            })?;
+            if !seen.insert(parameter) {
+                return Err(error(
+                    argument.parameter.span,
+                    "Duplicate resolved argument parameter.",
+                ));
+            }
+            self.occurrence(
+                &argument.parameter,
+                field,
+                Some(site),
+                Role::ArgumentLabel,
+                Target::Parameter {
+                    calculation,
+                    parameter,
+                },
+            )?;
+            parameters.push(parameter);
+        }
+        // Argument-set/type checking remains in existing semantic admission.
+        Ok(Call {
+            calculation,
+            parameters,
+        })
+    }
+
+    fn expression(
+        &mut self,
+        root: &Expression,
+        field: Field,
+        calculation: Option<Id>,
+    ) -> Result<a::Expr, Error> {
+        enum Work<'a> {
+            Visit(&'a Expression, Option<(usize, Child)>),
+            Build(&'a Expression, usize, Option<Call>, usize),
+        }
+        let mut work = vec![Work::Visit(root, None)];
+        let mut values = Vec::new();
+        while let Some(task) = work.pop() {
+            match task {
+                Work::Visit(expression, parent) => {
+                    self.budget
+                        .lowering_entries(self.output.expressions.len() + 1, expression.span)?;
+                    let site = self.output.expressions.len();
+                    self.output.expressions.push(ExpressionSite {
+                        file: self.file,
+                        owner: self.owner,
+                        field,
+                        parent,
+                        span: expression.span,
+                    });
+                    let call = if let ExpressionKind::Call {
+                        definition,
+                        arguments,
+                    } = &expression.kind
+                    {
+                        Some(self.call(definition, arguments, field, site)?)
+                    } else {
+                        None
+                    };
+                    let child_count = match &expression.kind {
+                        ExpressionKind::List(items) => items.len(),
+                        ExpressionKind::Call { arguments, .. } => arguments.len(),
+                        ExpressionKind::Unary { .. }
+                        | ExpressionKind::Power { .. }
+                        | ExpressionKind::AsKind { .. } => 1,
+                        ExpressionKind::Binary { .. } | ExpressionKind::Sum { .. } => 2,
+                        ExpressionKind::If { .. } => 3,
+                        _ => 0,
+                    };
+                    self.budget
+                        .lowering_entries(work.len() + child_count + 1, expression.span)?;
+                    let mut children = Vec::with_capacity(child_count);
+                    match &expression.kind {
+                        ExpressionKind::List(items) => children.extend(
+                            items
+                                .iter()
+                                .enumerate()
+                                .map(|(index, child)| (child, Child::Item(index))),
+                        ),
+                        ExpressionKind::Unary { operand, .. } => {
+                            children.push((operand.as_ref(), Child::Operand))
+                        }
+                        ExpressionKind::Binary { left, right, .. } => children
+                            .extend([(left.as_ref(), Child::Left), (right.as_ref(), Child::Right)]),
+                        ExpressionKind::If {
+                            condition,
+                            when_true,
+                            when_false,
+                        } => children.extend([
+                            (condition.as_ref(), Child::Condition),
+                            (when_true.as_ref(), Child::WhenTrue),
+                            (when_false.as_ref(), Child::WhenFalse),
+                        ]),
+                        ExpressionKind::Call { arguments, .. } => children.extend(
+                            arguments
+                                .iter()
+                                .zip(&call.as_ref().expect("call signature").parameters)
+                                .map(|(argument, id)| (&argument.value, Child::Argument(*id))),
+                        ),
+                        ExpressionKind::Sum { values, initial } => children.extend([
+                            (values.as_ref(), Child::Values),
+                            (initial.as_ref(), Child::Initial),
+                        ]),
+                        ExpressionKind::Power { base, .. } => {
+                            children.push((base.as_ref(), Child::Base))
+                        }
+                        ExpressionKind::AsKind { value, .. } => {
+                            children.push((value.as_ref(), Child::Value))
+                        }
+                        _ => {}
+                    }
+                    work.push(Work::Build(expression, site, call, children.len()));
+                    work.extend(
+                        children
+                            .into_iter()
+                            .rev()
+                            .map(|(child, edge)| Work::Visit(child, Some((site, edge)))),
+                    );
+                }
+                Work::Build(expression, site, call, count) => {
+                    let start = values.len() - count;
+                    let mut children = values.split_off(start).into_iter();
+                    let next = |children: &mut std::vec::IntoIter<a::Expr>| {
+                        Box::new(children.next().expect("visited expression child"))
+                    };
+                    use ExpressionKind as E;
+                    let value = match &expression.kind {
+                        E::Boolean(value) => a::Expr::Boolean(*value),
+                        E::Number(value) => a::Expr::Number(value.clone()),
+                        E::Quantity { magnitude, unit } => a::Expr::Quantity {
+                            magnitude: magnitude.clone(),
+                            unit: self.definition_ref(unit, field, Some(site), Category::Unit)?,
+                        },
+                        E::Property(reference) => a::Expr::Property(
+                            self.global(
+                                reference,
+                                field,
+                                Some(site),
+                                Role::Reference,
+                                |category| {
+                                    matches!(
+                                        category,
+                                        Category::Element(Kind::EngineeringProperty, _)
+                                    )
+                                },
+                            )?
+                            .id,
+                        ),
+                        E::Parameter(reference) => {
+                            let calculation = calculation.ok_or_else(|| {
+                                error(
+                                    reference.span,
+                                    "Parameter use is only valid in its calculation body.",
+                                )
+                            })?;
+                            let parameter = *self.tables.parameters[&calculation]
+                                .get(&reference.name)
+                                .ok_or_else(|| {
+                                    error(
+                                        reference.span,
+                                        "Unknown parameter in owning calculation.",
+                                    )
+                                })?;
+                            self.occurrence(
+                                reference,
+                                field,
+                                Some(site),
+                                Role::ParameterUse,
+                                Target::Parameter {
+                                    calculation,
+                                    parameter,
+                                },
+                            )?;
+                            a::Expr::Parameter(parameter)
+                        }
+                        E::List(_) => a::Expr::List(children.collect()),
+                        E::Unary { op, .. } => a::Expr::Unary {
+                            op: *op,
+                            operand: next(&mut children),
+                        },
+                        E::Binary { op, .. } => a::Expr::Binary {
+                            op: *op,
+                            left: next(&mut children),
+                            right: next(&mut children),
+                        },
+                        E::If { .. } => a::Expr::If {
+                            condition: next(&mut children),
+                            when_true: next(&mut children),
+                            when_false: next(&mut children),
+                        },
+                        E::Call { .. } => {
+                            let call = call.expect("resolved call");
+                            a::Expr::Call {
+                                definition: a::DefinitionRef::Local(call.calculation),
+                                arguments: call.parameters.into_iter().zip(children).collect(),
+                            }
+                        }
+                        E::Sum { .. } => a::Expr::Sum {
+                            values: next(&mut children),
+                            initial: next(&mut children),
+                        },
+                        E::Power { exponent, .. } => a::Expr::Power {
+                            base: next(&mut children),
+                            exponent: *exponent,
+                        },
+                        E::AsKind { kind, .. } => a::Expr::AsKind {
+                            kind: self.definition_ref(
+                                kind,
+                                field,
+                                Some(site),
+                                Category::QuantityKind,
+                            )?,
+                            value: next(&mut children),
+                        },
+                    };
+                    self.budget
+                        .lowering_entries(values.len() + 1, expression.span)?;
+                    values.push(value);
+                }
+            }
+        }
+        Ok(values.pop().expect("one lowered expression"))
+    }
+}
+
+struct Call {
+    calculation: Id,
+    parameters: Vec<a::ParameterId>,
+}
+
+#[cfg(test)]
+mod tests;

crates/oa-core/src/language/analysis_source/lower/fixtures/ordinary-oa.arcadia

@@ -0,0 +1,7 @@
+arcadia 7;
+project response_budget "Response budget" id "4210b9f2-7046-47f0-aa3b-153f626a579d" {
+    oa_activity respond "Respond" id "cabec6a1-7d5d-48f3-8d2d-a7fc8cf78f59" {
+        oa_activity receive "Receive" id "4ab9a8a7-7552-488d-9862-e14b89e7b353" {}
+        oa_activity dispatch "Dispatch" id "6df991ba-4c5e-4535-99e2-524ae274ee8b" {}
+    }
+}

crates/oa-core/src/language/analysis_source/lower/fixtures/ordinary-sa.arcadia

@@ -0,0 +1,7 @@
+arcadia 7;
+project response_budget "Response budget" id "c210b9f2-7046-47f0-aa3b-153f626a579d" {
+    sa_function respond "Respond" id "4abec6a1-7d5d-48f3-8d2d-a7fc8cf78f59" {
+        sa_function receive "Receive" id "cab9a8a7-7552-488d-9862-e14b89e7b353" {}
+        sa_function dispatch "Dispatch" id "edf991ba-4c5e-4535-99e2-524ae274ee8b" {}
+    }
+}

crates/oa-core/src/language/analysis_source/lower/fixtures/typed-oa.arcadia

@@ -0,0 +1,43 @@
+// Staged typed roots from the r2 example; ordinary roots are supplied separately.
+// Forward uses precede the neutral definitions. 雪 keeps offsets UTF-8 sensitive.
+oa_property receive_time "Receive time" id "63a931c2-675a-4fce-89e5-04361cb99450" {
+    subject @receive; type Quantity(@duration); display_unit @millisecond;
+    base 750 [@millisecond];
+}
+oa_property dispatch_time "Dispatch time" id "c33fc772-2a60-4044-9af9-73c61c563ace" {
+    subject @dispatch; type Quantity(@duration); display_unit @second;
+    base 1 [@second];
+}
+oa_property total_time "Total time" id "bd5b68e8-65fc-4e35-9071-a73061316a4b" {
+    subject @respond; type Quantity(@duration); display_unit @second;
+    base @combine(a: @receive_time, b: @dispatch_time);
+}
+oa_property limit "Allowed duration" id "437bedbb-2cf4-44ee-a139-6563cc5086ec" {
+    subject @respond; type Quantity(@duration); display_unit @second;
+    base 2 [@second];
+}
+oa_check budget "Response budget" id "bac0de99-9d2f-4e53-9158-d424ecac61bf" {
+    subject none; documented_constraint none; predicate @total_time <= @limit;
+}
+oa_analysis degraded "Degraded radio" id "38036c65-16d4-449c-837b-91eb141c1d93" {
+    subject none; base ModelBaseline;
+    overrides { @receive_time = 1250 [@millisecond]; };
+}
+oa_analysis unmeasured "Unmeasured radio" id "99d3e09a-0ec3-4194-9dd4-9f3de6625cde" {
+    subject none; base ModelBaseline;
+    overrides { @receive_time = unbound; };
+}
+calculation combine "Combine durations" id "fd7ce7ab-f789-40bc-b699-0c37f1b6902f" {
+    input a id "28ff40b0-1b8f-4735-8536-5a6ab21b56cb" : Quantity(@duration);
+    input b id "7a47cc1e-8ae5-4551-b2d8-8a68108e0976" : Quantity(@duration);
+    result Quantity(@duration); body $a + $b;
+}
+unit second "Second" id "534f4672-1ba5-4157-8b0a-b9cf41d0a3ce" {
+    kind @duration; scale 1; offset 0; symbol "s";
+}
+unit millisecond "Millisecond" id "39053f37-fec9-4708-9f0a-3959d223f891" {
+    kind @duration; scale ratio(1, 1000); offset 0; symbol "ms";
+}
+quantity_kind duration "Duration" id "188b911c-5f8b-431c-9eea-2d41f3953767" {
+    dimension { time 1; }; algebra Linear;
+}

crates/oa-core/src/language/analysis_source/lower/fixtures/typed-sa.arcadia

@@ -0,0 +1,43 @@
+// Staged typed roots from the r2 example; ordinary roots are supplied separately.
+// Forward uses precede the neutral definitions. 雪 keeps offsets UTF-8 sensitive.
+sa_property receive_time "Receive time" id "e3a931c2-675a-4fce-89e5-04361cb99450" {
+    subject @receive; type Quantity(@duration); display_unit @millisecond;
+    base 750 [@millisecond];
+}
+sa_property dispatch_time "Dispatch time" id "433fc772-2a60-4044-9af9-73c61c563ace" {
+    subject @dispatch; type Quantity(@duration); display_unit @second;
+    base 1 [@second];
+}
+sa_property total_time "Total time" id "3d5b68e8-65fc-4e35-9071-a73061316a4b" {
+    subject @respond; type Quantity(@duration); display_unit @second;
+    base @combine(a: @receive_time, b: @dispatch_time);
+}
+sa_property limit "Allowed duration" id "c37bedbb-2cf4-44ee-a139-6563cc5086ec" {
+    subject @respond; type Quantity(@duration); display_unit @second;
+    base 2 [@second];
+}
+sa_check budget "Response budget" id "3ac0de99-9d2f-4e53-9158-d424ecac61bf" {
+    subject none; documented_constraint none; predicate @total_time <= @limit;
+}
+sa_analysis degraded "Degraded radio" id "b8036c65-16d4-449c-837b-91eb141c1d93" {
+    subject none; base ModelBaseline;
+    overrides { @receive_time = 1250 [@millisecond]; };
+}
+sa_analysis unmeasured "Unmeasured radio" id "19d3e09a-0ec3-4194-9dd4-9f3de6625cde" {
+    subject none; base ModelBaseline;
+    overrides { @receive_time = unbound; };
+}
+calculation combine "Combine durations" id "7d7ce7ab-f789-40bc-b699-0c37f1b6902f" {
+    input a id "28ff40b0-1b8f-4735-8536-5a6ab21b56cb" : Quantity(@duration);
+    input b id "7a47cc1e-8ae5-4551-b2d8-8a68108e0976" : Quantity(@duration);
+    result Quantity(@duration); body $a + $b;
+}
+unit second "Second" id "d34f4672-1ba5-4157-8b0a-b9cf41d0a3ce" {
+    kind @duration; scale 1; offset 0; symbol "s";
+}
+unit millisecond "Millisecond" id "b9053f37-fec9-4708-9f0a-3959d223f891" {
+    kind @duration; scale ratio(1, 1000); offset 0; symbol "ms";
+}
+quantity_kind duration "Duration" id "988b911c-5f8b-431c-9eea-2d41f3953767" {
+    dimension { time 1; }; algebra Linear;
+}

crates/oa-core/src/language/analysis_source/lower/oracle.rs

@@ -0,0 +1,263 @@
+//! Independent model construction: never parses source or calls the writer.
+use crate::analysis::*;
+use crate::analysis_numeric::{Dimension, Exact, ExactWire, WorkLimits, WorkMeter};
+use crate::*;
+use std::collections::BTreeMap;
+
+pub(super) const NAMES: [(&str, &str); 14] = [
+    ("duration", "Duration"),
+    ("second", "Second"),
+    ("millisecond", "Millisecond"),
+    ("combine", "Combine durations"),
+    ("respond", "Respond"),
+    ("receive", "Receive"),
+    ("dispatch", "Dispatch"),
+    ("receive_time", "Receive time"),
+    ("dispatch_time", "Dispatch time"),
+    ("total_time", "Total time"),
+    ("limit", "Allowed duration"),
+    ("budget", "Response budget"),
+    ("degraded", "Degraded radio"),
+    ("unmeasured", "Unmeasured radio"),
+];
+
+fn named(alias: &str) -> String {
+    NAMES
+        .iter()
+        .find(|(key, _)| *key == alias)
+        .unwrap()
+        .1
+        .into()
+}
+fn local(id: Id) -> DefinitionRef {
+    DefinitionRef::Local(id)
+}
+fn quantity(value: i64, unit: Id) -> Expr {
+    Expr::Quantity {
+        magnitude: Exact::from_integer(value),
+        unit: local(unit),
+    }
+}
+fn expression(value: Expr) -> Binding {
+    Binding::Expression(value)
+}
+fn binary(op: BinaryOp, left: Expr, right: Expr) -> Expr {
+    Expr::Binary {
+        op,
+        left: Box::new(left),
+        right: Box::new(right),
+    }
+}
+
+pub(super) fn project(layer: Layer) -> Project {
+    // OA is the fixed r2 set; SA independently constructs fresh global IDs.
+    let id = |text| {
+        let id = Id::parse_str(text).unwrap();
+        if layer == Layer::Oa {
+            id
+        } else {
+            Id::from_u128(id.as_u128() ^ (1 << 127))
+        }
+    };
+    let project_id = id("4210b9f2-7046-47f0-aa3b-153f626a579d");
+    let duration = id("188b911c-5f8b-431c-9eea-2d41f3953767");
+    let second = id("534f4672-1ba5-4157-8b0a-b9cf41d0a3ce");
+    let millisecond = id("39053f37-fec9-4708-9f0a-3959d223f891");
+    let combine = id("fd7ce7ab-f789-40bc-b699-0c37f1b6902f");
+    // Parameter IDs may be reused in another calculation/project.
+    let a = ParameterId(Id::parse_str("28ff40b0-1b8f-4735-8536-5a6ab21b56cb").unwrap());
+    let b = ParameterId(Id::parse_str("7a47cc1e-8ae5-4551-b2d8-8a68108e0976").unwrap());
+    let respond = id("cabec6a1-7d5d-48f3-8d2d-a7fc8cf78f59");
+    let receive = id("4ab9a8a7-7552-488d-9862-e14b89e7b353");
+    let dispatch = id("6df991ba-4c5e-4535-99e2-524ae274ee8b");
+    let receive_time = id("63a931c2-675a-4fce-89e5-04361cb99450");
+    let dispatch_time = id("c33fc772-2a60-4044-9af9-73c61c563ace");
+    let total = id("bd5b68e8-65fc-4e35-9071-a73061316a4b");
+    let limit = id("437bedbb-2cf4-44ee-a139-6563cc5086ec");
+    let check = id("bac0de99-9d2f-4e53-9158-d424ecac61bf");
+    let degraded = id("38036c65-16d4-449c-837b-91eb141c1d93");
+    let unmeasured = id("99d3e09a-0ec3-4194-9dd4-9f3de6625cde");
+    let duration_type = || AnalysisType::Scalar(ScalarType::Quantity(local(duration)));
+    let definition = |id, alias: &str, body| Definition {
+        id,
+        alias: alias.into(),
+        name: named(alias),
+        description: String::new(),
+        body,
+    };
+    let shared = |id, alias: &str, body| Element {
+        id,
+        alias: alias.into(),
+        name: named(alias),
+        description: String::new(),
+        parent: None,
+        body: ElementBody::shared_in(layer, body),
+    };
+    let work = |id, alias: &str, parent| Element {
+        id,
+        alias: alias.into(),
+        name: named(alias),
+        description: String::new(),
+        parent,
+        body: if layer == Layer::Oa {
+            ElementBody::Oa(OaBody::Activity)
+        } else {
+            ElementBody::Sa(SaBody::Function)
+        },
+    };
+    let definitions = [
+        definition(
+            duration,
+            "duration",
+            DefinitionBody::QuantityKind(QuantityKindDefinition {
+                dimension: Dimension::new([0, 0, 1, 0, 0, 0, 0]).unwrap(),
+                algebra: QuantityAlgebra::Linear,
+            }),
+        ),
+        definition(
+            second,
+            "second",
+            DefinitionBody::Unit(UnitDefinition {
+                kind: local(duration),
+                scale: Exact::from_integer(1),
+                offset: Exact::from_integer(0),
+                symbol: "s".into(),
+            }),
+        ),
+        definition(
+            millisecond,
+            "millisecond",
+            DefinitionBody::Unit(UnitDefinition {
+                kind: local(duration),
+                scale: Exact::from_wire(
+                    &ExactWire {
+                        numerator: "1".into(),
+                        denominator: "1000".into(),
+                    },
+                    &mut WorkMeter::new(WorkLimits::REFERENCE),
+                )
+                .unwrap(),
+                offset: Exact::from_integer(0),
+                symbol: "ms".into(),
+            }),
+        ),
+        definition(
+            combine,
+            "combine",
+            DefinitionBody::Calculation(CalculationDefinition {
+                parameters: vec![
+                    Parameter {
+                        id: a,
+                        name: "a".into(),
+                        value_type: duration_type(),
+                    },
+                    Parameter {
+                        id: b,
+                        name: "b".into(),
+                        value_type: duration_type(),
+                    },
+                ],
+                result: duration_type(),
+                body: expression(binary(
+                    BinaryOp::Add,
+                    Expr::Parameter(a),
+                    Expr::Parameter(b),
+                )),
+            }),
+        ),
+    ]
+    .into_iter()
+    .map(|definition| (definition.id, definition))
+    .collect();
+    let property = |id, alias, subject, display, base| {
+        shared(
+            id,
+            alias,
+            SharedBody::EngineeringProperty {
+                subject: AnalysisSubject::Element(subject),
+                value_type: duration_type(),
+                display_unit: Some(local(display)),
+                base: expression(base),
+            },
+        )
+    };
+    let case = |id, alias, binding| {
+        shared(
+            id,
+            alias,
+            SharedBody::AnalysisCase {
+                subject: None,
+                base: BaselineBase::ModelBaseline,
+                overrides: BTreeMap::from([(receive_time, binding)]),
+            },
+        )
+    };
+    let elements = [
+        work(respond, "respond", None),
+        work(receive, "receive", Some(respond)),
+        work(dispatch, "dispatch", Some(respond)),
+        property(
+            receive_time,
+            "receive_time",
+            receive,
+            millisecond,
+            quantity(750, millisecond),
+        ),
+        property(
+            dispatch_time,
+            "dispatch_time",
+            dispatch,
+            second,
+            quantity(1, second),
+        ),
+        property(
+            total,
+            "total_time",
+            respond,
+            second,
+            Expr::Call {
+                definition: local(combine),
+                arguments: BTreeMap::from([
+                    (a, Expr::Property(receive_time)),
+                    (b, Expr::Property(dispatch_time)),
+                ]),
+            },
+        ),
+        property(limit, "limit", respond, second, quantity(2, second)),
+        shared(
+            check,
+            "budget",
+            SharedBody::AnalysisCheck {
+                subject: None,
+                documented_constraint: None,
+                predicate: expression(binary(
+                    BinaryOp::LessOrEqual,
+                    Expr::Property(total),
+                    Expr::Property(limit),
+                )),
+            },
+        ),
+        case(
+            degraded,
+            "degraded",
+            expression(quantity(1250, millisecond)),
+        ),
+        case(unmeasured, "unmeasured", Binding::Unbound),
+    ]
+    .into_iter()
+    .map(|element| (element.id, element))
+    .collect();
+    Project {
+        schema_version: 8,
+        id: project_id,
+        alias: "response_budget".into(),
+        name: "Response budget".into(),
+        description: String::new(),
+        definitions,
+        elements,
+        relations: BTreeMap::new(),
+        diagrams: BTreeMap::new(),
+        artifact_links: BTreeMap::new(),
+        traces: BTreeMap::new(),
+    }
+}

crates/oa-core/src/language/analysis_source/lower/tests.rs

@@ -0,0 +1,875 @@
+use super::*;
+use crate::language::ParseLimits;
+use crate::language::analysis_source::{budget::Limits, cursor::Cursor};
+
+#[path = "oracle.rs"]
+mod oracle;
+
+const OA: &str = include_str!("fixtures/typed-oa.arcadia");
+const SA: &str = include_str!("fixtures/typed-sa.arcadia");
+const ORDINARY_OA: &str = include_str!("fixtures/ordinary-oa.arcadia");
+const ORDINARY_SA: &str = include_str!("fixtures/ordinary-sa.arcadia");
+
+fn budget() -> Budget {
+    Budget::new(Limits::source8(ParseLimits::UNLIMITED)).unwrap()
+}
+fn id(text: &str) -> Id {
+    Id::parse_str(text).unwrap()
+}
+fn by_alias(project: &Project, alias: &str) -> Id {
+    project
+        .identities()
+        .into_iter()
+        .find(|(_, name)| *name == alias)
+        .unwrap()
+        .0
+}
+fn ordinary(source: &str) -> Project {
+    crate::language::parse(source).unwrap()
+}
+fn unit(source: &str, file: usize, budget: &mut Budget) -> Unit {
+    let tokens = lex::tokens(source, budget).unwrap();
+    let mut cursor = Cursor::new(source, &tokens, budget);
+    let mut declarations = Vec::new();
+    while cursor.cursor < tokens.len() {
+        declarations.push(d::parse(&mut cursor, 8, None).unwrap());
+    }
+    Unit { file, declarations }
+}
+fn merge(mut ordinary: Project, lowered: Lowered) -> Project {
+    ordinary.definitions.extend(lowered.definitions);
+    ordinary.elements.extend(lowered.elements);
+    ordinary
+}
+fn admit(project: &Project) {
+    a::admit(project, a::AdmissionLimits::REFERENCE).unwrap();
+}
+fn failure(source: &str, ordinary: &Project) -> Failure {
+    let mut budget = budget();
+    let unit = unit(source, 7, &mut budget);
+    lower(ordinary, &[unit], &budget).unwrap_err()
+}
+
+#[test]
+fn staged_oa_and_sa_lowering_match_complete_independent_17_uuid_oracles() {
+    for (layer, ordinary_source, typed_source) in
+        [(Layer::Oa, ORDINARY_OA, OA), (Layer::Sa, ORDINARY_SA, SA)]
+    {
+        let expected = oracle::project(layer);
+        assert_eq!(expected.name, "Response budget");
+        assert_eq!(expected.identities().len(), 15); // two additional scoped IDs
+        for (alias, name) in oracle::NAMES {
+            let object = by_alias(&expected, alias);
+            let actual_name = expected
+                .definitions
+                .get(&object)
+                .map(|value| value.name.as_str())
+                .or_else(|| {
+                    expected
+                        .elements
+                        .get(&object)
+                        .map(|value| value.name.as_str())
+                })
+                .unwrap();
+            assert_eq!(actual_name, name);
+            assert_ne!(actual_name, alias);
+        }
+        let mut budget = budget();
+        let units = [unit(typed_source, 17, &mut budget)];
+        let usage = budget.usage;
+        let numeric = budget.numeric_units();
+        let skeleton = ordinary(ordinary_source);
+        let first = lower(&skeleton, &units, &budget).unwrap();
+        let second = lower(&skeleton, &units, &budget).unwrap();
+        assert_eq!(first.occurrences, second.occurrences);
+        assert_eq!(first.expressions, second.expressions);
+        assert_eq!(budget.usage, usage);
+        assert_eq!(budget.numeric_units(), numeric);
+        assert_eq!(
+            first
+                .occurrences
+                .iter()
+                .filter(|occurrence| occurrence.role != Role::ParameterDeclaration)
+                .count(),
+            usage.references
+        );
+        let actual = merge(skeleton, first);
+        assert_eq!(actual, expected);
+        admit(&actual); // the complete model's one semantic admission
+    }
+    assert!(crate::language::parse(&ORDINARY_OA.replacen("arcadia 7", "arcadia 8", 1)).is_err());
+}
+
+#[test]
+fn forward_cross_unit_resolution_keeps_original_offsets_and_shared_work() {
+    let source = OA.replace('\n', "\r\n");
+    let split = source.find("calculation combine").unwrap();
+    let sources = [&source[..split], &source[split..]];
+    let mut budget = budget();
+    let mut units = [
+        unit(sources[0], 4, &mut budget),
+        unit(sources[1], 9, &mut budget),
+    ];
+    let usage = budget.usage;
+    assert_eq!(usage.bytes, source.len());
+    let lowered = lower(&ordinary(ORDINARY_OA), &units, &budget).unwrap();
+    units.reverse();
+    // This second order uses the same bounded lowerer; output models must not
+    // depend on declaration/file traversal order. It is not an include parser.
+    let reordered = lower(&ordinary(ORDINARY_OA), &units, &budget).unwrap();
+    assert_eq!(
+        merge(ordinary(ORDINARY_OA), reordered),
+        oracle::project(Layer::Oa)
+    );
+    for occurrence in &lowered.occurrences {
+        let source = if occurrence.file == 4 {
+            sources[0]
+        } else {
+            assert_eq!(occurrence.file, 9);
+            sources[1]
+        };
+        let text = &source[occurrence.span.start..occurrence.span.end];
+        assert!(crate::valid_alias(text));
+        assert!(!text.starts_with('@') && !text.starts_with('$'));
+    }
+    assert_eq!(budget.usage, usage);
+    assert_eq!(
+        merge(ordinary(ORDINARY_OA), lowered),
+        oracle::project(Layer::Oa)
+    );
+}
+
+fn number(value: i64) -> a::Expr {
+    a::Expr::Number(crate::analysis_numeric::Exact::from_integer(value))
+}
+fn binary(op: a::BinaryOp, left: a::Expr, right: a::Expr) -> a::Expr {
+    a::Expr::Binary {
+        op,
+        left: Box::new(left),
+        right: Box::new(right),
+    }
+}
+
+#[test]
+fn all_thirteen_expression_variants_lower_to_real_typed_values_and_admit() {
+    let mut project = oracle::project(Layer::Oa);
+    let duration = by_alias(&project, "duration");
+    let second = by_alias(&project, "second");
+    let property = by_alias(&project, "receive_time");
+    let owner = by_alias(&project, "total_time");
+    let calculation = by_alias(&project, "combine");
+    let parameter = a::ParameterId(id("28ff40b0-1b8f-4735-8536-5a6ab21b56cb"));
+    let b = a::ParameterId(id("7a47cc1e-8ae5-4551-b2d8-8a68108e0976"));
+    let quantity =
+        a::AnalysisType::Scalar(a::ScalarType::Quantity(a::DefinitionRef::Local(duration)));
+    let numeric = a::AnalysisType::Scalar(a::ScalarType::Number);
+    let boolean = a::AnalysisType::Scalar(a::ScalarType::Boolean);
+    let cases = [
+        ("true", a::Expr::Boolean(true), boolean.clone()),
+        (
+            "ratio(3, 2)",
+            a::Expr::Number(
+                Exact::from_wire(
+                    &crate::analysis_numeric::ExactWire {
+                        numerator: "3".into(),
+                        denominator: "2".into(),
+                    },
+                    &mut crate::analysis_numeric::WorkMeter::new(
+                        crate::analysis_numeric::WorkLimits::REFERENCE,
+                    ),
+                )
+                .unwrap(),
+            ),
+            numeric.clone(),
+        ),
+        (
+            "2 [@second]",
+            a::Expr::Quantity {
+                magnitude: Exact::from_integer(2),
+                unit: a::DefinitionRef::Local(second),
+            },
+            quantity.clone(),
+        ),
+        (
+            "@receive_time",
+            a::Expr::Property(property),
+            quantity.clone(),
+        ),
+        ("$a", a::Expr::Parameter(parameter), quantity.clone()),
+        (
+            "[1, 2]",
+            a::Expr::List(vec![number(1), number(2)]),
+            a::AnalysisType::List(a::ScalarType::Number),
+        ),
+        (
+            "abs(-2)",
+            a::Expr::Unary {
+                op: a::UnaryOp::Absolute,
+                operand: Box::new(a::Expr::Unary {
+                    op: a::UnaryOp::Negate,
+                    operand: Box::new(number(2)),
+                }),
+            },
+            numeric.clone(),
+        ),
+        (
+            "1 + 2",
+            binary(a::BinaryOp::Add, number(1), number(2)),
+            numeric.clone(),
+        ),
+        (
+            "if(true, 1, 2)",
+            a::Expr::If {
+                condition: Box::new(a::Expr::Boolean(true)),
+                when_true: Box::new(number(1)),
+                when_false: Box::new(number(2)),
+            },
+            numeric.clone(),
+        ),
+        (
+            "@combine(b: 2 [@second], a: 1 [@second])",
+            a::Expr::Call {
+                definition: a::DefinitionRef::Local(calculation),
+                arguments: BTreeMap::from([
+                    (
+                        parameter,
+                        a::Expr::Quantity {
+                            magnitude: Exact::from_integer(1),
+                            unit: a::DefinitionRef::Local(second),
+                        },
+                    ),
+                    (
+                        b,
+                        a::Expr::Quantity {
+                            magnitude: Exact::from_integer(2),
+                            unit: a::DefinitionRef::Local(second),
+                        },
+                    ),
+                ]),
+            },
+            quantity.clone(),
+        ),
+        (
+            "sum([1, 2], 0)",
+            a::Expr::Sum {
+                values: Box::new(a::Expr::List(vec![number(1), number(2)])),
+                initial: Box::new(number(0)),
+            },
+            numeric.clone(),
+        ),
+        (
+            "power(2, -2)",
+            a::Expr::Power {
+                base: Box::new(number(2)),
+                exponent: -2,
+            },
+            numeric.clone(),
+        ),
+        (
+            "as_kind(@duration, 1 [@second])",
+            a::Expr::AsKind {
+                kind: a::DefinitionRef::Local(duration),
+                value: Box::new(a::Expr::Quantity {
+                    magnitude: Exact::from_integer(1),
+                    unit: a::DefinitionRef::Local(second),
+                }),
+            },
+            quantity.clone(),
+        ),
+    ];
+    // Remove the original check's dependent quantity comparison: each case
+    // installs a different declared result type on total_time below.
+    project.elements.remove(&by_alias(&project, "budget"));
+    for (source, expected, result_type) in cases {
+        let mut budget = budget();
+        let Binding::Expression(syntax) = super::super::parse(source, &mut budget).unwrap() else {
+            panic!("expression")
+        };
+        let mut tables = Tables::default();
+        tables.ordinary(&project, &budget).unwrap();
+        let mut output = Lowered {
+            definitions: BTreeMap::new(),
+            elements: BTreeMap::new(),
+            occurrences: Vec::new(),
+            expressions: Vec::new(),
+        };
+        let is_parameter = source == "$a";
+        let expression_owner = if is_parameter { calculation } else { owner };
+        let actual = Resolver {
+            tables: &tables,
+            output: &mut output,
+            budget: &budget,
+            file: 3,
+            owner: expression_owner,
+        }
+        .expression(
+            &syntax,
+            if is_parameter {
+                Field::Body
+            } else {
+                Field::Base
+            },
+            is_parameter.then_some(calculation),
+        )
+        .unwrap();
+        assert_eq!(actual, expected, "{source}");
+        assert_eq!(output.expressions[0].span, syntax.span);
+        assert!(output.expressions[0].parent.is_none());
+        let mut candidate = project.clone();
+        if is_parameter {
+            let a::DefinitionBody::Calculation(definition) =
+                &mut candidate.definitions.get_mut(&calculation).unwrap().body
+            else {
+                panic!("calculation")
+            };
+            definition.body = a::Binding::Expression(actual);
+        } else {
+            let SharedBody::EngineeringProperty {
+                value_type,
+                display_unit,
+                base,
+                ..
+            } = candidate
+                .elements
+                .get_mut(&owner)
+                .unwrap()
+                .body
+                .shared_mut()
+                .unwrap()
+            else {
+                panic!("property")
+            };
+            *value_type = result_type;
+            *display_unit = None;
+            *base = a::Binding::Expression(actual);
+        }
+        admit(&candidate);
+    }
+}
+
+#[test]
+fn call_sites_and_parameter_scopes_preserve_distinct_original_occurrences() {
+    let source = OA.replace("base @combine(a: @receive_time, b: @dispatch_time);", "base @combine(a: @receive_time, /* first */ b: @dispatch_time) + @combine(/* second */ b: @dispatch_time, a: @receive_time);") + r#"
+calculation other "Other" id "00000000-0000-0000-0000-000000000020" {
+    input a id "28ff40b0-1b8f-4735-8536-5a6ab21b56cb" : Number;
+    result Number; body $a;
+}
+quantity_kind collision "Global ID equals a scoped ID" id "28ff40b0-1b8f-4735-8536-5a6ab21b56cb" { dimension {}; algebra Linear; }
+calculation caller "Caller" id "00000000-0000-0000-0000-000000000021" {
+    input a id "00000000-0000-0000-0000-000000000022" : Number;
+    result Number; body @other(a: $a) + @other(a: 3);
+}
+"#;
+    let mut budget = budget();
+    let units = [unit(&source, 2, &mut budget)];
+    let output = lower(&ordinary(ORDINARY_OA), &units, &budget).unwrap();
+    let total = id("bd5b68e8-65fc-4e35-9071-a73061316a4b");
+    let combine = id("fd7ce7ab-f789-40bc-b699-0c37f1b6902f");
+    let labels: Vec<_> = output
+        .occurrences
+        .iter()
+        .filter(|value| value.owner == total && value.role == Role::ArgumentLabel)
+        .collect();
+    assert_eq!(labels.len(), 4);
+    assert_eq!(
+        labels
+            .iter()
+            .map(|value| value.span.start)
+            .collect::<BTreeSet<_>>()
+            .len(),
+        4
+    );
+    let sites: BTreeSet<_> = labels
+        .iter()
+        .map(|value| value.expression.unwrap())
+        .collect();
+    assert_eq!(sites.len(), 2);
+    let paths: Vec<_> = sites
+        .iter()
+        .map(|site| output.expressions[*site].parent.unwrap().1)
+        .collect();
+    assert_eq!(paths, [Child::Left, Child::Right]);
+    for label in labels {
+        assert_eq!(label.field, Field::Base);
+        assert!(
+            matches!(label.target, Target::Parameter { calculation, .. } if calculation == combine)
+        );
+        assert!(matches!(
+            &source[label.span.start..label.span.end],
+            "a" | "b"
+        ));
+    }
+    let reused = a::ParameterId(id("28ff40b0-1b8f-4735-8536-5a6ab21b56cb"));
+    let scopes: BTreeSet<_> = output
+        .occurrences
+        .iter()
+        .filter_map(|occurrence| match occurrence.target {
+            Target::Parameter {
+                calculation,
+                parameter,
+            } if parameter == reused => Some(calculation),
+            _ => None,
+        })
+        .collect();
+    assert_eq!(
+        scopes,
+        BTreeSet::from([combine, id("00000000-0000-0000-0000-000000000020")])
+    );
+    let caller = id("00000000-0000-0000-0000-000000000021");
+    let use_in_caller = output
+        .occurrences
+        .iter()
+        .find(|value| value.owner == caller && value.role == Role::ParameterUse)
+        .unwrap();
+    assert_eq!(
+        use_in_caller.target,
+        Target::Parameter {
+            calculation: caller,
+            parameter: a::ParameterId(id("00000000-0000-0000-0000-000000000022"))
+        }
+    );
+    for site in &output.expressions {
+        assert_eq!(site.file, 2);
+        assert!(source.get(site.span.start..site.span.end).is_some());
+    }
+    admit(&merge(ordinary(ORDINARY_OA), output));
+}
+
+#[test]
+fn missing_ids_require_stabilization_without_uuid_or_budget_churn() {
+    for source in [
+        r#"calculation pending "Pending" { result Number; body unbound; }"#,
+        r#"calculation pending "Pending" id "00000000-0000-0000-0000-000000000040" { input value : Number; result Number; body $value; }"#,
+    ] {
+        let mut budget = budget();
+        let units = [unit(source, 3, &mut budget)];
+        let usage = budget.usage;
+        let skeleton = ordinary(ORDINARY_OA);
+        let first = lower(&skeleton, &units, &budget).unwrap_err();
+        assert_eq!(first, lower(&skeleton, &units, &budget).unwrap_err());
+        assert!(first.error.message.contains("stabilization"));
+        assert_eq!(budget.usage, usage);
+        let declaration = &units[0].declarations[0];
+        if declaration.header.identity.value.is_none() {
+            assert!(declaration.header.identity.insertion.is_some());
+        } else {
+            let d::Body::Calculation { parameters, .. } = &declaration.body else {
+                panic!("calculation")
+            };
+            assert!(parameters[0].identity.value.is_none());
+            assert!(parameters[0].identity.insertion.is_some());
+        }
+    }
+}
+
+#[test]
+fn duplicate_global_aliases_and_ids_fail_before_body_resolution() {
+    let ordinary = ordinary(ORDINARY_OA);
+    for (source, message) in [
+        (
+            OA.replace("quantity_kind duration", "quantity_kind respond"),
+            "Duplicate global alias",
+        ),
+        (
+            OA.replace(
+                "188b911c-5f8b-431c-9eea-2d41f3953767",
+                "cabec6a1-7d5d-48f3-8d2d-a7fc8cf78f59",
+            ),
+            "Duplicate global identity",
+        ),
+        (format!("{OA}\n{OA}"), "Duplicate global"),
+    ] {
+        let failed = failure(&source, &ordinary);
+        assert_eq!(failed.file, Some(7));
+        assert!(failed.error.message.contains(message), "{:?}", failed);
+        assert!(!failed.error.message.contains("Unknown"));
+    }
+    let mut budget = budget();
+    let units = [unit(OA, 3, &mut budget), unit(OA, 5, &mut budget)];
+    let failed = lower(&ordinary, &units, &budget).unwrap_err();
+    assert_eq!(failed.file, Some(5));
+    assert!(failed.error.message.contains("Duplicate global identity"));
+}
+
+#[test]
+fn typed_reference_domains_unknown_names_and_parameter_scope_fail_at_tokens() {
+    let skeleton = ordinary(ORDINARY_OA);
+    for (old, new, token, message) in [
+        (
+            "subject @receive",
+            "subject @second",
+            "second",
+            "Wrong reference domain",
+        ),
+        (
+            "Quantity(@duration)",
+            "Quantity(@second)",
+            "second",
+            "Wrong reference domain",
+        ),
+        (
+            "display_unit @second",
+            "display_unit @duration",
+            "duration",
+            "Wrong reference domain",
+        ),
+        (
+            "750 [@millisecond]",
+            "750 [@duration]",
+            "duration",
+            "Wrong reference domain",
+        ),
+        (
+            "base 1 [@second]",
+            "base @respond",
+            "respond",
+            "Wrong reference domain",
+        ),
+        (
+            "@combine(a:",
+            "@second(a:",
+            "second",
+            "Wrong reference domain",
+        ),
+        (
+            "@combine(a:",
+            "@combine(unknown:",
+            "unknown",
+            "Unknown argument",
+        ),
+        (
+            "body $a + $b",
+            "body $outside + $b",
+            "outside",
+            "Unknown parameter",
+        ),
+        (
+            "base 1 [@second]",
+            "base $a",
+            "a",
+            "only valid in its calculation",
+        ),
+        (
+            "subject @receive",
+            "subject @missing",
+            "missing",
+            "Unknown global",
+        ),
+        (
+            "documented_constraint none",
+            "documented_constraint @respond",
+            "respond",
+            "Wrong reference domain",
+        ),
+        (
+            "@receive_time = unbound",
+            "@second = unbound",
+            "second",
+            "Wrong reference domain",
+        ),
+    ] {
+        let source = OA.replace(old, new);
+        assert_ne!(source, OA, "mutation {old}");
+        let failed = failure(&source, &skeleton);
+        assert!(
+            failed.error.message.contains(message),
+            "{new}: {:?}",
+            failed
+        );
+        assert_eq!(
+            &source[failed.error.span.start..failed.error.span.end],
+            token
+        );
+    }
+}
+
+#[test]
+fn ordinary_non_element_categories_are_collected_and_never_property_fallbacks() {
+    let mut skeleton = ordinary(ORDINARY_OA);
+    let respond = by_alias(&skeleton, "respond");
+    let receive = by_alias(&skeleton, "receive");
+    let relation = Id::from_u128(100);
+    skeleton.relations.insert(
+        relation,
+        crate::Relation {
+            id: relation,
+            alias: "link".into(),
+            name: "Link".into(),
+            description: String::new(),
+            body: crate::RelationBody::new(
+                crate::RelationKind::FunctionalExchange,
+                respond,
+                receive,
+            ),
+        },
+    );
+    let diagram = skeleton.ensure_diagram(Layer::Oa);
+    skeleton.diagrams.get_mut(&diagram).unwrap().alias = "view".into();
+    let node = skeleton.place(diagram, respond, crate::Position { x: 0., y: 0. });
+    skeleton
+        .diagrams
+        .get_mut(&diagram)
+        .unwrap()
+        .nodes
+        .get_mut(&node)
+        .unwrap()
+        .alias = "placement".into();
+    let artifact = Id::from_u128(101);
+    skeleton.artifact_links.insert(
+        artifact,
+        crate::ArtifactLink {
+            id: artifact,
+            alias: "document".into(),
+            name: "Document".into(),
+            description: String::new(),
+            owner: respond,
+            relation: crate::ArtifactRelation::References,
+            uri: "urn:test".into(),
+            revision: None,
+            fragment: None,
+        },
+    );
+    let trace = Id::from_u128(102);
+    skeleton.traces.insert(
+        trace,
+        crate::Trace {
+            id: trace,
+            alias: "mapping".into(),
+            name: "Mapping".into(),
+            description: String::new(),
+            oa: respond,
+            sa: receive,
+            kind: crate::TraceKind::Manual,
+            baseline: None,
+        },
+    );
+    // Resolution classification is independent of whole-model admission; the
+    // synthetic trace is deliberately not asserted to be a valid OA/SA trace.
+    let budget = budget();
+    let mut tables = Tables::default();
+    tables.ordinary(&skeleton, &budget).unwrap();
+    for (alias, category) in [
+        ("response_budget", Category::Project),
+        ("link", Category::Relation),
+        ("view", Category::Diagram),
+        ("placement", Category::Node),
+        ("document", Category::Artifact),
+        ("mapping", Category::Trace),
+    ] {
+        assert_eq!(tables.aliases[alias].category, category);
+        let failed = failure(
+            &OA.replace("base 1 [@second]", &format!("base @{alias}")),
+            &skeleton,
+        );
+        assert!(
+            failed.error.message.contains("Wrong reference domain"),
+            "{:?}",
+            failed
+        );
+    }
+    let source = OA.replace("subject @receive", "subject @link");
+    let mut budget = self::budget();
+    let units = [unit(&source, 1, &mut budget)];
+    let output = lower(&skeleton, &units, &budget).unwrap();
+    let property = output
+        .elements
+        .values()
+        .find(|value| value.alias == "receive_time")
+        .unwrap();
+    assert!(
+        matches!(property.body.shared(), Some(SharedBody::EngineeringProperty { subject: a::AnalysisSubject::Relation(value), .. }) if *value == relation)
+    );
+}
+
+#[test]
+fn structural_lowering_defers_type_purity_layer_and_argument_sets_to_admission() {
+    for (old, new) in [
+        ("base 750 [@millisecond]", "base true"),
+        ("body $a + $b", "body @receive_time"),
+        ("a: @receive_time, b: @dispatch_time", "a: @receive_time"),
+        ("oa_property receive_time", "sa_property receive_time"),
+        ("base 1 [@second]", "base @dispatch_time"),
+    ] {
+        let source = OA.replace(old, new);
+        let mut budget = budget();
+        let units = [unit(&source, 1, &mut budget)];
+        let output = lower(&ordinary(ORDINARY_OA), &units, &budget).unwrap();
+        let project = merge(ordinary(ORDINARY_OA), output);
+        assert!(
+            a::admit(&project, a::AdmissionLimits::REFERENCE).is_err(),
+            "{new}"
+        );
+    }
+}
+
+#[test]
+fn lowering_phase_bounds_count_ordinary_globals_and_scoped_parameters_together() {
+    let ordinary = oracle::project(Layer::Oa);
+    for (maximum, passes) in [(0, false), (16, false), (17, true)] {
+        let mut limits = Limits::source8(ParseLimits::UNLIMITED);
+        limits.entries = maximum;
+        let budget = Budget::new(limits).unwrap();
+        let result = lower(&ordinary, &[], &budget);
+        assert_eq!(result.is_ok(), passes, "entry bound {maximum}");
+        if let Err(failure) = result {
+            assert!(failure.error.message.contains("lowering entry limit"));
+            assert_eq!(failure.file, None);
+        }
+        assert_eq!(budget.usage, budget::Usage::default());
+    }
+}
+
+#[test]
+fn affine_kinds_optional_fields_list_signatures_and_unused_unbound_definitions_survive() {
+    let source = r#"
+unit celsius "Celsius" id "00000000-0000-0000-0000-000000000061" {
+    kind @point; scale 1; offset ratio(27315, 100); symbol "°C";
+}
+quantity_kind point "Temperature point" id "00000000-0000-0000-0000-000000000062" {
+    dimension { temperature 1; }; algebra Affine(@interval);
+}
+quantity_kind interval "Temperature interval" id "00000000-0000-0000-0000-000000000063" {
+    dimension { temperature 1; }; algebra Linear;
+}
+calculation unused "Unused list calculation" id "00000000-0000-0000-0000-000000000064" {
+    input xs id "00000000-0000-0000-0000-000000000065" : List(Quantity(@interval));
+    result List(Quantity(@interval)); body unbound; description "保留";
+}
+calculation empty "Empty calculation" id "00000000-0000-0000-0000-000000000066" {
+    result Boolean; body unbound;
+}
+oa_property ambient "Ambient temperature" id "00000000-0000-0000-0000-000000000067" {
+    subject @respond; type Quantity(@point); display_unit none; base 0 [@celsius]; parent none;
+}
+oa_check documented "Documented check" id "00000000-0000-0000-0000-000000000068" {
+    subject @respond; documented_constraint @requirement; predicate unbound;
+}
+oa_analysis changed "Changed temperature" id "00000000-0000-0000-0000-000000000069" {
+    subject @respond; base ModelBaseline; overrides { @ambient = unbound; };
+}
+"#;
+    let mut skeleton = ordinary(ORDINARY_OA);
+    let requirement = Id::from_u128(70);
+    skeleton.elements.insert(
+        requirement,
+        Element {
+            id: requirement,
+            alias: "requirement".into(),
+            name: "Requirement".into(),
+            description: String::new(),
+            parent: None,
+            body: ElementBody::shared_in(
+                Layer::Oa,
+                SharedBody::Constraint {
+                    expression: String::new(),
+                    constrained: Vec::new(),
+                },
+            ),
+        },
+    );
+    let mut budget = budget();
+    let units = [unit(source, 8, &mut budget)];
+    let output = lower(&skeleton, &units, &budget).unwrap();
+    assert_eq!(output.definitions.len(), 5);
+    let point = id("00000000-0000-0000-0000-000000000062");
+    let interval = id("00000000-0000-0000-0000-000000000063");
+    let a::DefinitionBody::QuantityKind(kind) = &output.definitions[&point].body else {
+        panic!("quantity kind")
+    };
+    assert_eq!(
+        kind.algebra,
+        a::QuantityAlgebra::Affine {
+            difference: a::DefinitionRef::Local(interval)
+        }
+    );
+    let unused = &output.definitions[&id("00000000-0000-0000-0000-000000000064")];
+    assert_eq!(unused.description, "保留");
+    let a::DefinitionBody::Calculation(calculation) = &unused.body else {
+        panic!("calculation")
+    };
+    assert_eq!(calculation.body, a::Binding::Unbound);
+    assert_eq!(
+        calculation.parameters[0].value_type,
+        a::AnalysisType::List(a::ScalarType::Quantity(a::DefinitionRef::Local(interval)))
+    );
+    assert_eq!(calculation.result, calculation.parameters[0].value_type);
+    assert!(
+        output
+            .occurrences
+            .iter()
+            .any(|occurrence| occurrence.field == Field::DocumentedConstraint
+                && occurrence.target == Target::Global(requirement))
+    );
+    let override_id = id("00000000-0000-0000-0000-000000000067");
+    assert!(output.occurrences.iter().any(|occurrence| occurrence.field
+        == Field::Override(override_id)
+        && occurrence.role == Role::OverrideTarget));
+    assert!(
+        output
+            .occurrences
+            .iter()
+            .any(|occurrence| occurrence.owner == point
+                && occurrence.field == Field::Algebra
+                && occurrence.target == Target::Global(interval))
+    );
+    admit(&merge(skeleton, output));
+}
+
+#[test]
+fn duplicate_file_keys_and_exhausted_shared_budget_cannot_enter_lowering() {
+    let mut budget = budget();
+    let units = [unit("", 3, &mut budget), unit("", 3, &mut budget)];
+    let failed = lower(&ordinary(ORDINARY_OA), &units, &budget).unwrap_err();
+    assert_eq!(failed.file, Some(3));
+    assert!(failed.error.message.contains("Duplicate source file"));
+    let failure = budget
+        .bytes(usize::MAX, Span { start: 5, end: 6 })
+        .unwrap_err();
+    let failed = lower(&ordinary(ORDINARY_OA), &[], &budget).unwrap_err();
+    assert_eq!(failed.error, failure);
+}
+
+#[test]
+fn iterative_lowering_preserves_128_deep_and_1024_wide_accepted_expressions() {
+    let deep = format!("{}1{}", "abs(".repeat(127), ")".repeat(127));
+    let wide = std::iter::repeat_n("1", 1024)
+        .collect::<Vec<_>>()
+        .join(", ");
+    let source = format!(
+        r#"
+calculation deep "Deep" id "00000000-0000-0000-0000-000000000081" {{ result Number; body {deep}; }}
+calculation wide "Wide" id "00000000-0000-0000-0000-000000000082" {{ result List(Number); body [{wide}]; }}
+"#
+    );
+    let mut budget = budget();
+    let units = [unit(&source, 1, &mut budget)];
+    let usage = budget.usage;
+    let output = lower(&ordinary(ORDINARY_OA), &units, &budget).unwrap();
+    assert_eq!(output.expressions.len(), 128 + 1025);
+    let a::DefinitionBody::Calculation(deep) = &output.definitions[&Id::from_u128(0x81)].body
+    else {
+        panic!("deep calculation")
+    };
+    let a::Binding::Expression(root) = &deep.body else {
+        panic!("deep expression")
+    };
+    let mut current = root;
+    let mut depth = 1;
+    while let a::Expr::Unary { operand, .. } = current {
+        depth += 1;
+        current = operand;
+    }
+    assert_eq!(depth, 128);
+    assert_eq!(current, &number(1));
+    let a::DefinitionBody::Calculation(wide) = &output.definitions[&Id::from_u128(0x82)].body
+    else {
+        panic!("wide calculation")
+    };
+    let a::Binding::Expression(a::Expr::List(values)) = &wide.body else {
+        panic!("wide list")
+    };
+    assert_eq!(values.len(), 1024);
+    assert!(values.iter().all(|value| *value == number(1)));
+    assert_eq!(budget.usage, usage);
+    admit(&merge(ordinary(ORDINARY_OA), output));
+}