Parameter ownership and namespaces

Metewand keeps scientific parameters in three explicit namespaces. Their location records the benchmark author's classification; Metewand does not infer ownership from library option names or move a parameter between namespaces.

Namespace	Owner	Effect
dataset-parameters.<dataset>	One selected dataset definition	Acquires, generates, selects, or transforms a dataset artifact.
problem-parameters	The experiment's selected problem contract	Determines the requested computation and result semantics.
implementation-parameters.<implementation>	One selected implementation definition	Determines how that implementation performs the computation.

Budget and execution settings remain in their own policy structures. They do not become scientific parameters.

Dataset and implementation parameter mappings are name-qualified because an experiment may select several of either. Problem parameters are unqualified because an experiment selects exactly one problem. Named cases preserve the same structure and overlay the experiment-level axes during later expansion.

Structural validation

validate_parameter_namespaces checks the parts of ownership that require no filesystem access, contract loading, or matrix expansion:

• a dataset or implementation that declares parameter-defaults also declares parameter-schema;
• every name-qualified parameter mapping belongs to a definition selected by its enclosing experiment;
• the selected definition exists; and
• the definition declares a parameter schema. Fixed datasets never do and therefore cannot receive dataset parameters.

The checks apply equally to experiment-level axes and named-case overlays. They run in deterministic definition, experiment, case, and namespace order and return the first ParameterNamespaceError.

use std::path::Path;

use metewand_core::{
    manifest::parse_manifest,
    parameters::validate_parameter_namespaces,
};

# let source = "version: 1\nname: \"example\"\n";
let manifest = parse_manifest(Path::new("metewand.yaml"), source)?;
validate_parameter_namespaces(&manifest)?;

# Ok::<(), Box<dyn std::error::Error>>(())

Schema-content validation remains a separate step. In particular, this pass does not decide whether a parameter is scientifically a dataset, problem, or implementation concern. The same key may appear in all three namespaces; that is valid and remains visible for review in the manifest and problem contract.