Layer Boundary Contract

This page records the current public layer boundaries.

Canonical Flow

L0 -> L1 -> L2 -> L3 -> L4 -> L5 -> L6 -> L7 -> L8

Diagnostics attach as side branches:

L1.5 <- L1
L2.5 <- L1 + L2
L3.5 <- L1 + L2 + L3
L4.5 <- L4 + L3

Boundary Table

Layer	Owns	Consumes	Produces
L0	runtime policy	none	l0_meta_v1
L1	data definition	none	l1_data_definition_v1, l1_regime_metadata_v1
L2	preprocessing	l1_data_definition_v1	l2_clean_panel_v1
L3	feature engineering and target construction	L1 raw/regime access, l2_clean_panel_v1	l3_features_v1, l3_metadata_v1
L4	model fitting, forecasts, benchmarks, ensembles, tuning	l3_features_v1, l3_metadata_v1, optional regimes	l4_forecasts_v1, l4_model_artifacts_v1, l4_training_metadata_v1
L5	evaluation metrics and ranking	L4 forecasts/artifacts, L1 data/regimes, L3 metadata	l5_evaluation_v1
L6	statistical tests	L4, L5, L1 metadata	l6_tests_v1
L7	interpretation and importance	L4, L3, L5, optional L6	l7_importance_v1, optional l7_transformation_attribution_v1
L8	export and provenance	all active upstream sinks	l8_artifacts_v1

Non-Negotiable Rules

• L3 owns panel and target construction. It does not own forecast combination.

• L4 owns forecast generation and forecast combination.

• L5 owns descriptive evaluation. It does not own inferential p-values.

• L6 owns inferential tests and is default off.

• L7 owns interpretation and is default off.

• L8 owns file export, saved object selection, provenance, and artifact layout.

• Diagnostics do not mutate construction sinks.

Diagnostic Default-Off Contract

For L1.5-L4.5:

• absent layer key: no diagnostic layer;

• enabled: false: no DAG nodes, no sink, all axes inactive;

• enabled: true: diagnostic DAG and sink are available;

• L8 can include active diagnostics through explicit saved objects or diagnostics_all.

Naming

Concept	Current name
L3 YAML key	3_feature_engineering
L4 YAML key	4_forecasting_model
L5 YAML key	5_evaluation
L6 YAML key	6_statistical_tests
L7 YAML key	7_interpretation
L8 YAML key	8_output