Recipe Layers

Current layer-contract recipes use numeric YAML keys that map directly to layer IDs.

Canonical Keys

Layer ID	YAML key	Required in minimal path
`l0`	`0_meta`	optional; defaults apply
`l1`	`1_data`	yes
`l2`	`2_preprocessing`	yes
`l3`	`3_feature_engineering`	yes
`l4`	`4_forecasting_model`	yes
`l5`	`5_evaluation`	yes
`l6`	`6_statistical_tests`	no; default off
`l7`	`7_interpretation`	no; default off
`l8`	`8_output`	yes
`l1_5`	`1_5_data_summary`	no; default off
`l2_5`	`2_5_pre_post_preprocessing`	no; default off
`l3_5`	`3_5_feature_diagnostics`	no; default off
`l4_5`	`4_5_generator_diagnostics`	no; default off

Shape Rules

List layers use fixed_axes plus optional leaf_config.
Graph layers use nodes and sinks.
Diagnostics require enabled: true to produce a diagnostic sink.
L8 derives default saved objects from active upstream layers unless saved_objects is explicit.

Minimal Skeleton

1_data:
  fixed_axes: {}

2_preprocessing:
  fixed_axes: {}

3_feature_engineering:
  nodes: []
  sinks: {}

4_forecasting_model:
  nodes: []
  sinks: {}

5_evaluation:
  fixed_axes: {}

8_output:
  fixed_axes: {}

The skeleton above shows structure only. A runnable recipe must provide valid L3 and L4 DAG nodes and required sinks.