Fragments and include

Fragments keep the main step manifest small. Include them as a list of relative paths or globs.

include:
  - fragments/params.drtml
  - fragments/ui.drtml
  - fragments/metrics.drtml
  - fragments/datasets/*.drtml

Merge rules

1. Includes are expanded recursively and cycle-safe.
2. Mapping sections deep-merge.
3. Lists concatenate.
4. Scalars from a later include override earlier ones.
5. After all includes, the entry manifest overrides the merged result.

There is no merge: target. Put the section you want to contribute directly in the fragment:

fragments/params.drtml

params:
  runtime:
    document_batch_size: 32

fragments/datasets/documents.drtml

inputs:
  documents:
    schema: {document_id: string, text: string}
    run: mapping.upstream_runs
    feed: {batch: 256}

Typical split

Fragment	Contents
params.drtml	nested params defaults
ui.drtml	Streamlit form
metrics.drtml / observability	progress, Prometheus, dashboard
storage.drtml	store profiles
datasets/*.drtml	one input/output per file
processing.drtml	run.processor / run.derive
orchestrator.drtml	connections, artifacts root, XCom

Keep identity (drtml, step, run.type) in the entry file.