Fan-in bundle, consume, and flatten

Use this recipe when several parallel outputs should become one named collection for a downstream collection-aware tool, then nested results must be flattened before optional pooled aggregation.

This contrasts with manifest-to-mapped-collection-lifecycle: collection construction happens mid-workflow as fan-in, not just at the workflow boundary.

Recipe

1. Identify parallel outputs that represent comparable alternatives, bins, reports, or method results.
2. Build a named collection bundle from those individual outputs.
3. Feed the bundle into the downstream tool that expects a collection input.
4. Flatten nested collection output if the downstream tool emits one subcollection per input element.
5. Aggregate tabular/report outputs when the final consumer needs one file rather than a collection.

Reach For This When

• Multiple tools produce equivalent artifacts and a later tool compares, refines, or pools them.
• A workflow bundles related outputs because a later collection-aware tool consumes them, not merely for publication.
• A downstream collection consumer emits nested outputs that need pooled processing.

Operation Handoffs

• Use collection-build-named-bundle to assemble individual datasets or outputs into a list.
• Use collection-flatten-after-fanout when the consumer returns nested collections and the outer axis no longer matters.
• Use tabular-concatenate-collection-to-table or tabular-pivot-collection-to-wide when flattened tabular outputs should become one report table.

Bundle-only publication is related but narrower; use collection-build-named-bundle when there is no downstream collection consumer.

Pitfalls

• Do not use collection bundling when the real operation is file-content concatenation.
• Do not use positional identifiers for bundles that will become test-facing outputs.
• Do not flatten away an axis that still encodes method, sample, or replicate identity needed downstream.

See Also

• iwc-map-over-lifecycle-survey — Shape E evidence.
• manifest-to-mapped-collection-lifecycle — boundary collection construction in the opposite direction.