pipeio_cross_flow — cross-pipeline registry chain tracking

Goal

(promoted from note)

Context

(see source note)

Prompt

Implement pipeio_cross_flow(pipe=None, flow=None) — map output_registry → input_registry chains across flows. Show which flows consume which outputs, detect stale references.

Reference capture: 20260325-211452-7a9a6c.

Acceptance Criteria

• [ ]

Result

(pending)