diff_against_hub accepts hub_edges/edge_targets and reports edges to create,
remove, retain, unresolved and external, using the same pure planner that
receiving now calls (plan_source_edges + classify_source_edges). The classifier
works on a row list, fixing a collapse where an external duplicate of an owned
edge key could hide the owned row from removal. 7 new pure tests.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 692292@bnt-lap001
Assistant-Session: 89c7d8e8-e1b3-47eb-9411-a0ab227fca2f
