Place a new unit or move a branch in the tree
What It Does
Adding and moving units use one validated placement transaction. The tree lock protects validation against competing structural edits, and parentage, ancestry, depths and move publication commit together. Creation returns the unit through the HTTP route; the service itself also computes a rebuild summary.
The Flow
When Something Fails
A pre-commit refusal leaves no partial placement. After-commit telemetry cannot undo the edit, and its library failure behavior is not established here. Reparent events have no reacting subscriber at these sources; the registry alone does not certify delivery retries.
Open Design Questions
Future scheduling and repeat keys require product decisions. Same-day replacement retains the previous parent only in versions, which can weaken deletion checks that consult current parent-history rows.