Board and Swimlane crashed with "Maximum update depth exceeded" on first
paint of the Issues route. During cold load the member/agent/squad
directory queries are unresolved, so useActorName's `= []` defaults
allocated a fresh array every render and its `getActorName` memo changed
identity each render. BoardView's `groups` (and SwimLaneView's
`laneGroups`) list `getActorName` as a dep, so they churned every render
and re-fired the column-resync effect without end; react-virtuoso
escalated the loop into the reported crash. This predates MUL-4797 — it
was exposed when board/swimlane columns were virtualized with a real
<Virtuoso>.
- Share stable empty references for the loading directory snapshot so
getActorName is referentially stable across cold-load renders (root
cause).
- Equality-guard the shared column setter in useDragSettle so a
content-equal rebuild returns the previous reference and cannot spin
the resync effect (defense-in-depth).
Regression coverage: useActorName stability during cold load; the
column-setter equality guard; and Board (40 cards) + Swimlane rendered
with the REAL react-virtuoso under pending directories, which reproduce
"Maximum update depth exceeded" without the fix and pass with it.
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Co-authored-by: multica-agent <github@multica.ai>
