switchPage and deletePage ran side effects (loadState -> actions.deserialize,
setActivePageId, activePageIdRef mutation) INSIDE setPages/setHeaderPage/
setFooterPage updater callbacks -- using the functional-updater form purely
to peek at the latest `prev` value. React (in StrictMode dev builds)
double-invokes updater functions passed to setState to catch exactly this
kind of impurity, so every page switch deserialized the target's craft
state twice.
Add pagesRef/headerPageRef/footerPageRef mirroring the latest state on
every render (same pattern already used for activePageIdRef), so
switchPage/deletePage can read "what's current" synchronously in the
event-handler body and run their side effects there -- after the state
update is computed, not inside the updater. deletePage now passes a plain
next-value to setPages instead of a function updater. Switching/deleting
behavior (correct page loads, can't delete the last page) is unchanged.
Verified the added test fails against the pre-fix code (deserialize called
2x) and passes against the fix (1x).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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