Frontend pattern-consistency sweep (note #1026, the last DRY-thread item).
TagMaintenanceCard (4 flows) + PostMaintenanceCard (2 flows) each hand-rolled the
same sync preview→commit state machine: a previewData/previewing/committing
triple + onPreview/onCommit that dry-run-previews, then applies and collapses the
projection (the apply shares the backend predicate, so afterward it's empty).
Extract usePreviewCommit({preview, commit, emptyPreview}) owning that lifecycle.
The 6 flows become declarative: supply the two thunks + the collapse shape. The
normalize flow (commit dispatches a self-resuming background task, not a sync
apply) omits emptyPreview so the projection stays and a truthy result = queued.
Composable returns are aliased to the cards' existing local names, so the
templates only change where they read the apply result (the success badges).
Long-Celery-task cards (GatedPurge/VideoDedup) keep useMaintenanceTask — a
different pattern (navigable-away task lifecycle), deliberately not merged.
Exhaustiveness: no card hand-rolls the refs anymore; the only dryRun:false
callers are these two cards, both via the composable. Added a vitest spec for
the primitive (collapse static + fn, dispatch-variant, re-preview clears result).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
