fix(tables): re-broadcast selection when a peer's row change shifts it

End-to-end lifecycle audit (Low-Med): the selection emit resolved the stable
(rowId, columnId) only on selection/editing change, not when a live edit/schema
refetch inserted/deleted/reordered rows. The index-based local selection then sat
on a different logical row than the rowId peers held, so your outline showed on the
old row until you moved. Re-run the emit on rows/displayColumns change and dedup an
unchanged result (also drops the redundant null-on-open emit) so the broadcast stays
consistent with the local highlight.

apps/sim/app/workspace/[workspaceId]/tables/[tableId]/components/table-grid/table-grid.tsx

@@ -836,16 +836,15 @@ export function TableGrid({
     : null
 
   // Broadcast the local viewer's cell selection to the presence room. Resolves the
-  // index-based selection to stable (rowId, columnId) through refs so it re-emits only
+  // index-based selection to stable (rowId, columnId), re-running on `rows`/`displayColumns`
-  // on a real selection/editing change, not on every data update. `editing` marks the
+  // too so a peer's row insert/delete/reorder re-broadcasts the shifted id under the same
-  // active cell so peers darken it (the "someone is typing here" signal).
+  // index (the emitter dedups an unchanged result). `editing` marks the active cell so
+  // peers darken it (the "someone is typing here" signal).
   useEffect(() => {
-    const currentRows = rowsRef.current
-    const currentCols = columnsRef.current
     const resolve = (coord: CellCoord | null) => {
       if (!coord) return null
-      const rowId = currentRows[coord.rowIndex]?.id
+      const rowId = rows[coord.rowIndex]?.id
-      const columnId = currentCols[coord.colIndex]?.key
+      const columnId = displayColumns[coord.colIndex]?.key
       return rowId && columnId ? { rowId, columnId } : null
     }
     const anchor = resolve(selectionAnchor)
@@ -858,7 +857,7 @@ export function TableGrid({
     // most common selection would never broadcast and would clear the prior outline.
     const focus = resolve(selectionFocus) ?? anchor
     emitCellSelection({ anchor, focus, editing: editingCell !== null })
-  }, [selectionAnchor, selectionFocus, editingCell, emitCellSelection])
+  }, [selectionAnchor, selectionFocus, editingCell, rows, displayColumns, emitCellSelection])
 
   const { data: findData, isFetching: isFindFetching } = useFindTableRows({
     workspaceId,

apps/sim/app/workspace/[workspaceId]/tables/[tableId]/hooks/use-table-room.ts

@@ -150,6 +150,8 @@ export function useTableRoom(tableId: string): UseTableRoomResult {
   const lastEmitRef = useRef(0)
   const trailingTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null)
   const pendingCellRef = useRef<TableCellSelection>(null)
+  /** Key of the last selection sent, to skip re-emitting an unchanged selection. */
+  const lastSentKeyRef = useRef<string | null>(null)
 
   // Reset the throttle when the table changes (or on unmount): a pending selection for
   // the table we're leaving must not flush into the next table's room after a switch.
@@ -161,12 +163,19 @@ export function useTableRoom(tableId: string): UseTableRoomResult {
       }
       pendingCellRef.current = null
       currentCellRef.current = null
+      lastSentKeyRef.current = null
       lastEmitRef.current = 0
     },
     [tableId]
   )
 
   const emitCellSelection = useCallback((cell: TableCellSelection) => {
+    // Skip re-emitting an unchanged selection: the caller re-resolves on every data
+    // refetch (so a peer's row insert re-broadcasts the shifted rowId), but most refetches
+    // don't move the selection — dedup those, and the no-selection state on table open.
+    const key = cell === null ? 'null' : JSON.stringify(cell)
+    if (key === lastSentKeyRef.current) return
+    lastSentKeyRef.current = key
     currentCellRef.current = cell
     pendingCellRef.current = cell
     const flush = () => {