fix(plugin-grid): order a grouped grid's groups by the level's orderBy

.changeset/25858-grid-group-order-by.md

@@ -0,0 +1,14 @@
+---
+'@object-ui/plugin-grid': patch
+---
+
+fix(plugin-grid): a grouped grid orders a level's groups by its `grouping.fields[].orderBy`, the label still from `field`
+
+Clause-②: no
+Metadata-protocol: none
+
+A view grouped by `period_label` with `orderBy: 'period_start', order: 'desc'` now lists one header per label in descending `period_start` order, where it used to list the labels as text (`Nov 2026` before `Oct 2026` before `Q1 2027`).
+
+- **Server-grouped grid.** The grid forwards the level's `orderBy` into the group header query, so the query carries the `min` (asc) / `max` (desc) column the spec compiles for it, and sorts the header rows by the column `listViewGroupOrderColumn` names. An `orderBy` field the user may not read is not forwarded: that level orders by its own key.
+- **Rows handed in whole.** Each group's order value is the `min` (asc) or `max` (desc) of `orderBy` over its rows, so a group sits where its first row would if the rows were sorted by `orderBy`.
+- **Both paths.** A group with no `orderBy` value sorts last in both directions; equal values fall back to the existing key comparison (declared option order, then label) in the same direction. A level without `orderBy`, or with `orderBy` naming the grouping field itself, orders exactly as before.

scripts/sdui-manifest.record.json

@@ -49,6 +49,6 @@
       "ui/packages/types"
     ],
     "registrySources": 922,
-    "registrySourcesSha256": "ad9e0875b83f339e03c528fc3be774592615dfdc5ee5fe9becc4376ddb5f0d52"
+    "registrySourcesSha256": "7734fe6bc3763fe8318db624b9e0dd4c48b2dc7b15bf2a3fb1f78e46bb8d959e"
   }
 }

ui/packages/plugin-grid/src/ObjectGrid.tsx

@@ -3430,18 +3430,29 @@ export const ObjectGrid: React.FC<ObjectGridComponentProps> = ({
   // [objectui#7189] The entries the SERVER groups by: the render grouping less
   // any key this principal may not read (see `groupingKeyReadable`). Keyed on
   // the names, so a host rebuilding `grouping` every render re-asks nothing.
+  // [objectstack#25786] A level's `orderBy` rides along — the header query
+  // compiles its `min` / `max` column from it — under the same read gate: an
+  // `orderBy` this principal may not read is dropped, and the level orders by
+  // its own key, since the header row would carry that field's value and the
+  // group order would disclose it.
   const serverGroupingKey = serverGroupedFetch
     ? JSON.stringify(
       usableGroupingFields(groupingForRender?.fields)
         .filter((gf) => groupingKeyReadable(gf.field))
-        .map((gf) => [gf.field, gf.order ?? null, gf.collapsed ?? null]),
+        .map((gf) => [
+          gf.field,
+          gf.order ?? null,
+          gf.collapsed ?? null,
+          gf.orderBy && groupingKeyReadable(gf.orderBy) ? gf.orderBy : null,
+        ]),
     )
     : '[]';
   const serverGroupingFields = React.useMemo(
-    () => (JSON.parse(serverGroupingKey) as Array<[string, 'asc' | 'desc' | null, boolean | null]>)
-      .map(([field, order, collapsed]) => ({
+    () => (JSON.parse(serverGroupingKey) as Array<[string, 'asc' | 'desc' | null, boolean | null, string | null]>)
+      .map(([field, order, collapsed, orderBy]) => ({
         field,
         ...(order ? { order } : {}),
+        ...(orderBy !== null ? { orderBy } : {}),
         ...(collapsed !== null ? { collapsed } : {}),
       })),
     [serverGroupingKey],