feat(bases): add kanban empty state with group-by picker

apps/client/src/features/base/components/views/kanban/base-kanban.tsx

@@ -5,7 +5,9 @@ import {
   IBaseView,
 } from "@/features/base/types/base.types";
 import { useKanbanGroups } from "@/features/base/hooks/use-kanban-groups";
+import { useUpdateViewMutation } from "@/features/base/queries/base-view-query";
 import { KanbanColumn } from "./kanban-column";
+import { KanbanEmptyState } from "./kanban-empty-state";
 import classes from "@/features/base/styles/kanban.module.css";
 
 type BaseKanbanProps = {
@@ -34,6 +36,10 @@ export function BaseKanban({
     [base.properties],
   );
   const isGroupable = property?.type === "select" || property?.type === "status";
+  const updateViewMutation = useUpdateViewMutation();
+
+  // Rules of Hooks: call useKanbanGroups unconditionally with `undefined`
+  // when not groupable; switch the render path on isGroupable below.
   const { columns } = useKanbanGroups(
     rows,
     isGroupable ? property : undefined,
@@ -41,6 +47,19 @@ export function BaseKanban({
     effectiveView?.config?.choiceOrder,
   );
 
+  const handlePickProperty = (propertyId: string) => {
+    if (!effectiveView) return;
+    updateViewMutation.mutate({
+      viewId: effectiveView.id,
+      pageId: base.id,
+      config: { ...effectiveView.config, groupByPropertyId: propertyId },
+    });
+  };
+
+  if (!isGroupable) {
+    return <KanbanEmptyState base={base} onPick={handlePickProperty} />;
+  }
+
   return (
     <div className={classes.board}>
       {columns.map((column) => (

apps/client/src/features/base/components/views/kanban/kanban-empty-state.tsx

@@ -0,0 +1,52 @@
+import { Stack, Text } from "@mantine/core";
+import { IconColumns3 } from "@tabler/icons-react";
+import { useTranslation } from "react-i18next";
+import { IBase } from "@/features/base/types/base.types";
+import { KanbanGroupByPicker } from "./kanban-group-by-picker";
+import { CreatePropertyPopover } from "@/features/base/components/property/create-property-popover";
+
+type KanbanEmptyStateProps = {
+  base: IBase;
+  onPick: (propertyId: string) => void;
+};
+
+export function KanbanEmptyState({ base, onPick }: KanbanEmptyStateProps) {
+  const { t } = useTranslation();
+  const hasGroupable = base.properties.some(
+    (p) => p.type === "select" || p.type === "status",
+  );
+
+  return (
+    <Stack align="center" gap="md" p="xl" mt={48}>
+      <IconColumns3 size={48} color="var(--mantine-color-gray-5)" />
+      <Text size="lg" fw={500}>
+        {t("Choose a property to group by")}
+      </Text>
+      {hasGroupable ? (
+        <KanbanGroupByPicker
+          properties={base.properties}
+          value={null}
+          onChange={onPick}
+        />
+      ) : (
+        <Stack align="center" gap="xs">
+          <Text size="sm" c="dimmed">
+            {t("Create a select or status property to use the kanban view.")}
+          </Text>
+          <CreatePropertyPopover
+            pageId={base.id}
+            properties={base.properties}
+            onPropertyCreated={() => {
+              // The base query invalidates on property create — the empty
+              // state will re-render with the picker variant. The user
+              // then picks the new property explicitly. (Auto-picking the
+              // new property requires receiving its id from the create
+              // mutation, which the current popover doesn't expose. Keep
+              // the explicit step for now.)
+            }}
+          />
+        </Stack>
+      )}
+    </Stack>
+  );
+}

apps/client/src/features/base/components/views/kanban/kanban-group-by-picker.tsx

@@ -0,0 +1,39 @@
+import { useMemo } from "react";
+import { Select } from "@mantine/core";
+import { useTranslation } from "react-i18next";
+import { IBaseProperty } from "@/features/base/types/base.types";
+
+type KanbanGroupByPickerProps = {
+  properties: IBaseProperty[];
+  value: string | null;
+  onChange: (propertyId: string) => void;
+  // Allows the toolbar variant to render compact / narrow.
+  size?: "xs" | "sm" | "md";
+};
+
+export function KanbanGroupByPicker({
+  properties,
+  value,
+  onChange,
+  size = "sm",
+}: KanbanGroupByPickerProps) {
+  const { t } = useTranslation();
+  const data = useMemo(
+    () =>
+      properties
+        .filter((p) => p.type === "select" || p.type === "status")
+        .map((p) => ({ value: p.id, label: p.name || t("Untitled") })),
+    [properties, t],
+  );
+  return (
+    <Select
+      placeholder={t("Group by…")}
+      data={data}
+      value={value}
+      onChange={(v) => v && onChange(v)}
+      size={size}
+      allowDeselect={false}
+      searchable
+    />
+  );
+}