fix: show subcategory breakdown in a modal instead of expanding inline

Инлайн-раскрытие внутри строки при большом числе подкатегорий/сплитов
раздувало высоту строки и ломало вёрстку (донат на Dashboard и список
справа расходились по высоте). Теперь клик по шеврону открывает общее
модальное окно CategoryBreakdownModal со списком категорий-источников —
строка сама больше не меняет размер.

frontend/src/components/categories/CategoryBreakdownModal.tsx

@@ -0,0 +1,74 @@
+import { Dialog } from "@/components/ui/Dialog";
+import { getCategoryIcon } from "@/lib/icons";
+import { formatCurrency } from "@/lib/format";
+import { useTranslation } from "@/lib/i18n";
+import { translateCategoryName } from "@/lib/categoryLabels";
+
+interface CategoryBreakdownChild {
+  category_id: number;
+  name: string;
+  color: string;
+  icon: string | null;
+  amount: string;
+}
+
+interface CategoryBreakdownModalProps {
+  open: boolean;
+  onClose: () => void;
+  categoryId: number;
+  categoryName: string;
+  totalAmount: string;
+  children: CategoryBreakdownChild[];
+}
+
+/** Shows how a parent category's total splits across its subcategories — a
+ * modal rather than an inline expansion, since a category with many
+ * subcategories (or many split-across purchases) would otherwise push the
+ * Dashboard's donut/list layout out of alignment as rows grow taller. Shared
+ * between the Dashboard breakdown and the Reports category ranking, which
+ * expose the same shape (see services/category_rollup.py's
+ * CategoryRollupChildItem). */
+export function CategoryBreakdownModal({
+  open,
+  onClose,
+  categoryId,
+  categoryName,
+  totalAmount,
+  children,
+}: CategoryBreakdownModalProps) {
+  const { t } = useTranslation();
+  const total = Number(totalAmount);
+
+  return (
+    <Dialog open={open} onClose={onClose} title={translateCategoryName(categoryName)}>
+      <div className="mb-3 flex items-center justify-between border-b border-gridline pb-3 text-sm">
+        <span className="text-text-muted">{t("reports.categoryBreakdownTotalLabel")}</span>
+        <span className="font-semibold tabular-nums text-text-primary">{formatCurrency(totalAmount)}</span>
+      </div>
+      <ul className="divide-y divide-gridline">
+        {children.map((child) => {
+          const Icon = getCategoryIcon(child.icon);
+          const percent = total ? (Number(child.amount) / total) * 100 : 0;
+          const label = child.category_id === categoryId ? t("reports.directSpendLabel") : translateCategoryName(child.name);
+          return (
+            <li key={child.category_id} className="flex items-center gap-3 py-2.5 first:pt-0 last:pb-0">
+              <span
+                className="flex h-8 w-8 shrink-0 items-center justify-center rounded-full"
+                style={{ backgroundColor: `${child.color}26` }}
+              >
+                <Icon size={15} style={{ color: child.color }} />
+              </span>
+              <span className="min-w-0 flex-1 truncate text-sm text-text-primary">{label}</span>
+              <span className="w-9 shrink-0 text-right text-xs text-text-muted tabular-nums">
+                {percent.toFixed(0)}%
+              </span>
+              <span className="shrink-0 text-sm font-medium tabular-nums text-text-primary">
+                {formatCurrency(child.amount)}
+              </span>
+            </li>
+          );
+        })}
+      </ul>
+    </Dialog>
+  );
+}

frontend/src/components/dashboard/SpendingByCategoryCard.tsx

@@ -1,12 +1,13 @@
 import { useState } from "react";
-import { ChevronDown, ChevronRight } from "lucide-react";
+import { ChevronRight } from "lucide-react";
 import { Cell, Pie, PieChart, ResponsiveContainer, Tooltip } from "recharts";
 import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/Card";
+import { CategoryBreakdownModal } from "@/components/categories/CategoryBreakdownModal";
 import { getCategoryIcon } from "@/lib/icons";
 import { formatCurrency } from "@/lib/format";
-import { useTranslation, type TranslationKey } from "@/lib/i18n";
+import { useTranslation } from "@/lib/i18n";
 import { translateCategoryName } from "@/lib/categoryLabels";
-import type { CategoryBreakdownChildItem, CategoryBreakdownItem } from "@/types";
+import type { CategoryBreakdownItem } from "@/types";
 
 interface SpendingByCategoryCardProps {
   items: CategoryBreakdownItem[];
@@ -25,31 +26,18 @@ function DonutTooltip({ active, payload }: { active?: boolean; payload?: Array<{
   );
 }
 
-// A child's category_id equals its parent's own — the enclosing
-// CategoryBreakdownItem's — when that slice of spend was filed directly on
-// the parent with no more specific subcategory chosen (see
-// services/category_rollup.py's CategoryRollupChildItem).
-function childLabel(child: CategoryBreakdownChildItem, parentId: number | null, t: (key: TranslationKey) => string) {
-  return child.category_id === parentId ? t("reports.directSpendLabel") : translateCategoryName(child.name);
-}
-
 export function SpendingByCategoryCard({ items }: SpendingByCategoryCardProps) {
   const { t } = useTranslation();
-  const [expanded, setExpanded] = useState<Set<number>>(new Set());
+  // The breakdown lives in a modal, not expanded inline — a category with
+  // many subcategories (or many split purchases) would otherwise push this
+  // row taller than the fixed-height donut next to it, throwing the
+  // side-by-side layout out of alignment.
+  const [breakdownItem, setBreakdownItem] = useState<CategoryBreakdownItem | null>(null);
   const hasData = items.length > 0;
   // Recharts needs a numeric dataKey — API amounts arrive as strings (Decimal
   // is serialized as string to avoid float precision loss).
   const chartData = items.map((item) => ({ ...item, amount: Number(item.amount) }));
 
-  function toggle(categoryId: number) {
-    setExpanded((prev) => {
-      const next = new Set(prev);
-      if (next.has(categoryId)) next.delete(categoryId);
-      else next.add(categoryId);
-      return next;
-    });
-  }
-
   return (
     <Card>
       <CardHeader>
@@ -87,46 +75,29 @@ export function SpendingByCategoryCard({ items }: SpendingByCategoryCardProps) {
               {items.map((item) => {
                 const Icon = getCategoryIcon(item.icon);
                 const hasChildren = item.children.length > 0;
-                const isExpanded = item.category_id !== null && expanded.has(item.category_id);
                 return (
-                  <li key={item.category_id ?? "other"} className="py-2 first:pt-0 last:pb-0">
-                    <button
-                      type="button"
-                      disabled={!hasChildren}
-                      onClick={() => item.category_id !== null && toggle(item.category_id)}
-                      className="flex w-full items-center gap-3 text-left disabled:cursor-default"
+                  <li key={item.category_id ?? "other"} className="flex items-center gap-3 py-2 first:pt-0 last:pb-0">
+                    <span
+                      className="flex h-7 w-7 shrink-0 items-center justify-center rounded-full"
+                      style={{ backgroundColor: `${item.color}26` }}
                     >
-                      <span className="flex h-4 w-4 shrink-0 items-center justify-center text-text-muted">
-                        {hasChildren ? isExpanded ? <ChevronDown size={14} /> : <ChevronRight size={14} /> : null}
-                      </span>
-                      <span
-                        className="flex h-7 w-7 shrink-0 items-center justify-center rounded-full"
-                        style={{ backgroundColor: `${item.color}26` }}
+                      <Icon size={14} style={{ color: item.color }} />
+                    </span>
+                    <span className="min-w-0 flex-1 truncate text-sm text-text-primary">
+                      {translateCategoryName(item.name)}
+                    </span>
+                    <span className="shrink-0 text-sm font-medium tabular-nums text-text-primary">
+                      {formatCurrency(item.amount)}
+                    </span>
+                    {hasChildren && (
+                      <button
+                        type="button"
+                        aria-label={t("common.expand")}
+                        onClick={() => setBreakdownItem(item)}
+                        className="shrink-0 rounded-md p-1 text-text-muted hover:bg-surface-2 hover:text-text-primary"
                       >
-                        <Icon size={14} style={{ color: item.color }} />
-                      </span>
-                      <span className="min-w-0 flex-1 truncate text-sm text-text-primary">
-                        {translateCategoryName(item.name)}
-                      </span>
-                      <span className="shrink-0 text-sm font-medium tabular-nums text-text-primary">
-                        {formatCurrency(item.amount)}
-                      </span>
-                    </button>
-
-                    {hasChildren && isExpanded && (
-                      <ul className="ml-11 mt-1 space-y-1 border-l border-gridline pl-3">
-                        {item.children.map((child) => (
-                          <li key={child.category_id} className="flex items-center gap-2 text-xs">
-                            <span className="h-2 w-2 shrink-0 rounded-full" style={{ backgroundColor: child.color }} />
-                            <span className="min-w-0 flex-1 truncate text-text-secondary">
-                              {childLabel(child, item.category_id, t)}
-                            </span>
-                            <span className="shrink-0 tabular-nums text-text-secondary">
-                              {formatCurrency(child.amount)}
-                            </span>
-                          </li>
-                        ))}
-                      </ul>
+                        <ChevronRight size={15} />
+                      </button>
                     )}
                   </li>
                 );
@@ -135,6 +106,17 @@ export function SpendingByCategoryCard({ items }: SpendingByCategoryCardProps) {
           </div>
         )}
       </CardContent>
+
+      {breakdownItem && breakdownItem.category_id !== null && (
+        <CategoryBreakdownModal
+          open
+          onClose={() => setBreakdownItem(null)}
+          categoryId={breakdownItem.category_id}
+          categoryName={breakdownItem.name}
+          totalAmount={breakdownItem.amount}
+          children={breakdownItem.children}
+        />
+      )}
     </Card>
   );
 }

frontend/src/components/reports/CategoryRankingCard.tsx

@@ -1,11 +1,12 @@
 import { useState } from "react";
-import { ChevronDown, ChevronRight } from "lucide-react";
+import { ChevronRight } from "lucide-react";
 import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/Card";
+import { CategoryBreakdownModal } from "@/components/categories/CategoryBreakdownModal";
 import { getCategoryIcon } from "@/lib/icons";
 import { formatCurrency } from "@/lib/format";
-import { useTranslation, type TranslationKey } from "@/lib/i18n";
+import { useTranslation } from "@/lib/i18n";
 import { translateCategoryName } from "@/lib/categoryLabels";
-import type { CategoryRankingChildItem, CategoryRankingItem } from "@/types";
+import type { CategoryRankingItem } from "@/types";
 
 interface CategoryRankingCardProps {
   items: CategoryRankingItem[];
@@ -19,26 +20,12 @@ interface CategoryRankingCardProps {
  * detail chart below (locked to one category), this is "which category
  * costs the most" across the whole range at once. Clicking a row drills
  * into that category in the detail chart/transaction list below. */
-// A child's category_id equals its parent's own — the enclosing
-// CategoryRankingItem's — when that slice of spend was filed directly on
-// the parent with no more specific subcategory chosen (see
-// services/category_rollup.py's CategoryRollupChildItem).
-function childLabel(child: CategoryRankingChildItem, parentId: number, t: (key: TranslationKey) => string) {
-  return child.category_id === parentId ? t("reports.directSpendLabel") : translateCategoryName(child.name);
-}
-
 export function CategoryRankingCard({ items, isLoading, selectedCategoryId, onSelectCategory }: CategoryRankingCardProps) {
   const { t } = useTranslation();
-  const [expanded, setExpanded] = useState<Set<number>>(new Set());
-
-  function toggle(categoryId: number) {
-    setExpanded((prev) => {
-      const next = new Set(prev);
-      if (next.has(categoryId)) next.delete(categoryId);
-      else next.add(categoryId);
-      return next;
-    });
-  }
+  // The subcategory breakdown lives in a modal, not expanded inline — a
+  // category with many subcategories would otherwise push the whole ranking
+  // list taller and shift every row below it.
+  const [breakdownItem, setBreakdownItem] = useState<CategoryRankingItem | null>(null);
 
   return (
     <Card>
@@ -56,7 +43,6 @@ export function CategoryRankingCard({ items, isLoading, selectedCategoryId, onSe
               const Icon = getCategoryIcon(item.icon);
               const isSelected = item.category_id === selectedCategoryId;
               const hasChildren = item.children.length > 0;
-              const isExpanded = expanded.has(item.category_id);
               return (
                 <li key={item.category_id}>
                   <div
@@ -97,36 +83,31 @@ export function CategoryRankingCard({ items, isLoading, selectedCategoryId, onSe
                     {hasChildren && (
                       <button
                         type="button"
-                        aria-label={isExpanded ? t("common.collapse") : t("common.expand")}
-                        onClick={() => toggle(item.category_id)}
+                        aria-label={t("common.expand")}
+                        onClick={() => setBreakdownItem(item)}
                         className="mr-1 shrink-0 rounded-md p-1.5 text-text-muted hover:text-text-primary"
                       >
-                        {isExpanded ? <ChevronDown size={14} /> : <ChevronRight size={14} />}
+                        <ChevronRight size={14} />
                       </button>
                     )}
                   </div>
-
-                  {hasChildren && isExpanded && (
-                    <ul className="ml-11 mb-2 mt-1 space-y-1 border-l border-gridline pl-3">
-                      {item.children.map((child) => (
-                        <li key={child.category_id} className="flex items-center gap-2 text-xs">
-                          <span className="h-2 w-2 shrink-0 rounded-full" style={{ backgroundColor: child.color }} />
-                          <span className="min-w-0 flex-1 truncate text-text-secondary">
-                            {childLabel(child, item.category_id, t)}
-                          </span>
-                          <span className="shrink-0 tabular-nums text-text-secondary">
-                            {formatCurrency(child.amount)}
-                          </span>
-                        </li>
-                      ))}
-                    </ul>
-                  )}
                 </li>
               );
             })}
           </ul>
         )}
       </CardContent>
+
+      {breakdownItem && (
+        <CategoryBreakdownModal
+          open
+          onClose={() => setBreakdownItem(null)}
+          categoryId={breakdownItem.category_id}
+          categoryName={breakdownItem.name}
+          totalAmount={breakdownItem.amount}
+          children={breakdownItem.children}
+        />
+      )}
     </Card>
   );
 }

frontend/src/lib/i18n.ts

@@ -291,6 +291,7 @@ const ru = {
   "transactions.form.splitDirectOption": "— без конкретной подкатегории —",
   "transactions.form.splitNoChildren": "У этой категории пока нет подкатегорий — добавьте их на странице «Категории», чтобы разбивать покупки по ним.",
   "reports.directSpendLabel": "Без подкатегории",
+  "reports.categoryBreakdownTotalLabel": "Итого",
 
   "reports.categoryLabel": "Категория",
   "reports.expenseGroup": "Расходы",
@@ -772,6 +773,7 @@ const en: Record<keyof typeof ru, string> = {
   "transactions.form.splitDirectOption": "— no specific subcategory —",
   "transactions.form.splitNoChildren": "This category has no subcategories yet — add some on the Categories page to split purchases across them.",
   "reports.directSpendLabel": "No subcategory",
+  "reports.categoryBreakdownTotalLabel": "Total",
 
   "reports.categoryLabel": "Category",
   "reports.expenseGroup": "Expenses",