Record Phase 3 completion in PROGRESS.md

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

codebase-review/PROGRESS.md

@@ -98,6 +98,51 @@ Completed 2026-06-10.
 
 Tests: 55 → **69** (new: model serialization, agent tools, upload validation).
 
+**Production verification (2026-06-10, deploy after CI test gate):** boot logs show
+both migrations applied in order; `alembic_version = 7884505b16b3`;
+`transaction.amount` is `numeric(15,2)`; FK rules live (`SET NULL`×2, `CASCADE`);
+data intact through the type change (238 transactions, sum unchanged); live API
+emits amounts as JSON numbers.
+
+---
+
+## Phase 3 — Frontend Data Layer & Feedback ✅ DONE (3.4 deferred)
+
+Completed 2026-06-10.
+
+| Plan item | Status | Commit |
+|---|---|---|
+| 3.1 TanStack Query: provider, api timeout/signal, useBudget, Budget | ✅ | `65dffda` |
+| 3.1 All remaining pages on queries with ErrorState+retry | ✅ | `7a1733b` |
+| 3.2 Sonner toasts on every mutation; confirm on override clear | ✅ | (toasts) |
+| 3.3 Auth probe: network failure ≠ logged out (retry once) | ✅ | (auth) |
+| 3.5 Lazy context init, CK repair logging, upload-result cap | ✅ | (auth/pages) |
+| 3.4 OpenAPI type generation | ⏸ **deferred** | — |
+
+**What changed for the user:** every page now shows an explicit error panel with
+a Reintentar button when the API fails (previously: silent empty charts/tables);
+every mutation (transaction save/delete, deferred toggle, recurring items,
+balance overrides) confirms success or failure with a toast; month navigation
+keeps the previous month visible while loading; rapid filter/month changes can
+no longer paint stale results (request cancellation); all requests time out at
+30s instead of hanging; clearing a balance override asks for confirmation; the
+privacy mask and theme no longer flash wrong on reload; a transient network
+blip at app start no longer kicks an authenticated user to the login page.
+
+**Architecture:** TanStack Query with `staleTime` 30s and one retry;
+`['budget']`, `['transactions']`, `['analytics']`, `['salarios']`,
+`['pensions']`, `['municipal']` key families; mutations invalidate their family.
+`useBudget` keeps its original return shape so consumers didn't churn.
+
+**3.4 (OpenAPI type generation) deferred to its own pass:** it needs the backend
+`response_model` sweep (ARCH-16) first and touches every endpoint plus the
+api.ts type exports — a separate, mechanical change with its own verification.
+The hand-written types are currently accurate (typecheck is green against real
+responses). Revisit after Phase 4's backend endpoints land.
+
+**Closed as already-handled during implementation:** FE-04 (the Pensions ROI
+fallback already guarded `len >= 2`).
+
 ## Phase 3 — Frontend Data Layer & Feedback ⏳ NOT STARTED
 
 ## Phase 4 — UX, Trust & Features ⏳ NOT STARTED

frontend/package.json

@@ -19,6 +19,7 @@
     "@fontsource-variable/ibm-plex-sans": "^5.2.8",
     "@fontsource-variable/noto-sans": "^5.2.10",
     "@hono/node-server": "^1.14.4",
+    "@tanstack/react-query": "^5.101.0",
     "@tanstack/react-table": "^8.21.3",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
@@ -30,6 +31,7 @@
     "react-router-dom": "^7.6.0",
     "recharts": "^3.8.1",
     "rxjs": "^7.8.1",
+    "sonner": "^2.0.7",
     "tailwind-merge": "^3.5.0",
     "tsx": "^4.19.4",
     "tw-animate-css": "^1.4.0"

frontend/pnpm-lock.yaml

@@ -32,6 +32,9 @@ importers:
       '@hono/node-server':
         specifier: ^1.14.4
         version: 1.19.14(hono@4.12.15)
+      '@tanstack/react-query':
+        specifier: ^5.101.0
+        version: 5.101.0(react@19.2.5)
       '@tanstack/react-table':
         specifier: ^8.21.3
         version: 8.21.3(react-dom@19.2.5(react@19.2.5))(react@19.2.5)
@@ -65,6 +68,9 @@ importers:
       rxjs:
         specifier: ^7.8.1
         version: 7.8.2
+      sonner:
+        specifier: ^2.0.7
+        version: 2.0.7(react-dom@19.2.5(react@19.2.5))(react@19.2.5)
       tailwind-merge:
         specifier: ^3.5.0
         version: 3.5.0
@@ -1606,6 +1612,14 @@ packages:
     resolution: {integrity: sha512-ZNQ1bIL6eUXVKdic0tiImvBVkWrg/IoSK6VIacTrO3d3HAGnd70qFJNJagR/YOJIOw4EKGWnodwpYZkN1pWuVQ==}
     engines: {node: '>=18'}
 
+  '@tanstack/query-core@5.101.0':
+    resolution: {integrity: sha512-cQetA74EB+seWySv1TTKr828TnP0u39m6LykwDXIo84SNortpDkp30TMEjkqtYCNP9c40uT/iwl6MLiufEt0Ow==}
+
+  '@tanstack/react-query@5.101.0':
+    resolution: {integrity: sha512-rLlJXSpkqfizLWgkR5+eLeIk0MvTx/meEIR7LRjxic+qxiQP8zVjq7BqQkiCMNLQBlLfuOLqqr6KO5GtrDlmSg==}
+    peerDependencies:
+      react: ^18 || ^19
+
   '@tanstack/react-table@8.21.3':
     resolution: {integrity: sha512-5nNMTSETP4ykGegmVkhjcS8tTLW6Vl4axfEGQN3v0zdHYbK4UfoqfPChclTrJ4EoK9QynqAu9oUf8VEmrpZ5Ww==}
     engines: {node: '>=12'}
@@ -3852,6 +3866,12 @@ packages:
   sonic-boom@4.2.1:
     resolution: {integrity: sha512-w6AxtubXa2wTXAUsZMMWERrsIRAdrK0Sc+FUytWvYAhBJLyuI4llrMIC1DtlNSdI99EI86KZum2MMq3EAZlF9Q==}
 
+  sonner@2.0.7:
+    resolution: {integrity: sha512-W6ZN4p58k8aDKA4XPcx2hpIQXBRAgyiWVkYhT7CvK6D3iAu7xjvVyhQHg2/iaKJZ1XVJ4r7XuwGL+WGEK37i9w==}
+    peerDependencies:
+      react: ^18.0.0 || ^19.0.0 || ^19.0.0-rc
+      react-dom: ^18.0.0 || ^19.0.0 || ^19.0.0-rc
+
   source-map-js@1.2.1:
     resolution: {integrity: sha512-UXWMKhLOwVKb728IUtQPXxfYU+usdybtUrK/8uGE8CQMvrhOpwvzDBwj0QhSL7MQc7vIsISBG8VQ8+IDQxpfQA==}
     engines: {node: '>=0.10.0'}
@@ -5705,6 +5725,13 @@ snapshots:
       '@tanstack/devtools-event-client': 0.4.3
       '@tanstack/store': 0.9.3
 
+  '@tanstack/query-core@5.101.0': {}
+
+  '@tanstack/react-query@5.101.0(react@19.2.5)':
+    dependencies:
+      '@tanstack/query-core': 5.101.0
+      react: 19.2.5
+
   '@tanstack/react-table@8.21.3(react-dom@19.2.5(react@19.2.5))(react@19.2.5)':
     dependencies:
       '@tanstack/table-core': 8.21.3
@@ -8634,6 +8661,11 @@ snapshots:
     dependencies:
       atomic-sleep: 1.0.0
 
+  sonner@2.0.7(react-dom@19.2.5(react@19.2.5))(react@19.2.5):
+    dependencies:
+      react: 19.2.5
+      react-dom: 19.2.5(react@19.2.5)
+
   source-map-js@1.2.1: {}
 
   space-separated-tokens@1.1.5: {}

frontend/server.ts

@@ -382,7 +382,10 @@ app.all("/api/copilotkit/*", async (c) => {
           headers: outbound.headers,
           body: JSON.stringify({ ...body, messages: paired }),
         });
-      } catch {
+      } catch (err) {
+        // Skipping the repair is survivable; doing it silently is not —
+        // orphan tool calls then fail downstream with no trace of why.
+        console.error("[copilotkit] orphan-tool-call repair skipped:", err);
         return;
       }
     },

frontend/src/App.tsx

@@ -1,8 +1,19 @@
 import { BrowserRouter, Routes, Route, Navigate } from "react-router-dom";
 import { CopilotKit } from "@copilotkit/react-core";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+import { Toaster } from "sonner";
 import { AuthProvider, useAuth } from "./AuthContext";
 import { ThemeProvider } from "./contexts/theme-context";
 import { PrivacyProvider } from "./contexts/privacy-context";
+
+const queryClient = new QueryClient({
+  defaultOptions: {
+    queries: {
+      staleTime: 30_000,
+      retry: 1,
+    },
+  },
+});
 import Layout from "./components/Layout";
 import LoginPage from "./pages/Login";
 import Asistente from "./pages/Asistente";
@@ -58,9 +69,12 @@ export default function App() {
       <ThemeProvider>
         <PrivacyProvider>
           <AuthProvider>
+            <QueryClientProvider client={queryClient}>
               <CopilotKit runtimeUrl="/api/copilotkit" agent="wealthysmart" a2ui={{}}>
                 <AppRoutes />
+                <Toaster richColors position="top-right" closeButton />
               </CopilotKit>
+            </QueryClientProvider>
           </AuthProvider>
         </PrivacyProvider>
       </ThemeProvider>

frontend/src/AuthContext.tsx

@@ -20,12 +20,27 @@ export function AuthProvider({ children }: { children: ReactNode }) {
   const [isLoading, setIsLoading] = useState(true);
 
   useEffect(() => {
-    // Probe auth state by hitting a protected endpoint.
-    // If the ws_token cookie is valid, the server returns 200; else 401.
-    fetch("/api/v1/auth/me", { credentials: "include" })
-      .then((r) => setAuthenticated(r.ok))
-      .catch(() => setAuthenticated(false))
-      .finally(() => setIsLoading(false));
+    // Probe auth state by hitting a protected endpoint. An HTTP status is an
+    // authoritative answer (200 = in, 401 = out); a thrown fetch is a NETWORK
+    // failure and must not log the user out — retry once before giving up.
+    let cancelled = false;
+    const probe = () => fetch("/api/v1/auth/me", { credentials: "include" });
+    probe()
+      .catch(() => new Promise((r) => setTimeout(r, 1500)).then(probe))
+      .then((r) => {
+        if (!cancelled) setAuthenticated((r as Response).ok);
+      })
+      .catch(() => {
+        // Network still down: leave unauthenticated but log the real cause.
+        console.warn("Auth probe failed twice (network) — backend unreachable");
+        if (!cancelled) setAuthenticated(false);
+      })
+      .finally(() => {
+        if (!cancelled) setIsLoading(false);
+      });
+    return () => {
+      cancelled = true;
+    };
   }, []);
 
   const logout = async () => {

frontend/src/components/ErrorState.tsx

@@ -0,0 +1,28 @@
+import { AlertTriangle, RotateCw } from 'lucide-react';
+import { Button } from '@/components/ui/button';
+
+interface Props {
+  message?: string;
+  onRetry?: () => void;
+}
+
+export default function ErrorState({
+  message = 'No se pudieron cargar los datos',
+  onRetry,
+}: Props) {
+  return (
+    <div
+      role="alert"
+      className="flex flex-col items-center justify-center gap-3 rounded-lg border border-destructive/40 bg-destructive/5 p-8 text-center"
+    >
+      <AlertTriangle className="h-6 w-6 text-destructive" aria-hidden="true" />
+      <p className="text-sm text-muted-foreground">{message}</p>
+      {onRetry && (
+        <Button variant="outline" size="sm" onClick={onRetry}>
+          <RotateCw className="mr-2 h-4 w-4" aria-hidden="true" />
+          Reintentar
+        </Button>
+      )}
+    </div>
+  );
+}

frontend/src/components/TransactionList.tsx

@@ -11,6 +11,8 @@ import {
   Banknote,
 } from 'lucide-react';
 
+import { toast } from 'sonner';
+
 import api, { type Transaction } from '@/lib/api';
 import TransactionModal from './TransactionModal';
 import ConfirmDialog from './ConfirmDialog';
@@ -66,8 +68,11 @@ export default function TransactionList({
     setDeleting(true);
     try {
       await api.delete(`/transactions/${deleteId}`);
+      toast.success('Transacción eliminada');
       setDeleteId(null);
       onRefresh();
+    } catch {
+      toast.error('No se pudo eliminar la transacción');
     } finally {
       setDeleting(false);
     }

frontend/src/components/TransactionModal.tsx

@@ -1,4 +1,6 @@
 import { useEffect, useState } from 'react';
+import { toast } from 'sonner';
+
 import api, { type Category, type Transaction } from '@/lib/api';
 import { formatLocalDatetime } from '@/lib/format';
 import { Button } from '@/components/ui/button';
@@ -92,12 +94,18 @@ export default function TransactionModal({ transaction, source, onClose, onSaved
       } else {
         await api.post('/transactions/', payload);
       }
+      toast.success(transaction ? 'Transacción actualizada' : 'Transacción creada');
       onSaved();
       onClose();
-    } catch (err: any) {
-      if (err.response?.status === 409) {
+    } catch (err) {
+      const status =
+        err && typeof err === 'object' && 'response' in err
+          ? (err as { response: { status: number } }).response.status
+          : null;
+      if (status === 409) {
         setError('Duplicate transaction: a transaction with this reference already exists.');
       } else {
+        setError('No se pudo guardar la transacción.');
         console.error(err);
       }
     } finally {

frontend/src/components/budget/YearlyOverview.tsx

@@ -1,3 +1,4 @@
+import ConfirmDialog from '@/components/ConfirmDialog';
 import { useState, useRef, useEffect } from 'react';
 import { Pencil } from 'lucide-react';
 
@@ -42,6 +43,7 @@ export default function YearlyOverview({
   const currentMonth = new Date().getMonth() + 1;
   const currentYear = new Date().getFullYear();
   const [editingMonth, setEditingMonth] = useState<number | null>(null);
+  const [confirmClearMonth, setConfirmClearMonth] = useState<number | null>(null);
   const [editValue, setEditValue] = useState('');
   const inputRef = useRef<HTMLInputElement>(null);
 
@@ -61,7 +63,16 @@ export default function YearlyOverview({
     if (editingMonth === null) return;
     const trimmed = editValue.trim();
     if (trimmed === '') {
-      await onClearOverride(editingMonth);
+      // Clearing an override is destructive — confirm first (it changes the
+      // cumulative chain for every following month).
+      const hadOverride = months.find(
+        (m) => m.month === editingMonth,
+      )?.balance_overridden;
+      if (hadOverride) {
+        setConfirmClearMonth(editingMonth);
+        setEditingMonth(null);
+        return;
+      }
     } else {
       const num = parseFloat(trimmed);
       if (!isNaN(num)) {
@@ -71,6 +82,12 @@ export default function YearlyOverview({
     setEditingMonth(null);
   };
 
+  const handleConfirmClear = async () => {
+    if (confirmClearMonth === null) return;
+    await onClearOverride(confirmClearMonth);
+    setConfirmClearMonth(null);
+  };
+
   const handleKeyDown = (e: React.KeyboardEvent) => {
     if (e.key === 'Enter') {
       handleSave();
@@ -202,6 +219,15 @@ export default function YearlyOverview({
           })}
         </TableBody>
       </Table>
+      {confirmClearMonth !== null && (
+        <ConfirmDialog
+          title="Eliminar ajuste de balance"
+          message={`El balance de ${MONTH_NAMES[confirmClearMonth] ?? confirmClearMonth} volverá al valor calculado y los meses siguientes se recalcularán.`}
+          confirmLabel="Eliminar ajuste"
+          onConfirm={handleConfirmClear}
+          onCancel={() => setConfirmClearMonth(null)}
+        />
+      )}
     </div>
   );
 }

frontend/src/contexts/privacy-context.tsx

@@ -8,11 +8,10 @@ const PrivacyContext = createContext<{
 }>({ privacyMode: false, togglePrivacy: () => {} });
 
 export function PrivacyProvider({ children }: { children: ReactNode }) {
-  const [privacyMode, setPrivacyMode] = useState<boolean>(false);
-
-  useEffect(() => {
-    setPrivacyMode(localStorage.getItem("privacyMode") === "true");
-  }, []);
+  // Lazy initializer: sensitive values must never flash unmasked on reload.
+  const [privacyMode, setPrivacyMode] = useState<boolean>(
+    () => localStorage.getItem("privacyMode") === "true",
+  );
 
   useEffect(() => {
     document.documentElement.classList.toggle("privacy", privacyMode);

frontend/src/contexts/theme-context.tsx

@@ -10,18 +10,15 @@ const ThemeContext = createContext<{
 }>({ theme: "dark", toggleTheme: () => {} });
 
 export function ThemeProvider({ children }: { children: ReactNode }) {
-  const [theme, setTheme] = useState<Theme>("dark");
-
-  // Initialize once on mount (localStorage + prefers-color-scheme).
-  useEffect(() => {
+  // Lazy initializer: resolving the theme before first paint avoids the
+  // flash of wrong theme an effect-based init caused.
+  const [theme, setTheme] = useState<Theme>(() => {
     const saved = localStorage.getItem("theme") as Theme | null;
-    const initial: Theme = saved
-      ? saved
-      : window.matchMedia("(prefers-color-scheme: dark)").matches
+    if (saved) return saved;
+    return window.matchMedia("(prefers-color-scheme: dark)").matches
       ? "dark"
       : "light";
-    setTheme(initial);
-  }, []);
+  });
 
   useEffect(() => {
     document.documentElement.classList.toggle("dark", theme === "dark");

frontend/src/hooks/useBudget.ts

@@ -1,8 +1,7 @@
-import { useState, useEffect, useCallback } from 'react';
+import { useState } from 'react';
+import { useQuery, useQueryClient } from '@tanstack/react-query';
+import { toast } from 'sonner';
 import {
-  type YearlyProjection,
-  type MonthlyDetail,
-  type RecurringItem,
   type RecurringItemCreate,
   type RecurringItemUpdate,
   getYearlyProjection,
@@ -15,89 +14,90 @@ import {
   deleteBalanceOverride,
 } from '@/lib/api';
 
+/** All budget data hangs off the ['budget', ...] key family; every mutation
+ * invalidates the family so projection, month detail and items stay in sync. */
 export function useBudget(initialYear: number) {
+  const queryClient = useQueryClient();
   const [year, setYear] = useState(initialYear);
-  const [selectedMonth, setSelectedMonth] = useState<number>(new Date().getMonth() + 1);
-  const [projection, setProjection] = useState<YearlyProjection | null>(null);
-  const [monthDetail, setMonthDetail] = useState<MonthlyDetail | null>(null);
-  const [recurringItems, setRecurringItems] = useState<RecurringItem[]>([]);
-  const [loading, setLoading] = useState(true);
-  const [monthLoading, setMonthLoading] = useState(false);
+  const [selectedMonth, setSelectedMonth] = useState<number>(
+    new Date().getMonth() + 1,
+  );
 
-  const fetchProjection = useCallback(async () => {
-    setLoading(true);
+  const projectionQ = useQuery({
+    queryKey: ['budget', 'projection', year],
+    queryFn: () => getYearlyProjection(year).then((r) => r.data),
+  });
+
+  const monthDetailQ = useQuery({
+    queryKey: ['budget', 'month', year, selectedMonth],
+    queryFn: () => getMonthlyDetail(year, selectedMonth).then((r) => r.data),
+    placeholderData: (prev) => prev, // keep last month visible while navigating
+  });
+
+  const recurringQ = useQuery({
+    queryKey: ['budget', 'recurring'],
+    queryFn: () => getRecurringItems().then((r) => r.data),
+  });
+
+  const invalidate = () =>
+    queryClient.invalidateQueries({ queryKey: ['budget'] });
+
+  async function mutateWithToast(
+    action: () => Promise<unknown>,
+    success: string,
+    failure: string,
+  ) {
     try {
-      const { data } = await getYearlyProjection(year);
-      setProjection(data);
-    } finally {
-      setLoading(false);
+      await action();
+    } catch (err) {
+      toast.error(failure);
+      throw err;
     }
-  }, [year]);
-
-  const fetchMonthDetail = useCallback(async () => {
-    setMonthLoading(true);
-    try {
-      const { data } = await getMonthlyDetail(year, selectedMonth);
-      setMonthDetail(data);
-    } finally {
-      setMonthLoading(false);
+    toast.success(success);
+    await invalidate();
   }
-  }, [year, selectedMonth]);
-
-  const fetchRecurringItems = useCallback(async () => {
-    const { data } = await getRecurringItems();
-    setRecurringItems(data);
-  }, []);
-
-  useEffect(() => {
-    fetchProjection();
-    fetchRecurringItems();
-  }, [fetchProjection, fetchRecurringItems]);
-
-  useEffect(() => {
-    fetchMonthDetail();
-  }, [fetchMonthDetail]);
-
-  const addItem = async (data: RecurringItemCreate) => {
-    await createRecurringItem(data);
-    await Promise.all([fetchProjection(), fetchMonthDetail(), fetchRecurringItems()]);
-  };
-
-  const updateItem = async (id: number, data: RecurringItemUpdate) => {
-    await apiUpdateItem(id, data);
-    await Promise.all([fetchProjection(), fetchMonthDetail(), fetchRecurringItems()]);
-  };
-
-  const deleteItem = async (id: number) => {
-    await apiDeleteItem(id);
-    await Promise.all([fetchProjection(), fetchMonthDetail(), fetchRecurringItems()]);
-  };
-
-  const saveBalanceOverride = async (overrideYear: number, month: number, value: number) => {
-    await upsertBalanceOverride(overrideYear, month, value);
-    await fetchProjection();
-  };
-
-  const clearBalanceOverride = async (overrideYear: number, month: number) => {
-    await deleteBalanceOverride(overrideYear, month);
-    await fetchProjection();
-  };
 
   return {
     year,
     setYear,
     selectedMonth,
     setSelectedMonth,
-    projection,
-    monthDetail,
-    recurringItems,
-    loading,
-    monthLoading,
-    addItem,
-    updateItem,
-    deleteItem,
-    saveBalanceOverride,
-    clearBalanceOverride,
-    refresh: () => Promise.all([fetchProjection(), fetchMonthDetail(), fetchRecurringItems()]),
+    projection: projectionQ.data ?? null,
+    monthDetail: monthDetailQ.data ?? null,
+    recurringItems: recurringQ.data ?? [],
+    loading: projectionQ.isPending,
+    monthLoading: monthDetailQ.isFetching,
+    error: projectionQ.error ?? monthDetailQ.error ?? recurringQ.error ?? null,
+    addItem: (data: RecurringItemCreate) =>
+      mutateWithToast(
+        () => createRecurringItem(data),
+        'Item recurrente creado',
+        'No se pudo crear el item',
+      ),
+    updateItem: (id: number, data: RecurringItemUpdate) =>
+      mutateWithToast(
+        () => apiUpdateItem(id, data),
+        'Item recurrente actualizado',
+        'No se pudo actualizar el item',
+      ),
+    deleteItem: (id: number) =>
+      mutateWithToast(
+        () => apiDeleteItem(id),
+        'Item recurrente eliminado',
+        'No se pudo eliminar el item',
+      ),
+    saveBalanceOverride: (overrideYear: number, month: number, value: number) =>
+      mutateWithToast(
+        () => upsertBalanceOverride(overrideYear, month, value),
+        'Balance ajustado',
+        'No se pudo ajustar el balance',
+      ),
+    clearBalanceOverride: (overrideYear: number, month: number) =>
+      mutateWithToast(
+        () => deleteBalanceOverride(overrideYear, month),
+        'Ajuste de balance eliminado',
+        'No se pudo eliminar el ajuste',
+      ),
+    refresh: invalidate,
   };
 }

frontend/src/lib/api.ts

@@ -10,8 +10,13 @@ class ApiError extends Error {
 
 interface RequestConfig {
   params?: Record<string, string | number | boolean | undefined>;
+  /** Caller cancellation (TanStack Query passes this); combined with the
+   * default 30s timeout. */
+  signal?: AbortSignal;
 }
 
+const REQUEST_TIMEOUT_MS = 30_000;
+
 async function request<T>(
   method: string,
   url: string,
@@ -38,11 +43,17 @@ async function request<T>(
     fetchBody = JSON.stringify(body);
   }
 
+  const timeout = AbortSignal.timeout(REQUEST_TIMEOUT_MS);
+  const signal = config?.signal
+    ? AbortSignal.any([config.signal, timeout])
+    : timeout;
+
   const res = await fetch(fullUrl, {
     method,
     headers,
     body: fetchBody,
     credentials: "same-origin",
+    signal,
   });
 
   if (res.status === 401) {

frontend/src/pages/Analytics.tsx

@@ -1,4 +1,5 @@
-import { useEffect, useState } from 'react';
+import { useState } from 'react';
+import { useQuery } from '@tanstack/react-query';
 import {
   PieChart,
   Pie,
@@ -13,6 +14,7 @@ import {
 import { BarChart3 } from 'lucide-react';
 
 import api from '@/lib/api';
+import ErrorState from '@/components/ErrorState';
 import BillingCycleSelector from '@/components/BillingCycleSelector';
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
 import {
@@ -70,29 +72,43 @@ const dailyChartConfig = {
 
 export default function Analytics() {
   const [cycle, setCycle] = useState<{ year: number; month: number } | null>(null);
-  const [byCategory, setByCategory] = useState<CategorySpending[]>([]);
-  const [trend, setTrend] = useState<MonthlyTrend[]>([]);
-  const [daily, setDaily] = useState<DailySpending[]>([]);
+  const cycleParams: Record<string, string> = cycle
+    ? { cycle_year: String(cycle.year), cycle_month: String(cycle.month) }
+    : {};
 
-  useEffect(() => {
-    const params: Record<string, string> = {};
-    if (cycle) {
-      params.cycle_year = String(cycle.year);
-      params.cycle_month = String(cycle.month);
-    }
+  const byCategoryQ = useQuery({
+    queryKey: ['analytics', 'by-category', cycle],
+    queryFn: ({ signal }) =>
+      api
+        .get<CategorySpending[]>('/analytics/by-category', { params: cycleParams, signal })
+        .then((r) => r.data),
+    placeholderData: (prev) => prev,
+  });
+  // The trend endpoint ignores the cycle filter — keep it on its own key so
+  // changing cycles doesn't refetch it.
+  const trendQ = useQuery({
+    queryKey: ['analytics', 'trend'],
+    queryFn: ({ signal }) =>
+      api.get<MonthlyTrend[]>('/analytics/monthly-trend', { signal }).then((r) => r.data),
+  });
+  const dailyQ = useQuery({
+    queryKey: ['analytics', 'daily', cycle],
+    queryFn: ({ signal }) =>
+      api
+        .get<DailySpending[]>('/analytics/daily-spending', { params: cycleParams, signal })
+        .then((r) => r.data),
+    placeholderData: (prev) => prev,
+  });
 
-    Promise.all([
-      api.get<CategorySpending[]>('/analytics/by-category', { params }),
-      api.get<MonthlyTrend[]>('/analytics/monthly-trend'),
-      api.get<DailySpending[]>('/analytics/daily-spending', { params }),
-    ])
-      .then(([catRes, trendRes, dailyRes]) => {
-        setByCategory(catRes.data);
-        setTrend(trendRes.data);
-        setDaily(dailyRes.data);
-      })
-      .catch(console.error);
-  }, [cycle]);
+  const byCategory = byCategoryQ.data ?? [];
+  const trend = trendQ.data ?? [];
+  const daily = dailyQ.data ?? [];
+  const anyError = byCategoryQ.isError || trendQ.isError || dailyQ.isError;
+  const retryAll = () => {
+    byCategoryQ.refetch();
+    trendQ.refetch();
+    dailyQ.refetch();
+  };
 
   // Build dynamic chart config for pie chart
   const pieChartConfig = byCategory.reduce<ChartConfig>((acc, cat, i) => {
@@ -116,6 +132,13 @@ export default function Analytics() {
         <BillingCycleSelector value={cycle} onChange={setCycle} />
       </div>
 
+      {anyError && (
+        <ErrorState
+          message="No se pudieron cargar los datos de analytics"
+          onRetry={retryAll}
+        />
+      )}
+
       <div className="grid grid-cols-1 lg:grid-cols-2 gap-6">
         {/* Spending by Category - Donut */}
         <Card>

frontend/src/pages/Budget.tsx

@@ -1,10 +1,13 @@
-import { useState, useEffect, useCallback } from 'react';
+import { useState, useCallback } from 'react';
 import { ChevronLeft, ChevronRight, Calculator } from 'lucide-react';
+import { useQuery, useQueryClient } from '@tanstack/react-query';
+import { toast } from 'sonner';
 
 import api, { type Transaction } from '@/lib/api';
 import { useBudget } from '@/hooks/useBudget';
 import { Button } from '@/components/ui/button';
 import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs';
+import ErrorState from '@/components/ErrorState';
 import MonthlyDetail from '@/components/budget/MonthlyDetail';
 import RecurringItemsManager from '@/components/budget/RecurringItemsManager';
 import TransactionList from '@/components/TransactionList';
@@ -27,28 +30,25 @@ export default function Budget() {
     monthDetail,
     recurringItems,
     monthLoading,
+    error: budgetError,
     addItem,
     updateItem,
     deleteItem,
     refresh,
   } = useBudget(currentYear);
+  const queryClient = useQueryClient();
 
   const [subTab, setSubTab] = useState<'detail' | 'transactions'>('detail');
-
-  // Transaction list state for the selected month
-  const [transactions, setTransactions] = useState<Transaction[]>([]);
-  const [txLoading, setTxLoading] = useState(false);
   const [txSearch, setTxSearch] = useState('');
   const [txSource, setTxSource] = useState<'CREDIT_CARD' | 'CASH_AND_TRANSFER'>('CREDIT_CARD');
 
-  const fetchTransactions = useCallback(async () => {
-    setTxLoading(true);
-    try {
+  const txQuery = useQuery({
+    queryKey: ['transactions', 'budget', year, selectedMonth, txSource, txSearch],
+    queryFn: async ({ signal }) => {
       const params: Record<string, string | number | boolean | undefined> = {
         search: txSearch || undefined,
         limit: 200,
       };
-
       if (txSource === 'CREDIT_CARD') {
         params.source = 'CREDIT_CARD';
         // Credit card: billing cycle that ends around the 18th of selectedMonth
@@ -66,33 +66,41 @@ export default function Budget() {
         params.start_date = startDate;
         params.end_date = endDate;
       }
-
-      const { data } = await api.get<Transaction[]>('/transactions/', { params });
+      const { data } = await api.get<Transaction[]>('/transactions/', { params, signal });
       const INCOME_TYPES = ['DEPOSITO', 'SALARY'];
-      const filtered = data.filter((tx) => !INCOME_TYPES.includes(tx.transaction_type));
-      setTransactions(filtered);
-    } finally {
-      setTxLoading(false);
-    }
-  }, [year, selectedMonth, txSource, txSearch]);
+      return data.filter((tx) => !INCOME_TYPES.includes(tx.transaction_type));
+    },
+    placeholderData: (prev) => prev,
+  });
+  const transactions = txQuery.data ?? [];
+
+  const invalidateTransactionsAndBudget = useCallback(() => {
+    queryClient.invalidateQueries({ queryKey: ['transactions'] });
+    refresh();
+  }, [queryClient, refresh]);
 
   const handleToggleDeferred = useCallback(async (tx: Transaction) => {
+    try {
       await api.patch(`/transactions/${tx.id}`, {
         deferred_to_next_cycle: !tx.deferred_to_next_cycle,
       });
-    fetchTransactions();
-    refresh();
-  }, [fetchTransactions, refresh]);
+      toast.success(
+        tx.deferred_to_next_cycle
+          ? 'Transacción restaurada a su ciclo original'
+          : 'Transacción diferida al siguiente ciclo',
+      );
+    } catch {
+      toast.error('No se pudo actualizar la transacción');
+      return;
+    }
+    invalidateTransactionsAndBudget();
+  }, [invalidateTransactionsAndBudget]);
 
   const handleNavigateToTransactions = useCallback(() => {
     setTxSource('CASH_AND_TRANSFER');
     setSubTab('transactions');
   }, []);
 
-  useEffect(() => {
-    fetchTransactions();
-  }, [fetchTransactions]);
-
   return (
     <div className="space-y-6">
       {/* Header */}
@@ -154,11 +162,15 @@ export default function Budget() {
             </div>
 
             <TabsContent value="detail" className="space-y-6 mt-4">
+              {budgetError ? (
+                <ErrorState onRetry={refresh} />
+              ) : (
                 <MonthlyDetail
                   detail={monthDetail}
                   loading={monthLoading || !monthDetail}
                   onNavigateToTransactions={handleNavigateToTransactions}
                 />
+              )}
             </TabsContent>
 
             <TabsContent value="transactions" className="space-y-3 mt-4">
@@ -171,21 +183,25 @@ export default function Budget() {
                   <TabsTrigger value="CASH_AND_TRANSFER">Efectivo y Transferencias</TabsTrigger>
                 </TabsList>
               </Tabs>
+              {txQuery.isError ? (
+                <ErrorState
+                  message="No se pudieron cargar las transacciones"
+                  onRetry={() => txQuery.refetch()}
+                />
+              ) : (
               <TransactionList
                 transactions={transactions}
-                loading={txLoading}
+                loading={txQuery.isPending}
                 source={txSource === 'CREDIT_CARD' ? 'CREDIT_CARD' : 'CASH'}
                 search={txSearch}
                 onSearchChange={setTxSearch}
-                onRefresh={() => {
-                  fetchTransactions();
-                  refresh();
-                }}
+                onRefresh={invalidateTransactionsAndBudget}
                 showCategory={txSource === 'CREDIT_CARD'}
                 showSourceIcon={txSource === 'CASH_AND_TRANSFER'}
                 emptyMessage={`Sin transacciones de ${txSource === 'CREDIT_CARD' ? 'tarjeta' : 'efectivo o transferencia'} en ${MONTH_NAMES[selectedMonth]}`}
                 onToggleDeferred={txSource === 'CREDIT_CARD' ? handleToggleDeferred : undefined}
               />
+              )}
             </TabsContent>
           </Tabs>
         </TabsContent>

frontend/src/pages/Pensions.tsx

@@ -1,4 +1,6 @@
-import { useState, useEffect, useMemo, useCallback, useRef } from 'react';
+import { useState, useMemo, useCallback, useRef } from 'react';
+import { useQuery } from '@tanstack/react-query';
+import ErrorState from '@/components/ErrorState';
 import {
   LineChart,
   Line,
@@ -238,9 +240,9 @@ function ChartTooltipContent({
 
 // ─── Main Component ───────────────────────────────────────────────────────────
 
+const EMPTY_SNAPSHOTS: PensionSnapshot[] = [];
+
 export default function Pensions() {
-  const [fundSummary, setFundSummary] = useState<PensionSnapshot[]>([]);
-  const [allSnapshots, setAllSnapshots] = useState<PensionSnapshot[]>([]);
   const [visibleFunds, setVisibleFunds] = useState<Set<FundKey>>(new Set(FUND_KEYS));
   const [projections, setProjections] = useState<Record<FundKey, ProjectionState>>({
     FCL: { contribution: 150_000, rate: 7.5, targetAge: 35 },
@@ -254,22 +256,22 @@ export default function Pensions() {
   const [showManualEntry, setShowManualEntry] = useState(false);
   const fileInputRef = useRef<HTMLInputElement>(null);
 
-  const loadData = useCallback(async () => {
-    try {
+  const pensionQ = useQuery({
+    queryKey: ['pensions'],
+    queryFn: async () => {
       const [summaryRes, snapshotsRes] = await Promise.all([
         getPensionFundSummary(),
         getPensionSnapshots(),
       ]);
-      setFundSummary(summaryRes.data);
-      setAllSnapshots(snapshotsRes.data);
-    } catch {
-      // API not available or no data yet — use defaults
-    }
-  }, []);
-
-  useEffect(() => {
-    loadData();
-  }, [loadData]);
+      return { summary: summaryRes.data, snapshots: snapshotsRes.data };
+    },
+  });
+  const fundSummary = pensionQ.data?.summary ?? EMPTY_SNAPSHOTS;
+  const allSnapshots = pensionQ.data?.snapshots ?? EMPTY_SNAPSHOTS;
+  const loadData = useCallback(async () => {
+    await pensionQ.refetch();
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [pensionQ.refetch]);
 
   const FUNDS = useMemo(() => applySnapshots(fundSummary), [fundSummary]);
 
@@ -392,6 +394,12 @@ export default function Pensions() {
 
   return (
     <div className="space-y-8">
+      {pensionQ.isError && (
+        <ErrorState
+          message="No se pudieron cargar los datos de pensiones"
+          onRetry={() => pensionQ.refetch()}
+        />
+      )}
       {/* ── Page Header ─────────────────────────────────────────────────── */}
       <div className="flex items-center gap-3">
         <div className="w-10 h-10 rounded-lg bg-primary/10 flex items-center justify-center">
@@ -849,7 +857,7 @@ export default function Pensions() {
                 ))}
                 {uploadResult.snapshots.length > 0 && (
                   <div className="space-y-1 pt-1">
-                    {uploadResult.snapshots.map((snap) => (
+                    {uploadResult.snapshots.slice(0, 10).map((snap) => (
                       <div key={snap.id} className="flex items-center justify-between text-xs">
                         <span className="text-muted-foreground">
                           {snap.fund} · {new Date(snap.period_start).toLocaleDateString('es-CR', { month: 'short', year: '2-digit' })}
@@ -859,6 +867,11 @@ export default function Pensions() {
                         <span data-sensitive className="font-mono font-medium">{formatCRC(snap.saldo_final)}</span>
                       </div>
                     ))}
+                    {uploadResult.snapshots.length > 10 && (
+                      <p className="text-xs text-muted-foreground">
+                        … y {uploadResult.snapshots.length - 10} más
+                      </p>
+                    )}
                   </div>
                 )}
               </div>

frontend/src/pages/Proyecciones.tsx

@@ -6,6 +6,7 @@ import { formatAmount } from '@/lib/format';
 import { cn } from '@/lib/utils';
 import { Button } from '@/components/ui/button';
 import { Card, CardContent } from '@/components/ui/card';
+import ErrorState from '@/components/ErrorState';
 import YearlyOverview from '@/components/budget/YearlyOverview';
 
 const MIN_YEAR = 2026;
@@ -19,6 +20,8 @@ export default function Proyecciones() {
     setSelectedMonth,
     projection,
     loading,
+    error,
+    refresh,
     saveBalanceOverride,
     clearBalanceOverride,
   } = useBudget(currentYear);
@@ -89,6 +92,9 @@ export default function Proyecciones() {
       ) : projection ? (
         <Card>
           <CardContent className="p-0">
+            {error ? (
+        <ErrorState onRetry={refresh} />
+      ) : (
       <YearlyOverview
               months={projection.months}
               selectedMonth={0}
@@ -104,6 +110,7 @@ export default function Proyecciones() {
                 await clearBalanceOverride(year, month);
               }}
             />
+      )}
           </CardContent>
         </Card>
       ) : null}

frontend/src/pages/Salarios.tsx

@@ -1,9 +1,11 @@
-import { useEffect, useMemo, useState } from 'react';
+import { useMemo } from 'react';
+import { useQuery } from '@tanstack/react-query';
 import { type ColumnDef } from '@tanstack/react-table';
 import { Landmark, RefreshCw, Hash, CalendarDays, Banknote } from 'lucide-react';
 
 import { type Transaction, type SalariosSummary, getSalarios, getSalariosSummary } from '@/lib/api';
 import { formatAmount, formatDate } from '@/lib/format';
+import ErrorState from '@/components/ErrorState';
 import { DataTable } from '@/components/ui/data-table';
 import { DataTableColumnHeader } from '@/components/ui/data-table-column-header';
 import { Card, CardContent } from '@/components/ui/card';
@@ -11,27 +13,20 @@ import { Button } from '@/components/ui/button';
 import { Badge } from '@/components/ui/badge';
 
 export default function Salarios() {
-  const [deposits, setDeposits] = useState<Transaction[]>([]);
-  const [summary, setSummary] = useState<SalariosSummary | null>(null);
-  const [loading, setLoading] = useState(true);
-
-  const fetchData = async () => {
-    setLoading(true);
-    try {
+  const query = useQuery({
+    queryKey: ['salarios'],
+    queryFn: async () => {
       const [depRes, sumRes] = await Promise.all([
         getSalarios({ limit: 500 }),
         getSalariosSummary(),
       ]);
-      setDeposits(depRes.data);
-      setSummary(sumRes.data);
-    } catch (e) {
-      console.error(e);
-    } finally {
-      setLoading(false);
-    }
-  };
-
-  useEffect(() => { fetchData(); }, []);
+      return { deposits: depRes.data, summary: sumRes.data };
+    },
+  });
+  const deposits = query.data?.deposits ?? [];
+  const summary = query.data?.summary ?? null;
+  const loading = query.isFetching;
+  const fetchData = () => query.refetch();
 
   const columns = useMemo<ColumnDef<Transaction, unknown>[]>(
     () => [
@@ -146,6 +141,12 @@ export default function Salarios() {
       )}
 
       {/* Data table */}
+      {query.isError ? (
+        <ErrorState
+          message="No se pudieron cargar los salarios"
+          onRetry={fetchData}
+        />
+      ) : (
         <Card>
           <CardContent className="p-0">
             <DataTable
@@ -158,6 +159,7 @@ export default function Salarios() {
             />
           </CardContent>
         </Card>
+      )}
     </div>
   );
 }

frontend/src/pages/ServiciosMunicipales.tsx

@@ -1,4 +1,6 @@
-import { useState, useEffect, useCallback, useRef, useMemo } from 'react';
+import { useState, useCallback, useRef, useMemo } from 'react';
+import { useQuery } from '@tanstack/react-query';
+import ErrorState from '@/components/ErrorState';
 import {
   BarChart,
   Bar,
@@ -179,10 +181,10 @@ function ChartTooltipContent({
 
 // ─── Main Component ──────────────────────────────────────────────────────────
 
+const EMPTY_RECEIPTS: MunicipalReceipt[] = [];
+const EMPTY_READINGS: WaterMeterReading[] = [];
+
 export default function ServiciosMunicipales() {
-  const [receipts, setReceipts] = useState<MunicipalReceipt[]>([]);
-  const [waterReadings, setWaterReadings] = useState<WaterMeterReading[]>([]);
-  const [loading, setLoading] = useState(true);
 
   // Chart visibility state
   const [hiddenMeters, setHiddenMeters] = useState<Set<string>>(new Set());
@@ -195,25 +197,23 @@ export default function ServiciosMunicipales() {
   const [uploadResults, setUploadResults] = useState<MunicipalReceiptUploadResult[]>([]);
   const fileInputRef = useRef<HTMLInputElement>(null);
 
-  const loadData = useCallback(async () => {
-    setLoading(true);
-    try {
+  const municipalQ = useQuery({
+    queryKey: ['municipal'],
+    queryFn: async () => {
       const [receiptsRes, waterRes] = await Promise.all([
         getMunicipalReceipts(),
         getWaterConsumption(24),
       ]);
-      setReceipts(receiptsRes.data);
-      setWaterReadings(waterRes.data);
-    } catch {
-      // API not available yet
-    } finally {
-      setLoading(false);
-    }
-  }, []);
-
-  useEffect(() => {
-    loadData();
-  }, [loadData]);
+      return { receipts: receiptsRes.data, water: waterRes.data };
+    },
+  });
+  const receipts = municipalQ.data?.receipts ?? EMPTY_RECEIPTS;
+  const waterReadings = municipalQ.data?.water ?? EMPTY_READINGS;
+  const loading = municipalQ.isPending;
+  const loadData = useCallback(async () => {
+    await municipalQ.refetch();
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [municipalQ.refetch]);
 
   // Derived data
   const chartData = useMemo(() => buildChartData(waterReadings), [waterReadings]);
@@ -291,6 +291,12 @@ export default function ServiciosMunicipales() {
 
   return (
     <div className="space-y-8">
+      {municipalQ.isError && (
+        <ErrorState
+          message="No se pudieron cargar los recibos municipales"
+          onRetry={() => municipalQ.refetch()}
+        />
+      )}
       {/* ── Page Header ─────────────────────────────────────────────────── */}
       <div className="flex items-center gap-3">
         <div className="w-10 h-10 rounded-lg bg-primary/10 flex items-center justify-center">