fix(window): rain falling now vetoes the next hour of the day window

The window scored only the FORECAST slots: when the hourly model said
"dry" while the aggregated nowcast said it was raining — the exact
disagreement the nowcast exists for — the best-time verdict recommended
going out into the rain, right next to a "lloviendo ahora" badge.

buildDayWindow now takes the nowcast: with status 'raining', every slot
starting within the next 60 minutes is treated as wet (calidad 0). A
model already disproved by the sky cannot claim the immediate hour; one
hour is the minimum persistence an active event deserves, and the short
cache TTLs slide the veto forward while it keeps raining. The stretch
motive then tells the truth on its own ('sin_lluvia').

Both callers already hold the nowcast — featured fan-out and details
assembler (on the OpenWeather-slots fallback too, where the status can
be valid while Open-Meteo's slots are not) — so this costs zero extra
provider calls.

Tests: three new cases (veto over a dry-claiming forecast, no
recommendation with under an hour of window left while raining, dry
status changes nothing).

Claude-Session: https://claude.ai/code/session_01C4ffvC8qXXWYF9mGemXTvi

Author: oscaruiz

backend/src/__tests__/BeachWindowScorer.test.ts

@@ -130,6 +130,36 @@ describe('buildDayWindow — la mejor franja del día', () => {
     expect(señal?.horasConsideradas).toBe(5);
   });
 
+  it('lluvia AHORA veta la próxima hora aunque el modelo diga seco', () => {
+    // 11:30 Madrid, lloviendo según el nowcast; la previsión (BUENA) dice
+    // seco todo el día — que es exactamente el caso en que el modelo ya ha
+    // quedado desmentido y no puede recomendar salir ya.
+    const lloviendo = new Date('2026-07-15T09:30:00Z');
+    const señal = buildDayWindow(slots([9, 10, 11, 12, 13], BUENA), lloviendo, {
+      status: 'raining',
+    });
+
+    // Los slots de las 09:00 y 10:00 UTC (en curso y siguiente) caen dentro
+    // del veto de una hora: el tramo recomendable empieza a las 13:00 Madrid.
+    expect(señal?.mejor).toEqual({ inicio: utc(11), fin: utc(14) });
+    // Y el motivo cuenta la verdad: es el tramo sin lluvia.
+    expect(señal?.motivo).toBe('sin_lluvia');
+  });
+
+  it('lloviendo y con menos de una hora de franja por delante, no hay recomendación', () => {
+    const tarde = new Date('2026-07-15T17:30:00Z'); // 19:30 Madrid
+    expect(
+      buildDayWindow(slots([17, 18], BUENA), tarde, { status: 'raining' }),
+    ).toBeNull();
+  });
+
+  it('con el nowcast seco (o ausente) el veto no existe y nada cambia', () => {
+    const señal = buildDayWindow(slots([10, 11, 12, 13, 14], BUENA), MEDIA_MANANA, {
+      status: 'dry',
+    });
+    expect(señal?.mejor).toEqual({ inicio: utc(10), fin: utc(15) });
+  });
+
   it('un tramo que cubre toda la franja restante no tiene motivo: no venció a nadie', () => {
     const señal = buildDayWindow(slots([10, 11, 12, 13, 14], BUENA), MEDIA_MANANA);
 

backend/src/application/services/LegacyDetailsAssembler.ts

@@ -100,14 +100,22 @@ export class LegacyDetailsAssembler {
   private async resolverVentanaDia(
     lat: number,
     lon: number,
-    delNowcast: readonly HourlyOutlookSlot[] | null | undefined,
+    nowcast: RainNowcast | null,
   ): Promise<{ ventana: DayWindowSignal; fuente: string } | null> {
+    // The nowcast rides into the verdict on BOTH branches: rain falling now
+    // must veto the next hour even when the slots come from the OpenWeather
+    // fallback — its status can be valid while the Open-Meteo slots are not.
+    const delNowcast = nowcast?.outlook;
     if ((delNowcast?.length ?? 0) > 0) {
-      const ventana = buildDayWindow(delNowcast);
+      const ventana = buildDayWindow(delNowcast, new Date(), nowcast);
       return ventana ? { ventana, fuente: OPEN_METEO_NOMBRE } : null;
     }
     try {
-      const ventana = buildDayWindow(await this.openWeather.getOutlookSlots(lat, lon));
+      const ventana = buildDayWindow(
+        await this.openWeather.getOutlookSlots(lat, lon),
+        new Date(),
+        nowcast,
+      );
       return ventana ? { ventana, fuente: 'OpenWeather' } : null;
     } catch {
       return null;
@@ -404,7 +412,7 @@ export class LegacyDetailsAssembler {
         const ventana = await this.resolverVentanaDia(
           details.beach.latitude,
           details.beach.longitude,
-          rainSignal?.outlook,
+          rainSignal,
         );
         base.tiempoActual = {
           ...base.tiempoActual,

backend/src/domain/use-cases/BeachWindowScorer.ts

@@ -1,4 +1,4 @@
-import type { HourlyOutlookSlot } from '../entities/RainNowcast';
+import type { HourlyOutlookSlot, RainNowcast } from '../entities/RainNowcast';
 import {
   computeTemperatureScore,
   computeWindScore,
@@ -138,6 +138,7 @@ function media(valores: number[]): number {
 export function buildDayWindow(
   slots: readonly HourlyOutlookSlot[] | null | undefined,
   ahora: Date = new Date(),
+  lluviaAhora?: Pick<RainNowcast, 'status'> | null,
 ): DayWindowSignal | null {
   if (!slots || slots.length === 0) return null;
 
@@ -151,9 +152,24 @@ export function buildDayWindow(
   // window, not only when it starts inside it: dropping the in-progress slot
   // meant the window could never start "now" even when now was the best hour.
   const enFranja = ordenados.filter((s) => s.timestamp + paso > desde && s.timestamp <= hasta);
+
+  // Rain detected NOW (the aggregated multi-source nowcast) overrides the
+  // model for the next hour: these slots said "dry" while it was actually
+  // raining, so their claim is already disproved — the window must never
+  // recommend going out into rain the forecast cannot see. One hour is the
+  // minimum persistence an active event deserves; while it keeps raining the
+  // short cache TTLs slide this veto forward on every refresh. Same
+  // philosophy as the score's rain cap, and it costs zero extra calls: both
+  // callers already hold the nowcast.
+  const vetoHasta =
+    lluviaAhora?.status === 'raining' ? ahora.getTime() + 60 * 60_000 : null;
+
   const evaluados = enFranja
     .map(evaluarSlot)
-    .filter((s): s is SlotEvaluado => s !== null);
+    .filter((s): s is SlotEvaluado => s !== null)
+    .map((s) =>
+      vetoHasta != null && s.timestamp < vetoHasta ? { ...s, mojado: true, calidad: 0 } : s,
+    );
   if (evaluados.length < 2) return null;
 
   // The bar every recommended hour must clear: near the day's own best hour,

backend/src/domain/use-cases/GetFeaturedBeaches.ts

@@ -141,8 +141,10 @@ export class GetFeaturedBeaches {
 
       // WHEN to go: best stretch of the remaining beach window, from the same
       // slots. Open-Meteo only, symmetric with the outlook above: when it is
-      // down the field is null and the interface shows nothing.
-      const ventanaDia = buildDayWindow(rain?.outlook);
+      // down the field is null and the interface shows nothing. The nowcast
+      // rides along so rain falling NOW vetoes the next hour, whatever the
+      // forecast claims.
+      const ventanaDia = buildDayWindow(rain?.outlook, new Date(), rain);
 
       const { score, subScores, tope } = computeBeachScore(
         weather,