diff --git a/apps/api/src/modules/tracking/fast.routes.ts b/apps/api/src/modules/tracking/fast.routes.ts
index bef91bd..d1529a9 100644
--- a/apps/api/src/modules/tracking/fast.routes.ts
+++ b/apps/api/src/modules/tracking/fast.routes.ts
@@ -59,14 +59,17 @@ export const fastRoutes: FastifyPluginAsync = async (fastify) => {
     });
     if (!owned) return reply.code(404).send({ error: 'fast_event_not_found' });
 
+    // Costruiamo l'oggetto data omettendo le chiavi non fornite, perché con
+    // `exactOptionalPropertyTypes` Prisma rifiuta `undefined` esplicito.
+    const updateData: Parameters<typeof fastify.prisma.fastEvent.update>[0]['data'] = {};
+    if (data.endedAt) updateData.endedAt = data.endedAt;
+    if (data.status) updateData.status = data.status;
+    if (data.symptoms) updateData.symptoms = JSON.stringify(data.symptoms);
+    if (data.notes != null) updateData.notes = data.notes;
+
     const event = await fastify.prisma.fastEvent.update({
       where: { id },
-      data: {
-        endedAt: data.endedAt ?? undefined,
-        status: data.status ?? undefined,
-        symptoms: data.symptoms ? JSON.stringify(data.symptoms) : undefined,
-        notes: data.notes ?? undefined,
-      },
+      data: updateData,
     });
     return { event: { id: event.id, status: event.status } };
   });
diff --git a/apps/web/src/app/[locale]/plan/actions.ts b/apps/web/src/app/[locale]/plan/actions.ts
index 99d2374..9d41821 100644
--- a/apps/web/src/app/[locale]/plan/actions.ts
+++ b/apps/web/src/app/[locale]/plan/actions.ts
@@ -42,9 +42,9 @@ export async function fetchCurrentPlan(): Promise<CurrentPlan | null> {
   return data.plan;
 }
 
-export type RegenerateResult = { ok: true } | { ok: false; error: string };
-
-export async function regeneratePlan(): Promise<RegenerateResult> {
+// Server action invocata via `<form action={regeneratePlan}>`. La firma è
+// `(FormData) => Promise<void>` per allinearsi al type richiesto da React 18.
+export async function regeneratePlan(_formData?: FormData): Promise<void> {
   const res = await fetch(`${API_URL}/me/meal-plans`, {
     method: 'POST',
     headers: { cookie: cookieHeader() },
@@ -52,10 +52,9 @@ export async function regeneratePlan(): Promise<RegenerateResult> {
   });
   if (!res.ok) {
     const body = (await res.json().catch(() => ({}))) as { error?: string };
-    return { ok: false, error: body.error ?? `api_error_${res.status}` };
+    throw new Error(body.error ?? `api_error_${res.status}`);
   }
   revalidatePath('/plan');
-  return { ok: true };
 }
 
 export type SwapResult = { ok: true } | { ok: false; error: string };
diff --git a/apps/web/src/app/[locale]/tracking/weight-entry-form.tsx b/apps/web/src/app/[locale]/tracking/weight-entry-form.tsx
index 58c886d..7a7fa7a 100644
--- a/apps/web/src/app/[locale]/tracking/weight-entry-form.tsx
+++ b/apps/web/src/app/[locale]/tracking/weight-entry-form.tsx
@@ -29,12 +29,16 @@ export function WeightEntryForm({ latest }: { latest: WeightEntryRow | null }) {
   const [serverError, setServerError] = useState<string | null>(null);
   const [savedAt, setSavedAt] = useState<string | null>(null);
 
+  // L'input HTML type="date" passa stringhe ISO; zod le coerce a Date a runtime
+  // (vedi `weightEntryInputSchema.date = z.coerce.date()`). Il TS-side resta
+  // strict, perciò usiamo cast `unknown` agli ingressi dei defaultValues e di
+  // form.reset.
   const form = useForm<WeightEntryInput>({
     resolver: zodResolver(weightEntryInputSchema),
     defaultValues: {
       date: todayISO(),
       weightKg: latest?.weightKg,
-    } as WeightEntryInput,
+    } as unknown as WeightEntryInput,
   });
 
   const onSubmit = form.handleSubmit(async (input) => {
@@ -45,7 +49,7 @@ export function WeightEntryForm({ latest }: { latest: WeightEntryRow | null }) {
       return;
     }
     setSavedAt(new Date().toISOString());
-    form.reset({ date: todayISO(), weightKg: input.weightKg } as WeightEntryInput);
+    form.reset({ date: todayISO(), weightKg: input.weightKg } as unknown as WeightEntryInput);
   });
 
   return (
@@ -59,7 +63,7 @@ export function WeightEntryForm({ latest }: { latest: WeightEntryRow | null }) {
               <FormItem className="space-y-3">
                 <FormLabel>{t('date')}</FormLabel>
                 <FormControl>
-                  <Input type="date" {...field} value={field.value as string} />
+                  <Input type="date" {...field} value={field.value as unknown as string} />
                 </FormControl>
                 <FormMessage />
               </FormItem>