Persist values, tighten validation, and a11y on /onboarding

- Server action echoes kitaName, the three module booleans, and the
  Mindest-Verfügbarkeiten value on every error path so failed submits no
  longer wipe what the user typed; OnboardingState gains an `attempt`
  counter that drives a per-field remount key on the client.
- Schema now rejects min=0 when the Notdienst module is active (via
  superRefine) — previously a kita could be created with 0 minimum days,
  which is fachlich sinnlos. When the module is off, 0 stays valid.
- Validation error messages reworded from terse fragments ("Nicht
  negativ.", "Bitte ganze Zahl.") to full sentences.
- Field error <p> elements gain role="alert" + aria-live="polite" so
  screen readers announce them on submit.
- CardTitle now accepts as="h1" and the onboarding page uses it for
  "Willkommen, …" — the page now has a real top-level heading.
- ModuleCheckbox uses aria-labelledby + aria-describedby so the
  accessible name is just the module title; the longer description is
  exposed as secondary info instead of being concatenated into the AN.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app/onboarding/actions.ts

@@ -16,20 +16,34 @@ import { prisma } from "@/lib/prisma";
 // — kein "halb-eingerichteter" Zwischenzustand.
 // =====================================================================
 
-const onboardingSchema = z.object({
+const onboardingSchema = z
+  .object({
     kitaName: z
       .string()
-    .min(2, "Mindestens 2 Zeichen.")
+      .trim()
-    .max(120, "Maximal 120 Zeichen.")
+      .min(2, "Bitte mindestens 2 Zeichen angeben.")
-    .trim(),
+      .max(120, "Maximal 120 Zeichen."),
     notdienstModuleEnabled: z.preprocess(checkboxToBool, z.boolean()),
     terminModuleEnabled: z.preprocess(checkboxToBool, z.boolean()),
     adressbuchModuleEnabled: z.preprocess(checkboxToBool, z.boolean()),
     notdienstMinPerChildPerMonth: z.coerce
       .number()
-    .int("Bitte ganze Zahl.")
+      .int("Bitte eine ganze Zahl angeben.")
-    .min(0, "Nicht negativ.")
+      .min(0, "Bitte einen Wert von 0 oder mehr angeben.")
       .max(31, "Maximal 31 Tage pro Monat."),
+  })
+  .superRefine((data, ctx) => {
+    // Mindest-Verfügbarkeit nur relevant, wenn das Notdienst-Modul aktiv ist.
+    // Bei aktivem Modul muss mindestens 1 Tag eingetragen sein — 0 wäre
+    // fachlich sinnlos und würde den Planer leerlaufen lassen.
+    if (data.notdienstModuleEnabled && data.notdienstMinPerChildPerMonth < 1) {
+      ctx.addIssue({
+        path: ["notdienstMinPerChildPerMonth"],
+        code: "custom",
+        message:
+          "Bei aktivem Notdienst-Modul: mindestens 1 Tag pro Monat angeben.",
+      });
+    }
   });
 
 function checkboxToBool(value: unknown): boolean {
@@ -38,6 +52,17 @@ function checkboxToBool(value: unknown): boolean {
 }
 
 export type OnboardingState = {
+  // Bumped after every action call so the client can key uncontrolled inputs
+  // and force a remount with the echoed values from a failed submit.
+  attempt: number;
+  // Echoed inputs so a failed submit doesn't wipe the form.
+  values?: {
+    kitaName?: string;
+    notdienstModuleEnabled?: boolean;
+    terminModuleEnabled?: boolean;
+    adressbuchModuleEnabled?: boolean;
+    notdienstMinPerChildPerMonth?: number;
+  };
   errors?: {
     kitaName?: string[];
     notdienstMinPerChildPerMonth?: string[];
@@ -45,10 +70,25 @@ export type OnboardingState = {
   };
 };
 
+export const initialOnboardingState: OnboardingState = { attempt: 0 };
+
+function echoValues(formData: FormData): OnboardingState["values"] {
+  const min = formData.get("notdienstMinPerChildPerMonth");
+  return {
+    kitaName: String(formData.get("kitaName") ?? ""),
+    notdienstModuleEnabled: formData.get("notdienstModuleEnabled") === "on",
+    terminModuleEnabled: formData.get("terminModuleEnabled") === "on",
+    adressbuchModuleEnabled: formData.get("adressbuchModuleEnabled") === "on",
+    notdienstMinPerChildPerMonth:
+      min === null || min === "" ? undefined : Number(min),
+  };
+}
+
 export async function completeOnboardingAction(
-  _prev: OnboardingState,
+  prev: OnboardingState,
   formData: FormData,
 ): Promise<OnboardingState> {
+  const attempt = prev.attempt + 1;
   const session = await auth();
   if (!session?.user) {
     redirect("/login");
@@ -61,7 +101,11 @@ export async function completeOnboardingAction(
 
   const parsed = onboardingSchema.safeParse(Object.fromEntries(formData));
   if (!parsed.success) {
-    return { errors: parsed.error.flatten().fieldErrors };
+    return {
+      attempt,
+      values: echoValues(formData),
+      errors: parsed.error.flatten().fieldErrors,
+    };
   }
   const data = parsed.data;
 
@@ -99,6 +143,8 @@ export async function completeOnboardingAction(
     }
     if (err instanceof Prisma.PrismaClientKnownRequestError) {
       return {
+        attempt,
+        values: echoValues(formData),
         errors: { _form: ["Datenbankfehler — bitte erneut versuchen."] },
       };
     }

src/app/onboarding/onboarding-form.tsx

@@ -1,22 +1,31 @@
 "use client";
 
-import { useActionState } from "react";
+import { useActionState, useId } from "react";
 
 import { Button } from "@/components/ui/button";
 import { Checkbox } from "@/components/ui/checkbox";
 import { Input } from "@/components/ui/input";
 import { Label } from "@/components/ui/label";
 
-import { completeOnboardingAction, type OnboardingState } from "./actions";
+import {
-
+  completeOnboardingAction,
-const initialState: OnboardingState = {};
+  initialOnboardingState,
+} from "./actions";
 
 export function OnboardingForm() {
   const [state, formAction, pending] = useActionState(
     completeOnboardingAction,
-    initialState,
+    initialOnboardingState,
   );
 
+  // Bumping the key on each attempt forces uncontrolled inputs to remount with
+  // the echoed defaultValue from the server — otherwise React's <form action>
+  // semantics would wipe them after a failed submit.
+  const attemptKey = state.attempt;
+
+  const kitaError = state.errors?.kitaName?.[0];
+  const minError = state.errors?.notdienstMinPerChildPerMonth?.[0];
+
   return (
     <form action={formAction} className="space-y-8">
       {/* ----- Schritt 1: Name ----- */}
@@ -27,14 +36,24 @@ export function OnboardingForm() {
         <div className="space-y-1.5">
           <Label htmlFor="kitaName">Name des Elternvereins / der Kita</Label>
           <Input
+            key={`kitaName-${attemptKey}`}
             id="kitaName"
             name="kitaName"
             required
             placeholder="z.B. Waldameisen e.V."
-            aria-invalid={!!state.errors?.kitaName}
+            defaultValue={state.values?.kitaName ?? ""}
+            aria-invalid={!!kitaError}
+            aria-describedby={kitaError ? "kitaName-error" : undefined}
           />
-          {state.errors?.kitaName?.[0] && (
+          {kitaError && (
-            <p className="text-xs text-destructive">{state.errors.kitaName[0]}</p>
+            <p
+              id="kitaName-error"
+              role="alert"
+              aria-live="polite"
+              className="text-xs text-destructive"
+            >
+              {kitaError}
+            </p>
           )}
         </div>
       </fieldset>
@@ -45,22 +64,25 @@ export function OnboardingForm() {
           Schritt 2 · Module aktivieren
         </legend>
         <ModuleCheckbox
+          key={`notdienstModuleEnabled-${attemptKey}`}
           name="notdienstModuleEnabled"
           label="Notdienst-Planung"
           description="Verfügbarkeiten erfassen, Plan generieren, bei Krankheitsausfall alarmieren."
-          defaultChecked
+          defaultChecked={state.values?.notdienstModuleEnabled ?? true}
         />
         <ModuleCheckbox
+          key={`terminModuleEnabled-${attemptKey}`}
           name="terminModuleEnabled"
           label="Terminkalender"
           description="Kita-Feste, Schließtage und private Anfragen koordinieren."
-          defaultChecked
+          defaultChecked={state.values?.terminModuleEnabled ?? true}
         />
         <ModuleCheckbox
+          key={`adressbuchModuleEnabled-${attemptKey}`}
           name="adressbuchModuleEnabled"
           label="Eltern-Adressbuch"
           description="Eltern können sich auf Opt-In-Basis untereinander finden."
-          defaultChecked
+          defaultChecked={state.values?.adressbuchModuleEnabled ?? true}
         />
       </fieldset>
 
@@ -74,29 +96,49 @@ export function OnboardingForm() {
             Mindest-Verfügbarkeiten pro Kind und Monat
           </Label>
           <Input
+            key={`notdienstMinPerChildPerMonth-${attemptKey}`}
             id="notdienstMinPerChildPerMonth"
             name="notdienstMinPerChildPerMonth"
             type="number"
             min={0}
             max={31}
-            defaultValue={2}
+            defaultValue={state.values?.notdienstMinPerChildPerMonth ?? 2}
             required
-            aria-invalid={!!state.errors?.notdienstMinPerChildPerMonth}
+            aria-invalid={!!minError}
+            aria-describedby={
+              minError
+                ? "notdienstMinPerChildPerMonth-error"
+                : "notdienstMinPerChildPerMonth-helper"
+            }
           />
-          <p className="text-xs text-muted-foreground">
+          {!minError && (
+            <p
+              id="notdienstMinPerChildPerMonth-helper"
+              className="text-xs text-muted-foreground"
+            >
               Wie viele Tage müssen Eltern pro Monat als verfügbar markieren?
               Diesen Wert kannst du später jederzeit ändern.
             </p>
-          {state.errors?.notdienstMinPerChildPerMonth?.[0] && (
+          )}
-            <p className="text-xs text-destructive">
+          {minError && (
-              {state.errors.notdienstMinPerChildPerMonth[0]}
+            <p
+              id="notdienstMinPerChildPerMonth-error"
+              role="alert"
+              aria-live="polite"
+              className="text-xs text-destructive"
+            >
+              {minError}
             </p>
           )}
         </div>
       </fieldset>
 
       {state.errors?._form?.[0] && (
-        <p className="rounded-md border border-destructive/50 bg-destructive/10 p-3 text-sm text-destructive">
+        <p
+          role="alert"
+          aria-live="polite"
+          className="rounded-md border border-destructive/50 bg-destructive/10 p-3 text-sm text-destructive"
+        >
           {state.errors._form[0]}
         </p>
       )}
@@ -119,12 +161,34 @@ function ModuleCheckbox({
   description: string;
   defaultChecked?: boolean;
 }) {
+  const id = useId();
+  const titleId = `${id}-title`;
+  const descId = `${id}-desc`;
   return (
-    <label className="flex items-start gap-3 rounded-md border p-4 transition-colors hover:bg-muted/40">
+    // The wrapping <label htmlFor> keeps the whole card clickable to toggle
-      <Checkbox name={name} defaultChecked={defaultChecked} className="mt-0.5" />
+    // the checkbox. aria-labelledby narrows the accessible name to just the
+    // module title, with the description exposed via aria-describedby so
+    // screen readers can present it as secondary info rather than as part of
+    // the primary label.
+    <label
+      htmlFor={id}
+      className="flex cursor-pointer items-start gap-3 rounded-md border p-4 transition-colors hover:bg-muted/40"
+    >
+      <Checkbox
+        id={id}
+        name={name}
+        defaultChecked={defaultChecked}
+        aria-labelledby={titleId}
+        aria-describedby={descId}
+        className="mt-0.5"
+      />
       <div className="grid gap-1 leading-none">
-        <span className="text-sm font-medium">{label}</span>
+        <span id={titleId} className="text-sm font-medium">
-        <span className="text-xs text-muted-foreground">{description}</span>
+          {label}
+        </span>
+        <span id={descId} className="text-xs text-muted-foreground">
+          {description}
+        </span>
       </div>
     </label>
   );

src/app/onboarding/page.tsx

@@ -30,7 +30,9 @@ export default async function OnboardingPage() {
     <div className="flex min-h-screen items-center justify-center bg-muted/30 px-4 py-12">
       <Card className="w-full max-w-2xl">
         <CardHeader className="space-y-2">
-          <CardTitle>Willkommen, {session.user.name?.split(" ")[0] ?? "Gründer:in"}!</CardTitle>
+          <CardTitle as="h1">
+            Willkommen, {session.user.name?.split(" ")[0] ?? "Gründer:in"}!
+          </CardTitle>
           <CardDescription>
             Lass uns deine Kita in 3 kurzen Schritten einrichten. Du kannst alle
             Einstellungen später noch anpassen.

src/components/ui/card.tsx

@@ -24,7 +24,7 @@ const CardHeader = React.forwardRef<HTMLDivElement, React.HTMLAttributes<HTMLDiv
 CardHeader.displayName = "CardHeader";
 
 type CardTitleProps = React.HTMLAttributes<HTMLElement> & {
-  as?: "div" | "h2" | "h3" | "h4" | "h5" | "h6";
+  as?: "div" | "h1" | "h2" | "h3" | "h4" | "h5" | "h6";
 };
 
 const CardTitle = React.forwardRef<HTMLElement, CardTitleProps>(