diff --git a/i18n/en.json b/i18n/en.json
index e7d218a7..752d97ed 100644
--- a/i18n/en.json
+++ b/i18n/en.json
@@ -239,6 +239,10 @@
       "total": "Total",
       "winner": "🏆 Winner",
       "notPrizeNote": "Not eligible for the prize."
+    },
+    "membership": {
+      "message": "Hackathons are for NaN members. Join the community (from €14.99/month) to take part.",
+      "cta": "Join the community"
     }
   },
   "nan": {
diff --git a/i18n/es.json b/i18n/es.json
index a932b8ed..76a1879d 100644
--- a/i18n/es.json
+++ b/i18n/es.json
@@ -239,6 +239,10 @@
       "total": "Total",
       "winner": "🏆 Ganador",
       "notPrizeNote": "No opta al premio."
+    },
+    "membership": {
+      "message": "Los hackathons son para miembros de NaN. Únete a la comunidad (desde 14,99 €/mes) para participar.",
+      "cta": "Únete a la comunidad"
     }
   },
   "nan": {
diff --git a/src/components/events/MembershipRequired.tsx b/src/components/events/MembershipRequired.tsx
new file mode 100644
index 00000000..7228ea74
--- /dev/null
+++ b/src/components/events/MembershipRequired.tsx
@@ -0,0 +1,22 @@
+import { HACKATHON_UNLOCK_URL, type MembershipStrings } from '../../lib/eventEntitlement';
+
+/**
+ * Shown when cloud-api answers `entitlement_required`: the account has no
+ * plan that unlocks hackathons. Says so and links to the community plan.
+ */
+export default function MembershipRequired({ t, compact = false }: { t: MembershipStrings; compact?: boolean }) {
+  if (compact) {
+    return (
+      <span role="alert" class="font-mono text-xs text-neutral-400">
+        {t.message}{' '}
+        <a href={HACKATHON_UNLOCK_URL} rel="noopener" class="text-violet-400 underline hover:text-violet-300">{t.cta} →</a>
+      </span>
+    );
+  }
+  return (
+    <div role="alert" class="border border-violet-500/40 bg-violet-500/10 p-4">
+      <p class="text-sm leading-relaxed text-white">{t.message}</p>
+      <a href={HACKATHON_UNLOCK_URL} rel="noopener" class="btn btn-primary mt-4">{t.cta} →</a>
+    </div>
+  );
+}
diff --git a/src/components/events/ReassignForm.tsx b/src/components/events/ReassignForm.tsx
index 600ff17c..3cd7057a 100644
--- a/src/components/events/ReassignForm.tsx
+++ b/src/components/events/ReassignForm.tsx
@@ -1,4 +1,6 @@
 import { useState } from 'preact/hooks';
+import { isEntitlementRequired, type MembershipStrings } from '../../lib/eventEntitlement';
+import MembershipRequired from './MembershipRequired';
 
 interface Member {
   id: string;
@@ -30,15 +32,18 @@ export default function ReassignForm({
   ctaLabel,
   info,
   labels,
+  membership,
 }: {
   slug: string;
   members: Member[];
   ctaLabel: string;
   info: ReassignInfo;
   labels: ReassignLabels;
+  /** Notice for `entitlement_required` (no plan that unlocks hackathons). */
+  membership: MembershipStrings;
 }) {
   const [ghostId, setGhostId] = useState('');
-  const [state, setState] = useState<'idle' | 'busy' | 'done' | 'error'>('idle');
+  const [state, setState] = useState<'idle' | 'busy' | 'done' | 'error' | 'membership'>('idle');
   const [result, setResult] = useState('');
   // La convocatoria que se ejecuta cambia el equipo (sale el ausente, entra la
   // reserva), y la lista de compañeros viene del servidor: sin recargar seguiría
@@ -63,6 +68,10 @@ export default function ReassignForm({
           setState('done');
           return;
         }
+        if (isEntitlementRequired(body?.error)) {
+          setState('membership');
+          return;
+        }
         setState('error');
         return;
       }
@@ -131,6 +140,7 @@ export default function ReassignForm({
         ))}
       </select>
       {state === 'error' && <p role="alert" class="text-sm text-red-400 font-mono">{labels.errorSubmit}</p>}
+      {state === 'membership' && <MembershipRequired t={membership} />}
       <button type="button" onClick={submit} disabled={state === 'busy' || !ghostId}
         class="font-mono text-xs px-5 py-2 rounded-lg bg-violet-600 text-white hover:bg-violet-500 disabled:opacity-50">
         {state === 'busy' ? labels.sending : ctaLabel}
diff --git a/src/components/events/RegisterForm.tsx b/src/components/events/RegisterForm.tsx
index 0bc68e7b..0734ffd8 100644
--- a/src/components/events/RegisterForm.tsx
+++ b/src/components/events/RegisterForm.tsx
@@ -1,6 +1,8 @@
 import { useState } from 'preact/hooks';
 import type { TargetedSubmitEvent } from 'preact';
 import { optionLabel } from '../../lib/i18n';
+import { isEntitlementRequired, type MembershipStrings } from '../../lib/eventEntitlement';
+import MembershipRequired from './MembershipRequired';
 
 export interface FormStrings {
   name: string; discord: string; discordHelp: string; discordOptional: string;
@@ -15,7 +17,25 @@ type Status =
   | { kind: 'idle' }
   | { kind: 'submitting' }
   | { kind: 'success'; reserve: boolean }
-  | { kind: 'error'; message: string };
+  | { kind: 'error'; message: string }
+  | { kind: 'membership' };
+
+type ErrorKey = 'errorFull' | 'errorClosed' | 'errorEligible' | 'errorRate' | 'errorDiscord' | 'errorServer';
+
+/**
+ * Which message a failed registration shows. `entitlement_required` (no plan
+ * that unlocks hackathons) is its own notice with a CTA; any other 403 keeps
+ * the "not eligible" message.
+ */
+export function registerErrorKey(status: number, code: string): ErrorKey | 'membership' {
+  if (isEntitlementRequired(code)) return 'membership';
+  if (code === 'registration_full') return 'errorFull';
+  if (code === 'registration_closed') return 'errorClosed';
+  if (status === 403 || code === 'not_eligible') return 'errorEligible';
+  if (status === 429 || code === 'rate_limited') return 'errorRate';
+  if (code === 'discord_required') return 'errorDiscord';
+  return 'errorServer';
+}
 
 /**
  * Inscripción a un evento (SPEC §6.3 `POST /api/events/{slug}/register`).
@@ -24,9 +44,10 @@ type Status =
  * no se pregunta). `options` traduce cada valor; los que no conoce (v3 los deja
  * escribir a quien organiza) salen tal cual, con la inicial en mayúscula.
  */
-export default function RegisterForm({ slug, t, meHref, discordMode, specialties, levels, options }: {
+export default function RegisterForm({ slug, t, membership, meHref, discordMode, specialties, levels, options }: {
   slug: string;
   t: FormStrings;
+  membership: MembershipStrings;
   meHref: string;
   discordMode: 'required' | 'optional' | 'none';
   specialties: string[];
@@ -74,14 +95,8 @@ export default function RegisterForm({ slug, t, meHref, discordMode, specialties
       setStatus({ kind: 'success', reserve: !!body?.data?.is_reserve });
       return;
     }
-    let message = t.errorServer;
-    const code = body?.error ?? '';
-    if (code === 'registration_full') message = t.errorFull;
-    else if (code === 'registration_closed') message = t.errorClosed;
-    else if (resp.status === 403 || code === 'not_eligible') message = t.errorEligible;
-    else if (resp.status === 429 || code === 'rate_limited') message = t.errorRate;
-    else if (code === 'discord_required') message = t.errorDiscord;
-    setStatus({ kind: 'error', message });
+    const key = registerErrorKey(resp.status, body?.error ?? '');
+    setStatus(key === 'membership' ? { kind: 'membership' } : { kind: 'error', message: t[key] });
   }
 
   if (status.kind === 'success') {
@@ -143,6 +158,7 @@ export default function RegisterForm({ slug, t, meHref, discordMode, specialties
         </div>
       )}
       {err && <p role="alert" class="font-mono text-sm text-red-400">{err}</p>}
+      {status.kind === 'membership' && <MembershipRequired t={membership} />}
       <button type="submit" disabled={submitting} class="btn btn-primary w-full disabled:opacity-50">
         {submitting ? t.submitting : t.submit}
       </button>
diff --git a/src/components/events/SubmissionForm.tsx b/src/components/events/SubmissionForm.tsx
index cb844c31..bef99776 100644
--- a/src/components/events/SubmissionForm.tsx
+++ b/src/components/events/SubmissionForm.tsx
@@ -2,6 +2,8 @@ import { useState } from 'preact/hooks';
 import type { TargetedSubmitEvent } from 'preact';
 import { optionLabel } from '../../lib/i18n';
 import type { Check } from '../../lib/events';
+import { isEntitlementRequired, type MembershipStrings } from '../../lib/eventEntitlement';
+import MembershipRequired from './MembershipRequired';
 
 type FieldMode = 'required' | 'optional' | 'hidden';
 interface Fields {
@@ -43,6 +45,8 @@ function toResult(raw: unknown): Result | null {
 interface Props {
   slug: string;
   t: Record<string, string>;
+  /** Notice for `entitlement_required` (no plan that unlocks hackathons). */
+  membership: MembershipStrings;
   existing?: Existing | null;
   /** Modo de cada campo opcional del evento (SPEC §3.3). `title` y `public_url` son siempre obligatorios. */
   fields: Fields;
@@ -70,7 +74,7 @@ interface Props {
  * (equipo o participante) a partir de la sesión.
  */
 export default function SubmissionForm({
-  slug, t, existing, fields, format, hasParticipant, checks, autoMax, discordMode, specialties, levels, options,
+  slug, t, membership, existing, fields, format, hasParticipant, checks, autoMax, discordMode, specialties, levels, options,
 }: Props) {
   const [f, setF] = useState({
     title: existing?.title ?? '',
@@ -86,6 +90,7 @@ export default function SubmissionForm({
   const [submitted, setSubmitted] = useState(Boolean(existing));
   const [busy, setBusy] = useState(false);
   const [error, setError] = useState('');
+  const [needsPlan, setNeedsPlan] = useState(false);
   const [withdrawn, setWithdrawn] = useState(false);
   const askParticipant = format === 'solo' && !hasParticipant && !submitted;
   const mediaConfigured = fields.image_url !== 'hidden' || fields.video_url !== 'hidden';
@@ -110,6 +115,7 @@ export default function SubmissionForm({
     e.preventDefault();
     setBusy(true);
     setError('');
+    setNeedsPlan(false);
     const body: Record<string, unknown> = { ...f };
     if (askParticipant) {
       const part: Record<string, string> = { name: p.name.trim() };
@@ -141,6 +147,7 @@ export default function SubmissionForm({
     const code = b?.error ?? '';
     const data = b?.data ?? {};
     if (resp.status === 401) setError(t.errorLogin);
+    else if (isEntitlementRequired(code)) setNeedsPlan(true);
     else if (code === 'submission_closed') setError(t.errorClosed);
     else if (code === 'validation_failed') {
       const names = (Array.isArray(data.fields) ? data.fields as string[] : []).map((k) => fieldLabel[k] ?? k);
@@ -297,6 +304,7 @@ export default function SubmissionForm({
         )}
       </div>
       {error && <p role="alert" class="text-sm font-mono text-red-400">{error}</p>}
+      {needsPlan && <MembershipRequired t={membership} />}
       {result && checks.length > 0 && (
         <div class="mt-4 text-sm font-mono text-neutral-300">
           <p>{t.checks}: {result.auto_points}/{autoMax}</p>
diff --git a/src/components/events/VoteButton.tsx b/src/components/events/VoteButton.tsx
index 97fc9efa..458401d4 100644
--- a/src/components/events/VoteButton.tsx
+++ b/src/components/events/VoteButton.tsx
@@ -1,4 +1,18 @@
 import { useState, useEffect } from 'preact/hooks';
+import { isEntitlementRequired, type MembershipStrings } from '../../lib/eventEntitlement';
+import MembershipRequired from './MembershipRequired';
+
+type VoteState = 'idle' | 'busy' | 'voted' | 'self' | 'login' | 'not_eligible' | 'closed' | 'membership' | 'error';
+
+/** State after a failed vote. `entitlement_required` = no plan that unlocks hackathons. */
+export function voteOutcome(status: number, code: string): VoteState {
+  if (status === 401) return 'login';
+  if (isEntitlementRequired(code)) return 'membership';
+  if (code === 'self_vote') return 'self';
+  if (code === 'not_eligible') return 'not_eligible';
+  if (code === 'voting_closed') return 'closed';
+  return 'error';
+}
 
 /**
  * Botón de voto de una entrega (SPEC §6.3 `POST /api/events/{slug}/vote`).
@@ -6,13 +20,13 @@ import { useState, useEffect } from 'preact/hooks';
  * `nan:voted` para que solo una muestre el ✓.
  */
 export default function VoteButton(
-  { slug, submissionId, votedSubmissionId, loginHref, t }:
-  { slug: string; submissionId: string; votedSubmissionId?: string | null; loginHref: string; t: Record<string, string> }
+  { slug, submissionId, votedSubmissionId, loginHref, t, membership }:
+  { slug: string; submissionId: string; votedSubmissionId?: string | null; loginHref: string; t: Record<string, string>; membership: MembershipStrings }
 ) {
   // ¿Ya votó (a cualquier entrega)? ¿Es ESTA la entrega votada?
   const hasVoted = Boolean(votedSubmissionId);
   const initial: 'idle' | 'voted' = votedSubmissionId === submissionId ? 'voted' : 'idle';
-  const [state, setState] = useState<'idle' | 'busy' | 'voted' | 'self' | 'login' | 'not_eligible' | 'closed' | 'error'>(initial);
+  const [state, setState] = useState<VoteState>(initial);
 
   useEffect(() => {
     // Otra tarjeta registró un voto: si fue para esta entrega, marca ✓; si fue
@@ -39,18 +53,14 @@ export default function VoteButton(
       return;
     }
     const body = await resp.json().catch(() => null) as { error?: string } | null;
-    const code = body?.error ?? '';
-    if (resp.status === 401) { setState('login'); return; }
-    if (code === 'self_vote') { setState('self'); return; }
-    if (code === 'not_eligible') { setState('not_eligible'); return; }
-    if (code === 'voting_closed') { setState('closed'); return; }
-    setState('error');
+    setState(voteOutcome(resp.status, body?.error ?? ''));
   }
 
   if (state === 'voted') return <span class="font-mono text-xs text-violet-400">{t.yourVote}</span>;
   if (state === 'self') return <span class="font-mono text-xs text-neutral-500">{t.selfVote}</span>;
   if (state === 'login') return <a href={loginHref} class="font-mono text-xs text-violet-400">{t.loginToVote}</a>;
   if (state === 'not_eligible') return <span class="font-mono text-xs text-neutral-500">{t.notEligible}</span>;
+  if (state === 'membership') return <MembershipRequired t={membership} compact />;
   if (state === 'closed') return <span class="font-mono text-xs text-neutral-500">{t.votingClosed}</span>;
   return (
     <button onClick={vote} disabled={state === 'busy'}
diff --git a/src/lib/eventEntitlement.ts b/src/lib/eventEntitlement.ts
new file mode 100644
index 00000000..a15bd5ed
--- /dev/null
+++ b/src/lib/eventEntitlement.ts
@@ -0,0 +1,24 @@
+/**
+ * Hackathons are unlocked by a NaN plan (Community, Inference or Premium).
+ * cloud-api answers register / submission PUT / reassign / vote for an account
+ * without one with:
+ *   403 {"error":"entitlement_required","capability":"hackathons",
+ *        "unlockedBy":["community","inference","premium"]}
+ * The events forms turn that into a notice linking to the community plan.
+ */
+
+/**
+ * Community is the cheapest plan that unlocks hackathons. The platform's
+ * /signup sends an account that is already signed in to /welcome?plan=community,
+ * which goes straight to checkout, so one link works for everyone.
+ */
+export const HACKATHON_UNLOCK_URL = 'https://cloud.nan.builders/signup?plan=community';
+
+export interface MembershipStrings {
+  message: string;
+  cta: string;
+}
+
+export function isEntitlementRequired(code: string | null | undefined): boolean {
+  return code === 'entitlement_required';
+}
diff --git a/src/pages/events/[slug]/_index.astro b/src/pages/events/[slug]/_index.astro
index 4fb3f8ea..e769eae3 100644
--- a/src/pages/events/[slug]/_index.astro
+++ b/src/pages/events/[slug]/_index.astro
@@ -1,6 +1,7 @@
 ---
 // Landing de un evento (SPEC §8.2): copy desde la API, CTA según fase/ventanas.
 // El marcado sigue escrito con utilidades de Tailwind (tema → tokens, ver styles/global.css).
+import type { MembershipStrings } from '../../../lib/eventEntitlement';
 import '../../../styles/global.css';
 import NanPage from '../../../layouts/NanPage.astro';
 import EventHeader from '../../../components/events/EventHeader.astro';
@@ -39,6 +40,7 @@ const hasCapacity = capacity > 0;
 const full = hasCapacity && ev.counts.registered >= capacity + reserve;
 
 const form = tObj<FormStrings>('events.form', locale);
+const membership = tObj<MembershipStrings>('events.membership', locale);
 const options = tObj<Record<string, string>>('events.options', locale);
 const already = tObj<Record<string, string>>('events.alreadyRegistered', locale);
 const login = tObj<LoginStrings>('events.login', locale);
@@ -256,7 +258,7 @@ const closedNote = fill(cap.closedNote, { cap: capacity, res: reserve });
             ) : !sessionOk ? (
               <LoginForm client:load t={login} />
             ) : (
-              <RegisterForm client:load slug={slug} t={form} meHref={meUrl}
+              <RegisterForm client:load slug={slug} t={form} membership={membership} meHref={meUrl}
                 discordMode={ev.registration.discord_user}
                 specialties={ev.registration.specialties ?? []} levels={ev.registration.levels ?? []}
                 options={options} />
diff --git a/src/pages/events/[slug]/_me.astro b/src/pages/events/[slug]/_me.astro
index ef440ae3..eeb5d2c6 100644
--- a/src/pages/events/[slug]/_me.astro
+++ b/src/pages/events/[slug]/_me.astro
@@ -1,5 +1,6 @@
 ---
 // Estado del participante (SPEC §8.2): equipo en `team`, ficha + entrega en `solo`.
+import type { MembershipStrings } from '../../../lib/eventEntitlement';
 import '../../../styles/global.css';
 import NanPage from '../../../layouts/NanPage.astro';
 import EventHeader from '../../../components/events/EventHeader.astro';
@@ -24,6 +25,7 @@ const isTeam = ev.format === 'team';
 const options = tObj<Record<string, string>>('events.options', locale);
 const label = (v?: string | null) => optionLabel(options, v);
 const m = tObj<Record<string, string>>('events.me', locale);
+const membership = tObj<MembershipStrings>('events.membership', locale);
 const login = tObj<LoginStrings>('events.login', locale);
 const submissionUrl = withLang(`/events/${slug}/submission`, locale);
 const title = isTeam ? m.title : m.titleSolo;
@@ -86,7 +88,7 @@ const absent = (team?.members ?? []).filter((x) => x.id !== participant?.id);
               {ev.phase === 'building' && absent.length > 0 && (
                 <div class="mt-6">
                   <ReassignForm client:visible slug={slug} members={absent.map((x) => ({ id: x.id, name: x.name, discord_user: x.discord_user ?? undefined }))}
-                    ctaLabel={m.reassignCta} info={tObj('events.me.reassignInfo', locale)}
+                    ctaLabel={m.reassignCta} membership={membership} info={tObj('events.me.reassignInfo', locale)}
                     labels={{ pending: m.reassignPending, filled: m.reassignFilled, noPool: m.reassignNoPool, already: m.reassignAlready, selectAbsent: m.reassignSelectAbsent, errorSubmit: m.reassignErrorSubmit, sending: m.reassignSending, refresh: m.reassignRefresh }} />
                 </div>
               )}
diff --git a/src/pages/events/[slug]/_projects.astro b/src/pages/events/[slug]/_projects.astro
index 1c7118c8..3b5300ac 100644
--- a/src/pages/events/[slug]/_projects.astro
+++ b/src/pages/events/[slug]/_projects.astro
@@ -1,5 +1,6 @@
 ---
 // Galería pública de entregas (SPEC §8.2). Vacía hasta que `windows.gallery.visible`.
+import type { MembershipStrings } from '../../../lib/eventEntitlement';
 import '../../../styles/global.css';
 import NanPage from '../../../layouts/NanPage.astro';
 import EventHeader from '../../../components/events/EventHeader.astro';
@@ -25,6 +26,7 @@ const list = projects ?? [];
 const myVote = me?.my_vote ?? null;
 const canVote = ev.windows.voting.open;
 const pr = tObj<Record<string, string>>('events.projects', locale);
+const membership = tObj<MembershipStrings>('events.membership', locale);
 
 // Solo http/https en enlaces de proyecto (defensa en profundidad frente a
 // javascript:, data:, etc. aunque el backend ya valide).
@@ -61,7 +63,7 @@ const safeUrl = (u?: string): string | null =>
             {canVote && (
               <div class="mt-5">
                 <VoteButton client:visible slug={slug} submissionId={p.id} votedSubmissionId={myVote}
-                  loginHref={withLang(`/events/${slug}`, locale)} t={pr} />
+                  loginHref={withLang(`/events/${slug}`, locale)} t={pr} membership={membership} />
               </div>
             )}
           </article>
diff --git a/src/pages/events/[slug]/_submission.astro b/src/pages/events/[slug]/_submission.astro
index ccd84689..f99c0451 100644
--- a/src/pages/events/[slug]/_submission.astro
+++ b/src/pages/events/[slug]/_submission.astro
@@ -1,5 +1,6 @@
 ---
 // Alta/edición de la entrega (SPEC §8.2). Solo edita mientras `windows.submission.open`.
+import type { MembershipStrings } from '../../../lib/eventEntitlement';
 import '../../../styles/global.css';
 import NanPage from '../../../layouts/NanPage.astro';
 import EventHeader from '../../../components/events/EventHeader.astro';
@@ -25,6 +26,7 @@ const canEdit = ev.windows.submission.open;
 const beforeOpen = ev.phase === 'draft' || ev.phase === 'published' || ev.phase === 'registration' || ev.phase === 'building_pending';
 
 const s = tObj<Record<string, string>>('events.submission', locale);
+const membership = tObj<MembershipStrings>('events.membership', locale);
 const options = tObj<Record<string, string>>('events.options', locale);
 const login = tObj<LoginStrings>('events.login', locale);
 const fill = (str: string, vars: Record<string, string>) =>
@@ -71,7 +73,7 @@ const readonlyRows = existing
       ) : isTeam && !hasTeam ? (
         <p class="text-sm text-neutral-400">{s.noTeam}</p>
       ) : canEdit ? (
-        <SubmissionForm client:load slug={slug} t={s} existing={existing}
+        <SubmissionForm client:load slug={slug} t={s} membership={membership} existing={existing}
           fields={fields} format={ev.format} hasParticipant={hasParticipant}
           checks={checks} autoMax={ev.voting.auto_max}
           discordMode={ev.registration.discord_user}
diff --git a/src/tests/pages/eventsEntitlement.test.ts b/src/tests/pages/eventsEntitlement.test.ts
new file mode 100644
index 00000000..6646c79f
--- /dev/null
+++ b/src/tests/pages/eventsEntitlement.test.ts
@@ -0,0 +1,155 @@
+import { describe, expect, test } from 'vitest';
+import { h } from 'preact';
+import { render } from 'preact-render-to-string';
+import { readFileSync } from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import { dirname, resolve } from 'node:path';
+import { tObj } from '../../lib/i18n';
+import {
+  HACKATHON_UNLOCK_URL,
+  isEntitlementRequired,
+  type MembershipStrings,
+} from '../../lib/eventEntitlement';
+import MembershipRequired from '../../components/events/MembershipRequired';
+import { registerErrorKey } from '../../components/events/RegisterForm';
+import { voteOutcome } from '../../components/events/VoteButton';
+
+/**
+ * Hackathons are unlocked by Community, Inference or Premium. For an account
+ * without a plan cloud-api answers register / submission PUT / reassign / vote
+ * with 403 {"error":"entitlement_required","capability":"hackathons",...}.
+ * Every events form must say so and link to the community plan, instead of
+ * "not eligible" or a generic error. `not_eligible` keeps its own message.
+ */
+
+const here = dirname(fileURLToPath(import.meta.url));
+const src = resolve(here, '../..');
+const read = (p: string) => readFileSync(resolve(src, p), 'utf-8');
+
+const entitlementBody = {
+  error: 'entitlement_required',
+  capability: 'hackathons',
+  unlockedBy: ['community', 'inference', 'premium'],
+};
+
+describe('entitlement_required detection', () => {
+  test('matches the backend error code', () => {
+    expect(isEntitlementRequired(entitlementBody.error)).toBe(true);
+  });
+
+  test('does not swallow the other codes', () => {
+    for (const code of ['not_eligible', 'tier_restricted', 'registration_full', '', undefined, null]) {
+      expect(isEntitlementRequired(code as string), String(code)).toBe(false);
+    }
+  });
+
+  test('the CTA goes to the community plan (logged-in accounts land on /welcome?plan=community)', () => {
+    expect(HACKATHON_UNLOCK_URL).toBe('https://cloud.nan.builders/signup?plan=community');
+  });
+});
+
+describe('copy', () => {
+  test.each(['en', 'es'] as const)('events.membership exists in %s', (locale) => {
+    const m = tObj<MembershipStrings>('events.membership', locale);
+    expect(m.message.trim().length).toBeGreaterThan(0);
+    expect(m.cta.trim().length).toBeGreaterThan(0);
+  });
+
+  test('says who hackathons are for and the starting price', () => {
+    const en = tObj<MembershipStrings>('events.membership', 'en');
+    const es = tObj<MembershipStrings>('events.membership', 'es');
+    expect(en.message).toBe('Hackathons are for NaN members. Join the community (from €14.99/month) to take part.');
+    expect(es.message).toBe('Los hackathons son para miembros de NaN. Únete a la comunidad (desde 14,99 €/mes) para participar.');
+  });
+});
+
+describe('MembershipRequired notice', () => {
+  const t: MembershipStrings = { message: 'Hackathons are for NaN members.', cta: 'Join the community' };
+
+  test('is an alert with the message and a link to the community plan', () => {
+    const html = render(h(MembershipRequired, { t }));
+    expect(html).toContain('role="alert"');
+    expect(html).toContain('Hackathons are for NaN members.');
+    expect(html).toContain(`href="${HACKATHON_UNLOCK_URL}"`);
+    expect(html).toContain('Join the community');
+  });
+
+  test('has a compact variant for the vote button', () => {
+    const html = render(h(MembershipRequired, { t, compact: true }));
+    expect(html).toContain(`href="${HACKATHON_UNLOCK_URL}"`);
+  });
+});
+
+describe('RegisterForm maps the backend answer', () => {
+  test('entitlement_required is the membership notice, not "not eligible"', () => {
+    expect(registerErrorKey(403, 'entitlement_required')).toBe('membership');
+  });
+
+  test('the other codes keep their messages', () => {
+    expect(registerErrorKey(403, 'not_eligible')).toBe('errorEligible');
+    expect(registerErrorKey(403, '')).toBe('errorEligible');
+    expect(registerErrorKey(409, 'registration_full')).toBe('errorFull');
+    expect(registerErrorKey(409, 'registration_closed')).toBe('errorClosed');
+    expect(registerErrorKey(429, '')).toBe('errorRate');
+    expect(registerErrorKey(400, 'discord_required')).toBe('errorDiscord');
+    expect(registerErrorKey(500, '')).toBe('errorServer');
+  });
+});
+
+describe('VoteButton maps the backend answer', () => {
+  test('entitlement_required is the membership state', () => {
+    expect(voteOutcome(403, 'entitlement_required')).toBe('membership');
+  });
+
+  test('the other codes keep their states', () => {
+    expect(voteOutcome(401, '')).toBe('login');
+    expect(voteOutcome(400, 'self_vote')).toBe('self');
+    expect(voteOutcome(403, 'not_eligible')).toBe('not_eligible');
+    expect(voteOutcome(409, 'voting_closed')).toBe('closed');
+    expect(voteOutcome(500, '')).toBe('error');
+  });
+});
+
+describe('every events form handles it', () => {
+  const forms = {
+    RegisterForm: 'components/events/RegisterForm.tsx',
+    VoteButton: 'components/events/VoteButton.tsx',
+    SubmissionForm: 'components/events/SubmissionForm.tsx',
+    ReassignForm: 'components/events/ReassignForm.tsx',
+  };
+
+  test.each(Object.entries(forms))('%s detects entitlement_required and renders the notice', (_name, file) => {
+    const source = read(file);
+    expect(source).toContain('isEntitlementRequired(');
+    expect(source).toContain('<MembershipRequired');
+  });
+
+  test('SubmissionForm checks it before falling back to not_eligible / generic', () => {
+    const source = read(forms.SubmissionForm);
+    const putHandler = source.slice(source.indexOf("method: 'PUT'"), source.indexOf('async function onWithdraw'));
+    const check = putHandler.indexOf('isEntitlementRequired(');
+    expect(check).toBeGreaterThan(-1);
+    expect(check).toBeLessThan(putHandler.indexOf("'not_eligible'"));
+  });
+
+  test('ReassignForm checks it before the generic error', () => {
+    const source = read(forms.ReassignForm);
+    const notOk = source.slice(source.indexOf('if (!resp.ok)'));
+    expect(notOk.indexOf('isEntitlementRequired(')).toBeGreaterThan(-1);
+    expect(notOk.indexOf('isEntitlementRequired(')).toBeLessThan(notOk.indexOf("setState('error')"));
+  });
+
+  const pages = {
+    '_index.astro': 'RegisterForm',
+    '_projects.astro': 'VoteButton',
+    '_submission.astro': 'SubmissionForm',
+    '_me.astro': 'ReassignForm',
+  };
+
+  test.each(Object.entries(pages))('%s passes the membership strings to %s', (page, component) => {
+    const source = read(`pages/events/[slug]/${page}`);
+    expect(source).toContain("tObj<MembershipStrings>('events.membership', locale)");
+    const tag = source.slice(source.indexOf(`<${component}`), source.indexOf('/>', source.indexOf(`<${component}`)));
+    expect(tag).toContain('membership={membership}');
+  });
+});