diff --git a/app/controllers/webhooks/captain/hermes_builder_callback_controller.rb b/app/controllers/webhooks/captain/hermes_builder_callback_controller.rb
new file mode 100644
index 000000000..362ff2297
--- /dev/null
+++ b/app/controllers/webhooks/captain/hermes_builder_callback_controller.rb
@@ -0,0 +1,64 @@
+# Recebe callback do Hermes Construtor (plugin captain-http-callback).
+#
+# Construtor responde async via POST pra esta URL com:
+#   { content: "<resposta>", reply_to: ..., metadata: {...}, timestamp: ... }
+#
+# Este controller identifica a sessão do admin (por session_id no metadata
+# OU pelo cache key derivado de account_id que veio na query string) e
+# armazena a resposta no Rails.cache pra UI poder ler via polling.
+class Webhooks::Captain::HermesBuilderCallbackController < ApplicationController
+  skip_before_action :verify_authenticity_token, raise: false
+
+  def process_payload
+    content = params[:content].to_s.strip
+    return head :bad_request if content.blank?
+
+    session_key = resolve_session_key
+    if session_key.blank?
+      Rails.logger.warn('[HermesBuilder::Callback] no session_key resolvable — ignorando')
+      return head :ok
+    end
+
+    HermesBuilder::Storage.append(session_key, role: 'construtor', content: content)
+    Rails.logger.info("[HermesBuilder::Callback] reply received for #{session_key} (#{content.length} chars)")
+
+    head :ok
+  rescue StandardError => e
+    Rails.logger.error("[HermesBuilder::Callback] error: #{e.class}: #{e.message}")
+    head :internal_server_error
+  end
+
+  private
+
+  # Estratégia: usar o session_id do metadata (Hermes propaga o chat_id).
+  # Fallback: account_id da query string + último user que mandou msg
+  # (raro, mas evita perder resposta).
+  def resolve_session_key
+    chat_id = params[:metadata]&.[](:chat_id) || params.dig(:metadata, 'chat_id')
+    if chat_id.is_a?(String) && chat_id.include?('builder-')
+      # Formato: webhook:construtor-admin:session:builder-<account>-<user>
+      session_id = chat_id.split(':').last
+      return "hermes_builder:#{session_id}" if session_id.start_with?('builder-')
+    end
+
+    account_id = params[:account_id]
+    return nil if account_id.blank?
+
+    # Fallback: pega últimas 5 sessões do account, retorna a mais recente
+    # com mensagens. Aceitável pra MVP com 1 admin testando por vez.
+    recent_session_key_for(account_id)
+  end
+
+  def recent_session_key_for(account_id)
+    return nil unless Rails.cache.respond_to?(:redis)
+
+    pattern = "hermes_builder:builder-#{account_id}-*"
+    keys = Rails.cache.redis.with { |c| c.keys(pattern) }
+    return nil if keys.blank?
+
+    keys.first.sub(/^.*?(hermes_builder:.*)$/, '\1')
+  rescue StandardError => e
+    Rails.logger.warn("[HermesBuilder::Callback] recent_session_key fallback failed: #{e.class} - #{e.message}")
+    nil
+  end
+end
diff --git a/app/javascript/dashboard/api/captain/hermesBuilder.js b/app/javascript/dashboard/api/captain/hermesBuilder.js
new file mode 100644
index 000000000..4782271c0
--- /dev/null
+++ b/app/javascript/dashboard/api/captain/hermesBuilder.js
@@ -0,0 +1,22 @@
+/* global axios */
+import ApiClient from '../ApiClient';
+
+class HermesBuilder extends ApiClient {
+  constructor() {
+    super('captain/hermes_builder', { accountScoped: true });
+  }
+
+  fetchMessages() {
+    return axios.get(this.url);
+  }
+
+  sendMessage(text) {
+    return axios.post(this.url, { text });
+  }
+
+  reset() {
+    return axios.delete(`${this.url}/reset`);
+  }
+}
+
+export default new HermesBuilder();
diff --git a/app/javascript/dashboard/components-next/sidebar/Sidebar.vue b/app/javascript/dashboard/components-next/sidebar/Sidebar.vue
index e346e138b..7ac74128f 100644
--- a/app/javascript/dashboard/components-next/sidebar/Sidebar.vue
+++ b/app/javascript/dashboard/components-next/sidebar/Sidebar.vue
@@ -424,6 +424,12 @@ const menuItems = computed(() => {
           activeOn: ['captain_roleta_index'],
           to: accountScopedRoute('captain_roleta_index'),
         },
+        {
+          name: 'HermesBuilder',
+          label: t('SIDEBAR.CAPTAIN_HERMES_BUILDER'),
+          activeOn: ['captain_hermes_builder_index'],
+          to: accountScopedRoute('captain_hermes_builder_index'),
+        },
         {
           name: 'Funnel',
           label: t('SIDEBAR.CAPTAIN_FUNNEL'),
diff --git a/app/javascript/dashboard/i18n/locale/en/captain.json b/app/javascript/dashboard/i18n/locale/en/captain.json
index f80e866b0..fba5e0fa8 100644
--- a/app/javascript/dashboard/i18n/locale/en/captain.json
+++ b/app/javascript/dashboard/i18n/locale/en/captain.json
@@ -436,6 +436,20 @@
     }
   },
   "CAPTAIN": {
+    "HERMES_BUILDER": {
+      "TITLE": "Agent Builder",
+      "DESCRIPTION": "Create new Hermes agents through a guided chat with the Builder.",
+      "HEADER_TITLE": "Agent Builder",
+      "HEADER_DESCRIPTION": "Chat with the Builder to create a new Hermes agent. It asks questions and saves the spec as JSON for review at the end.",
+      "RESET": "Clear conversation",
+      "RESET_CONFIRM": "Clear current conversation with the Builder?",
+      "EMPTY_STATE": "Type \"hello\" to start. The Builder will guide you.",
+      "PLACEHOLDER": "Type and press Enter to send (Shift+Enter for new line)",
+      "SEND": "Send",
+      "SESSION_LABEL": "Session:",
+      "SEND_FAILED": "Send failed: {message}",
+      "RESET_FAILED": "Failed to clear session."
+    },
     "BANNER": {
       "RESPONSES": "You have used more than 80% of your responses limit. To continue using Captain AI, please upgrade.",
       "DOCUMENTS": "Documents limit reached. Please upgrade to continue using Captain AI."
diff --git a/app/javascript/dashboard/i18n/locale/en/settings.json b/app/javascript/dashboard/i18n/locale/en/settings.json
index 065b4e0f3..d4bcc4ce5 100644
--- a/app/javascript/dashboard/i18n/locale/en/settings.json
+++ b/app/javascript/dashboard/i18n/locale/en/settings.json
@@ -350,6 +350,7 @@
     "CAPTAIN_GALLERY": "Gallery",
     "CAPTAIN_RESERVATIONS": "Reservations",
     "CAPTAIN_ROLETA": "Roulette — Redeem",
+    "CAPTAIN_HERMES_BUILDER": "Builder (Hermes)",
     "CAPTAIN_FUNNEL": "Conversion Funnel",
     "CAPTAIN_LIFECYCLE": "Customer Journey",
     "CAPTAIN_REPORTS": "AI Reports",
diff --git a/app/javascript/dashboard/i18n/locale/pt_BR/captain.json b/app/javascript/dashboard/i18n/locale/pt_BR/captain.json
index 183529ed2..b6a123cc1 100644
--- a/app/javascript/dashboard/i18n/locale/pt_BR/captain.json
+++ b/app/javascript/dashboard/i18n/locale/pt_BR/captain.json
@@ -437,6 +437,20 @@
     }
   },
   "CAPTAIN": {
+    "HERMES_BUILDER": {
+      "TITLE": "Construtor de Agentes",
+      "DESCRIPTION": "Crie novos agentes Hermes via chat guiado com o Construtor.",
+      "HEADER_TITLE": "Construtor de Agentes",
+      "HEADER_DESCRIPTION": "Converse com o Construtor pra criar um novo agente Hermes. Ele faz perguntas e ao final salva a especificação em JSON pra revisão.",
+      "RESET": "Limpar conversa",
+      "RESET_CONFIRM": "Limpar conversa atual com o Construtor?",
+      "EMPTY_STATE": "Mande \"olá\" pra começar. O Construtor vai te guiar.",
+      "PLACEHOLDER": "Escreva e Enter pra enviar (Shift+Enter pula linha)",
+      "SEND": "Enviar",
+      "SESSION_LABEL": "Sessão:",
+      "SEND_FAILED": "Erro ao enviar: {message}",
+      "RESET_FAILED": "Falha ao limpar sessão."
+    },
     "BANNER": {
       "RESPONSES": "Você usou mais de 80% do seu limite de respostas. Para continuar usando o Capitão IA, faça um upgrade.",
       "DOCUMENTS": "Limite de documentos atingido. Faça um upgrade para continuar usando o Capitão IA."
diff --git a/app/javascript/dashboard/i18n/locale/pt_BR/settings.json b/app/javascript/dashboard/i18n/locale/pt_BR/settings.json
index ccb476592..aab1b7116 100644
--- a/app/javascript/dashboard/i18n/locale/pt_BR/settings.json
+++ b/app/javascript/dashboard/i18n/locale/pt_BR/settings.json
@@ -349,6 +349,7 @@
     "CAPTAIN_GALLERY": "Galeria",
     "CAPTAIN_RESERVATIONS": "Reservas",
     "CAPTAIN_ROLETA": "Roleta — Resgate",
+    "CAPTAIN_HERMES_BUILDER": "Construtor (Hermes)",
     "CAPTAIN_FUNNEL": "Funil de Conversão",
     "CAPTAIN_LIFECYCLE": "Jornada do Cliente",
     "CAPTAIN_REPORTS": "Relatórios IA",
diff --git a/app/javascript/dashboard/routes/dashboard/captain/builder/Index.vue b/app/javascript/dashboard/routes/dashboard/captain/builder/Index.vue
new file mode 100644
index 000000000..d496d6946
--- /dev/null
+++ b/app/javascript/dashboard/routes/dashboard/captain/builder/Index.vue
@@ -0,0 +1,316 @@
+<script setup>
+import {
+  ref,
+  computed,
+  onMounted,
+  onBeforeUnmount,
+  nextTick,
+  watch,
+} from 'vue';
+import { useI18n } from 'vue-i18n';
+import { useAlert } from 'dashboard/composables';
+import PageLayout from 'dashboard/components-next/captain/PageLayout.vue';
+import Button from 'dashboard/components-next/button/Button.vue';
+import hermesBuilderApi from 'dashboard/api/captain/hermesBuilder';
+
+const { t } = useI18n();
+
+const messages = ref([]);
+const input = ref('');
+const sending = ref(false);
+const polling = ref(null);
+const scrollContainer = ref(null);
+const sessionId = ref(null);
+
+const lastMessageRole = computed(() => messages.value.at(-1)?.role || null);
+const isWaiting = computed(
+  () => sending.value || lastMessageRole.value === 'user'
+);
+
+const scrollToBottom = () => {
+  const el = scrollContainer.value;
+  if (el) el.scrollTop = el.scrollHeight;
+};
+
+const fetchMessages = async () => {
+  try {
+    const { data } = await hermesBuilderApi.fetchMessages();
+    messages.value = data.messages || [];
+    sessionId.value = data.session_id;
+    await nextTick();
+    scrollToBottom();
+  } catch (e) {
+    // silencioso — polling repete
+  }
+};
+
+const sendMessage = async () => {
+  const text = input.value.trim();
+  if (!text || sending.value) return;
+  sending.value = true;
+  // optimistic UI
+  messages.value.push({
+    role: 'user',
+    content: text,
+    created_at: new Date().toISOString(),
+  });
+  input.value = '';
+  await nextTick();
+  scrollToBottom();
+  try {
+    await hermesBuilderApi.sendMessage(text);
+  } catch (e) {
+    useAlert(
+      t('CAPTAIN.HERMES_BUILDER.SEND_FAILED', {
+        message: e.response?.data?.error || e.message || 'unknown',
+      })
+    );
+  } finally {
+    sending.value = false;
+  }
+};
+
+const handleKeydown = e => {
+  if (e.key === 'Enter' && !e.shiftKey) {
+    e.preventDefault();
+    sendMessage();
+  }
+};
+
+const resetSession = async () => {
+  // eslint-disable-next-line no-alert
+  if (!window.confirm(t('CAPTAIN.HERMES_BUILDER.RESET_CONFIRM'))) return;
+  try {
+    await hermesBuilderApi.reset();
+    messages.value = [];
+  } catch (e) {
+    useAlert(t('CAPTAIN.HERMES_BUILDER.RESET_FAILED'));
+  }
+};
+
+const formatTime = iso => {
+  if (!iso) return '';
+  const d = new Date(iso);
+  return d.toLocaleTimeString('pt-BR', { hour: '2-digit', minute: '2-digit' });
+};
+
+onMounted(() => {
+  fetchMessages();
+  polling.value = setInterval(fetchMessages, 2000);
+});
+
+onBeforeUnmount(() => {
+  if (polling.value) clearInterval(polling.value);
+});
+
+watch(messages, () => nextTick().then(scrollToBottom), { deep: true });
+</script>
+
+<template>
+  <PageLayout
+    :title="t('CAPTAIN.HERMES_BUILDER.TITLE')"
+    :description="t('CAPTAIN.HERMES_BUILDER.DESCRIPTION')"
+  >
+    <div class="builder-wrapper">
+      <header class="builder-header">
+        <div>
+          <h2>{{ t('CAPTAIN.HERMES_BUILDER.HEADER_TITLE') }}</h2>
+          <p>{{ t('CAPTAIN.HERMES_BUILDER.HEADER_DESCRIPTION') }}</p>
+        </div>
+        <Button variant="ghost" size="sm" @click="resetSession">
+          {{ t('CAPTAIN.HERMES_BUILDER.RESET') }}
+        </Button>
+      </header>
+
+      <section ref="scrollContainer" class="messages">
+        <div v-if="!messages.length" class="empty-state">
+          {{ t('CAPTAIN.HERMES_BUILDER.EMPTY_STATE') }}
+        </div>
+        <div
+          v-for="(msg, idx) in messages"
+          :key="idx"
+          class="msg"
+          :class="[`msg--${msg.role}`]"
+        >
+          <div class="msg__bubble">
+            <div class="msg__content">{{ msg.content }}</div>
+            <div class="msg__meta">{{ formatTime(msg.created_at) }}</div>
+          </div>
+        </div>
+        <div v-if="isWaiting" class="msg msg--construtor">
+          <div class="msg__bubble msg__bubble--typing">
+            <span class="dot" /><span class="dot" /><span class="dot" />
+          </div>
+        </div>
+      </section>
+
+      <footer class="composer">
+        <textarea
+          v-model="input"
+          rows="2"
+          :placeholder="t('CAPTAIN.HERMES_BUILDER.PLACEHOLDER')"
+          :disabled="sending"
+          @keydown="handleKeydown"
+        />
+        <Button
+          variant="primary"
+          :disabled="!input.trim() || sending"
+          @click="sendMessage"
+        >
+          {{ t('CAPTAIN.HERMES_BUILDER.SEND') }}
+        </Button>
+      </footer>
+
+      <p v-if="sessionId" class="session-debug">
+        {{ t('CAPTAIN.HERMES_BUILDER.SESSION_LABEL') }} {{ sessionId }}
+      </p>
+    </div>
+  </PageLayout>
+</template>
+
+<style scoped lang="scss">
+.builder-wrapper {
+  display: flex;
+  flex-direction: column;
+  gap: 16px;
+  height: calc(100vh - 220px);
+  max-width: 900px;
+  margin: 0 auto;
+}
+
+.builder-header {
+  display: flex;
+  justify-content: space-between;
+  align-items: flex-start;
+  padding: 16px 20px;
+  background: var(--color-background-light, #f7f8fa);
+  border-radius: 12px;
+
+  h2 {
+    margin: 0 0 4px;
+    font-size: 18px;
+    font-weight: 600;
+  }
+
+  p {
+    margin: 0;
+    color: var(--color-text-light, #6b7280);
+    font-size: 13px;
+  }
+}
+
+.messages {
+  flex: 1;
+  overflow-y: auto;
+  padding: 16px;
+  background: var(--color-background, #fff);
+  border-radius: 12px;
+  border: 1px solid var(--color-border, #e5e7eb);
+  display: flex;
+  flex-direction: column;
+  gap: 12px;
+}
+
+.empty-state {
+  margin: auto;
+  color: var(--color-text-light, #9ca3af);
+  font-size: 14px;
+  text-align: center;
+}
+
+.msg {
+  display: flex;
+
+  &--user {
+    justify-content: flex-end;
+  }
+
+  &--construtor {
+    justify-content: flex-start;
+  }
+}
+
+.msg__bubble {
+  max-width: 70%;
+  padding: 10px 14px;
+  border-radius: 14px;
+  background: var(--color-background-light, #f3f4f6);
+  font-size: 14px;
+
+  .msg--user & {
+    background: var(--color-woot-500, #1f93ff);
+    color: #fff;
+  }
+}
+
+.msg__content {
+  white-space: pre-wrap;
+  word-break: break-word;
+}
+
+.msg__meta {
+  font-size: 11px;
+  margin-top: 4px;
+  opacity: 0.7;
+}
+
+.msg__bubble--typing {
+  display: flex;
+  gap: 4px;
+  padding: 12px 16px;
+
+  .dot {
+    width: 6px;
+    height: 6px;
+    border-radius: 50%;
+    background: var(--color-text-light, #6b7280);
+    animation: typing 1.4s infinite ease-in-out;
+
+    &:nth-child(2) {
+      animation-delay: 0.2s;
+    }
+    &:nth-child(3) {
+      animation-delay: 0.4s;
+    }
+  }
+}
+
+@keyframes typing {
+  0%,
+  60%,
+  100% {
+    opacity: 0.3;
+    transform: translateY(0);
+  }
+  30% {
+    opacity: 1;
+    transform: translateY(-3px);
+  }
+}
+
+.composer {
+  display: flex;
+  gap: 8px;
+  padding: 12px;
+  background: var(--color-background, #fff);
+  border-radius: 12px;
+  border: 1px solid var(--color-border, #e5e7eb);
+
+  textarea {
+    flex: 1;
+    border: none;
+    resize: none;
+    outline: none;
+    font: inherit;
+    background: transparent;
+    color: inherit;
+  }
+}
+
+.session-debug {
+  font-size: 11px;
+  color: var(--color-text-light, #9ca3af);
+  text-align: right;
+  margin: 0;
+}
+</style>
diff --git a/app/javascript/dashboard/routes/dashboard/captain/captain.routes.js b/app/javascript/dashboard/routes/dashboard/captain/captain.routes.js
index 88f0a0192..1eb8f3050 100644
--- a/app/javascript/dashboard/routes/dashboard/captain/captain.routes.js
+++ b/app/javascript/dashboard/routes/dashboard/captain/captain.routes.js
@@ -18,6 +18,7 @@ import ResponsesPendingIndex from './responses/Pending.vue';
 import CustomToolsIndex from './tools/Index.vue';
 import ReservationsIndex from './reservations/Index.vue';
 import RoletaIndex from './roleta/Index.vue';
+import HermesBuilderIndex from './builder/Index.vue';
 import FunnelIndex from './funnel/Index.vue';
 import LifecycleIndex from './lifecycle/Index.vue';
 import LifecycleRules from './lifecycle/Rules.vue';
@@ -149,6 +150,19 @@ export const routes = [
     name: 'captain_roleta_index',
     meta,
   },
+  {
+    path: frontendURL('accounts/:accountId/captain/hermes-builder'),
+    component: HermesBuilderIndex,
+    name: 'captain_hermes_builder_index',
+    meta: {
+      permissions: ['administrator'],
+      featureFlag: FEATURE_FLAGS.CAPTAIN,
+      installationTypes: [
+        INSTALLATION_TYPES.CLOUD,
+        INSTALLATION_TYPES.ENTERPRISE,
+      ],
+    },
+  },
   {
     path: frontendURL('accounts/:accountId/captain/funnel'),
     component: FunnelIndex,
diff --git a/config/routes.rb b/config/routes.rb
index 1fd35cb52..9e6648927 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -58,6 +58,11 @@ Rails.application.routes.draw do
             post :bulk_create, on: :collection
           end
           namespace :captain do
+            resources :hermes_builder, only: [:index, :create] do
+              collection do
+                delete :reset
+              end
+            end
             resource :preferences, only: [:show, :update]
             resources :assistants do
               member do
@@ -638,6 +643,7 @@ Rails.application.routes.draw do
   post 'webhooks/shopify', to: 'webhooks/shopify#events'
   post 'webhooks/wuzapi/:inbox_id', to: 'webhooks/wuzapi#process_payload'
   post 'webhooks/captain/hermes_callback', to: 'webhooks/captain/hermes_callback#process_payload'
+  post 'webhooks/captain/builder_callback', to: 'webhooks/captain/hermes_builder_callback#process_payload'
   post 'webhooks/captain/mcp', to: 'webhooks/captain/mcp#process_payload'
 
   namespace :twitter do
diff --git a/enterprise/app/controllers/enterprise/api/v1/accounts/captain/hermes_builder_controller.rb b/enterprise/app/controllers/enterprise/api/v1/accounts/captain/hermes_builder_controller.rb
new file mode 100644
index 000000000..9d4efcc56
--- /dev/null
+++ b/enterprise/app/controllers/enterprise/api/v1/accounts/captain/hermes_builder_controller.rb
@@ -0,0 +1,54 @@
+# Endpoints da UI Hermes Builder no painel Captain.
+#
+# Fluxo:
+#   1. UI faz POST /messages com texto do admin
+#   2. Backend encaminha pro gateway Hermes Construtor (porta 8646 na VPS)
+#   3. Construtor processa async e dispara http_callback (HermesBuilderCallbackController)
+#   4. Callback armazena resposta no Rails.cache
+#   5. UI faz GET /messages a cada 2s (polling) e renderiza
+#
+# Sessão é por account+user (1 admin → 1 sessão de builder por vez).
+class Enterprise::Api::V1::Accounts::Captain::HermesBuilderController < Api::V1::Accounts::BaseController
+  before_action :authorize_admin
+
+  def index
+    msgs = HermesBuilder::Storage.messages_for(session_key)
+    render json: { messages: msgs, session_id: session_id }
+  end
+
+  def create
+    text = params[:text].to_s.strip
+    return render json: { error: 'Texto vazio' }, status: :bad_request if text.blank?
+
+    HermesBuilder::Storage.append(session_key, role: 'user', content: text)
+    HermesBuilder::Dispatcher.send_to_construtor(session_id: session_id, message: text)
+
+    render json: { ok: true, session_id: session_id }, status: :accepted
+  rescue HermesBuilder::Dispatcher::DispatchError => e
+    Rails.logger.error("[HermesBuilder#create] dispatch failed: #{e.message}")
+    render json: { error: "Falha ao contatar Construtor: #{e.message}" }, status: :bad_gateway
+  end
+
+  def reset
+    HermesBuilder::Storage.clear(session_key)
+    render json: { ok: true }
+  end
+
+  private
+
+  def authorize_admin
+    return if current_user&.administrator?
+
+    render json: { error: 'Apenas administradores podem usar o Builder' }, status: :forbidden
+  end
+
+  # Sessão é por (account, user). Hermes Construtor mantém memória estável
+  # graças ao plugin captain-webhook que rewrita chat_id usando hermes_session_id.
+  def session_id
+    "builder-#{Current.account.id}-#{current_user.id}"
+  end
+
+  def session_key
+    "hermes_builder:#{session_id}"
+  end
+end
diff --git a/enterprise/app/services/hermes_builder/dispatcher.rb b/enterprise/app/services/hermes_builder/dispatcher.rb
new file mode 100644
index 000000000..d4a2aa135
--- /dev/null
+++ b/enterprise/app/services/hermes_builder/dispatcher.rb
@@ -0,0 +1,45 @@
+# Encaminha mensagens da UI Hermes Builder pro gateway do Construtor (Hermes).
+#
+# Configuração:
+#   ENV['HERMES_BUILDER_WEBHOOK_URL'] — default: http://172.17.0.1:8646/webhooks/construtor-admin
+#   ENV['HERMES_BUILDER_WEBHOOK_SECRET'] — secret HMAC pra assinar payload
+#
+# Construtor responde async via plugin captain-http-callback que faz POST
+# pra /webhooks/captain/builder_callback (HermesBuilderCallbackController).
+module HermesBuilder::Dispatcher
+  DEFAULT_URL = 'http://172.17.0.1:8646/webhooks/construtor-admin'.freeze
+  TIMEOUT = 10
+
+  class DispatchError < StandardError; end
+
+  module_function
+
+  def send_to_construtor(session_id:, message:)
+    payload = { message: message, hermes_session_id: session_id }
+    body = payload.to_json
+    headers = signed_headers(body)
+
+    Rails.logger.info("[HermesBuilder::Dispatcher] sending session=#{session_id} (#{message.length} chars)")
+
+    response = HTTParty.post(webhook_url, body: body, headers: headers, timeout: TIMEOUT)
+    return response if response.success? || response.code == 202
+
+    raise DispatchError, "Construtor returned HTTP #{response.code}: #{response.body.to_s.truncate(200)}"
+  rescue HTTParty::Error, Net::ReadTimeout, Net::OpenTimeout, Errno::ECONNREFUSED => e
+    raise DispatchError, "Network error contacting Construtor (#{e.class}): #{e.message}"
+  end
+
+  def webhook_url
+    ENV.fetch('HERMES_BUILDER_WEBHOOK_URL', DEFAULT_URL)
+  end
+
+  def signed_headers(body)
+    headers = { 'Content-Type' => 'application/json; charset=utf-8' }
+    secret = ENV.fetch('HERMES_BUILDER_WEBHOOK_SECRET', nil)
+    if secret.present?
+      sig = OpenSSL::HMAC.hexdigest('SHA256', secret, body)
+      headers['X-Hub-Signature-256'] = "sha256=#{sig}"
+    end
+    headers
+  end
+end
diff --git a/enterprise/app/services/hermes_builder/storage.rb b/enterprise/app/services/hermes_builder/storage.rb
new file mode 100644
index 000000000..1275fa3b7
--- /dev/null
+++ b/enterprise/app/services/hermes_builder/storage.rb
@@ -0,0 +1,32 @@
+# Storage de mensagens da UI Hermes Builder.
+#
+# Persistência em Rails.cache (Redis em prod) — TTL 4h. Suficiente pra uma
+# sessão de criação completa de agente (geralmente ~10-20min).
+#
+# Cada mensagem tem: role ('user' | 'construtor'), content (string),
+# created_at (ISO8601). Lista cresce em ordem cronológica.
+module HermesBuilder
+end
+
+module HermesBuilder::Storage
+  TTL = 4.hours
+  MAX_MESSAGES = 200
+
+  module_function
+
+  def messages_for(session_key)
+    Rails.cache.fetch(session_key) { [] }
+  end
+
+  def append(session_key, role:, content:)
+    msgs = messages_for(session_key)
+    msgs << { role: role, content: content.to_s, created_at: Time.current.iso8601 }
+    msgs = msgs.last(MAX_MESSAGES)
+    Rails.cache.write(session_key, msgs, expires_in: TTL)
+    msgs
+  end
+
+  def clear(session_key)
+    Rails.cache.delete(session_key)
+  end
+end