diff --git a/src/features/conversations/services/_tenantGuards.js b/src/features/conversations/services/_tenantGuards.js
new file mode 100644
index 0000000..a115880
--- /dev/null
+++ b/src/features/conversations/services/_tenantGuards.js
@@ -0,0 +1,22 @@
+/*
+|--------------------------------------------------------------------------
+| Agência PSI
+|--------------------------------------------------------------------------
+| Arquivo: src/features/conversations/services/_tenantGuards.js
+|--------------------------------------------------------------------------
+*/
+import { supabase } from '@/lib/supabase/client';
+
+export function assertTenantId(tenantId) {
+    if (!tenantId || tenantId === 'null' || tenantId === 'undefined') {
+        throw new Error('Tenant ativo inválido. Selecione a clínica antes de acessar conversas.');
+    }
+}
+
+export async function getUid() {
+    const { data, error } = await supabase.auth.getUser();
+    if (error) throw error;
+    const uid = data?.user?.id;
+    if (!uid) throw new Error('Usuário não autenticado.');
+    return uid;
+}
diff --git a/src/features/conversations/services/conversationsRepository.js b/src/features/conversations/services/conversationsRepository.js
new file mode 100644
index 0000000..44968de
--- /dev/null
+++ b/src/features/conversations/services/conversationsRepository.js
@@ -0,0 +1,115 @@
+/*
+|--------------------------------------------------------------------------
+| Agência PSI
+|--------------------------------------------------------------------------
+| Arquivo: src/features/conversations/services/conversationsRepository.js
+|
+| Repository de conversas (threads + messages). Foundation pra Módulo 6.
+|
+| ⚠️ src/composables/useConversations.js (existente) AINDA tem supabase direto.
+| Migração pra usar este repository fica pra sessão dedicada (composable é fat
+| e mistura listing + threading + realtime — audit baseline pediu split em
+| useConversationsList + useConversationThreadDetail).
+|
+| Channel send (WhatsApp Evolution/Twilio, SMS Twilio) NÃO está aqui — é
+| operação cross-canal que precisa de factory dedicada (ver audit alta:
+| conversationDrawerStore lógica de envio sem abstração).
+|--------------------------------------------------------------------------
+*/
+import { supabase } from '@/lib/supabase/client';
+import { useTenantStore } from '@/stores/tenantStore';
+import { assertTenantId } from './_tenantGuards';
+import {
+    CONVERSATION_THREAD_SELECT,
+    CONVERSATION_MESSAGE_SELECT,
+    CONVERSATION_MESSAGE_SELECT_BRIEF
+} from './conversationsSelects';
+
+function resolveTenantId(tenantIdArg) {
+    const tenantStore = useTenantStore();
+    const tenantId = tenantIdArg || tenantStore.activeTenantId || tenantStore.tenantId;
+    assertTenantId(tenantId);
+    return tenantId;
+}
+
+// ─── Threads ─────────────────────────────────────────────────────────────
+
+/**
+ * Lista threads do tenant. Limit 500 (default UI usage), ordem desc por
+ * last_message_at.
+ */
+export async function listThreads({ tenantId, limit = 500 } = {}) {
+    const tid = resolveTenantId(tenantId);
+
+    const { data, error } = await supabase.from('conversation_threads').select(CONVERSATION_THREAD_SELECT).eq('tenant_id', tid).order('last_message_at', { ascending: false }).limit(limit);
+
+    if (error) throw error;
+    return data || [];
+}
+
+/**
+ * Lê thread por id.
+ */
+export async function getThreadById(threadId, { tenantId } = {}) {
+    if (!threadId) throw new Error('threadId obrigatório.');
+    const tid = resolveTenantId(tenantId);
+
+    const { data, error } = await supabase.from('conversation_threads').select(CONVERSATION_THREAD_SELECT).eq('id', threadId).eq('tenant_id', tid).maybeSingle();
+
+    if (error) throw error;
+    return data || null;
+}
+
+/**
+ * Atualiza thread (assigned_to, kanban_status, etc).
+ */
+export async function updateThread(threadId, patch, { tenantId } = {}) {
+    if (!threadId) throw new Error('threadId obrigatório.');
+    const tid = resolveTenantId(tenantId);
+
+    const { data, error } = await supabase.from('conversation_threads').update({ ...patch, updated_at: new Date().toISOString() }).eq('id', threadId).eq('tenant_id', tid).select(CONVERSATION_THREAD_SELECT).single();
+
+    if (error) throw error;
+    return data;
+}
+
+// ─── Messages ────────────────────────────────────────────────────────────
+
+/**
+ * Lista mensagens de uma thread. Limit 500 desc por created_at.
+ */
+export async function listMessagesByThread(threadId, { tenantId, limit = 500 } = {}) {
+    if (!threadId) return [];
+    const tid = resolveTenantId(tenantId);
+
+    const { data, error } = await supabase.from('conversation_messages').select(CONVERSATION_MESSAGE_SELECT).eq('tenant_id', tid).eq('thread_id', threadId).order('created_at', { ascending: true }).limit(limit);
+
+    if (error) throw error;
+    return data || [];
+}
+
+/**
+ * Lista mensagens por paciente (brief — sem attachments pesados).
+ * Usado em prontuário (PatientConversationsTab).
+ */
+export async function listMessagesByPatient(patientId, { tenantId, limit = 200 } = {}) {
+    if (!patientId) return [];
+    const tid = resolveTenantId(tenantId);
+
+    const { data, error } = await supabase.from('conversation_messages').select(CONVERSATION_MESSAGE_SELECT_BRIEF).eq('tenant_id', tid).eq('patient_id', patientId).order('created_at', { ascending: false }).limit(limit);
+
+    if (error) throw error;
+    return data || [];
+}
+
+/**
+ * Atualiza kanban_status de uma mensagem (in-app workflow).
+ */
+export async function updateMessageKanban(messageId, kanbanStatus, { tenantId } = {}) {
+    if (!messageId) throw new Error('messageId obrigatório.');
+    const tid = resolveTenantId(tenantId);
+
+    const { error } = await supabase.from('conversation_messages').update({ kanban_status: kanbanStatus, updated_at: new Date().toISOString() }).eq('id', messageId).eq('tenant_id', tid);
+
+    if (error) throw error;
+}
diff --git a/src/features/conversations/services/conversationsSelects.js b/src/features/conversations/services/conversationsSelects.js
new file mode 100644
index 0000000..75f52aa
--- /dev/null
+++ b/src/features/conversations/services/conversationsSelects.js
@@ -0,0 +1,35 @@
+/*
+|--------------------------------------------------------------------------
+| Agência PSI
+|--------------------------------------------------------------------------
+| Arquivo: src/features/conversations/services/conversationsSelects.js
+|
+| SELECTs canônicos de conversation_threads e conversation_messages.
+| Threads usa `*` porque a UI usa muitos campos derivados (last_message_at,
+| unread_count, assigned_to, contact_number, patient_name, etc).
+|--------------------------------------------------------------------------
+*/
+
+/** Thread — UI usa praticamente todos os campos. */
+export const CONVERSATION_THREAD_SELECT = '*';
+
+/** Mensagem — campos canônicos pra timeline. */
+export const CONVERSATION_MESSAGE_SELECT = `
+    id, tenant_id, thread_id, patient_id, body, direction, channel,
+    created_at, sent_at, delivered_at, read_at,
+    kanban_status, status, contact_number, attachments
+`
+    .replace(/\s+/g, ' ')
+    .trim();
+
+/** Mensagem brief — listings em prontuário (sem campos pesados). */
+export const CONVERSATION_MESSAGE_SELECT_BRIEF = `
+    id, body, direction, created_at, channel, kanban_status
+`
+    .replace(/\s+/g, ' ')
+    .trim();
+
+/**
+ * Canais identificados no sistema (memória audit baseline M6).
+ */
+export const CHANNEL_TYPES = Object.freeze(['whatsapp', 'sms', 'email', 'in_app']);
diff --git a/src/features/notices/noticeService.js b/src/features/notices/noticeService.js
index 704f7cd..482ca1d 100644
--- a/src/features/notices/noticeService.js
+++ b/src/features/notices/noticeService.js
@@ -17,6 +17,7 @@
 // Serviço central de acesso ao Supabase para Global Notices
 
 import { supabase } from '@/lib/supabase/client';
+import { GLOBAL_NOTICE_SELECT, NOTICE_DISMISSAL_SELECT } from './noticesSelects';
 
 // ── Leitura ────────────────────────────────────────────────────
 
@@ -28,7 +29,7 @@ import { supabase } from '@/lib/supabase/client';
 export async function fetchActiveNotices() {
     const now = new Date().toISOString();
 
-    const { data, error } = await supabase.from('global_notices').select('*').eq('is_active', true).or(`starts_at.is.null,starts_at.lte.${now}`).or(`ends_at.is.null,ends_at.gte.${now}`).order('priority', { ascending: false });
+    const { data, error } = await supabase.from('global_notices').select(GLOBAL_NOTICE_SELECT).eq('is_active', true).or(`starts_at.is.null,starts_at.lte.${now}`).or(`ends_at.is.null,ends_at.gte.${now}`).order('priority', { ascending: false });
 
     if (error) throw error;
     return data || [];
@@ -38,7 +39,7 @@ export async function fetchActiveNotices() {
  * Busca todos os notices (sem filtro de ativo) — para o painel admin.
  */
 export async function fetchAllNotices() {
-    const { data, error } = await supabase.from('global_notices').select('*').order('priority', { ascending: false }).order('created_at', { ascending: false });
+    const { data, error } = await supabase.from('global_notices').select(GLOBAL_NOTICE_SELECT).order('priority', { ascending: false }).order('created_at', { ascending: false });
 
     if (error) throw error;
     return data || [];
@@ -77,7 +78,7 @@ export async function loadUserDismissals() {
     } = await supabase.auth.getUser();
     if (!user?.id) return [];
 
-    const { data } = await supabase.from('notice_dismissals').select('notice_id, version').eq('user_id', user.id);
+    const { data } = await supabase.from('notice_dismissals').select(NOTICE_DISMISSAL_SELECT).eq('user_id', user.id);
 
     return data || [];
 }
diff --git a/src/features/notices/noticesSelects.js b/src/features/notices/noticesSelects.js
new file mode 100644
index 0000000..3200753
--- /dev/null
+++ b/src/features/notices/noticesSelects.js
@@ -0,0 +1,17 @@
+/*
+|--------------------------------------------------------------------------
+| Agência PSI
+|--------------------------------------------------------------------------
+| Arquivo: src/features/notices/noticesSelects.js
+|
+| SELECTs canônicos de notices. Extraídos de noticeService.js (audit alta).
+| global_notices tem muitos campos usados pela UI — usa `*` por simplicidade.
+| notice_dismissals tem só 2 colunas relevantes.
+|--------------------------------------------------------------------------
+*/
+
+/** SELECT completo de global_notices. */
+export const GLOBAL_NOTICE_SELECT = '*';
+
+/** SELECT mínimo de notice_dismissals (pra checar se user já dismissou). */
+export const NOTICE_DISMISSAL_SELECT = 'notice_id, version';