diff --git a/services/platform-service/src/lib/cosmos-init.ts b/services/platform-service/src/lib/cosmos-init.ts
index 708b3144..a8cf9a30 100644
--- a/services/platform-service/src/lib/cosmos-init.ts
+++ b/services/platform-service/src/lib/cosmos-init.ts
@@ -39,6 +39,9 @@ const CONTAINER_DEFS: Record<string, ContainerConfig> = {
   fasting_protocols: { partitionKeyPath: '/userId' },
   // ChronoMind timers
   timers: { partitionKeyPath: '/userId' },
+  routines: { partitionKeyPath: '/userId' },
+  households: { partitionKeyPath: '/id' },
+  shared_timers: { partitionKeyPath: '/householdId' },
   // Telemetry (client diagnostics — see docs/WINDSURF/CLIENT_TELEMETRY_DESIGN.md)
   telemetry_events: { partitionKeyPath: '/pk', defaultTtl: 30 * 86400 },
   telemetry_error_clusters: { partitionKeyPath: '/pk', defaultTtl: 90 * 86400 },
diff --git a/services/platform-service/src/modules/households/households.test.ts b/services/platform-service/src/modules/households/households.test.ts
new file mode 100644
index 00000000..b178f919
--- /dev/null
+++ b/services/platform-service/src/modules/households/households.test.ts
@@ -0,0 +1,198 @@
+/**
+ * Households module unit tests — validates schemas, constants, and types.
+ */
+
+import { describe, it, expect } from 'vitest';
+import {
+  CreateHouseholdSchema,
+  UpdateHouseholdSchema,
+  CreateInviteSchema,
+  AcceptInviteSchema,
+  RemoveMemberSchema,
+  HouseholdQuerySchema,
+  MEMBER_ROLES,
+  INVITE_STATUSES,
+  MAX_HOUSEHOLD_MEMBERS,
+} from './types.js';
+
+// ── Constants ──
+
+describe('household constants', () => {
+  it('has 2 member roles', () => {
+    expect(MEMBER_ROLES).toEqual(['admin', 'member']);
+  });
+
+  it('has 4 invite statuses', () => {
+    expect(INVITE_STATUSES).toEqual(['pending', 'accepted', 'expired', 'revoked']);
+  });
+
+  it('has max 6 members', () => {
+    expect(MAX_HOUSEHOLD_MEMBERS).toBe(6);
+  });
+});
+
+// ── CreateHouseholdSchema ──
+
+describe('CreateHouseholdSchema', () => {
+  it('accepts valid input', () => {
+    const result = CreateHouseholdSchema.safeParse({
+      name: 'Smith Family',
+      displayName: 'John Smith',
+    });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.name).toBe('Smith Family');
+      expect(result.data.displayName).toBe('John Smith');
+    }
+  });
+
+  it('rejects missing name', () => {
+    const result = CreateHouseholdSchema.safeParse({ displayName: 'John' });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects missing displayName', () => {
+    const result = CreateHouseholdSchema.safeParse({ name: 'Family' });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects empty name', () => {
+    const result = CreateHouseholdSchema.safeParse({ name: '', displayName: 'John' });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects name > 200 chars', () => {
+    const result = CreateHouseholdSchema.safeParse({
+      name: 'x'.repeat(201),
+      displayName: 'John',
+    });
+    expect(result.success).toBe(false);
+  });
+});
+
+// ── UpdateHouseholdSchema ──
+
+describe('UpdateHouseholdSchema', () => {
+  it('accepts name update', () => {
+    const result = UpdateHouseholdSchema.safeParse({ name: 'New Name' });
+    expect(result.success).toBe(true);
+  });
+
+  it('accepts empty update', () => {
+    const result = UpdateHouseholdSchema.safeParse({});
+    expect(result.success).toBe(true);
+  });
+
+  it('rejects empty name string', () => {
+    const result = UpdateHouseholdSchema.safeParse({ name: '' });
+    expect(result.success).toBe(false);
+  });
+});
+
+// ── CreateInviteSchema ──
+
+describe('CreateInviteSchema', () => {
+  it('provides default 72h expiry', () => {
+    const result = CreateInviteSchema.safeParse({});
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.expiresInHours).toBe(72);
+    }
+  });
+
+  it('accepts custom expiry', () => {
+    const result = CreateInviteSchema.safeParse({ expiresInHours: 24 });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.expiresInHours).toBe(24);
+    }
+  });
+
+  it('rejects expiry > 168 hours', () => {
+    const result = CreateInviteSchema.safeParse({ expiresInHours: 200 });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects expiry < 1 hour', () => {
+    const result = CreateInviteSchema.safeParse({ expiresInHours: 0 });
+    expect(result.success).toBe(false);
+  });
+});
+
+// ── AcceptInviteSchema ──
+
+describe('AcceptInviteSchema', () => {
+  it('accepts valid invite', () => {
+    const result = AcceptInviteSchema.safeParse({
+      code: 'ABC123DEF456',
+      displayName: 'Jane Smith',
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it('rejects missing code', () => {
+    const result = AcceptInviteSchema.safeParse({ displayName: 'Jane' });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects missing displayName', () => {
+    const result = AcceptInviteSchema.safeParse({ code: 'ABC123' });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects empty code', () => {
+    const result = AcceptInviteSchema.safeParse({ code: '', displayName: 'Jane' });
+    expect(result.success).toBe(false);
+  });
+});
+
+// ── RemoveMemberSchema ──
+
+describe('RemoveMemberSchema', () => {
+  it('accepts valid userId', () => {
+    const result = RemoveMemberSchema.safeParse({ userId: 'user_123' });
+    expect(result.success).toBe(true);
+  });
+
+  it('rejects empty userId', () => {
+    const result = RemoveMemberSchema.safeParse({ userId: '' });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects missing userId', () => {
+    const result = RemoveMemberSchema.safeParse({});
+    expect(result.success).toBe(false);
+  });
+});
+
+// ── HouseholdQuerySchema ──
+
+describe('HouseholdQuerySchema', () => {
+  it('provides defaults for empty query', () => {
+    const result = HouseholdQuerySchema.safeParse({});
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.limit).toBe(20);
+      expect(result.data.offset).toBe(0);
+    }
+  });
+
+  it('coerces string numbers', () => {
+    const result = HouseholdQuerySchema.safeParse({ limit: '10', offset: '5' });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.limit).toBe(10);
+      expect(result.data.offset).toBe(5);
+    }
+  });
+
+  it('rejects limit > 50', () => {
+    const result = HouseholdQuerySchema.safeParse({ limit: 100 });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects negative offset', () => {
+    const result = HouseholdQuerySchema.safeParse({ offset: -1 });
+    expect(result.success).toBe(false);
+  });
+});
diff --git a/services/platform-service/src/modules/households/repository.ts b/services/platform-service/src/modules/households/repository.ts
new file mode 100644
index 00000000..377d1584
--- /dev/null
+++ b/services/platform-service/src/modules/households/repository.ts
@@ -0,0 +1,95 @@
+/**
+ * Households repository — Cosmos DB CRUD for household membership.
+ *
+ * Container: households (partition key: /id)
+ *
+ * Unlike timers/routines (partitioned by /userId), households are
+ * partitioned by their own /id since multiple users share the same doc.
+ */
+
+import { getContainer } from '../../lib/cosmos.js';
+import type { HouseholdDoc, HouseholdQuery } from './types.js';
+
+function container() {
+  return getContainer('households');
+}
+
+export async function getHousehold(id: string): Promise<HouseholdDoc | null> {
+  try {
+    const { resource } = await container().item(id, id).read<HouseholdDoc>();
+    return resource ?? null;
+  } catch {
+    return null;
+  }
+}
+
+export async function createHousehold(doc: HouseholdDoc): Promise<HouseholdDoc> {
+  const { resource } = await container().items.create(doc);
+  return resource as HouseholdDoc;
+}
+
+export async function replaceHousehold(doc: HouseholdDoc): Promise<HouseholdDoc> {
+  const { resource } = await container().item(doc.id, doc.id).replace(doc);
+  return resource as HouseholdDoc;
+}
+
+export async function deleteHousehold(id: string): Promise<boolean> {
+  try {
+    const existing = await getHousehold(id);
+    if (!existing) return false;
+    await container().item(id, id).delete();
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+export async function listHouseholdsForUser(
+  userId: string,
+  productId: string,
+  query: HouseholdQuery
+): Promise<{ items: HouseholdDoc[]; total: number }> {
+  const countResult = await container()
+    .items.query<number>({
+      query:
+        'SELECT VALUE COUNT(1) FROM c WHERE c.productId = @productId AND ARRAY_CONTAINS(c.members, { "userId": @userId }, true)',
+      parameters: [
+        { name: '@productId', value: productId },
+        { name: '@userId', value: userId },
+      ],
+    })
+    .fetchAll();
+  const total = countResult.resources[0] ?? 0;
+
+  const { resources } = await container()
+    .items.query<HouseholdDoc>({
+      query:
+        'SELECT * FROM c WHERE c.productId = @productId AND ARRAY_CONTAINS(c.members, { "userId": @userId }, true) ORDER BY c.createdAt DESC OFFSET @offset LIMIT @limit',
+      parameters: [
+        { name: '@productId', value: productId },
+        { name: '@userId', value: userId },
+        { name: '@offset', value: query.offset },
+        { name: '@limit', value: query.limit },
+      ],
+    })
+    .fetchAll();
+
+  return { items: resources, total };
+}
+
+export async function findHouseholdByInviteCode(
+  code: string,
+  productId: string
+): Promise<HouseholdDoc | null> {
+  const { resources } = await container()
+    .items.query<HouseholdDoc>({
+      query:
+        'SELECT * FROM c WHERE c.productId = @productId AND ARRAY_CONTAINS(c.invites, { "code": @code, "status": "pending" }, true)',
+      parameters: [
+        { name: '@productId', value: productId },
+        { name: '@code', value: code },
+      ],
+    })
+    .fetchAll();
+  return resources[0] ?? null;
+}
diff --git a/services/platform-service/src/modules/households/routes.ts b/services/platform-service/src/modules/households/routes.ts
new file mode 100644
index 00000000..5eb49313
--- /dev/null
+++ b/services/platform-service/src/modules/households/routes.ts
@@ -0,0 +1,264 @@
+/**
+ * Household REST endpoints — ChronoMind Family tier.
+ *
+ * GET    /households           — list user's households
+ * GET    /households/:id       — single household
+ * POST   /households           — create household
+ * PUT    /households/:id       — update household name (admin only)
+ * DELETE /households/:id       — delete household (admin only)
+ * POST   /households/:id/invite — generate invite code (admin only)
+ * POST   /households/join      — accept invite code
+ * DELETE /households/:id/members — remove member (admin only)
+ * DELETE /households/:id/leave  — leave household (non-admin)
+ */
+
+import crypto from 'node:crypto';
+import type { FastifyInstance } from 'fastify';
+import { BadRequestError, NotFoundError, ForbiddenError, ConflictError } from '../../lib/errors.js';
+import { extractAuth } from '../../lib/auth.js';
+import * as repo from './repository.js';
+import {
+  CreateHouseholdSchema,
+  UpdateHouseholdSchema,
+  CreateInviteSchema,
+  AcceptInviteSchema,
+  RemoveMemberSchema,
+  HouseholdQuerySchema,
+  MAX_HOUSEHOLD_MEMBERS,
+  type HouseholdDoc,
+  type HouseholdMember,
+  type HouseholdInvite,
+} from './types.js';
+
+const PRODUCT_ID = 'chronomind';
+
+function isAdmin(household: HouseholdDoc, userId: string): boolean {
+  return household.members.some(m => m.userId === userId && m.role === 'admin');
+}
+
+function isMember(household: HouseholdDoc, userId: string): boolean {
+  return household.members.some(m => m.userId === userId);
+}
+
+function generateInviteCode(): string {
+  return crypto.randomBytes(6).toString('hex').toUpperCase();
+}
+
+export async function householdRoutes(app: FastifyInstance) {
+  // List households for current user
+  app.get('/households', async req => {
+    const auth = await extractAuth(req);
+    const parsed = HouseholdQuerySchema.safeParse(req.query);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+    const { items, total } = await repo.listHouseholdsForUser(auth.sub, PRODUCT_ID, parsed.data);
+    return { items, total, limit: parsed.data.limit, offset: parsed.data.offset };
+  });
+
+  // Get single household
+  app.get('/households/:id', async req => {
+    const auth = await extractAuth(req);
+    const { id } = req.params as { id: string };
+    const household = await repo.getHousehold(id);
+    if (!household || household.productId !== PRODUCT_ID)
+      throw new NotFoundError('Household not found');
+    if (!isMember(household, auth.sub)) throw new ForbiddenError('Not a member of this household');
+    return household;
+  });
+
+  // Create household
+  app.post('/households', async (req, reply) => {
+    const auth = await extractAuth(req);
+    const parsed = CreateHouseholdSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    const now = new Date().toISOString();
+    const member: HouseholdMember = {
+      userId: auth.sub,
+      displayName: parsed.data.displayName,
+      role: 'admin',
+      joinedAt: now,
+    };
+
+    const doc: HouseholdDoc = {
+      id: crypto.randomUUID(),
+      productId: PRODUCT_ID,
+      name: parsed.data.name,
+      members: [member],
+      invites: [],
+      createdAt: now,
+      createdBy: auth.sub,
+    };
+
+    req.log.info({ householdId: doc.id }, 'Creating household');
+    const created = await repo.createHousehold(doc);
+    reply.code(201);
+    return created;
+  });
+
+  // Update household name (admin only)
+  app.put('/households/:id', async req => {
+    const auth = await extractAuth(req);
+    const { id } = req.params as { id: string };
+    const parsed = UpdateHouseholdSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    const household = await repo.getHousehold(id);
+    if (!household || household.productId !== PRODUCT_ID)
+      throw new NotFoundError('Household not found');
+    if (!isAdmin(household, auth.sub)) throw new ForbiddenError('Only admin can update household');
+
+    const updated: HouseholdDoc = { ...household, ...parsed.data };
+    const result = await repo.replaceHousehold(updated);
+    return result;
+  });
+
+  // Delete household (admin only)
+  app.delete('/households/:id', async req => {
+    const auth = await extractAuth(req);
+    const { id } = req.params as { id: string };
+    const household = await repo.getHousehold(id);
+    if (!household || household.productId !== PRODUCT_ID)
+      throw new NotFoundError('Household not found');
+    if (!isAdmin(household, auth.sub)) throw new ForbiddenError('Only admin can delete household');
+
+    await repo.deleteHousehold(id);
+    req.log.info({ householdId: id }, 'Deleted household');
+    return { success: true };
+  });
+
+  // Generate invite code (admin only)
+  app.post('/households/:id/invite', async req => {
+    const auth = await extractAuth(req);
+    const { id } = req.params as { id: string };
+    const parsed = CreateInviteSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    const household = await repo.getHousehold(id);
+    if (!household || household.productId !== PRODUCT_ID)
+      throw new NotFoundError('Household not found');
+    if (!isAdmin(household, auth.sub)) throw new ForbiddenError('Only admin can create invites');
+
+    if (household.members.length >= MAX_HOUSEHOLD_MEMBERS) {
+      throw new BadRequestError(
+        `Household is at maximum capacity (${MAX_HOUSEHOLD_MEMBERS} members)`
+      );
+    }
+
+    const now = new Date();
+    const invite: HouseholdInvite = {
+      code: generateInviteCode(),
+      createdBy: auth.sub,
+      createdAt: now.toISOString(),
+      expiresAt: new Date(now.getTime() + parsed.data.expiresInHours * 3600_000).toISOString(),
+      status: 'pending',
+    };
+
+    household.invites.push(invite);
+    await repo.replaceHousehold(household);
+    req.log.info({ householdId: id, inviteCode: invite.code }, 'Created invite');
+    return { code: invite.code, expiresAt: invite.expiresAt };
+  });
+
+  // Accept invite code (join household)
+  app.post('/households/join', async req => {
+    const auth = await extractAuth(req);
+    const parsed = AcceptInviteSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    const household = await repo.findHouseholdByInviteCode(parsed.data.code, PRODUCT_ID);
+    if (!household) throw new NotFoundError('Invalid or expired invite code');
+
+    if (isMember(household, auth.sub)) {
+      throw new ConflictError('Already a member of this household');
+    }
+
+    if (household.members.length >= MAX_HOUSEHOLD_MEMBERS) {
+      throw new BadRequestError(
+        `Household is at maximum capacity (${MAX_HOUSEHOLD_MEMBERS} members)`
+      );
+    }
+
+    const now = new Date().toISOString();
+    const invite = household.invites.find(
+      i => i.code === parsed.data.code && i.status === 'pending'
+    );
+    if (!invite || new Date(invite.expiresAt) < new Date()) {
+      throw new NotFoundError('Invite code has expired');
+    }
+
+    // Mark invite as accepted
+    invite.status = 'accepted';
+    invite.acceptedBy = auth.sub;
+    invite.acceptedAt = now;
+
+    // Add member
+    const member: HouseholdMember = {
+      userId: auth.sub,
+      displayName: parsed.data.displayName,
+      role: 'member',
+      joinedAt: now,
+    };
+    household.members.push(member);
+
+    const updated = await repo.replaceHousehold(household);
+    req.log.info({ householdId: household.id, userId: auth.sub }, 'Member joined household');
+    return updated;
+  });
+
+  // Remove member (admin only)
+  app.delete('/households/:id/members', async req => {
+    const auth = await extractAuth(req);
+    const { id } = req.params as { id: string };
+    const parsed = RemoveMemberSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    const household = await repo.getHousehold(id);
+    if (!household || household.productId !== PRODUCT_ID)
+      throw new NotFoundError('Household not found');
+    if (!isAdmin(household, auth.sub)) throw new ForbiddenError('Only admin can remove members');
+
+    if (parsed.data.userId === auth.sub) {
+      throw new BadRequestError('Admin cannot remove themselves. Delete the household instead.');
+    }
+
+    const memberIdx = household.members.findIndex(m => m.userId === parsed.data.userId);
+    if (memberIdx === -1) throw new NotFoundError('Member not found in household');
+
+    household.members.splice(memberIdx, 1);
+    const updated = await repo.replaceHousehold(household);
+    req.log.info({ householdId: id, removedUserId: parsed.data.userId }, 'Removed member');
+    return updated;
+  });
+
+  // Leave household (non-admin)
+  app.delete('/households/:id/leave', async req => {
+    const auth = await extractAuth(req);
+    const { id } = req.params as { id: string };
+
+    const household = await repo.getHousehold(id);
+    if (!household || household.productId !== PRODUCT_ID)
+      throw new NotFoundError('Household not found');
+    if (!isMember(household, auth.sub)) throw new NotFoundError('Not a member of this household');
+
+    if (isAdmin(household, auth.sub)) {
+      throw new BadRequestError('Admin cannot leave. Transfer admin or delete the household.');
+    }
+
+    household.members = household.members.filter(m => m.userId !== auth.sub);
+    const updated = await repo.replaceHousehold(household);
+    req.log.info({ householdId: id, userId: auth.sub }, 'Member left household');
+    return { success: true, householdId: updated.id };
+  });
+}
diff --git a/services/platform-service/src/modules/households/types.ts b/services/platform-service/src/modules/households/types.ts
new file mode 100644
index 00000000..583dbfee
--- /dev/null
+++ b/services/platform-service/src/modules/households/types.ts
@@ -0,0 +1,93 @@
+/**
+ * Household types — ChronoMind Family tier.
+ *
+ * Cosmos container: `households` (partition key: `/id`)
+ * Product ID: "chronomind"
+ *
+ * A household is a group of up to 6 members who can share timers.
+ * One admin (creator) manages members. Members join via invite code.
+ */
+
+import { z } from 'zod';
+
+// ── Enums / constants ──
+
+export const MEMBER_ROLES = ['admin', 'member'] as const;
+export type MemberRole = (typeof MEMBER_ROLES)[number];
+
+export const INVITE_STATUSES = ['pending', 'accepted', 'expired', 'revoked'] as const;
+export type InviteStatus = (typeof INVITE_STATUSES)[number];
+
+export const MAX_HOUSEHOLD_MEMBERS = 6;
+
+// ── Sub-document interfaces ──
+
+export interface HouseholdMember {
+  userId: string;
+  displayName: string;
+  role: MemberRole;
+  joinedAt: string;
+}
+
+export interface HouseholdInvite {
+  code: string;
+  createdBy: string;
+  createdAt: string;
+  expiresAt: string;
+  status: InviteStatus;
+  acceptedBy?: string;
+  acceptedAt?: string;
+}
+
+// ── Main document ──
+
+export interface HouseholdDoc {
+  id: string;
+  productId: string;
+  name: string;
+  members: HouseholdMember[];
+  invites: HouseholdInvite[];
+  createdAt: string;
+  createdBy: string;
+
+  _ts?: number;
+  _etag?: string;
+}
+
+// ── Zod schemas ──
+
+export const CreateHouseholdSchema = z.object({
+  name: z.string().min(1).max(200),
+  displayName: z.string().min(1).max(200),
+});
+
+export const UpdateHouseholdSchema = z.object({
+  name: z.string().min(1).max(200).optional(),
+});
+
+export const CreateInviteSchema = z.object({
+  expiresInHours: z.number().int().min(1).max(168).default(72),
+});
+
+export const AcceptInviteSchema = z.object({
+  code: z.string().min(1).max(32),
+  displayName: z.string().min(1).max(200),
+});
+
+export const RemoveMemberSchema = z.object({
+  userId: z.string().min(1),
+});
+
+export const HouseholdQuerySchema = z.object({
+  limit: z.coerce.number().int().min(1).max(50).default(20),
+  offset: z.coerce.number().int().min(0).default(0),
+});
+
+// ── Inferred types ──
+
+export type CreateHouseholdInput = z.infer<typeof CreateHouseholdSchema>;
+export type UpdateHouseholdInput = z.infer<typeof UpdateHouseholdSchema>;
+export type CreateInviteInput = z.infer<typeof CreateInviteSchema>;
+export type AcceptInviteInput = z.infer<typeof AcceptInviteSchema>;
+export type RemoveMemberInput = z.infer<typeof RemoveMemberSchema>;
+export type HouseholdQuery = z.infer<typeof HouseholdQuerySchema>;
diff --git a/services/platform-service/src/modules/routines/repository.ts b/services/platform-service/src/modules/routines/repository.ts
new file mode 100644
index 00000000..6892b69d
--- /dev/null
+++ b/services/platform-service/src/modules/routines/repository.ts
@@ -0,0 +1,182 @@
+/**
+ * Routines repository — Cosmos DB CRUD + sync + batch upsert.
+ *
+ * Container: routines (partition key: /userId)
+ */
+
+import { getContainer } from '../../lib/cosmos.js';
+import type { RoutineDoc, RoutineQuery, BatchUpsertRoutinesResult } from './types.js';
+
+function container() {
+  return getContainer('routines');
+}
+
+export async function listRoutines(
+  userId: string,
+  productId: string,
+  query: RoutineQuery
+): Promise<{ items: RoutineDoc[]; total: number }> {
+  const conditions: string[] = ['c.userId = @userId', 'c.productId = @productId'];
+  const params: { name: string; value: string | number | boolean }[] = [
+    { name: '@userId', value: userId },
+    { name: '@productId', value: productId },
+  ];
+
+  if (query.status) {
+    conditions.push('c.status = @status');
+    params.push({ name: '@status', value: query.status });
+  }
+  if (query.isTemplate !== undefined) {
+    conditions.push('c.isTemplate = @isTemplate');
+    params.push({ name: '@isTemplate', value: query.isTemplate });
+  }
+  if (query.category) {
+    conditions.push('c.category = @category');
+    params.push({ name: '@category', value: query.category });
+  }
+
+  const where = `WHERE ${conditions.join(' AND ')}`;
+  const sortField = `c.${query.sortBy}`;
+  const orderDir = query.sortOrder.toUpperCase();
+
+  const countResult = await container()
+    .items.query<number>({
+      query: `SELECT VALUE COUNT(1) FROM c ${where}`,
+      parameters: params,
+    })
+    .fetchAll();
+  const total = countResult.resources[0] ?? 0;
+
+  const { resources } = await container()
+    .items.query<RoutineDoc>({
+      query: `SELECT * FROM c ${where} ORDER BY ${sortField} ${orderDir} OFFSET @offset LIMIT @limit`,
+      parameters: [
+        ...params,
+        { name: '@offset', value: query.offset },
+        { name: '@limit', value: query.limit },
+      ],
+    })
+    .fetchAll();
+
+  return { items: resources, total };
+}
+
+export async function getRoutine(id: string, userId: string): Promise<RoutineDoc | null> {
+  try {
+    const { resource } = await container().item(id, userId).read<RoutineDoc>();
+    return resource ?? null;
+  } catch {
+    return null;
+  }
+}
+
+export async function createRoutine(doc: RoutineDoc): Promise<RoutineDoc> {
+  const { resource } = await container().items.create(doc);
+  return resource as RoutineDoc;
+}
+
+export async function updateRoutine(
+  id: string,
+  userId: string,
+  updates: Partial<RoutineDoc>,
+  expectedSyncVersion: number
+): Promise<{ doc: RoutineDoc | null; conflict: boolean; serverVersion?: number }> {
+  try {
+    const { resource: existing } = await container().item(id, userId).read<RoutineDoc>();
+    if (!existing) return { doc: null, conflict: false };
+
+    if (expectedSyncVersion <= existing.syncVersion) {
+      return { doc: null, conflict: true, serverVersion: existing.syncVersion };
+    }
+
+    const now = new Date().toISOString();
+    const merged: RoutineDoc = {
+      ...existing,
+      ...updates,
+      syncVersion: expectedSyncVersion,
+      lastSyncedAt: now,
+    };
+    const { resource } = await container().item(id, userId).replace(merged);
+    return { doc: resource as RoutineDoc, conflict: false };
+  } catch {
+    return { doc: null, conflict: false };
+  }
+}
+
+export async function deleteRoutine(id: string, userId: string): Promise<boolean> {
+  try {
+    const { resource: existing } = await container().item(id, userId).read<RoutineDoc>();
+    if (!existing) return false;
+    await container().item(id, userId).delete();
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+export async function getRoutinesSince(
+  userId: string,
+  productId: string,
+  sinceTimestamp: string,
+  limit: number
+): Promise<RoutineDoc[]> {
+  const { resources } = await container()
+    .items.query<RoutineDoc>({
+      query:
+        'SELECT * FROM c WHERE c.userId = @userId AND c.productId = @productId AND c.lastSyncedAt >= @since ORDER BY c.lastSyncedAt ASC OFFSET 0 LIMIT @limit',
+      parameters: [
+        { name: '@userId', value: userId },
+        { name: '@productId', value: productId },
+        { name: '@since', value: sinceTimestamp },
+        { name: '@limit', value: limit },
+      ],
+    })
+    .fetchAll();
+  return resources;
+}
+
+export async function batchUpsertRoutines(
+  userId: string,
+  productId: string,
+  routines: Array<Record<string, unknown> & { id: string; syncVersion: number }>
+): Promise<BatchUpsertRoutinesResult> {
+  const synced: string[] = [];
+  const conflicts: Array<{ id: string; serverVersion: number }> = [];
+  const errors: Array<{ id: string; error: string }> = [];
+
+  for (const routine of routines) {
+    try {
+      const existing = await getRoutine(routine.id, userId);
+      const now = new Date().toISOString();
+
+      if (existing) {
+        if (routine.syncVersion >= existing.syncVersion) {
+          const merged: RoutineDoc = {
+            ...existing,
+            ...routine,
+            userId,
+            productId,
+            lastSyncedAt: now,
+          } as RoutineDoc;
+          await container().item(routine.id, userId).replace(merged);
+          synced.push(routine.id);
+        } else {
+          conflicts.push({ id: routine.id, serverVersion: existing.syncVersion });
+        }
+      } else {
+        const doc = {
+          ...routine,
+          userId,
+          productId,
+          lastSyncedAt: now,
+        };
+        await container().items.create(doc);
+        synced.push(routine.id);
+      }
+    } catch (err) {
+      errors.push({ id: routine.id, error: err instanceof Error ? err.message : 'Unknown error' });
+    }
+  }
+
+  return { synced, conflicts, errors };
+}
diff --git a/services/platform-service/src/modules/routines/routes.ts b/services/platform-service/src/modules/routines/routes.ts
new file mode 100644
index 00000000..e5f5c6d8
--- /dev/null
+++ b/services/platform-service/src/modules/routines/routes.ts
@@ -0,0 +1,155 @@
+/**
+ * Routine REST endpoints — ChronoMind cloud sync.
+ *
+ * GET    /routines           — list user's routines (filterable, paginated)
+ * GET    /routines/sync      — delta sync (routines modified since timestamp)
+ * GET    /routines/:id       — single routine
+ * POST   /routines           — create routine
+ * PUT    /routines/:id       — update routine (with syncVersion conflict check)
+ * DELETE /routines/:id       — delete routine
+ * POST   /routines/batch     — batch upsert
+ */
+
+import type { FastifyInstance } from 'fastify';
+import { BadRequestError, NotFoundError, ConflictError } from '../../lib/errors.js';
+import { extractAuth } from '../../lib/auth.js';
+import * as repo from './repository.js';
+import {
+  CreateRoutineSchema,
+  UpdateRoutineSchema,
+  RoutineQuerySchema,
+  RoutineSyncQuerySchema,
+  BatchUpsertRoutinesSchema,
+  type RoutineDoc,
+} from './types.js';
+
+const PRODUCT_ID = 'chronomind';
+
+export async function routineRoutes(app: FastifyInstance) {
+  // Sync — must be before :id param route
+  app.get('/routines/sync', async req => {
+    const auth = await extractAuth(req);
+    const parsed = RoutineSyncQuerySchema.safeParse(req.query);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+    const routines = await repo.getRoutinesSince(
+      auth.sub,
+      PRODUCT_ID,
+      parsed.data.since,
+      parsed.data.limit
+    );
+    return { routines, count: routines.length };
+  });
+
+  // List routines
+  app.get('/routines', async req => {
+    const auth = await extractAuth(req);
+    const parsed = RoutineQuerySchema.safeParse(req.query);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+    const { items, total } = await repo.listRoutines(auth.sub, PRODUCT_ID, parsed.data);
+    return { items, total, limit: parsed.data.limit, offset: parsed.data.offset };
+  });
+
+  // Get single routine
+  app.get('/routines/:id', async req => {
+    const auth = await extractAuth(req);
+    const { id } = req.params as { id: string };
+    const routine = await repo.getRoutine(id, auth.sub);
+    if (!routine) throw new NotFoundError('Routine not found');
+    if (routine.productId !== PRODUCT_ID) throw new NotFoundError('Routine not found');
+    return routine;
+  });
+
+  // Create routine
+  app.post('/routines', async (req, reply) => {
+    const auth = await extractAuth(req);
+    const parsed = CreateRoutineSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+    const input = parsed.data;
+    const now = new Date().toISOString();
+
+    const doc: RoutineDoc = {
+      id: input.id,
+      userId: auth.sub,
+      productId: PRODUCT_ID,
+      name: input.name,
+      description: input.description,
+      steps: input.steps,
+      totalDurationMinutes: input.totalDurationMinutes,
+      status: input.status,
+      currentStepIndex: input.currentStepIndex,
+      isTemplate: input.isTemplate,
+      category: input.category,
+      createdAt: now,
+      startedAt: input.startedAt,
+      elapsedBeforePause: input.elapsedBeforePause,
+      deviceId: input.deviceId,
+      lastSyncedAt: now,
+      syncVersion: input.syncVersion,
+    };
+
+    req.log.info({ routineId: doc.id, isTemplate: doc.isTemplate }, 'Creating routine');
+    const created = await repo.createRoutine(doc);
+    reply.code(201);
+    return created;
+  });
+
+  // Update routine (with syncVersion conflict check)
+  app.put('/routines/:id', async req => {
+    const auth = await extractAuth(req);
+    const { id } = req.params as { id: string };
+
+    const parsed = UpdateRoutineSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    const { syncVersion, ...updates } = parsed.data;
+    const result = await repo.updateRoutine(id, auth.sub, updates, syncVersion);
+
+    if (result.conflict) {
+      throw new ConflictError(
+        `Sync conflict: server version is ${result.serverVersion}, received ${syncVersion}`
+      );
+    }
+    if (!result.doc) throw new NotFoundError('Routine not found');
+
+    req.log.info({ routineId: id, syncVersion }, 'Updated routine');
+    return result.doc;
+  });
+
+  // Delete routine
+  app.delete('/routines/:id', async req => {
+    const auth = await extractAuth(req);
+    const { id } = req.params as { id: string };
+    const success = await repo.deleteRoutine(id, auth.sub);
+    if (!success) throw new NotFoundError('Routine not found');
+    req.log.info({ routineId: id }, 'Deleted routine');
+    return { success: true };
+  });
+
+  // Batch upsert
+  app.post('/routines/batch', async req => {
+    const auth = await extractAuth(req);
+    const parsed = BatchUpsertRoutinesSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    const now = new Date().toISOString();
+    const enriched = parsed.data.routines.map(r => ({
+      ...r,
+      createdAt: now,
+      lastSyncedAt: now,
+    }));
+
+    req.log.info({ count: enriched.length }, 'Batch upsert routines');
+    const result = await repo.batchUpsertRoutines(auth.sub, PRODUCT_ID, enriched);
+    return result;
+  });
+}
diff --git a/services/platform-service/src/modules/routines/routines.test.ts b/services/platform-service/src/modules/routines/routines.test.ts
new file mode 100644
index 00000000..d52976f4
--- /dev/null
+++ b/services/platform-service/src/modules/routines/routines.test.ts
@@ -0,0 +1,345 @@
+/**
+ * Routines module unit tests — validates schemas, constants, and types.
+ */
+
+import { describe, it, expect } from 'vitest';
+import {
+  CreateRoutineSchema,
+  UpdateRoutineSchema,
+  RoutineQuerySchema,
+  RoutineSyncQuerySchema,
+  BatchUpsertRoutinesSchema,
+  TRANSITION_TYPES,
+  ROUTINE_STATUSES,
+  STEP_STATUSES,
+} from './types.js';
+
+// ── Constants ──
+
+describe('routine constants', () => {
+  it('has 4 transition types', () => {
+    expect(TRANSITION_TYPES).toEqual(['immediate', '1m_break', '5m_break', 'custom']);
+  });
+
+  it('has 6 routine statuses', () => {
+    expect(ROUTINE_STATUSES).toEqual([
+      'template',
+      'ready',
+      'active',
+      'paused',
+      'completed',
+      'cancelled',
+    ]);
+    expect(ROUTINE_STATUSES).toHaveLength(6);
+  });
+
+  it('has 4 step statuses', () => {
+    expect(STEP_STATUSES).toEqual(['pending', 'active', 'skipped', 'completed']);
+  });
+});
+
+// ── CreateRoutineSchema ──
+
+describe('CreateRoutineSchema', () => {
+  const validStep = {
+    id: 'step_1',
+    label: 'Warm up',
+    durationMinutes: 5,
+    transition: 'immediate',
+  };
+
+  const validMinimal = {
+    id: 'routine_001',
+    name: 'Morning Routine',
+    steps: [validStep],
+    totalDurationMinutes: 5,
+  };
+
+  it('accepts minimal valid input with defaults', () => {
+    const result = CreateRoutineSchema.safeParse(validMinimal);
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.status).toBe('ready');
+      expect(result.data.isTemplate).toBe(false);
+      expect(result.data.currentStepIndex).toBe(0);
+      expect(result.data.syncVersion).toBe(1);
+      expect(result.data.elapsedBeforePause).toBe(0);
+    }
+  });
+
+  it('accepts template routine', () => {
+    const result = CreateRoutineSchema.safeParse({
+      ...validMinimal,
+      status: 'template',
+      isTemplate: true,
+    });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.isTemplate).toBe(true);
+      expect(result.data.status).toBe('template');
+    }
+  });
+
+  it('accepts multi-step routine with transitions', () => {
+    const result = CreateRoutineSchema.safeParse({
+      ...validMinimal,
+      steps: [
+        validStep,
+        {
+          id: 'step_2',
+          label: 'Exercise',
+          durationMinutes: 20,
+          transition: '5m_break',
+          notes: 'Stretch first',
+        },
+        {
+          id: 'step_3',
+          label: 'Cool down',
+          durationMinutes: 10,
+          transition: 'custom',
+          customTransitionMinutes: 3,
+        },
+      ],
+      totalDurationMinutes: 43,
+      category: 'health',
+    });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.steps).toHaveLength(3);
+      expect(result.data.steps[1].notes).toBe('Stretch first');
+      expect(result.data.steps[2].customTransitionMinutes).toBe(3);
+    }
+  });
+
+  it('rejects missing id', () => {
+    const result = CreateRoutineSchema.safeParse({
+      name: 'Test',
+      steps: [validStep],
+      totalDurationMinutes: 5,
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects missing name', () => {
+    const result = CreateRoutineSchema.safeParse({
+      id: 'routine_001',
+      steps: [validStep],
+      totalDurationMinutes: 5,
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects empty steps array', () => {
+    const result = CreateRoutineSchema.safeParse({
+      ...validMinimal,
+      steps: [],
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects step with invalid transition', () => {
+    const result = CreateRoutineSchema.safeParse({
+      ...validMinimal,
+      steps: [{ ...validStep, transition: 'invalid' }],
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects step duration > 480 minutes', () => {
+    const result = CreateRoutineSchema.safeParse({
+      ...validMinimal,
+      steps: [{ ...validStep, durationMinutes: 500 }],
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects step duration < 0.5 minutes', () => {
+    const result = CreateRoutineSchema.safeParse({
+      ...validMinimal,
+      steps: [{ ...validStep, durationMinutes: 0.1 }],
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects > 50 steps', () => {
+    const steps = Array.from({ length: 51 }, (_, i) => ({
+      ...validStep,
+      id: `step_${i}`,
+    }));
+    const result = CreateRoutineSchema.safeParse({ ...validMinimal, steps });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects invalid status', () => {
+    const result = CreateRoutineSchema.safeParse({
+      ...validMinimal,
+      status: 'deleted',
+    });
+    expect(result.success).toBe(false);
+  });
+});
+
+// ── UpdateRoutineSchema ──
+
+describe('UpdateRoutineSchema', () => {
+  it('accepts status update with syncVersion', () => {
+    const result = UpdateRoutineSchema.safeParse({ status: 'paused', syncVersion: 2 });
+    expect(result.success).toBe(true);
+  });
+
+  it('accepts step updates', () => {
+    const result = UpdateRoutineSchema.safeParse({
+      steps: [
+        {
+          id: 's1',
+          label: 'Step 1',
+          durationMinutes: 5,
+          transition: 'immediate',
+          status: 'completed',
+        },
+        {
+          id: 's2',
+          label: 'Step 2',
+          durationMinutes: 10,
+          transition: '1m_break',
+          status: 'active',
+        },
+      ],
+      currentStepIndex: 1,
+      syncVersion: 3,
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it('requires syncVersion', () => {
+    const result = UpdateRoutineSchema.safeParse({ status: 'active' });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects syncVersion < 1', () => {
+    const result = UpdateRoutineSchema.safeParse({ status: 'active', syncVersion: 0 });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects invalid status', () => {
+    const result = UpdateRoutineSchema.safeParse({ status: 'deleted', syncVersion: 2 });
+    expect(result.success).toBe(false);
+  });
+});
+
+// ── RoutineQuerySchema ──
+
+describe('RoutineQuerySchema', () => {
+  it('provides defaults for empty query', () => {
+    const result = RoutineQuerySchema.safeParse({});
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.sortBy).toBe('createdAt');
+      expect(result.data.sortOrder).toBe('desc');
+      expect(result.data.limit).toBe(50);
+      expect(result.data.offset).toBe(0);
+    }
+  });
+
+  it('accepts all filter combinations', () => {
+    const result = RoutineQuerySchema.safeParse({
+      status: 'template',
+      isTemplate: 'true',
+      category: 'health',
+      sortBy: 'name',
+      sortOrder: 'asc',
+    });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.isTemplate).toBe(true);
+    }
+  });
+
+  it('coerces string numbers', () => {
+    const result = RoutineQuerySchema.safeParse({ limit: '25', offset: '5' });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.limit).toBe(25);
+      expect(result.data.offset).toBe(5);
+    }
+  });
+
+  it('rejects limit > 100', () => {
+    const result = RoutineQuerySchema.safeParse({ limit: 200 });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects invalid sortBy', () => {
+    const result = RoutineQuerySchema.safeParse({ sortBy: 'random' });
+    expect(result.success).toBe(false);
+  });
+});
+
+// ── RoutineSyncQuerySchema ──
+
+describe('RoutineSyncQuerySchema', () => {
+  it('accepts valid since timestamp', () => {
+    const result = RoutineSyncQuerySchema.safeParse({ since: '2026-03-01T00:00:00.000Z' });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.limit).toBe(100);
+    }
+  });
+
+  it('rejects missing since', () => {
+    const result = RoutineSyncQuerySchema.safeParse({});
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects invalid since format', () => {
+    const result = RoutineSyncQuerySchema.safeParse({ since: 'yesterday' });
+    expect(result.success).toBe(false);
+  });
+});
+
+// ── BatchUpsertRoutinesSchema ──
+
+describe('BatchUpsertRoutinesSchema', () => {
+  const validRoutine = {
+    id: 'routine_batch_1',
+    name: 'Batch Routine',
+    steps: [{ id: 's1', label: 'Step', durationMinutes: 5, transition: 'immediate' }],
+    totalDurationMinutes: 5,
+  };
+
+  it('accepts array of valid routines', () => {
+    const result = BatchUpsertRoutinesSchema.safeParse({
+      routines: [validRoutine, { ...validRoutine, id: 'routine_batch_2', name: 'Second' }],
+    });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.routines).toHaveLength(2);
+    }
+  });
+
+  it('rejects empty routines array', () => {
+    const result = BatchUpsertRoutinesSchema.safeParse({ routines: [] });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects missing routines field', () => {
+    const result = BatchUpsertRoutinesSchema.safeParse({});
+    expect(result.success).toBe(false);
+  });
+
+  it('validates each routine in the array', () => {
+    const result = BatchUpsertRoutinesSchema.safeParse({
+      routines: [validRoutine, { id: 'bad' }],
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects > 50 routines', () => {
+    const routines = Array.from({ length: 51 }, (_, i) => ({
+      ...validRoutine,
+      id: `routine_${i}`,
+    }));
+    const result = BatchUpsertRoutinesSchema.safeParse({ routines });
+    expect(result.success).toBe(false);
+  });
+});
diff --git a/services/platform-service/src/modules/routines/types.ts b/services/platform-service/src/modules/routines/types.ts
new file mode 100644
index 00000000..773aa59f
--- /dev/null
+++ b/services/platform-service/src/modules/routines/types.ts
@@ -0,0 +1,154 @@
+/**
+ * Routine types — ChronoMind cross-platform cloud sync.
+ *
+ * Cosmos container: `routines` (partition key: `/userId`)
+ * Product ID: "chronomind"
+ */
+
+import { z } from 'zod';
+
+// ── Enums / constants ──
+
+export const TRANSITION_TYPES = ['immediate', '1m_break', '5m_break', 'custom'] as const;
+export type TransitionType = (typeof TRANSITION_TYPES)[number];
+
+export const ROUTINE_STATUSES = [
+  'template',
+  'ready',
+  'active',
+  'paused',
+  'completed',
+  'cancelled',
+] as const;
+export type RoutineStatus = (typeof ROUTINE_STATUSES)[number];
+
+export const STEP_STATUSES = ['pending', 'active', 'skipped', 'completed'] as const;
+export type StepStatus = (typeof STEP_STATUSES)[number];
+
+// ── Sub-document interfaces ──
+
+export interface RoutineStep {
+  id: string;
+  label: string;
+  durationMinutes: number;
+  transition: TransitionType;
+  customTransitionMinutes?: number;
+  notes?: string;
+  status: StepStatus;
+  startedAt?: string;
+  completedAt?: string;
+}
+
+// ── Main document ──
+
+export interface RoutineDoc {
+  id: string;
+  userId: string;
+  productId: string;
+
+  name: string;
+  description?: string;
+  steps: RoutineStep[];
+  totalDurationMinutes: number;
+  status: RoutineStatus;
+  currentStepIndex: number;
+  isTemplate: boolean;
+  category?: string;
+
+  createdAt: string;
+  startedAt?: string;
+  pausedAt?: string;
+  completedAt?: string;
+  elapsedBeforePause: number;
+
+  // Sync metadata
+  deviceId?: string;
+  lastSyncedAt?: string;
+  syncVersion: number;
+
+  _ts?: number;
+  _etag?: string;
+}
+
+// ── Zod schemas ──
+
+const RoutineStepSchema = z.object({
+  id: z.string().min(1).max(128),
+  label: z.string().min(1).max(500),
+  durationMinutes: z.number().min(0.5).max(480),
+  transition: z.enum(TRANSITION_TYPES),
+  customTransitionMinutes: z.number().min(0).max(60).optional(),
+  notes: z.string().max(2000).optional(),
+  status: z.enum(STEP_STATUSES).default('pending'),
+  startedAt: z.string().datetime().optional(),
+  completedAt: z.string().datetime().optional(),
+});
+
+export const CreateRoutineSchema = z.object({
+  id: z.string().min(1).max(128),
+  name: z.string().min(1).max(500),
+  description: z.string().max(2000).optional(),
+  steps: z.array(RoutineStepSchema).min(1).max(50),
+  totalDurationMinutes: z.number().min(0),
+  status: z.enum(ROUTINE_STATUSES).default('ready'),
+  currentStepIndex: z.number().int().min(0).default(0),
+  isTemplate: z.boolean().default(false),
+  category: z.string().max(128).optional(),
+  elapsedBeforePause: z.number().min(0).default(0),
+  startedAt: z.string().datetime().optional(),
+  deviceId: z.string().max(256).optional(),
+  syncVersion: z.number().int().min(0).default(1),
+});
+
+export const UpdateRoutineSchema = z.object({
+  name: z.string().min(1).max(500).optional(),
+  description: z.string().max(2000).optional(),
+  steps: z.array(RoutineStepSchema).min(1).max(50).optional(),
+  totalDurationMinutes: z.number().min(0).optional(),
+  status: z.enum(ROUTINE_STATUSES).optional(),
+  currentStepIndex: z.number().int().min(0).optional(),
+  isTemplate: z.boolean().optional(),
+  category: z.string().max(128).optional(),
+  startedAt: z.string().datetime().optional(),
+  pausedAt: z.string().datetime().optional(),
+  completedAt: z.string().datetime().optional(),
+  elapsedBeforePause: z.number().min(0).optional(),
+  deviceId: z.string().max(256).optional(),
+  syncVersion: z.number().int().min(1),
+});
+
+export const RoutineQuerySchema = z.object({
+  status: z.enum(ROUTINE_STATUSES).optional(),
+  isTemplate: z
+    .string()
+    .transform(v => v === 'true')
+    .optional(),
+  category: z.string().optional(),
+  sortBy: z.enum(['createdAt', 'name', 'totalDurationMinutes']).default('createdAt'),
+  sortOrder: z.enum(['asc', 'desc']).default('desc'),
+  limit: z.coerce.number().int().min(1).max(100).default(50),
+  offset: z.coerce.number().int().min(0).default(0),
+});
+
+export const RoutineSyncQuerySchema = z.object({
+  since: z.string().datetime(),
+  limit: z.coerce.number().int().min(1).max(500).default(100),
+});
+
+export const BatchUpsertRoutinesSchema = z.object({
+  routines: z.array(CreateRoutineSchema).min(1).max(50),
+});
+
+// ── Inferred types ──
+
+export type CreateRoutineInput = z.infer<typeof CreateRoutineSchema>;
+export type UpdateRoutineInput = z.infer<typeof UpdateRoutineSchema>;
+export type RoutineQuery = z.infer<typeof RoutineQuerySchema>;
+export type RoutineSyncQuery = z.infer<typeof RoutineSyncQuerySchema>;
+export type BatchUpsertRoutinesInput = z.infer<typeof BatchUpsertRoutinesSchema>;
+
+export interface BatchUpsertRoutinesResult {
+  synced: string[];
+  conflicts: Array<{ id: string; serverVersion: number }>;
+  errors: Array<{ id: string; error: string }>;
+}
diff --git a/services/platform-service/src/modules/shared-timers/repository.ts b/services/platform-service/src/modules/shared-timers/repository.ts
new file mode 100644
index 00000000..75930299
--- /dev/null
+++ b/services/platform-service/src/modules/shared-timers/repository.ts
@@ -0,0 +1,91 @@
+/**
+ * Shared timers repository — Cosmos DB CRUD for household shared timers.
+ *
+ * Container: shared_timers (partition key: /householdId)
+ */
+
+import { getContainer } from '../../lib/cosmos.js';
+import type { SharedTimerDoc, SharedTimerQuery } from './types.js';
+
+function container() {
+  return getContainer('shared_timers');
+}
+
+export async function listSharedTimers(
+  householdId: string,
+  productId: string,
+  query: SharedTimerQuery
+): Promise<{ items: SharedTimerDoc[]; total: number }> {
+  const conditions: string[] = ['c.householdId = @householdId', 'c.productId = @productId'];
+  const params: { name: string; value: string | number }[] = [
+    { name: '@householdId', value: householdId },
+    { name: '@productId', value: productId },
+  ];
+
+  if (query.state) {
+    conditions.push('c.state = @state');
+    params.push({ name: '@state', value: query.state });
+  }
+  if (query.type) {
+    conditions.push('c.type = @type');
+    params.push({ name: '@type', value: query.type });
+  }
+
+  const where = `WHERE ${conditions.join(' AND ')}`;
+  const sortField = `c.${query.sortBy}`;
+  const orderDir = query.sortOrder.toUpperCase();
+
+  const countResult = await container()
+    .items.query<number>({
+      query: `SELECT VALUE COUNT(1) FROM c ${where}`,
+      parameters: params,
+    })
+    .fetchAll();
+  const total = countResult.resources[0] ?? 0;
+
+  const { resources } = await container()
+    .items.query<SharedTimerDoc>({
+      query: `SELECT * FROM c ${where} ORDER BY ${sortField} ${orderDir} OFFSET @offset LIMIT @limit`,
+      parameters: [
+        ...params,
+        { name: '@offset', value: query.offset },
+        { name: '@limit', value: query.limit },
+      ],
+    })
+    .fetchAll();
+
+  return { items: resources, total };
+}
+
+export async function getSharedTimer(
+  id: string,
+  householdId: string
+): Promise<SharedTimerDoc | null> {
+  try {
+    const { resource } = await container().item(id, householdId).read<SharedTimerDoc>();
+    return resource ?? null;
+  } catch {
+    return null;
+  }
+}
+
+export async function createSharedTimer(doc: SharedTimerDoc): Promise<SharedTimerDoc> {
+  const { resource } = await container().items.create(doc);
+  return resource as SharedTimerDoc;
+}
+
+export async function replaceSharedTimer(doc: SharedTimerDoc): Promise<SharedTimerDoc> {
+  const { resource } = await container().item(doc.id, doc.householdId).replace(doc);
+  return resource as SharedTimerDoc;
+}
+
+export async function deleteSharedTimer(id: string, householdId: string): Promise<boolean> {
+  try {
+    const existing = await getSharedTimer(id, householdId);
+    if (!existing) return false;
+    await container().item(id, householdId).delete();
+    return true;
+  } catch {
+    return false;
+  }
+}
diff --git a/services/platform-service/src/modules/shared-timers/routes.ts b/services/platform-service/src/modules/shared-timers/routes.ts
new file mode 100644
index 00000000..32f46e3f
--- /dev/null
+++ b/services/platform-service/src/modules/shared-timers/routes.ts
@@ -0,0 +1,183 @@
+/**
+ * Shared timer REST endpoints — ChronoMind Family tier.
+ *
+ * All endpoints require the caller to be a member of the household.
+ *
+ * GET    /households/:householdId/timers           — list shared timers
+ * GET    /households/:householdId/timers/:id       — single shared timer
+ * POST   /households/:householdId/timers           — create shared timer
+ * PUT    /households/:householdId/timers/:id       — update shared timer (creator only)
+ * DELETE /households/:householdId/timers/:id       — delete shared timer (creator or admin)
+ * POST   /households/:householdId/timers/:id/ack   — acknowledge (dismiss/snooze) a timer
+ */
+
+import crypto from 'node:crypto';
+import type { FastifyInstance } from 'fastify';
+import { BadRequestError, NotFoundError, ForbiddenError } from '../../lib/errors.js';
+import { extractAuth } from '../../lib/auth.js';
+import { getHousehold } from '../households/repository.js';
+import * as repo from './repository.js';
+import {
+  CreateSharedTimerSchema,
+  UpdateSharedTimerSchema,
+  AcknowledgeTimerSchema,
+  SharedTimerQuerySchema,
+  type SharedTimerDoc,
+} from './types.js';
+
+const PRODUCT_ID = 'chronomind';
+
+async function requireMembership(householdId: string, userId: string) {
+  const household = await getHousehold(householdId);
+  if (!household || household.productId !== PRODUCT_ID) {
+    throw new NotFoundError('Household not found');
+  }
+  const member = household.members.find(m => m.userId === userId);
+  if (!member) throw new ForbiddenError('Not a member of this household');
+  return { household, member };
+}
+
+export async function sharedTimerRoutes(app: FastifyInstance) {
+  // List shared timers for a household
+  app.get('/households/:householdId/timers', async req => {
+    const auth = await extractAuth(req);
+    const { householdId } = req.params as { householdId: string };
+    await requireMembership(householdId, auth.sub);
+
+    const parsed = SharedTimerQuerySchema.safeParse(req.query);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+    const { items, total } = await repo.listSharedTimers(householdId, PRODUCT_ID, parsed.data);
+    return { items, total, limit: parsed.data.limit, offset: parsed.data.offset };
+  });
+
+  // Get single shared timer
+  app.get('/households/:householdId/timers/:id', async req => {
+    const auth = await extractAuth(req);
+    const { householdId, id } = req.params as { householdId: string; id: string };
+    await requireMembership(householdId, auth.sub);
+
+    const timer = await repo.getSharedTimer(id, householdId);
+    if (!timer) throw new NotFoundError('Shared timer not found');
+    return timer;
+  });
+
+  // Create shared timer
+  app.post('/households/:householdId/timers', async (req, reply) => {
+    const auth = await extractAuth(req);
+    const { householdId } = req.params as { householdId: string };
+    await requireMembership(householdId, auth.sub);
+
+    const parsed = CreateSharedTimerSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    if (parsed.data.householdId !== householdId) {
+      throw new BadRequestError('householdId in body must match URL param');
+    }
+
+    const now = new Date().toISOString();
+    const doc: SharedTimerDoc = {
+      id: crypto.randomUUID(),
+      householdId,
+      productId: PRODUCT_ID,
+      createdBy: auth.sub,
+      label: parsed.data.label,
+      description: parsed.data.description,
+      type: parsed.data.type,
+      state: 'active',
+      urgency: parsed.data.urgency,
+      duration: parsed.data.duration,
+      targetTime: parsed.data.targetTime,
+      category: parsed.data.category,
+      cascade: parsed.data.cascade,
+      acknowledgements: [],
+      createdAt: now,
+      updatedAt: now,
+    };
+
+    req.log.info({ sharedTimerId: doc.id, householdId }, 'Creating shared timer');
+    const created = await repo.createSharedTimer(doc);
+    reply.code(201);
+    return created;
+  });
+
+  // Update shared timer (creator only)
+  app.put('/households/:householdId/timers/:id', async req => {
+    const auth = await extractAuth(req);
+    const { householdId, id } = req.params as { householdId: string; id: string };
+    await requireMembership(householdId, auth.sub);
+
+    const timer = await repo.getSharedTimer(id, householdId);
+    if (!timer) throw new NotFoundError('Shared timer not found');
+    if (timer.createdBy !== auth.sub)
+      throw new ForbiddenError('Only the creator can update this timer');
+
+    const parsed = UpdateSharedTimerSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    const now = new Date().toISOString();
+    const updated: SharedTimerDoc = { ...timer, ...parsed.data, updatedAt: now };
+    const result = await repo.replaceSharedTimer(updated);
+    req.log.info({ sharedTimerId: id, householdId }, 'Updated shared timer');
+    return result;
+  });
+
+  // Delete shared timer (creator or admin)
+  app.delete('/households/:householdId/timers/:id', async req => {
+    const auth = await extractAuth(req);
+    const { householdId, id } = req.params as { householdId: string; id: string };
+    const { household } = await requireMembership(householdId, auth.sub);
+
+    const timer = await repo.getSharedTimer(id, householdId);
+    if (!timer) throw new NotFoundError('Shared timer not found');
+
+    const isCreator = timer.createdBy === auth.sub;
+    const isAdmin = household.members.some(m => m.userId === auth.sub && m.role === 'admin');
+    if (!isCreator && !isAdmin) {
+      throw new ForbiddenError('Only the creator or admin can delete this timer');
+    }
+
+    await repo.deleteSharedTimer(id, householdId);
+    req.log.info({ sharedTimerId: id, householdId }, 'Deleted shared timer');
+    return { success: true };
+  });
+
+  // Acknowledge (dismiss/snooze) a shared timer — per-user
+  app.post('/households/:householdId/timers/:id/ack', async req => {
+    const auth = await extractAuth(req);
+    const { householdId, id } = req.params as { householdId: string; id: string };
+    await requireMembership(householdId, auth.sub);
+
+    const timer = await repo.getSharedTimer(id, householdId);
+    if (!timer) throw new NotFoundError('Shared timer not found');
+
+    const parsed = AcknowledgeTimerSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    // Replace or add acknowledgement for this user
+    const now = new Date().toISOString();
+    const existingIdx = timer.acknowledgements.findIndex(a => a.userId === auth.sub);
+    const ack = { userId: auth.sub, state: parsed.data.state, at: now };
+
+    if (existingIdx >= 0) {
+      timer.acknowledgements[existingIdx] = ack;
+    } else {
+      timer.acknowledgements.push(ack);
+    }
+    timer.updatedAt = now;
+
+    const result = await repo.replaceSharedTimer(timer);
+    req.log.info(
+      { sharedTimerId: id, householdId, ackState: parsed.data.state },
+      'Timer acknowledged'
+    );
+    return result;
+  });
+}
diff --git a/services/platform-service/src/modules/shared-timers/shared-timers.test.ts b/services/platform-service/src/modules/shared-timers/shared-timers.test.ts
new file mode 100644
index 00000000..aa54014d
--- /dev/null
+++ b/services/platform-service/src/modules/shared-timers/shared-timers.test.ts
@@ -0,0 +1,249 @@
+/**
+ * Shared timers module unit tests — validates schemas, constants, and types.
+ */
+
+import { describe, it, expect } from 'vitest';
+import {
+  CreateSharedTimerSchema,
+  UpdateSharedTimerSchema,
+  AcknowledgeTimerSchema,
+  SharedTimerQuerySchema,
+  TIMER_TYPES,
+  TIMER_STATES,
+  URGENCY_LEVELS,
+  CASCADE_PRESETS,
+} from './types.js';
+
+// ── Constants ──
+
+describe('shared timer constants', () => {
+  it('has 3 timer types', () => {
+    expect(TIMER_TYPES).toEqual(['countdown', 'alarm', 'pomodoro']);
+  });
+
+  it('has 7 timer states', () => {
+    expect(TIMER_STATES).toHaveLength(7);
+  });
+
+  it('has 5 urgency levels', () => {
+    expect(URGENCY_LEVELS).toHaveLength(5);
+  });
+
+  it('has 4 cascade presets', () => {
+    expect(CASCADE_PRESETS).toEqual(['minimal', 'standard', 'aggressive', 'custom']);
+  });
+});
+
+// ── CreateSharedTimerSchema ──
+
+describe('CreateSharedTimerSchema', () => {
+  const validMinimal = {
+    householdId: 'household_001',
+    label: 'Dinner ready',
+    type: 'countdown',
+    duration: 1800,
+  };
+
+  it('accepts minimal valid input', () => {
+    const result = CreateSharedTimerSchema.safeParse(validMinimal);
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.urgency).toBe('standard');
+      expect(result.data.label).toBe('Dinner ready');
+    }
+  });
+
+  it('accepts full input with cascade', () => {
+    const result = CreateSharedTimerSchema.safeParse({
+      ...validMinimal,
+      description: 'Let everyone know dinner is ready',
+      urgency: 'important',
+      targetTime: '2026-03-01T18:00:00.000Z',
+      category: 'cooking',
+      cascade: { preset: 'standard', intervals: [15, 5, 1] },
+    });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.cascade?.intervals).toEqual([15, 5, 1]);
+    }
+  });
+
+  it('accepts alarm type with targetTime', () => {
+    const result = CreateSharedTimerSchema.safeParse({
+      ...validMinimal,
+      type: 'alarm',
+      targetTime: '2026-03-01T07:00:00.000Z',
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it('rejects missing householdId', () => {
+    const result = CreateSharedTimerSchema.safeParse({
+      label: 'Test',
+      type: 'countdown',
+      duration: 300,
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects missing label', () => {
+    const result = CreateSharedTimerSchema.safeParse({
+      householdId: 'h1',
+      type: 'countdown',
+      duration: 300,
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects invalid type', () => {
+    const result = CreateSharedTimerSchema.safeParse({
+      ...validMinimal,
+      type: 'stopwatch',
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects invalid urgency', () => {
+    const result = CreateSharedTimerSchema.safeParse({
+      ...validMinimal,
+      urgency: 'extreme',
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects negative duration', () => {
+    const result = CreateSharedTimerSchema.safeParse({
+      ...validMinimal,
+      duration: -10,
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects invalid targetTime', () => {
+    const result = CreateSharedTimerSchema.safeParse({
+      ...validMinimal,
+      targetTime: 'not-a-date',
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects label > 500 chars', () => {
+    const result = CreateSharedTimerSchema.safeParse({
+      ...validMinimal,
+      label: 'x'.repeat(501),
+    });
+    expect(result.success).toBe(false);
+  });
+});
+
+// ── UpdateSharedTimerSchema ──
+
+describe('UpdateSharedTimerSchema', () => {
+  it('accepts state update', () => {
+    const result = UpdateSharedTimerSchema.safeParse({ state: 'fired' });
+    expect(result.success).toBe(true);
+  });
+
+  it('accepts label and urgency update', () => {
+    const result = UpdateSharedTimerSchema.safeParse({
+      label: 'New label',
+      urgency: 'critical',
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it('accepts cascade update', () => {
+    const result = UpdateSharedTimerSchema.safeParse({
+      cascade: { preset: 'aggressive', intervals: [30, 10, 5] },
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it('accepts empty update', () => {
+    const result = UpdateSharedTimerSchema.safeParse({});
+    expect(result.success).toBe(true);
+  });
+
+  it('rejects invalid state', () => {
+    const result = UpdateSharedTimerSchema.safeParse({ state: 'deleted' });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects invalid urgency', () => {
+    const result = UpdateSharedTimerSchema.safeParse({ urgency: 'extreme' });
+    expect(result.success).toBe(false);
+  });
+});
+
+// ── AcknowledgeTimerSchema ──
+
+describe('AcknowledgeTimerSchema', () => {
+  it('accepts dismissed', () => {
+    const result = AcknowledgeTimerSchema.safeParse({ state: 'dismissed' });
+    expect(result.success).toBe(true);
+  });
+
+  it('accepts snoozed', () => {
+    const result = AcknowledgeTimerSchema.safeParse({ state: 'snoozed' });
+    expect(result.success).toBe(true);
+  });
+
+  it('rejects other states', () => {
+    const result = AcknowledgeTimerSchema.safeParse({ state: 'active' });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects missing state', () => {
+    const result = AcknowledgeTimerSchema.safeParse({});
+    expect(result.success).toBe(false);
+  });
+});
+
+// ── SharedTimerQuerySchema ──
+
+describe('SharedTimerQuerySchema', () => {
+  it('provides defaults for empty query', () => {
+    const result = SharedTimerQuerySchema.safeParse({});
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.sortBy).toBe('createdAt');
+      expect(result.data.sortOrder).toBe('desc');
+      expect(result.data.limit).toBe(50);
+      expect(result.data.offset).toBe(0);
+    }
+  });
+
+  it('accepts state and type filters', () => {
+    const result = SharedTimerQuerySchema.safeParse({
+      state: 'active',
+      type: 'countdown',
+      sortBy: 'targetTime',
+      sortOrder: 'asc',
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it('coerces string numbers', () => {
+    const result = SharedTimerQuerySchema.safeParse({ limit: '25', offset: '10' });
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data.limit).toBe(25);
+      expect(result.data.offset).toBe(10);
+    }
+  });
+
+  it('rejects limit > 100', () => {
+    const result = SharedTimerQuerySchema.safeParse({ limit: 200 });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects invalid sortBy', () => {
+    const result = SharedTimerQuerySchema.safeParse({ sortBy: 'random' });
+    expect(result.success).toBe(false);
+  });
+
+  it('rejects invalid state filter', () => {
+    const result = SharedTimerQuerySchema.safeParse({ state: 'deleted' });
+    expect(result.success).toBe(false);
+  });
+});
diff --git a/services/platform-service/src/modules/shared-timers/types.ts b/services/platform-service/src/modules/shared-timers/types.ts
new file mode 100644
index 00000000..0e60e161
--- /dev/null
+++ b/services/platform-service/src/modules/shared-timers/types.ts
@@ -0,0 +1,118 @@
+/**
+ * Shared timer types — ChronoMind Family tier.
+ *
+ * Cosmos container: `shared_timers` (partition key: `/householdId`)
+ * Product ID: "chronomind"
+ *
+ * Shared timers are visible to all household members. The creator
+ * owns the timer; any member can snooze/dismiss their own view.
+ */
+
+import { z } from 'zod';
+
+// ── Reuse timer enums ──
+
+export const TIMER_TYPES = ['countdown', 'alarm', 'pomodoro'] as const;
+export const TIMER_STATES = [
+  'active',
+  'paused',
+  'fired',
+  'snoozed',
+  'dismissed',
+  'completed',
+  'warning',
+] as const;
+export const URGENCY_LEVELS = ['critical', 'important', 'standard', 'gentle', 'passive'] as const;
+export const CASCADE_PRESETS = ['minimal', 'standard', 'aggressive', 'custom'] as const;
+
+// ── Sub-document interfaces ──
+
+export interface SharedCascadeConfig {
+  preset: (typeof CASCADE_PRESETS)[number];
+  intervals?: number[];
+}
+
+export interface SharedTimerAck {
+  userId: string;
+  state: 'dismissed' | 'snoozed';
+  at: string;
+}
+
+// ── Main document ──
+
+export interface SharedTimerDoc {
+  id: string;
+  householdId: string;
+  productId: string;
+  createdBy: string;
+
+  label: string;
+  description?: string;
+  type: (typeof TIMER_TYPES)[number];
+  state: (typeof TIMER_STATES)[number];
+  urgency: (typeof URGENCY_LEVELS)[number];
+  duration: number;
+  targetTime?: string;
+  category?: string;
+
+  cascade?: SharedCascadeConfig;
+  acknowledgements: SharedTimerAck[];
+
+  createdAt: string;
+  updatedAt: string;
+  completedAt?: string;
+
+  _ts?: number;
+  _etag?: string;
+}
+
+// ── Zod schemas ──
+
+const CascadeSchema = z.object({
+  preset: z.enum(CASCADE_PRESETS),
+  intervals: z.array(z.number().min(0).max(120)).max(20).optional(),
+});
+
+export const CreateSharedTimerSchema = z.object({
+  householdId: z.string().min(1).max(128),
+  label: z.string().min(1).max(500),
+  description: z.string().max(2000).optional(),
+  type: z.enum(TIMER_TYPES),
+  urgency: z.enum(URGENCY_LEVELS).default('standard'),
+  duration: z.number().min(0),
+  targetTime: z.string().datetime().optional(),
+  category: z.string().max(128).optional(),
+  cascade: CascadeSchema.optional(),
+});
+
+export const UpdateSharedTimerSchema = z.object({
+  label: z.string().min(1).max(500).optional(),
+  description: z.string().max(2000).optional(),
+  state: z.enum(TIMER_STATES).optional(),
+  urgency: z.enum(URGENCY_LEVELS).optional(),
+  duration: z.number().min(0).optional(),
+  targetTime: z.string().datetime().optional(),
+  category: z.string().max(128).optional(),
+  cascade: CascadeSchema.optional(),
+  completedAt: z.string().datetime().optional(),
+});
+
+export const AcknowledgeTimerSchema = z.object({
+  state: z.enum(['dismissed', 'snoozed'] as const),
+});
+
+export const SharedTimerQuerySchema = z.object({
+  state: z.enum(TIMER_STATES).optional(),
+  type: z.enum(TIMER_TYPES).optional(),
+  sortBy: z.enum(['createdAt', 'targetTime', 'updatedAt']).default('createdAt'),
+  sortOrder: z.enum(['asc', 'desc']).default('desc'),
+  limit: z.coerce.number().int().min(1).max(100).default(50),
+  offset: z.coerce.number().int().min(0).default(0),
+});
+
+// ── Inferred types ──
+
+export type CreateSharedTimerInput = z.infer<typeof CreateSharedTimerSchema>;
+export type UpdateSharedTimerInput = z.infer<typeof UpdateSharedTimerSchema>;
+export type AcknowledgeTimerInput = z.infer<typeof AcknowledgeTimerSchema>;
+export type SharedTimerQuery = z.infer<typeof SharedTimerQuerySchema>;
diff --git a/services/platform-service/src/server.ts b/services/platform-service/src/server.ts
index ad4773d3..9b684424 100644
--- a/services/platform-service/src/server.ts
+++ b/services/platform-service/src/server.ts
@@ -51,6 +51,9 @@ import { fastingSessionRoutes } from './modules/fasting-sessions/routes.js';
 import { fastingProtocolRoutes } from './modules/fasting-protocols/routes.js';
 import { bodyStageRoutes } from './modules/body-stages/routes.js';
 import { timerRoutes } from './modules/timers/routes.js';
+import { routineRoutes } from './modules/routines/routes.js';
+import { householdRoutes } from './modules/households/routes.js';
+import { sharedTimerRoutes } from './modules/shared-timers/routes.js';
 import { initCosmosIfNeeded } from './lib/cosmos-init.js';
 import { config } from './lib/config.js';
 
@@ -129,7 +132,10 @@ await app.register(publicRoutes, { prefix: '/api' });
 await app.register(fastingSessionRoutes, { prefix: '/api' });
 await app.register(fastingProtocolRoutes, { prefix: '/api' });
 await app.register(bodyStageRoutes, { prefix: '/api' });
-// ChronoMind timer module
+// ChronoMind modules
 await app.register(timerRoutes, { prefix: '/api' });
+await app.register(routineRoutes, { prefix: '/api' });
+await app.register(householdRoutes, { prefix: '/api' });
+await app.register(sharedTimerRoutes, { prefix: '/api' });
 
 await startService(app, { port: config.PORT, host: config.HOST });