diff --git a/dashboards/admin-web/e2e/smartauth-account-linking.spec.ts b/dashboards/admin-web/e2e/smartauth-account-linking.spec.ts
new file mode 100644
index 00000000..1c535e67
--- /dev/null
+++ b/dashboards/admin-web/e2e/smartauth-account-linking.spec.ts
@@ -0,0 +1,71 @@
+/**
+ * SmartAuth E2E — Account Linking
+ * Tests OAuth provider linking/unlinking flows in admin dashboard.
+ */
+
+import { test, expect } from '@playwright/test';
+
+test.describe('SmartAuth: Account Linking', () => {
+  test.beforeEach(async ({ page }) => {
+    // Mock auth state — logged in as admin
+    await page.route('**/api/auth/me', route =>
+      route.fulfill({
+        status: 200,
+        body: JSON.stringify({
+          id: 'usr_test',
+          email: 'admin@acme.com',
+          role: 'admin',
+          displayName: 'Test Admin',
+          providers: [{ provider: 'google', email: 'admin@acme.com', linkedAt: '2026-01-01' }],
+          mfaEnabled: false,
+        }),
+      })
+    );
+  });
+
+  test('should display linked providers', async ({ page }) => {
+    await page.route('**/api/auth/providers', route =>
+      route.fulfill({
+        status: 200,
+        body: JSON.stringify([
+          { provider: 'google', email: 'admin@acme.com', linkedAt: '2026-01-01T00:00:00Z' },
+        ]),
+      })
+    );
+    await page.goto('/settings/security');
+    await expect(page.getByText('Google')).toBeVisible();
+    await expect(page.getByText('admin@acme.com')).toBeVisible();
+  });
+
+  test('should show link provider button', async ({ page }) => {
+    await page.route('**/api/auth/providers', route =>
+      route.fulfill({ status: 200, body: JSON.stringify([]) })
+    );
+    await page.goto('/settings/security');
+    await expect(page.getByRole('button', { name: /link/i })).toBeVisible();
+  });
+
+  test('should prevent unlinking last provider', async ({ page }) => {
+    await page.route('**/api/auth/providers', route =>
+      route.fulfill({
+        status: 200,
+        body: JSON.stringify([
+          { provider: 'google', email: 'admin@acme.com', linkedAt: '2026-01-01T00:00:00Z' },
+        ]),
+      })
+    );
+    await page.route('**/api/auth/providers/google', route =>
+      route.fulfill({
+        status: 400,
+        body: JSON.stringify({ error: 'Cannot unlink last auth method' }),
+      })
+    );
+    await page.goto('/settings/security');
+    // Attempt unlink
+    const unlinkButton = page.getByRole('button', { name: /unlink/i });
+    if (await unlinkButton.isVisible()) {
+      await unlinkButton.click();
+      await expect(page.getByText(/cannot unlink/i)).toBeVisible();
+    }
+  });
+});
diff --git a/dashboards/admin-web/e2e/smartauth-enterprise.spec.ts b/dashboards/admin-web/e2e/smartauth-enterprise.spec.ts
new file mode 100644
index 00000000..959d2110
--- /dev/null
+++ b/dashboards/admin-web/e2e/smartauth-enterprise.spec.ts
@@ -0,0 +1,130 @@
+/**
+ * SmartAuth E2E — Enterprise SAML/OIDC
+ * Tests IdP configuration, email domain lookup, and SSO login flows.
+ */
+
+import { test, expect } from '@playwright/test';
+
+test.describe('SmartAuth: Enterprise SSO', () => {
+  test.beforeEach(async ({ page }) => {
+    await page.route('**/api/auth/me', route =>
+      route.fulfill({
+        status: 200,
+        body: JSON.stringify({
+          id: 'usr_admin',
+          email: 'admin@bytelyst.com',
+          role: 'super_admin',
+          displayName: 'Super Admin',
+        }),
+      })
+    );
+  });
+
+  test('should lookup IdP by email domain', async ({ page }) => {
+    await page.route('**/api/auth/enterprise/lookup?email=*', route =>
+      route.fulfill({
+        status: 200,
+        body: JSON.stringify({
+          found: true,
+          idp: {
+            id: 'idp_acme_saml_abc123',
+            orgId: 'org_acme',
+            protocol: 'saml',
+            name: 'Acme Corp SAML',
+            emailDomains: ['acme.com'],
+          },
+        }),
+      })
+    );
+    await page.goto('/settings/security');
+    const response = await page.evaluate(async () => {
+      const res = await fetch('/api/auth/enterprise/lookup?email=user@acme.com');
+      return res.json();
+    });
+    expect(response.found).toBe(true);
+    expect(response.idp.protocol).toBe('saml');
+  });
+
+  test('should return not found for unknown domain', async ({ page }) => {
+    await page.route('**/api/auth/enterprise/lookup?email=*', route =>
+      route.fulfill({
+        status: 200,
+        body: JSON.stringify({ found: false, idp: null }),
+      })
+    );
+    await page.goto('/settings/security');
+    const response = await page.evaluate(async () => {
+      const res = await fetch('/api/auth/enterprise/lookup?email=user@unknown.com');
+      return res.json();
+    });
+    expect(response.found).toBe(false);
+  });
+
+  test('should create IdP config (admin)', async ({ page }) => {
+    await page.route('**/api/auth/enterprise/idps', route => {
+      if (route.request().method() === 'POST') {
+        route.fulfill({
+          status: 200,
+          body: JSON.stringify({
+            id: 'idp_acme_oidc_def456',
+            orgId: 'org_acme',
+            protocol: 'oidc',
+            name: 'Acme OIDC',
+            emailDomains: ['acme.com'],
+            enabled: true,
+          }),
+        });
+      } else {
+        route.fulfill({ status: 200, body: '[]' });
+      }
+    });
+    await page.goto('/settings/security');
+    const response = await page.evaluate(async () => {
+      const res = await fetch('/api/auth/enterprise/idps', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({
+          orgId: 'org_acme',
+          protocol: 'oidc',
+          name: 'Acme OIDC',
+          emailDomains: ['acme.com'],
+          oidc: {
+            issuer: 'https://login.acme.com',
+            clientId: 'client123',
+            clientSecret: 'secret456',
+            authorizationUrl: 'https://login.acme.com/authorize',
+            tokenUrl: 'https://login.acme.com/token',
+          },
+        }),
+      });
+      return res.json();
+    });
+    expect(response.id).toMatch(/^idp_/);
+    expect(response.protocol).toBe('oidc');
+  });
+
+  test('should handle SAML callback', async ({ page }) => {
+    await page.route('**/api/auth/saml/callback', route =>
+      route.fulfill({
+        status: 200,
+        body: JSON.stringify({
+          accessToken: 'at_test',
+          refreshToken: 'rt_test',
+          user: { id: 'usr_saml', email: 'user@acme.com', displayName: 'SAML User' },
+        }),
+      })
+    );
+    await page.goto('/');
+    const response = await page.evaluate(async () => {
+      const samlResponse = btoa('<saml:NameID>user@acme.com</saml:NameID>');
+      const res = await fetch('/api/auth/saml/callback', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ SAMLResponse: samlResponse }),
+      });
+      return res.json();
+    });
+    expect(response).toHaveProperty('accessToken');
+    expect(response.user.email).toBe('user@acme.com');
+  });
+});
diff --git a/dashboards/admin-web/e2e/smartauth-step-up.spec.ts b/dashboards/admin-web/e2e/smartauth-step-up.spec.ts
new file mode 100644
index 00000000..8b7efbf3
--- /dev/null
+++ b/dashboards/admin-web/e2e/smartauth-step-up.spec.ts
@@ -0,0 +1,85 @@
+/**
+ * SmartAuth E2E — Step-Up Authentication
+ * Tests re-verification flows for sensitive operations.
+ */
+
+import { test, expect } from '@playwright/test';
+
+test.describe('SmartAuth: Step-Up Auth', () => {
+  test.beforeEach(async ({ page }) => {
+    await page.route('**/api/auth/me', route =>
+      route.fulfill({
+        status: 200,
+        body: JSON.stringify({
+          id: 'usr_test',
+          email: 'admin@acme.com',
+          role: 'admin',
+          displayName: 'Test Admin',
+          mfaEnabled: true,
+          mfaMethods: ['totp'],
+        }),
+      })
+    );
+  });
+
+  test('should require step-up for sensitive operations', async ({ page }) => {
+    // Mock a sensitive endpoint that returns 403 without step-up
+    await page.route('**/api/auth/mfa/totp', route => {
+      const method = route.request().method();
+      if (method === 'DELETE') {
+        route.fulfill({
+          status: 403,
+          body: JSON.stringify({ error: 'Step-up authentication required' }),
+        });
+      } else {
+        route.fulfill({ status: 200, body: '{}' });
+      }
+    });
+    await page.goto('/settings/security');
+    // Look for step-up prompt or re-verify dialog
+    const disableButton = page.getByRole('button', { name: /disable mfa/i });
+    if (await disableButton.isVisible()) {
+      await disableButton.click();
+      await expect(page.getByText(/step-up|re-verify|confirm your identity/i)).toBeVisible();
+    }
+  });
+
+  test('should complete step-up with password', async ({ page }) => {
+    await page.route('**/api/auth/step-up', route =>
+      route.fulfill({
+        status: 200,
+        body: JSON.stringify({ stepUpToken: 'step_test_token', expiresIn: 300 }),
+      })
+    );
+    await page.goto('/settings/security');
+    // Verify step-up flow returns token
+    const response = await page.evaluate(async () => {
+      const res = await fetch('/api/auth/step-up', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ method: 'password', credential: 'test123' }),
+      });
+      return res.json();
+    });
+    expect(response).toHaveProperty('stepUpToken');
+  });
+
+  test('should complete step-up with TOTP', async ({ page }) => {
+    await page.route('**/api/auth/step-up', route =>
+      route.fulfill({
+        status: 200,
+        body: JSON.stringify({ stepUpToken: 'step_totp_token', expiresIn: 300 }),
+      })
+    );
+    await page.goto('/settings/security');
+    const response = await page.evaluate(async () => {
+      const res = await fetch('/api/auth/step-up', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ method: 'totp', credential: '123456' }),
+      });
+      return res.json();
+    });
+    expect(response).toHaveProperty('stepUpToken');
+  });
+});
diff --git a/services/platform-service/src/modules/auth/enterprise/repository.ts b/services/platform-service/src/modules/auth/enterprise/repository.ts
new file mode 100644
index 00000000..dedcc2d1
--- /dev/null
+++ b/services/platform-service/src/modules/auth/enterprise/repository.ts
@@ -0,0 +1,54 @@
+/**
+ * Enterprise IdP repository — CRUD for auth_enterprise_idps container.
+ */
+
+import { getCollection } from '../../../lib/datastore.js';
+import type { EnterpriseIdpDoc } from './types.js';
+
+function idpCollection() {
+  return getCollection<EnterpriseIdpDoc>('auth_enterprise_idps', '/orgId');
+}
+
+export async function create(doc: EnterpriseIdpDoc): Promise<EnterpriseIdpDoc> {
+  return idpCollection().create(doc);
+}
+
+export async function getById(id: string, orgId: string): Promise<EnterpriseIdpDoc | null> {
+  try {
+    return await idpCollection().findById(id, orgId);
+  } catch {
+    return null;
+  }
+}
+
+export async function listByOrg(orgId: string): Promise<EnterpriseIdpDoc[]> {
+  return idpCollection().findMany({ filter: { orgId } });
+}
+
+export async function getByEmailDomain(domain: string): Promise<EnterpriseIdpDoc | null> {
+  // findOne doesn't support ARRAY_CONTAINS; fetch all enabled and filter in-memory
+  const all = await idpCollection().findMany({ filter: { enabled: true } });
+  return all.find(d => d.emailDomains.includes(domain.toLowerCase())) ?? null;
+}
+
+export async function updateIdp(
+  id: string,
+  orgId: string,
+  updates: Partial<EnterpriseIdpDoc>
+): Promise<EnterpriseIdpDoc | null> {
+  const existing = await getById(id, orgId);
+  if (!existing) return null;
+  return idpCollection().update(id, orgId, {
+    ...updates,
+    updatedAt: new Date().toISOString(),
+  } as Partial<EnterpriseIdpDoc>);
+}
+
+export async function remove(id: string, orgId: string): Promise<boolean> {
+  try {
+    await idpCollection().delete(id, orgId);
+    return true;
+  } catch {
+    return false;
+  }
+}
diff --git a/services/platform-service/src/modules/auth/enterprise/routes.ts b/services/platform-service/src/modules/auth/enterprise/routes.ts
new file mode 100644
index 00000000..e62511bf
--- /dev/null
+++ b/services/platform-service/src/modules/auth/enterprise/routes.ts
@@ -0,0 +1,346 @@
+/**
+ * Enterprise IdP endpoints for SmartAuth Phase 6A.
+ *
+ * Admin IdP management:
+ * POST   /auth/enterprise/idps          — create IdP config
+ * GET    /auth/enterprise/idps/:orgId    — list IdPs for org
+ * GET    /auth/enterprise/idps/:orgId/:id — get single IdP
+ * PUT    /auth/enterprise/idps/:orgId/:id — update IdP
+ * DELETE /auth/enterprise/idps/:orgId/:id — delete IdP
+ *
+ * Federation callbacks:
+ * POST /auth/saml/callback  — SAML assertion consumer
+ * POST /auth/oidc/callback  — OIDC authorization code exchange
+ *
+ * Lookup:
+ * GET /auth/enterprise/lookup?email=... — find IdP by email domain
+ */
+
+import type { FastifyInstance } from 'fastify';
+import { BadRequestError, ForbiddenError, NotFoundError } from '../../../lib/errors.js';
+import * as repo from './repository.js';
+import * as userRepo from '../repository.js';
+import * as jwt from '../jwt.js';
+import {
+  CreateIdpSchema,
+  UpdateIdpSchema,
+  SamlCallbackSchema,
+  OidcCallbackSchema,
+} from './types.js';
+import type { EnterpriseIdpDoc } from './types.js';
+import { randomUUID } from 'node:crypto';
+
+export async function enterpriseRoutes(app: FastifyInstance) {
+  // ── Admin: Create IdP ──────────────────────────────────────
+
+  app.post('/auth/enterprise/idps', async req => {
+    const payload = req.jwtPayload;
+    if (!payload?.role || !['super_admin', 'admin'].includes(payload.role)) {
+      throw new ForbiddenError('Admin access required');
+    }
+
+    const parsed = CreateIdpSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    const data = parsed.data;
+    if (data.protocol === 'saml' && !data.saml) {
+      throw new BadRequestError('SAML config required for saml protocol');
+    }
+    if (data.protocol === 'oidc' && !data.oidc) {
+      throw new BadRequestError('OIDC config required for oidc protocol');
+    }
+
+    const now = new Date().toISOString();
+    const doc: EnterpriseIdpDoc = {
+      id: `idp_${data.orgId}_${data.protocol}_${randomUUID().slice(0, 6)}`,
+      orgId: data.orgId,
+      productId: 'smartauth',
+      protocol: data.protocol,
+      name: data.name,
+      emailDomains: data.emailDomains.map(d => d.toLowerCase()),
+      enabled: data.enabled,
+      saml: data.saml,
+      oidc: data.oidc,
+      createdAt: now,
+      updatedAt: now,
+    };
+
+    const created = await repo.create(doc);
+    req.log.info(
+      { idpId: created.id, orgId: data.orgId, protocol: data.protocol },
+      '[auth] Enterprise IdP created'
+    );
+    return created;
+  });
+
+  // ── Admin: List IdPs for org ───────────────────────────────
+
+  app.get('/auth/enterprise/idps/:orgId', async req => {
+    const payload = req.jwtPayload;
+    if (!payload?.role || !['super_admin', 'admin'].includes(payload.role)) {
+      throw new ForbiddenError('Admin access required');
+    }
+    const { orgId } = req.params as { orgId: string };
+    return repo.listByOrg(orgId);
+  });
+
+  // ── Admin: Get single IdP ─────────────────────────────────
+
+  app.get('/auth/enterprise/idps/:orgId/:id', async req => {
+    const payload = req.jwtPayload;
+    if (!payload?.role || !['super_admin', 'admin'].includes(payload.role)) {
+      throw new ForbiddenError('Admin access required');
+    }
+    const { orgId, id } = req.params as { orgId: string; id: string };
+    const idp = await repo.getById(id, orgId);
+    if (!idp) throw new NotFoundError('IdP not found');
+    return idp;
+  });
+
+  // ── Admin: Update IdP ─────────────────────────────────────
+
+  app.put('/auth/enterprise/idps/:orgId/:id', async req => {
+    const payload = req.jwtPayload;
+    if (!payload?.role || !['super_admin', 'admin'].includes(payload.role)) {
+      throw new ForbiddenError('Admin access required');
+    }
+    const { orgId, id } = req.params as { orgId: string; id: string };
+
+    const parsed = UpdateIdpSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    const updated = await repo.updateIdp(id, orgId, parsed.data as Partial<EnterpriseIdpDoc>);
+    if (!updated) throw new NotFoundError('IdP not found');
+    req.log.info({ idpId: id, orgId }, '[auth] Enterprise IdP updated');
+    return updated;
+  });
+
+  // ── Admin: Delete IdP ─────────────────────────────────────
+
+  app.delete('/auth/enterprise/idps/:orgId/:id', async req => {
+    const payload = req.jwtPayload;
+    if (!payload?.role || !['super_admin', 'admin'].includes(payload.role)) {
+      throw new ForbiddenError('Admin access required');
+    }
+    const { orgId, id } = req.params as { orgId: string; id: string };
+    const ok = await repo.remove(id, orgId);
+    if (!ok) throw new NotFoundError('IdP not found');
+    req.log.info({ idpId: id, orgId }, '[auth] Enterprise IdP deleted');
+    return { message: 'IdP deleted' };
+  });
+
+  // ── Lookup IdP by email domain ────────────────────────────
+
+  app.get('/auth/enterprise/lookup', async req => {
+    const { email } = req.query as { email?: string };
+    if (!email) throw new BadRequestError('email query parameter required');
+
+    const domain = email.split('@')[1]?.toLowerCase();
+    if (!domain) throw new BadRequestError('Invalid email');
+
+    const idp = await repo.getByEmailDomain(domain);
+    if (!idp) {
+      return { found: false, idp: null };
+    }
+    // Return sanitized — no secrets
+    return {
+      found: true,
+      idp: {
+        id: idp.id,
+        orgId: idp.orgId,
+        protocol: idp.protocol,
+        name: idp.name,
+        emailDomains: idp.emailDomains,
+      },
+    };
+  });
+
+  // ── SAML Callback ─────────────────────────────────────────
+
+  app.post('/auth/saml/callback', async req => {
+    const parsed = SamlCallbackSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError('Invalid SAML response');
+    }
+
+    // Decode SAMLResponse (base64 XML) — simplified validation
+    // In production, use @node-saml/node-saml for full signature verification
+    let samlData: { email?: string; nameId?: string; attributes?: Record<string, string> };
+    try {
+      const xml = Buffer.from(parsed.data.SAMLResponse, 'base64').toString('utf-8');
+      // Extract email from basic XML parsing (simplified — use node-saml in production)
+      const emailMatch = xml.match(/<saml:NameID[^>]*>([^<]+)<\/saml:NameID>/);
+      const email = emailMatch?.[1];
+      if (!email) throw new Error('No NameID in SAML response');
+      samlData = { email, nameId: email };
+    } catch {
+      throw new BadRequestError('Failed to parse SAML assertion');
+    }
+
+    const email = samlData.email!;
+    const domain = email.split('@')[1]?.toLowerCase();
+    if (!domain) throw new BadRequestError('Invalid email in SAML assertion');
+
+    // Find IdP by domain
+    const idp = await repo.getByEmailDomain(domain);
+    if (!idp || idp.protocol !== 'saml') {
+      throw new BadRequestError('No SAML IdP configured for this email domain');
+    }
+
+    // Find or create user (cross-product lookup for enterprise SSO)
+    let user = await userRepo.getByEmailCrossProduct(email);
+    if (!user) {
+      const now = new Date().toISOString();
+      user = await userRepo.create({
+        id: `usr_${randomUUID()}`,
+        productId: idp.productId,
+        email,
+        passwordHash: `sso_${randomUUID()}`, // SSO-only — no password login
+        plan: 'free',
+        role: 'user',
+        displayName: samlData.attributes?.displayName ?? email.split('@')[0],
+        status: 'active',
+        emailVerified: true,
+        lastLoginAt: now,
+        createdAt: now,
+        updatedAt: now,
+        primaryProductId: idp.productId,
+        memberships: [{ productId: idp.productId, plan: 'free', role: 'user', firstAccessAt: now }],
+      });
+    }
+
+    // Issue tokens
+    const accessToken = await jwt.createAccessToken({
+      sub: user.id,
+      email: user.email,
+      role: user.role as string,
+      productId: idp.productId,
+      plan: (user.plan ?? 'free') as 'free' | 'pro' | 'enterprise',
+    });
+    const refreshToken = await jwt.createRefreshToken({
+      sub: user.id,
+      productId: idp.productId,
+    });
+
+    req.log.info(
+      { userId: user.id, idpId: idp.id, protocol: 'saml' },
+      '[auth] Enterprise SAML login'
+    );
+    return {
+      accessToken,
+      refreshToken,
+      user: { id: user.id, email: user.email, displayName: user.displayName },
+    };
+  });
+
+  // ── OIDC Callback ─────────────────────────────────────────
+
+  app.post('/auth/oidc/callback', async req => {
+    const parsed = OidcCallbackSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError('Invalid OIDC callback');
+    }
+
+    // The state parameter encodes the IdP ID + orgId
+    let stateData: { idpId: string; orgId: string };
+    try {
+      stateData = JSON.parse(Buffer.from(parsed.data.state, 'base64url').toString());
+    } catch {
+      throw new BadRequestError('Invalid state parameter');
+    }
+
+    const idp = await repo.getById(stateData.idpId, stateData.orgId);
+    if (!idp || idp.protocol !== 'oidc' || !idp.oidc) {
+      throw new BadRequestError('OIDC IdP not found or not configured');
+    }
+
+    // Exchange authorization code for tokens (simplified — use openid-client in production)
+    let email: string;
+    let displayName: string | undefined;
+    try {
+      const tokenRes = await fetch(idp.oidc.tokenUrl, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
+        body: new URLSearchParams({
+          grant_type: 'authorization_code',
+          code: parsed.data.code,
+          client_id: idp.oidc.clientId,
+          client_secret: idp.oidc.clientSecret,
+          redirect_uri: `${req.protocol}://${req.hostname}/auth/oidc/callback`,
+        }),
+      });
+
+      if (!tokenRes.ok) throw new Error(`Token exchange failed: ${tokenRes.status}`);
+      const tokenData = (await tokenRes.json()) as {
+        id_token?: string;
+        access_token?: string;
+        email?: string;
+      };
+
+      // If id_token is returned, decode it (simplified)
+      if (tokenData.id_token) {
+        const idPayload = JSON.parse(
+          Buffer.from(tokenData.id_token.split('.')[1], 'base64url').toString()
+        );
+        email = idPayload.email;
+        displayName = idPayload.name;
+      } else {
+        throw new Error('No id_token in response');
+      }
+    } catch (e) {
+      req.log.error({ error: (e as Error).message }, '[auth] OIDC token exchange failed');
+      throw new BadRequestError('OIDC token exchange failed');
+    }
+
+    if (!email) throw new BadRequestError('No email in OIDC token');
+
+    // Find or create user (cross-product lookup for enterprise SSO)
+    let user = await userRepo.getByEmailCrossProduct(email);
+    if (!user) {
+      const now = new Date().toISOString();
+      user = await userRepo.create({
+        id: `usr_${randomUUID()}`,
+        productId: idp.productId,
+        email,
+        passwordHash: `sso_${randomUUID()}`,
+        plan: 'free',
+        role: 'user',
+        displayName: displayName ?? email.split('@')[0],
+        status: 'active',
+        emailVerified: true,
+        lastLoginAt: now,
+        createdAt: now,
+        updatedAt: now,
+        primaryProductId: idp.productId,
+        memberships: [{ productId: idp.productId, plan: 'free', role: 'user', firstAccessAt: now }],
+      });
+    }
+
+    // Issue tokens
+    const accessToken = await jwt.createAccessToken({
+      sub: user.id,
+      email: user.email,
+      role: user.role as string,
+      productId: idp.productId,
+      plan: (user.plan ?? 'free') as 'free' | 'pro' | 'enterprise',
+    });
+    const refreshToken = await jwt.createRefreshToken({
+      sub: user.id,
+      productId: idp.productId,
+    });
+
+    req.log.info(
+      { userId: user.id, idpId: idp.id, protocol: 'oidc' },
+      '[auth] Enterprise OIDC login'
+    );
+    return {
+      accessToken,
+      refreshToken,
+      user: { id: user.id, email: user.email, displayName: user.displayName },
+    };
+  });
+}
diff --git a/services/platform-service/src/modules/auth/enterprise/types.ts b/services/platform-service/src/modules/auth/enterprise/types.ts
new file mode 100644
index 00000000..2fb12151
--- /dev/null
+++ b/services/platform-service/src/modules/auth/enterprise/types.ts
@@ -0,0 +1,77 @@
+/**
+ * Enterprise IdP types for SmartAuth Phase 6A.
+ * Supports SAML 2.0 and OIDC federation per organization.
+ */
+
+import { z } from 'zod';
+
+export interface EnterpriseIdpDoc {
+  id: string; // "idp_{orgId}_{protocol}"
+  orgId: string;
+  productId: string;
+  protocol: 'saml' | 'oidc';
+  name: string;
+  /** Email domains that auto-link to this IdP (e.g. ["acme.com"]) */
+  emailDomains: string[];
+  enabled: boolean;
+  /** SAML-specific config */
+  saml?: {
+    entityId: string;
+    ssoUrl: string;
+    certificate: string; // X.509 PEM
+    signatureAlgorithm?: string;
+    digestAlgorithm?: string;
+  };
+  /** OIDC-specific config */
+  oidc?: {
+    issuer: string;
+    clientId: string;
+    clientSecret: string;
+    authorizationUrl: string;
+    tokenUrl: string;
+    userinfoUrl?: string;
+    scopes: string[];
+  };
+  createdAt: string;
+  updatedAt: string;
+}
+
+export const CreateIdpSchema = z.object({
+  orgId: z.string().min(1),
+  protocol: z.enum(['saml', 'oidc']),
+  name: z.string().min(1).max(100),
+  emailDomains: z.array(z.string().min(3)).min(1),
+  enabled: z.boolean().default(true),
+  saml: z
+    .object({
+      entityId: z.string().min(1),
+      ssoUrl: z.string().url(),
+      certificate: z.string().min(1),
+      signatureAlgorithm: z.string().optional(),
+      digestAlgorithm: z.string().optional(),
+    })
+    .optional(),
+  oidc: z
+    .object({
+      issuer: z.string().url(),
+      clientId: z.string().min(1),
+      clientSecret: z.string().min(1),
+      authorizationUrl: z.string().url(),
+      tokenUrl: z.string().url(),
+      userinfoUrl: z.string().url().optional(),
+      scopes: z.array(z.string()).default(['openid', 'email', 'profile']),
+    })
+    .optional(),
+});
+
+export const UpdateIdpSchema = CreateIdpSchema.partial().omit({ orgId: true, protocol: true });
+
+export const SamlCallbackSchema = z.object({
+  SAMLResponse: z.string().min(1),
+  RelayState: z.string().optional(),
+});
+
+export const OidcCallbackSchema = z.object({
+  code: z.string().min(1),
+  state: z.string().min(1),
+});
diff --git a/services/platform-service/src/modules/auth/hibp.ts b/services/platform-service/src/modules/auth/hibp.ts
new file mode 100644
index 00000000..009ee0e7
--- /dev/null
+++ b/services/platform-service/src/modules/auth/hibp.ts
@@ -0,0 +1,54 @@
+/**
+ * Have I Been Pwned (HIBP) breach check — k-anonymity model.
+ * Checks if a password appears in known breaches via the Pwned Passwords API.
+ *
+ * Uses SHA-1 prefix (first 5 chars) for privacy — the full hash is never sent.
+ */
+
+import { createHash } from 'node:crypto';
+
+const HIBP_API = 'https://api.pwnedpasswords.com/range';
+
+/**
+ * Check if a password has been seen in data breaches.
+ * Returns the number of times seen (0 = not breached).
+ * Fails open (returns 0) if HIBP API is unreachable.
+ */
+export async function checkBreached(password: string): Promise<number> {
+  const sha1 = createHash('sha1').update(password).digest('hex').toUpperCase();
+  const prefix = sha1.slice(0, 5);
+  const suffix = sha1.slice(5);
+
+  try {
+    const res = await fetch(`${HIBP_API}/${prefix}`, {
+      headers: {
+        'User-Agent': 'ByteLyst-SmartAuth/1.0',
+        ...(process.env.HIBP_API_KEY ? { 'hibp-api-key': process.env.HIBP_API_KEY } : {}),
+      },
+      signal: AbortSignal.timeout(5000),
+    });
+
+    if (!res.ok) return 0; // fail open
+
+    const text = await res.text();
+    for (const line of text.split('\n')) {
+      const [hashSuffix, countStr] = line.trim().split(':');
+      if (hashSuffix === suffix) {
+        return parseInt(countStr, 10) || 0;
+      }
+    }
+    return 0;
+  } catch {
+    // Fail open — HIBP is advisory, not blocking
+    return 0;
+  }
+}
+
+/**
+ * Returns true if the password is breached and should be rejected.
+ * Threshold: seen 3+ times in breaches.
+ */
+export async function isPasswordBreached(password: string): Promise<boolean> {
+  const count = await checkBreached(password);
+  return count >= 3;
+}
diff --git a/services/platform-service/src/modules/auth/magic-link/repository.ts b/services/platform-service/src/modules/auth/magic-link/repository.ts
new file mode 100644
index 00000000..99ae8051
--- /dev/null
+++ b/services/platform-service/src/modules/auth/magic-link/repository.ts
@@ -0,0 +1,38 @@
+/**
+ * Magic link repository — CRUD for magic_link_tokens container.
+ */
+
+import { getCollection } from '../../../lib/datastore.js';
+import { createHash, randomBytes } from 'node:crypto';
+import type { MagicLinkTokenDoc } from './types.js';
+
+function tokensCollection() {
+  return getCollection<MagicLinkTokenDoc>('magic_link_tokens', '/productId');
+}
+
+export function generateToken(): string {
+  return randomBytes(32).toString('base64url');
+}
+
+export function hashToken(token: string): string {
+  return createHash('sha256').update(token).digest('hex');
+}
+
+export async function create(doc: MagicLinkTokenDoc): Promise<MagicLinkTokenDoc> {
+  return tokensCollection().create(doc);
+}
+
+export async function findByHash(
+  tokenHash: string,
+  productId: string
+): Promise<MagicLinkTokenDoc | null> {
+  return tokensCollection().findOne({
+    filter: { tokenHash, productId },
+  });
+}
+
+export async function markUsed(id: string, productId: string): Promise<void> {
+  await tokensCollection().update(id, productId, {
+    usedAt: new Date().toISOString(),
+  } as Partial<MagicLinkTokenDoc>);
+}
diff --git a/services/platform-service/src/modules/auth/magic-link/routes.ts b/services/platform-service/src/modules/auth/magic-link/routes.ts
new file mode 100644
index 00000000..363863dc
--- /dev/null
+++ b/services/platform-service/src/modules/auth/magic-link/routes.ts
@@ -0,0 +1,138 @@
+/**
+ * Magic link endpoints for SmartAuth Phase 6B.
+ *
+ * POST /auth/magic-link        — send magic link email (15 min TTL)
+ * POST /auth/magic-link/verify — verify token, issue JWT
+ */
+
+import type { FastifyInstance } from 'fastify';
+import { BadRequestError, UnauthorizedError } from '../../../lib/errors.js';
+import { bus } from '../../../lib/event-bus.js';
+import * as repo from './repository.js';
+import * as userRepo from '../repository.js';
+import * as jwt from '../jwt.js';
+import { MagicLinkRequestSchema, MagicLinkVerifySchema } from './types.js';
+import type { MagicLinkTokenDoc } from './types.js';
+import { randomUUID } from 'node:crypto';
+
+const MAGIC_LINK_TTL_MS = 15 * 60 * 1000; // 15 minutes
+
+export async function magicLinkRoutes(app: FastifyInstance) {
+  // ── Send magic link ────────────────────────────────────────
+
+  app.post('/auth/magic-link', async req => {
+    const parsed = MagicLinkRequestSchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    const { email, productId } = parsed.data;
+
+    // Anti-enumeration: always return success regardless of whether user exists
+    const user = await userRepo.getByEmail(email, productId);
+
+    if (user) {
+      const token = repo.generateToken();
+      const tokenHash = repo.hashToken(token);
+      const now = new Date();
+
+      const doc: MagicLinkTokenDoc = {
+        id: `ml_${randomUUID()}`,
+        productId,
+        email: email.toLowerCase(),
+        tokenHash,
+        expiresAt: new Date(now.getTime() + MAGIC_LINK_TTL_MS).toISOString(),
+        usedAt: null,
+        createdAt: now.toISOString(),
+      };
+
+      await repo.create(doc);
+
+      // Emit event for delivery module to send email
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      (bus as any).emit('auth.magic_link_requested', {
+        userId: user.id,
+        email: user.email,
+        token,
+        productId,
+        expiresAt: doc.expiresAt,
+      });
+
+      req.log.info({ email: user.email, productId }, '[auth] Magic link sent');
+    } else {
+      req.log.info(
+        { email, productId },
+        '[auth] Magic link requested for unknown email (anti-enumeration)'
+      );
+    }
+
+    // Always return success
+    return { message: 'If the email exists, a magic link has been sent' };
+  });
+
+  // ── Verify magic link ──────────────────────────────────────
+
+  app.post('/auth/magic-link/verify', async req => {
+    const parsed = MagicLinkVerifySchema.safeParse(req.body);
+    if (!parsed.success) {
+      throw new BadRequestError(parsed.error.issues.map(i => i.message).join('; '));
+    }
+
+    const { token, email } = parsed.data;
+    const tokenHash = repo.hashToken(token);
+
+    // Find the user first to get productId
+    const user = await userRepo.getByEmailCrossProduct(email);
+    if (!user) {
+      throw new UnauthorizedError('Invalid or expired magic link');
+    }
+
+    const doc = await repo.findByHash(tokenHash, user.productId);
+    if (!doc) {
+      throw new UnauthorizedError('Invalid or expired magic link');
+    }
+
+    // Check expiry
+    if (new Date(doc.expiresAt).getTime() < Date.now()) {
+      throw new UnauthorizedError('Magic link has expired');
+    }
+
+    // Check already used
+    if (doc.usedAt) {
+      throw new UnauthorizedError('Magic link has already been used');
+    }
+
+    // Check email match
+    if (doc.email.toLowerCase() !== email.toLowerCase()) {
+      throw new UnauthorizedError('Invalid or expired magic link');
+    }
+
+    // Mark as used
+    await repo.markUsed(doc.id, doc.productId);
+
+    // Mark email as verified if not already
+    if (!user.emailVerified) {
+      await userRepo.update(user.id, { emailVerified: true });
+    }
+
+    // Issue tokens
+    const accessToken = await jwt.createAccessToken({
+      sub: user.id,
+      email: user.email,
+      role: user.role as string,
+      productId: user.productId,
+      plan: (user.plan ?? 'free') as 'free' | 'pro' | 'enterprise',
+    });
+    const refreshToken = await jwt.createRefreshToken({
+      sub: user.id,
+      productId: user.productId,
+    });
+
+    req.log.info({ userId: user.id, email: user.email }, '[auth] Magic link login successful');
+    return {
+      accessToken,
+      refreshToken,
+      user: { id: user.id, email: user.email, displayName: user.displayName },
+    };
+  });
+}
diff --git a/services/platform-service/src/modules/auth/magic-link/types.ts b/services/platform-service/src/modules/auth/magic-link/types.ts
new file mode 100644
index 00000000..c21d3dea
--- /dev/null
+++ b/services/platform-service/src/modules/auth/magic-link/types.ts
@@ -0,0 +1,25 @@
+/**
+ * Magic link types for SmartAuth Phase 6B.
+ */
+
+import { z } from 'zod';
+
+export interface MagicLinkTokenDoc {
+  id: string;
+  productId: string;
+  email: string;
+  tokenHash: string;
+  expiresAt: string;
+  usedAt: string | null;
+  createdAt: string;
+}
+
+export const MagicLinkRequestSchema = z.object({
+  email: z.string().email(),
+  productId: z.string().min(1),
+});
+
+export const MagicLinkVerifySchema = z.object({
+  token: z.string().min(1),
+  email: z.string().email(),
+});
diff --git a/services/platform-service/src/server.ts b/services/platform-service/src/server.ts
index ee9e5651..14d085df 100644
--- a/services/platform-service/src/server.ts
+++ b/services/platform-service/src/server.ts
@@ -31,6 +31,8 @@ import { deviceRoutes } from './modules/auth/devices/routes.js';
 import { loginEventRoutes } from './modules/auth/login-events/routes.js';
 import { pushApprovalRoutes } from './modules/auth/push-approvals/routes.js';
 import { qrAuthRoutes } from './modules/auth/qr-auth/routes.js';
+import { enterpriseRoutes } from './modules/auth/enterprise/routes.js';
+import { magicLinkRoutes } from './modules/auth/magic-link/routes.js';
 import { auditRoutes } from './modules/audit/routes.js';
 import { notificationRoutes } from './modules/notifications/routes.js';
 import { flagRoutes } from './modules/flags/routes.js';
@@ -126,6 +128,8 @@ await app.register(deviceRoutes, { prefix: '/api' });
 await app.register(loginEventRoutes, { prefix: '/api' });
 await app.register(pushApprovalRoutes, { prefix: '/api' });
 await app.register(qrAuthRoutes, { prefix: '/api' });
+await app.register(enterpriseRoutes, { prefix: '/api' });
+await app.register(magicLinkRoutes, { prefix: '/api' });
 await app.register(auditRoutes, { prefix: '/api' });
 await app.register(notificationRoutes, { prefix: '/api' });
 await app.register(flagRoutes, { prefix: '/api' });