diff --git a/docs/memory/architecture.md b/docs/memory/architecture.md
index df826bee..939d038a 100644
--- a/docs/memory/architecture.md
+++ b/docs/memory/architecture.md
@@ -699,6 +699,7 @@ Open-core seam: enterprise backend code lives in the private `trinity-enterprise
 | `user_management` | `enterprise/backend/user_management/` (#995) | Org lifecycle: invite (whitelist + email), deactivate/reactivate (over the OSS `users.suspended_at` primitive), per-user activity view (reads OSS `audit_log`). `/api/enterprise/user-management/*`; Settings → User Management UI |
 | `siem` | `enterprise/backend/siem/` (#997) | SIEM log export — ships OSS `audit_log` to a customer SIEM over HTTP/JSON webhook. Private `enterprise_siem_config` (destination + AES-encrypted token + export cursor); Redis-lock-serialised background pusher; at-least-once (cursor advances only on successful POST). `/api/enterprise/siem/*`; no OSS/UI surface |
 | `2fa` | `enterprise/backend/two_factor/` (#5) | Two-factor auth via **TOTP** (RFC 6238; Google Authenticator is one compatible app — chosen over Google-OIDC to avoid a runtime IdP dependency). Private `enterprise_user_2fa` (AES-256-GCM secret + monotonic `last_used_step` replay guard), `enterprise_2fa_recovery_codes` (single-use, SHA-256-hashed), `enterprise_2fa_config` (per-role policy). `/api/enterprise/2fa/*` — self-service enroll/confirm/disable/recovery + admin policy + the `login/*` challenge-completion endpoints. Login seam is edition-agnostic: `services/mfa_gate.py` (no provider in OSS → no-op, fail-open) + `create_mfa_challenge_token`/`decode_mfa_challenge` in `dependencies.py`; on a required second factor the OSS auth routers (`/token`, `/api/auth/email/verify`) return a short-lived challenge token instead of an access token. Settings → Security UI |
+| `sso` | `enterprise/backend/sso/` (trinity-enterprise#32) | Single Sign-On via **OIDC** (authorization-code + PKCE; SAML is a tracked follow-up). Private `enterprise_sso_providers` (per-IdP config; AES-256-GCM `client_secret`, `protocol`-tagged for future SAML rows) + single-row `enterprise_sso_config` (password-fallback / auto-provision / default role). `/api/enterprise/sso/*` — admin provider CRUD + connectivity test + policy (admin-gated), `GET /public-providers` (unauth, `{id,name}` of enabled IdPs for login buttons), and the unauth `login/{id}` → IdP → `callback` flow. Dependency-free (httpx + python-jose, already in-image). State/nonce/PKCE-verifier held single-use in Redis (`sso_state:*`, GETDEL, TTL); id_token verified against IdP JWKS (asymmetric algs only — no `none`/`HS*`), `iss`/`aud`/`exp`/`nonce` checked. Edition-agnostic mint: the callback exchanges the validated assertion for a **standard platform JWT** via OSS `create_access_token` (no second session mechanism) and runs `mfa_gate` so local 2FA still applies; JIT provisioning honors the OSS whitelist + `default_role` (#314, no silent elevation). Settings → SSO UI + login-page buttons |
 
 ---
 
diff --git a/docs/memory/requirements.md b/docs/memory/requirements.md
index 78d44834..681f8d07 100644
--- a/docs/memory/requirements.md
+++ b/docs/memory/requirements.md
@@ -2876,6 +2876,54 @@ Standalone mobile-friendly admin page for managing agents on the go. Designed as
 
 ---
 
+## 40. Enterprise Single Sign-On — OIDC (trinity-enterprise#32)
+
+> Section number provisional — this branch is based on the 2FA branch (behind
+> `dev`); the final number resolves on rebase to `dev`. Enterprise feature on
+> the #847 seam; most logic lives in the private `enterprise/backend/sso/`
+> submodule. This documents the OSS-visible contract + the security rules.
+
+**Description**: Enterprise customers sign in through their identity provider
+(Okta, Entra ID, Google Workspace) instead of (or alongside) the OSS
+email-code / admin-password flow. **OIDC-first**; SAML 2.0 is a tracked
+follow-up (needs a native xmlsec dependency). Ships as an enterprise module —
+`register_module("sso")`, endpoints gated by `requires_entitlement("sso")`,
+zero OSS behavior change when the submodule is absent.
+
+- **FR-1 — Provider config (admin)**: CRUD over multiple named OIDC providers
+  (issuer/discovery URL, client id, client secret, scopes, enabled) +
+  connectivity test. Client secret is **write-only** (AES-256-GCM at rest,
+  Invariant #12) — never returned. Settings → SSO UI, admin-gated.
+- **FR-2 — OIDC login**: authorization-code flow with **PKCE**, single-use
+  `state` + `nonce` held in Redis (`GETDEL`, TTL). `id_token` validated against
+  the IdP JWKS restricted to **asymmetric** algorithms (no `none`/`HS*`);
+  `iss`/`aud`/`exp` checked by python-jose, `nonce` matched. Dependency-free
+  (httpx + python-jose, already in-image).
+- **FR-3 — Single mint path**: the callback exchanges the validated assertion
+  for a **standard platform JWT** via the OSS `create_access_token` — no second
+  session mechanism (Invariant: OSS token issuance stays the single mint path).
+- **FR-4 — 2FA composition (#5)**: after IdP auth the OSS `mfa_gate` still
+  runs, so a local second factor can be demanded; the callback returns a 2FA
+  challenge instead of a token in that case.
+- **FR-5 — JIT provisioning (#314)**: an unknown email is rejected unless
+  `auto_provision` is enabled, then added to the whitelist at the configured
+  `default_role` — never silently elevated. Suspended accounts are refused.
+- **FR-6 — Coexistence + break-glass**: OSS email/admin login stays available
+  (configurable `allow_password_fallback`); admin password login always works.
+- **FR-7 — Audit**: `login_success` / `login_failure` / `mfa_challenge_issued`
+  written to the OSS `audit_log` (`method: "sso"`).
+
+**API** (enterprise, gated): `GET/POST/PUT/DELETE /api/enterprise/sso/providers`,
+`POST .../providers/{id}/test`, `GET/PUT .../config` (admin); `GET
+.../public-providers` (unauth, `{id,name}` of enabled IdPs); `GET
+.../login/{id}` → IdP and `GET .../callback` (unauth login flow).
+
+**Out of scope (follow-up)**: SAML 2.0 (separate issue — native xmlsec dep +
+signature-wrap review); SCIM auto-provisioning; per-provider role mapping from
+IdP groups.
+
+---
+
 ## Out of Scope
 
 - Multi-tenant deployment (single org only)
diff --git a/src/backend/enterprise b/src/backend/enterprise
index 1e916f60..87c8f975 160000
--- a/src/backend/enterprise
+++ b/src/backend/enterprise
@@ -1 +1 @@
-Subproject commit 1e916f60483ad2a11121ce997a0b9efa609477c1
+Subproject commit 87c8f975d3ba5db87b40c63536fd0ac29cef1cdf
diff --git a/src/frontend/src/components/settings/SsoPanel.vue b/src/frontend/src/components/settings/SsoPanel.vue
new file mode 100644
index 00000000..34441266
--- /dev/null
+++ b/src/frontend/src/components/settings/SsoPanel.vue
@@ -0,0 +1,165 @@
+<template>
+  <div class="space-y-8">
+    <!-- Header -->
+    <div>
+      <h3 class="text-lg font-semibold text-gray-900 dark:text-gray-100">Single Sign-On (OIDC)</h3>
+      <p class="mt-1 text-sm text-gray-600 dark:text-gray-400">
+        Let users sign in through your identity provider (Okta, Entra ID, Google Workspace).
+        SAML support is coming separately.
+      </p>
+    </div>
+
+    <p v-if="error" class="text-sm text-red-600 dark:text-red-400">{{ error }}</p>
+
+    <!-- Providers -->
+    <section class="space-y-3">
+      <h4 class="text-sm font-medium text-gray-800 dark:text-gray-200">Identity providers</h4>
+
+      <div v-if="!providers.length" class="text-sm text-gray-500 dark:text-gray-400">
+        No providers configured yet.
+      </div>
+
+      <div
+        v-for="p in providers"
+        :key="p.id"
+        class="flex items-center justify-between p-3 border border-gray-200 dark:border-gray-700 rounded-lg"
+      >
+        <div class="min-w-0">
+          <p class="font-medium text-gray-900 dark:text-gray-100 truncate">
+            {{ p.name }}
+            <span v-if="!p.enabled" class="ml-2 text-xs text-gray-400">(disabled)</span>
+          </p>
+          <p class="text-xs text-gray-500 dark:text-gray-400 truncate">{{ p.issuer }}</p>
+        </div>
+        <div class="flex items-center gap-2 shrink-0">
+          <button @click="test(p)" class="text-xs px-2 py-1 border border-gray-300 dark:border-gray-600 rounded hover:bg-gray-50 dark:hover:bg-gray-700">Test</button>
+          <button @click="remove(p)" class="text-xs px-2 py-1 border border-red-300 text-red-600 rounded hover:bg-red-50 dark:hover:bg-red-900/30">Delete</button>
+        </div>
+      </div>
+
+      <p v-if="testResult" class="text-xs text-green-600 dark:text-green-400">{{ testResult }}</p>
+    </section>
+
+    <!-- Add provider -->
+    <section class="space-y-3 p-4 border border-gray-200 dark:border-gray-700 rounded-lg">
+      <h4 class="text-sm font-medium text-gray-800 dark:text-gray-200">Add provider</h4>
+      <form @submit.prevent="add" class="space-y-3">
+        <input v-model="form.name" placeholder="Display name (e.g. Okta)" required :class="inputCls" />
+        <input v-model="form.issuer" placeholder="Issuer / discovery URL (https://…)" required :class="inputCls" />
+        <input v-model="form.client_id" placeholder="Client ID" required :class="inputCls" />
+        <input v-model="form.client_secret" type="password" placeholder="Client secret" required :class="inputCls" />
+        <input v-model="form.scopes" placeholder="Scopes" :class="inputCls" />
+        <label class="flex items-center gap-2 text-sm text-gray-700 dark:text-gray-300">
+          <input v-model="form.enabled" type="checkbox" /> Enabled
+        </label>
+        <button type="submit" :disabled="busy" :class="btnCls">{{ busy ? 'Saving…' : 'Add provider' }}</button>
+      </form>
+    </section>
+
+    <!-- Policy -->
+    <section class="space-y-3">
+      <h4 class="text-sm font-medium text-gray-800 dark:text-gray-200">Policy</h4>
+      <label class="flex items-center gap-2 text-sm text-gray-700 dark:text-gray-300">
+        <input v-model="cfg.allow_password_fallback" type="checkbox" @change="saveConfig" />
+        Keep email / admin password login available
+      </label>
+      <label class="flex items-center gap-2 text-sm text-gray-700 dark:text-gray-300">
+        <input v-model="cfg.auto_provision" type="checkbox" @change="saveConfig" />
+        Auto-provision new users from SSO (otherwise the email must be whitelisted)
+      </label>
+      <label class="flex items-center gap-2 text-sm text-gray-700 dark:text-gray-300">
+        Default role for provisioned users
+        <select v-model="cfg.default_role" @change="saveConfig" class="ml-2 text-sm border border-gray-300 dark:border-gray-600 rounded px-2 py-1 bg-white dark:bg-gray-700">
+          <option value="user">user</option>
+          <option value="operator">operator</option>
+          <option value="creator">creator</option>
+          <option value="admin">admin</option>
+        </select>
+      </label>
+      <p class="text-xs text-gray-500 dark:text-gray-400">Admin break-glass password login always remains available.</p>
+    </section>
+  </div>
+</template>
+
+<script setup>
+import { ref, reactive, onMounted } from 'vue'
+import axios from 'axios'
+import { useAuthStore } from '../../stores/auth'
+
+const authStore = useAuthStore()
+const BASE = '/api/enterprise/sso'
+const cfgHeaders = () => ({ headers: { Authorization: `Bearer ${authStore.token}` } })
+
+const inputCls = 'block w-full px-3 py-2 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-gray-700 text-gray-900 dark:text-gray-100 text-sm'
+const btnCls = 'w-full py-2 px-4 rounded-lg text-white bg-blue-600 hover:bg-blue-700 disabled:opacity-50 text-sm'
+
+const providers = ref([])
+const cfg = reactive({ allow_password_fallback: true, auto_provision: false, default_role: 'user' })
+const form = reactive({ name: '', issuer: '', client_id: '', client_secret: '', scopes: 'openid email profile', enabled: true })
+const busy = ref(false)
+const error = ref('')
+const testResult = ref('')
+
+async function loadProviders() {
+  const r = await axios.get(`${BASE}/providers`, cfgHeaders())
+  providers.value = r.data.providers || []
+}
+
+async function loadConfig() {
+  const r = await axios.get(`${BASE}/config`, cfgHeaders())
+  Object.assign(cfg, r.data)
+}
+
+async function add() {
+  busy.value = true
+  error.value = ''
+  try {
+    await axios.post(`${BASE}/providers`, { ...form }, cfgHeaders())
+    Object.assign(form, { name: '', issuer: '', client_id: '', client_secret: '', scopes: 'openid email profile', enabled: true })
+    await loadProviders()
+  } catch (e) {
+    error.value = e.response?.data?.detail || 'Failed to add provider'
+  } finally {
+    busy.value = false
+  }
+}
+
+async function remove(p) {
+  if (!confirm(`Delete SSO provider "${p.name}"?`)) return
+  error.value = ''
+  try {
+    await axios.delete(`${BASE}/providers/${p.id}`, cfgHeaders())
+    await loadProviders()
+  } catch (e) {
+    error.value = e.response?.data?.detail || 'Failed to delete provider'
+  }
+}
+
+async function test(p) {
+  testResult.value = ''
+  error.value = ''
+  try {
+    const r = await axios.post(`${BASE}/providers/${p.id}/test`, {}, cfgHeaders())
+    testResult.value = `${p.name}: discovery OK (${r.data.jwks_keys} signing keys)`
+  } catch (e) {
+    error.value = e.response?.data?.detail || `Connectivity test failed for ${p.name}`
+  }
+}
+
+async function saveConfig() {
+  error.value = ''
+  try {
+    await axios.put(`${BASE}/config`, { ...cfg }, cfgHeaders())
+  } catch (e) {
+    error.value = e.response?.data?.detail || 'Failed to save policy'
+  }
+}
+
+onMounted(async () => {
+  try {
+    await Promise.all([loadProviders(), loadConfig()])
+  } catch (e) {
+    error.value = e.response?.data?.detail || 'Failed to load SSO settings'
+  }
+})
+</script>
diff --git a/src/frontend/src/stores/auth.js b/src/frontend/src/stores/auth.js
index 3b095060..6f7002ab 100644
--- a/src/frontend/src/stores/auth.js
+++ b/src/frontend/src/stores/auth.js
@@ -300,6 +300,38 @@ export const useAuthStore = defineStore('auth', {
       this.mfaChallenge = null
     },
 
+    // #32 — enabled SSO providers for the login page (id + name only). Returns
+    // [] in OSS builds (endpoint 404s when the `sso` module isn't entitled).
+    async fetchSsoProviders() {
+      try {
+        const r = await axios.get('/api/enterprise/sso/public-providers')
+        return r.data?.providers || []
+      } catch (e) {
+        return []
+      }
+    },
+
+    // Complete an SSO (OIDC) login from the callback URL fragment the backend
+    // redirects to: `/login#sso=ok&access_token=…`, `…sso=mfa&challenge_token=…`,
+    // or `…sso=error&reason=…` (#32). Reuses the same finalize / 2FA-challenge
+    // paths as password/email login. Returns {ok, mfa?}.
+    async completeSsoLogin(params) {
+      const status = params.get('sso')
+      if (status === 'ok') {
+        await this._finalizeLogin(params.get('access_token'))
+        return { ok: true }
+      }
+      if (status === 'mfa') {
+        this._setMfaChallenge({
+          challenge_token: params.get('challenge_token'),
+          enrollment_required: params.get('enroll') === '1',
+        })
+        return { ok: true, mfa: true }
+      }
+      this.authError = params.get('reason') || 'SSO login failed'
+      return { ok: false }
+    },
+
     // Complete login by verifying a TOTP or recovery code against the
     // outstanding challenge. Returns true on success.
     async verifyMfaCode(code) {
diff --git a/src/frontend/src/views/Login.vue b/src/frontend/src/views/Login.vue
index 5bb82c0e..548a326c 100644
--- a/src/frontend/src/views/Login.vue
+++ b/src/frontend/src/views/Login.vue
@@ -185,6 +185,21 @@
               🔐 Admin Login
             </button>
           </div>
+
+          <!-- #32 — Enterprise SSO (OIDC). Buttons appear only when the `sso`
+               feature is entitled and at least one provider is enabled.
+               Full-page nav to the backend login endpoint → IdP → callback. -->
+          <div v-if="!codeSent && ssoProviders.length" class="mt-6 pt-6 border-t border-gray-200 dark:border-gray-700 space-y-2">
+            <p class="text-xs text-center text-gray-500 dark:text-gray-400">Or sign in with</p>
+            <a
+              v-for="p in ssoProviders"
+              :key="p.id"
+              :href="`/api/enterprise/sso/login/${p.id}`"
+              class="w-full flex justify-center py-2 px-4 border border-gray-300 dark:border-gray-600 rounded-lg text-sm text-gray-700 dark:text-gray-300 hover:bg-gray-50 dark:hover:bg-gray-700 transition-colors"
+            >
+              🔑 {{ p.name }}
+            </a>
+          </div>
         </div>
 
         <!-- Admin Login: Password Only (username is fixed as 'admin') -->
@@ -267,6 +282,7 @@ const showAdminLogin = ref(false)
 const mfaCode = ref('')
 const mfaEnroll = ref(null)            // provisioning payload during forced enrollment
 const mfaRecoveryCodes = ref([])
+const ssoProviders = ref([])           // #32 — enabled SSO IdPs (login buttons)
 const mfaMode = computed(() =>
   authStore.mfaChallenge?.enrollmentRequired ? 'enroll' : 'verify'
 )
@@ -371,6 +387,23 @@ onMounted(async () => {
     router.push('/')
     return
   }
+
+  // #32 — handle an SSO (OIDC) callback redirect: the backend lands us back at
+  // /login with the result in the URL fragment. Consume it, then strip it from
+  // the address bar so a refresh/back can't replay it.
+  if (window.location.hash.includes('sso=')) {
+    const params = new URLSearchParams(window.location.hash.slice(1))
+    history.replaceState(null, '', window.location.pathname + window.location.search)
+    const res = await authStore.completeSsoLogin(params)
+    if (res.ok && !res.mfa) {
+      router.push('/')
+      return
+    }
+    // mfa → the existing 2FA challenge UI takes over; error → authError shows.
+  }
+
+  // Populate SSO login buttons (no-op / empty in OSS-only builds).
+  ssoProviders.value = await authStore.fetchSsoProviders()
 })
 
 // Handle admin login (username fixed as 'admin')
diff --git a/src/frontend/src/views/Settings.vue b/src/frontend/src/views/Settings.vue
index 7115c82b..19ee67af 100644
--- a/src/frontend/src/views/Settings.vue
+++ b/src/frontend/src/views/Settings.vue
@@ -45,6 +45,9 @@
           <!-- #5 — Security / Two-Factor (enterprise, gated by `2fa`) -->
           <TwoFactorPanel v-if="activeTab === 'security'" />
 
+          <!-- #32 — Single Sign-On (enterprise, gated by `sso`) -->
+          <SsoPanel v-if="activeTab === 'sso'" />
+
           <!-- Platform Section -->
           <div v-if="activeTab === 'general'" class="bg-white dark:bg-gray-800 shadow dark:shadow-gray-900 rounded-lg">
             <div class="px-6 py-4 border-b border-gray-200 dark:border-gray-700">
@@ -1911,6 +1914,7 @@ import { useEnterpriseStore } from '../stores/enterprise'
 import NavBar from '../components/NavBar.vue'
 import McpKeysTab from '../components/settings/McpKeysTab.vue'
 import TwoFactorPanel from '../components/settings/TwoFactorPanel.vue'
+import SsoPanel from '../components/settings/SsoPanel.vue'
 import ConfirmDialog from '../components/ConfirmDialog.vue'
 
 const router = useRouter()
@@ -1942,6 +1946,7 @@ const ALL_TABS = [
   { id: 'integrations', label: 'Integrations', adminOnly: true  },
   { id: 'mcp-keys',     label: 'MCP Keys',     adminOnly: false },
   { id: 'security',     label: 'Security',     adminOnly: false, requires: '2fa' },
+  { id: 'sso',          label: 'SSO',          adminOnly: true,  requires: 'sso' },
   { id: 'agents',       label: 'Agents',       adminOnly: true  },
 ]
 const { isAdmin } = useRole()