add SSO session extend flow (management)

Adds the management-server half of the SSO session-extension feature:

- New ExtendAuthSession gRPC RPC that refreshes a peer's session expiry
  using a fresh JWT, validated through the same pipeline as Login but
  without tearing down the tunnel or redoing the NetworkMap sync.
- Per-peer SessionExpiresAt timestamp on every LoginResponse and
  SyncResponse so connected clients learn the deadline on the existing
  long-lived stream, and admin-side changes (toggling expiration,
  changing the expiration window) reach every peer within seconds.
- SessionExpiresAt(...) helper on Peer that derives the absolute UTC
  deadline from LastLogin + the account-level PeerLoginExpiration
  setting, returning zero when the peer is not SSO-tracked or expiration
  is disabled.

The matching client-side consumer of these fields lands separately.

management/server/account.go

@@ -355,7 +355,17 @@ func (am *DefaultAccountManager) UpdateAccountSettings(ctx context.Context, acco
 			oldSettings.LazyConnectionEnabled != newSettings.LazyConnectionEnabled ||
 			oldSettings.DNSDomain != newSettings.DNSDomain ||
 			oldSettings.AutoUpdateVersion != newSettings.AutoUpdateVersion ||
-			oldSettings.AutoUpdateAlways != newSettings.AutoUpdateAlways {
+			oldSettings.AutoUpdateAlways != newSettings.AutoUpdateAlways ||
+			oldSettings.PeerLoginExpirationEnabled != newSettings.PeerLoginExpirationEnabled ||
+			oldSettings.PeerLoginExpiration != newSettings.PeerLoginExpiration {
+			// Session deadline is derived from LastLogin + PeerLoginExpiration
+			// on every Login/Sync response. Without a fan-out push, connected
+			// peers keep the deadline they received at login time and only see
+			// the new value after the next unrelated NetworkMap change. Add
+			// these two fields to the trigger list so admin-side expiry tweaks
+			// (e.g. shortening from 24h to 1h) reach every connected peer
+			// within seconds, which is what the proactive-warning feature
+			// relies on (see client/internal/auth/sessionwatch).
 			updateAccountPeers = true
 		}
 

management/server/account/manager.go

@@ -109,6 +109,7 @@ type Manager interface {
 	UpdateAccountSettings(ctx context.Context, accountID, userID string, newSettings *types.Settings) (*types.Settings, error)
 	UpdateAccountOnboarding(ctx context.Context, accountID, userID string, newOnboarding *types.AccountOnboarding) (*types.AccountOnboarding, error)
 	LoginPeer(ctx context.Context, login types.PeerLogin) (*nbpeer.Peer, *types.NetworkMap, []*posture.Checks, error)                       // used by peer gRPC API
+	ExtendPeerSession(ctx context.Context, peerPubKey, userID string) (time.Time, error)                                                   // used by peer gRPC API for ExtendAuthSession
 	SyncPeer(ctx context.Context, sync types.PeerSync, accountID string) (*nbpeer.Peer, *types.NetworkMap, []*posture.Checks, int64, error) // used by peer gRPC API
 	GetExternalCacheManager() ExternalCacheManager
 	GetPostureChecks(ctx context.Context, accountID, postureChecksID, userID string) (*posture.Checks, error)

management/server/account/manager_mock.go

@@ -1304,6 +1304,21 @@ func (mr *MockManagerMockRecorder) LoginPeer(ctx, login interface{}) *gomock.Cal
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "LoginPeer", reflect.TypeOf((*MockManager)(nil).LoginPeer), ctx, login)
 }
 
+// ExtendPeerSession mocks base method.
+func (m *MockManager) ExtendPeerSession(ctx context.Context, peerPubKey, userID string) (time.Time, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "ExtendPeerSession", ctx, peerPubKey, userID)
+	ret0, _ := ret[0].(time.Time)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// ExtendPeerSession indicates an expected call of ExtendPeerSession.
+func (mr *MockManagerMockRecorder) ExtendPeerSession(ctx, peerPubKey, userID interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "ExtendPeerSession", reflect.TypeOf((*MockManager)(nil).ExtendPeerSession), ctx, peerPubKey, userID)
+}
+
 // MarkPeerConnected mocks base method.
 func (m *MockManager) MarkPeerConnected(ctx context.Context, peerKey string, realIP net.IP, accountID string, sessionStartedAt int64) error {
 	m.ctrl.T.Helper()

management/server/mock_server/account_mock.go

@@ -98,6 +98,7 @@ type MockAccountManager struct {
 	GetPeerFunc                           func(ctx context.Context, accountID, peerID, userID string) (*nbpeer.Peer, error)
 	UpdateAccountSettingsFunc             func(ctx context.Context, accountID, userID string, newSettings *types.Settings) (*types.Settings, error)
 	LoginPeerFunc                         func(ctx context.Context, login types.PeerLogin) (*nbpeer.Peer, *types.NetworkMap, []*posture.Checks, error)
+	ExtendPeerSessionFunc                 func(ctx context.Context, peerPubKey, userID string) (time.Time, error)
 	SyncPeerFunc                          func(ctx context.Context, sync types.PeerSync, accountID string) (*nbpeer.Peer, *types.NetworkMap, []*posture.Checks, int64, error)
 	InviteUserFunc                        func(ctx context.Context, accountID string, initiatorUserID string, targetUserEmail string) error
 	ApproveUserFunc                       func(ctx context.Context, accountID, initiatorUserID, targetUserID string) (*types.UserInfo, error)
@@ -860,6 +861,14 @@ func (am *MockAccountManager) LoginPeer(ctx context.Context, login types.PeerLog
 	return nil, nil, nil, status.Errorf(codes.Unimplemented, "method LoginPeer is not implemented")
 }
 
+// ExtendPeerSession mocks ExtendPeerSession of the AccountManager interface
+func (am *MockAccountManager) ExtendPeerSession(ctx context.Context, peerPubKey, userID string) (time.Time, error) {
+	if am.ExtendPeerSessionFunc != nil {
+		return am.ExtendPeerSessionFunc(ctx, peerPubKey, userID)
+	}
+	return time.Time{}, status.Errorf(codes.Unimplemented, "method ExtendPeerSession is not implemented")
+}
+
 // SyncPeer mocks SyncPeer of the AccountManager interface
 func (am *MockAccountManager) SyncPeer(ctx context.Context, sync types.PeerSync, accountID string) (*nbpeer.Peer, *types.NetworkMap, []*posture.Checks, int64, error) {
 	if am.SyncPeerFunc != nil {

management/server/peer.go

@@ -1128,6 +1128,79 @@ func (am *DefaultAccountManager) LoginPeer(ctx context.Context, login types.Peer
 	return p, nmap, pc, err
 }
 
+// ExtendPeerSession refreshes the peer's SSO session deadline by updating
+// LastLogin after a successful JWT validation. The tunnel is untouched: no
+// network map sync, no peer reconnect.
+//
+// Preconditions enforced here:
+//   - userID must be present (caller validated the JWT and extracted the user ID).
+//   - The peer must exist and be SSO-registered (AddedWithSSOLogin) with
+//     LoginExpirationEnabled.
+//   - Account-level PeerLoginExpirationEnabled must be true.
+//   - The JWT user must match peer.UserID (mirrors LoginPeer at peer.go ~1028).
+//
+// Returns the new absolute UTC deadline.
+func (am *DefaultAccountManager) ExtendPeerSession(ctx context.Context, peerPubKey, userID string) (time.Time, error) {
+	if userID == "" {
+		return time.Time{}, status.Errorf(status.PermissionDenied, "session extend requires a JWT")
+	}
+
+	accountID, err := am.Store.GetAccountIDByPeerPubKey(ctx, peerPubKey)
+	if err != nil {
+		return time.Time{}, err
+	}
+
+	settings, err := am.Store.GetAccountSettings(ctx, store.LockingStrengthNone, accountID)
+	if err != nil {
+		return time.Time{}, err
+	}
+	if !settings.PeerLoginExpirationEnabled {
+		return time.Time{}, status.Errorf(status.PreconditionFailed, "peer login expiration is disabled for the account")
+	}
+
+	var refreshed *nbpeer.Peer
+	err = am.Store.ExecuteInTransaction(ctx, func(transaction store.Store) error {
+		peer, err := transaction.GetPeerByPeerPubKey(ctx, store.LockingStrengthUpdate, peerPubKey)
+		if err != nil {
+			return err
+		}
+
+		if !peer.AddedWithSSOLogin() || !peer.LoginExpirationEnabled {
+			return status.Errorf(status.PreconditionFailed, "peer is not eligible for session extension")
+		}
+
+		if peer.UserID != userID {
+			log.WithContext(ctx).Warnf("user mismatch when extending session for peer %s: peer user %s, jwt user %s", peer.ID, peer.UserID, userID)
+			return status.NewPeerLoginMismatchError()
+		}
+
+		peer = peer.UpdateLastLogin()
+		if err := transaction.SavePeer(ctx, accountID, peer); err != nil {
+			return err
+		}
+
+		if err := transaction.SaveUserLastLogin(ctx, accountID, userID, peer.GetLastLogin()); err != nil {
+			log.WithContext(ctx).Debugf("failed to update user last login during session extend: %v", err)
+		}
+
+		am.StoreEvent(ctx, userID, peer.ID, accountID, activity.UserLoggedInPeer, peer.EventMeta(am.networkMapController.GetDNSDomain(settings)))
+		refreshed = peer
+		return nil
+	})
+	if err != nil {
+		return time.Time{}, err
+	}
+
+	// Reschedule the per-account expiration job. schedulePeerLoginExpiration
+	// is a no-op when a job is already running, but the running job will pick
+	// up the new LastLogin on its next tick. Calling it here is harmless and
+	// guarantees a job is in flight even if a prior one ended right before
+	// the extend.
+	am.schedulePeerLoginExpiration(ctx, accountID)
+
+	return refreshed.SessionExpiresAt(settings.PeerLoginExpirationEnabled, settings.PeerLoginExpiration), nil
+}
+
 // getPeerPostureChecks returns the posture checks for the peer.
 func getPeerPostureChecks(ctx context.Context, transaction store.Store, accountID, peerID string) ([]*posture.Checks, error) {
 	policies, err := transaction.GetAccountPolicies(ctx, store.LockingStrengthNone, accountID)

management/server/peer/peer.go

@@ -367,6 +367,22 @@ func (p *Peer) LoginExpired(expiresIn time.Duration) (bool, time.Duration) {
 	return timeLeft <= 0, timeLeft
 }
 
+// SessionExpiresAt returns the absolute UTC instant at which the peer's SSO
+// session expires, derived from LastLogin and the account-level
+// PeerLoginExpiration setting. Returns the zero value when login expiration
+// does not apply (peer not SSO-registered, peer-level toggle off, or account
+// expiry disabled). Callers should treat the zero value as "no deadline".
+func (p *Peer) SessionExpiresAt(accountExpirationEnabled bool, expiresIn time.Duration) time.Time {
+	if !accountExpirationEnabled || !p.AddedWithSSOLogin() || !p.LoginExpirationEnabled {
+		return time.Time{}
+	}
+	last := p.GetLastLogin()
+	if last.IsZero() {
+		return time.Time{}
+	}
+	return last.Add(expiresIn).UTC()
+}
+
 // FQDN returns peers FQDN combined of the peer's DNS label and the system's DNS domain
 func (p *Peer) FQDN(dnsDomain string) string {
 	if dnsDomain == "" {