diff --git a/go.mod b/go.mod
index af38224..ba59d5a 100644
--- a/go.mod
+++ b/go.mod
@@ -9,7 +9,7 @@ require (
 	github.com/fxamacker/cbor/v2 v2.9.4
 	github.com/gorilla/websocket v1.5.3
 	github.com/quic-go/quic-go v0.63.0
-	github.com/srcfl/ftw/go/protocol v0.0.0-20261017070253-cbdd8a587105
+	github.com/srcfl/ftw/go/protocol v0.0.0-20261017085842-8a7bd9c6e597
 	golang.org/x/crypto v0.57.0
 	golang.org/x/net v0.58.0
 	golang.org/x/sys v0.48.0
diff --git a/go.sum b/go.sum
index a605893..06141cc 100644
--- a/go.sum
+++ b/go.sum
@@ -52,10 +52,8 @@ github.com/quic-go/quic-go v0.63.0 h1:LIFGHI4PFUhhw2dDD1ARHdCff143ffMHwZtbnbuJ78
 github.com/quic-go/quic-go v0.63.0/go.mod h1:RAro2j2yN9a9EiPACLHT9IB2NXCvGQmmo/alT0yYI0w=
 github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec h1:W09IVJc94icq4NjY3clb7Lk8O1qJ8BdBEF8z0ibU0rE=
 github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec/go.mod h1:qqbHyh8v60DhA7CoWK5oRCqLrMHRGoxYCSS9EjAz6Eo=
-github.com/srcfl/ftw/go/protocol v0.0.0-20261016102129-7fb84d6ed573 h1:1OOC4RdeERT9r6cLMTlcmTjg8+ML2kU6hCvhx/x+8xI=
-github.com/srcfl/ftw/go/protocol v0.0.0-20261016102129-7fb84d6ed573/go.mod h1:VEjr/o0yZijJ1nApuJK+nak6FxJ/fubAUBNOunqNrUU=
-github.com/srcfl/ftw/go/protocol v0.0.0-20261017070253-cbdd8a587105 h1:56AF3FQxXwfTVacD+AtJQM96TdzntTeQy1f4yiN54ic=
-github.com/srcfl/ftw/go/protocol v0.0.0-20261017070253-cbdd8a587105/go.mod h1:VEjr/o0yZijJ1nApuJK+nak6FxJ/fubAUBNOunqNrUU=
+github.com/srcfl/ftw/go/protocol v0.0.0-20261017085842-8a7bd9c6e597 h1:oQkKbo+YEhcUYE6IwzSUR5xDvkDOAa/SNQfsI2JJGqQ=
+github.com/srcfl/ftw/go/protocol v0.0.0-20261017085842-8a7bd9c6e597/go.mod h1:VEjr/o0yZijJ1nApuJK+nak6FxJ/fubAUBNOunqNrUU=
 github.com/stretchr/testify v1.12.1 h1:EuwCh5fleGS7H32xRwO3wRGT7DxrDhLAT6FF8MpWDWE=
 github.com/stretchr/testify v1.12.1/go.mod h1:MDEgiDPPsNp5cuIrHPPCyornHKgEVbtFUmoNlxoYthg=
 github.com/x448/float16 v0.8.4 h1:qLwI1I70+NjRFUR3zs1JPUCgaCXSh3SW62uAKT1mSBM=
diff --git a/internal/oauth/oauth.go b/internal/oauth/oauth.go
index ded9a6b..1e2c0ff 100644
--- a/internal/oauth/oauth.go
+++ b/internal/oauth/oauth.go
@@ -64,9 +64,13 @@ const (
 	// AccessTTL is an access token's life. Short: a token that leaks is
 	// worth little, and a revoked agent loses access at its box anyway.
 	AccessTTL = 10 * time.Minute
-	// RefreshTTL caps a refresh token, and an agent's own end caps it
-	// sooner.
-	RefreshTTL = 30 * 24 * time.Hour
+	// RefreshTTL is a refresh token's life: the longest grant an agent may
+	// have. The agent's end does not shorten it, so a grant the owner renews
+	// while its client is idle keeps its tokens; an agent past its end is
+	// refused at every refresh and swept.
+	RefreshTTL = maxGrant
+	// maxGrant is the longest end the service takes from a roster.
+	maxGrant = time.Duration(protocol.AgentMaxMs) * time.Millisecond
 )
 
 // Scopes. Each is a right the box grants an agent, by its registry name
@@ -416,7 +420,7 @@ func (s *Server) applyRoster(ctx context.Context, home string, devices []cloudwi
 			s.revoke(ctx, a)
 			continue
 		}
-		if err := s.st.setGrant(a.Home, a.Agent, grantOf(d)); err != nil {
+		if err := s.st.setGrant(a.Home, a.Agent, grantOf(d, s.now())); err != nil {
 			s.log.Warn("could not update an agent's grant", "err", err)
 		}
 	}
@@ -442,7 +446,7 @@ func (s *Server) approve(ctx context.Context, home string, listed map[string]clo
 		}
 		c.Home, c.Agent, c.Shard = home, d.ID, s.shard(home)
 		c.Granted = strings.Join(intersect(splitScope(c.Scope), d.Agent.Scopes), " ")
-		if err := s.st.approve(ridHash, c, grantOf(d), now); err != nil {
+		if err := s.st.approve(ridHash, c, grantOf(d, now), now); err != nil {
 			s.log.Warn("could not record an approval", "err", err)
 			continue
 		}
@@ -480,9 +484,15 @@ func (s *Server) retryApprovals(ctx context.Context) {
 }
 
 // grantOf is an agent row's grant, as the box signed it in the roster.
-func grantOf(d cloudwire.Device) agentGrant {
+// The service never takes an end past the longest grant from now, whatever a
+// roster says.
+func grantOf(d cloudwire.Device, now time.Time) agentGrant {
+	end := time.UnixMilli(d.Agent.ExpiresAtMs)
+	if most := now.Add(maxGrant); end.After(most) {
+		end = most
+	}
 	return agentGrant{Scopes: slices.Clone(d.Agent.Scopes), Ops: slices.Clone(d.Agent.Ops), Caps: d.Agent.Caps,
-		Expires: time.UnixMilli(d.Agent.ExpiresAtMs)}
+		Expires: end}
 }
 
 // revoke drops an agent and its tokens, and has its key forgotten.
diff --git a/internal/oauth/oauth_test.go b/internal/oauth/oauth_test.go
index afabddb..bf34797 100644
--- a/internal/oauth/oauth_test.go
+++ b/internal/oauth/oauth_test.go
@@ -802,6 +802,63 @@ func TestRevokeAtTheBoxEndsTheTokens(t *testing.T) {
 	}
 }
 
+// A grant the owner renews keeps its tokens past its first end, even when
+// the assistant made no call in between: the refresh token does not end with
+// the grant it was issued under. An access token never outlives the grant,
+// and once the grant the box sets has ended, a refresh fails.
+func TestARefreshTokenFollowsTheGrantTheBoxSets(t *testing.T) {
+	g := newRig(t)
+	f := g.start(cimdID, cimdBack, "")
+	tk := g.approve(f, cimdID) // the box grants 30 days
+	key := f.agentKey(t)
+	refresh := func(tok string) (int, tokens) {
+		g.t.Helper()
+		return g.token(url.Values{"grant_type": {grantRefresh}, "refresh_token": {tok}, "client_id": {cimdID}})
+	}
+
+	// The assistant goes quiet after day 0. On day 29 the owner renews the
+	// grant for a year; on day 31 the assistant comes back with the refresh
+	// token it was given on day 0.
+	g.advance(29 * 24 * time.Hour)
+	g.roster(home, agentFor(key, cimdID, g.now().Add(365*24*time.Hour), ScopeLiveRead, ScopePlanRead))
+	g.advance(2 * 24 * time.Hour)
+	status, tk2 := refresh(tk.Refresh)
+	if status != http.StatusOK {
+		t.Fatalf("an idle assistant lost a renewed grant at its first end: %d", status)
+	}
+	if _, aerr := g.bearer(tk2.Access); aerr != nil {
+		t.Fatalf("the token after the first end: %+v", aerr)
+	}
+
+	// The owner cuts it to five minutes: the access token ends with it.
+	g.roster(home, agentFor(key, cimdID, g.now().Add(5*time.Minute), ScopeLiveRead, ScopePlanRead))
+	status, tk3 := refresh(tk2.Refresh)
+	if status != http.StatusOK || tk3.Expires > 300 {
+		t.Fatalf("refresh after the cut: %d, access for %d s", status, tk3.Expires)
+	}
+	g.advance(5*time.Minute + time.Second)
+	if _, aerr := g.bearer(tk3.Access); aerr == nil {
+		t.Fatal("an access token outlived the grant")
+	}
+	if status, _ := refresh(tk3.Refresh); status != http.StatusBadRequest {
+		t.Fatalf("refresh after the grant ended: %d", status)
+	}
+}
+
+// A roster that sets an end past the longest grant is taken as a year from
+// now.
+func TestARosterEndPastAYearIsCut(t *testing.T) {
+	g := newRig(t)
+	f := g.start(cimdID, cimdBack, "")
+	g.approve(f, cimdID)
+	key := f.agentKey(t)
+	g.roster(home, agentFor(key, cimdID, g.now().Add(2*365*24*time.Hour), ScopeLiveRead, ScopePlanRead))
+	a, ok, _ := g.s.st.agent(home, cloudwire.DeviceID(key))
+	if most := g.now().Add(365 * 24 * time.Hour); !ok || a.Expires.After(most) {
+		t.Fatalf("the agent ends %v, past %v", a.Expires, most)
+	}
+}
+
 // An agent whose time the box set runs out fails, and is swept.
 func TestAnExpiredAgentFails(t *testing.T) {
 	g := newRig(t)
@@ -1071,8 +1128,9 @@ func TestApprovalOutlastsAKeysPartThatIsAway(t *testing.T) {
 
 // The offer: the contract's SignedOffer, which protocol.OpenOffer opens
 // with the offer key pinned by its kid. It carries the agent's key, the
-// client and its host, what it asks for, the code and an end within ten
-// minutes, and no home; in the QR, the link and the request's details alike.
+// client and its host, what it asks for, a year as the longest the owner may
+// grant, the code and an end within ten minutes, and no home; in the QR, the
+// link and the request's details alike.
 func TestTheOfferIsSignedAndCarriesTheConsent(t *testing.T) {
 	g := newRig(t)
 	f := g.start(cimdID, cimdBack, ScopeLiveRead+" "+ScopeDispatchHold)
@@ -1092,7 +1150,7 @@ func TestTheOfferIsSignedAndCarriesTheConsent(t *testing.T) {
 	if o.Home != "" || !bytes.Equal(o.Key, f.agentKey(t)) || o.Role != protocol.RoleAgent || o.Client != "Claude" ||
 		o.ClientID != cimdID || o.ClientHost != "example.com" || o.Verified || o.Code != f.view.Code ||
 		!slices.Equal(o.Scopes, []string{ScopeDispatchHold, ScopeLiveRead}) || !slices.Equal(o.Ops, []string{"loadpoint.hold"}) ||
-		o.Caps.HoldS == 0 || o.TTLS != uint64(protocol.AgentMaxMs/1000) || o.ExpMs > g.now().UnixMilli()+protocol.OfferTTLMs {
+		o.Caps.HoldS == 0 || o.TTLS != 365*24*60*60 || o.ExpMs > g.now().UnixMilli()+protocol.OfferTTLMs {
 		t.Fatalf("offer %+v", o)
 	}
 	// Another key does not open it, and it ends.
diff --git a/internal/oauth/offer.go b/internal/oauth/offer.go
index 753fc18..6704b18 100644
--- a/internal/oauth/offer.go
+++ b/internal/oauth/offer.go
@@ -32,7 +32,9 @@ var proposedHoldCaps = protocol.Caps{HoldS: protocol.HoldSMax, MaxW: 11_000, Per
 
 // buildOffer is the offer for one consent: the agent's key, what its client
 // asks for, and the code on the page. The home is left empty: the owner
-// picks it, in the app or on the box's page.
+// picks it, in the app or on the box's page. So the offer asks for the
+// longest an agent may have; the app and the box page start at 30 days and
+// offer a box no more than it takes (docs/agents.md, Mixed versions).
 func buildOffer(c consent) protocol.GrantOffer {
 	scopes := slices.Sorted(slices.Values(splitScope(c.Scope)))
 	var ops []string
diff --git a/internal/oauth/store.go b/internal/oauth/store.go
index da84700..b8ee4db 100644
--- a/internal/oauth/store.go
+++ b/internal/oauth/store.go
@@ -363,8 +363,8 @@ func (s *store) issueCode(rid, code string, expires time.Time) error {
 
 // redeem spends an authorization code once. A code presented a second time
 // is reported as reused, and the caller revokes what the first use got:
-// the spent code's hash outlives its consent for as long as those tokens
-// may live.
+// the spent code's hash outlives its consent for as long as one refresh
+// token may live.
 func (s *store) redeem(code string, now time.Time) (c consent, ridHash []byte, reused bool, err error) {
 	tx, err := s.db.Begin()
 	if err != nil {
diff --git a/internal/oauth/token.go b/internal/oauth/token.go
index a67c232..c611dff 100644
--- a/internal/oauth/token.go
+++ b/internal/oauth/token.go
@@ -199,7 +199,7 @@ func (s *Server) exchangeCode(w http.ResponseWriter, r *http.Request, cl client)
 		tokenError(w, http.StatusBadRequest, "invalid_grant", "the owner removed this assistant")
 		return
 	}
-	s.issue(w, ridHash, cl.ID, a, c.Granted, s.now().Add(RefreshTTL))
+	s.issue(w, ridHash, cl.ID, a, c.Granted)
 }
 
 func (s *Server) refresh(w http.ResponseWriter, r *http.Request, cl client) {
@@ -236,19 +236,21 @@ func (s *Server) refresh(w http.ResponseWriter, r *http.Request, cl client) {
 		tokenError(w, http.StatusBadRequest, "invalid_grant", "the owner removed this assistant")
 		return
 	}
-	s.issue(w, t.Family, cl.ID, a, scope, t.Expires)
+	s.issue(w, t.Family, cl.ID, a, scope)
 }
 
 // issue writes a new access token and a new refresh token of one family.
-// The refresh token ends no later than refreshEnd or the agent.
-func (s *Server) issue(w http.ResponseWriter, family []byte, clientID string, a agentRow, scope string, refreshEnd time.Time) {
+// The access token ends within AccessTTL and never after the agent's end as
+// the box's newest roster sets it. The refresh token lasts RefreshTTL and is
+// not clamped to that end: the owner may renew the grant while the client is
+// idle, and an agent past its end is refused at every refresh and every call
+// (agentGone) and swept with its tokens.
+func (s *Server) issue(w http.ResponseWriter, family []byte, clientID string, a agentRow, scope string) {
 	now := s.now()
-	if a.Expires.Before(refreshEnd) {
-		refreshEnd = a.Expires
-	}
+	refreshEnd := now.Add(RefreshTTL)
 	accessEnd := now.Add(AccessTTL)
-	if accessEnd.After(refreshEnd) {
-		accessEnd = refreshEnd
+	if accessEnd.After(a.Expires) {
+		accessEnd = a.Expires
 	}
 	access, refresh := s.route.newToken(accessPrefix, a.Home), s.route.newToken(refreshPrefix, a.Home)
 	base := tokenRow{Family: family, ClientID: clientID, Home: a.Home, Agent: a.Agent, Scope: scope, Resource: Resource}