diff --git a/internal/provider/migrate_zcode.go b/internal/provider/migrate_zcode.go
index 79ee11fc..63db3f50 100644
--- a/internal/provider/migrate_zcode.go
+++ b/internal/provider/migrate_zcode.go
@@ -21,7 +21,7 @@ import (
 func init() {
 	movers["zcode"] = &mover{
 		pkg:    "@magpie-community/opencode-zcode-auth",
-		min:    "0.1.9", // the gift's models are trial entries (GLM-5.3-Flash-Trial) the user picks; a plain model spends the GLM Coding Plan (plugins #21)
+		min:    "0.1.10", // a gift-only account's spent bucket (the Start Plan's GLM-5.3-Flash) doesn't hold up a model another plan (Trust Build) still has; 0.1.9's trial entries (plugins #21) kept
 		agents: []string{"zcode"},
 		// a Start Plan account was never served GLM-5.3, by the built-in
 		// or by ZCode, and the plugin lists it no more than they do; its
diff --git a/internal/provider/zcode_start.go b/internal/provider/zcode_start.go
index 9ca8807c..aa4852f2 100644
--- a/internal/provider/zcode_start.go
+++ b/internal/provider/zcode_start.go
@@ -487,6 +487,7 @@ func zcodeStartQuota(ctx context.Context, l Login, jwt string) SubscriptionQuota
 	if until != nil {
 		q.Until, q.Renew = until, "off"
 	}
+	var buckets []zcodeBucket
 	for _, x := range b.Balances {
 		total, hasTotal := zcodeNum(x.Total)
 		used, hasUsed := zcodeNum(x.Used)
@@ -529,17 +530,58 @@ func zcodeStartQuota(ctx context.Context, l Login, jwt string) SubscriptionQuota
 				w.Span = time.Duration(e-s) * time.Second
 			}
 		}
-		if len(models) > 0 {
-			w.matches = func(model string) bool {
-				for _, m := range models {
-					if strings.EqualFold(m, model) {
-						return true
-					}
-				}
-				return false
-			}
-		}
 		q.Windows = append(q.Windows, w)
+		buckets = append(buckets, zcodeBucket{models, hasLeft && left <= 0 || hasTotal && total > 0 && used >= total})
 	}
+	zcodeAlternatives(q.Windows, buckets)
 	return q
 }
+
+// zcodeBucket is what zcodeAlternatives reads of a window's bucket.
+type zcodeBucket struct {
+	models []string
+	spent  bool
+}
+
+// zcodeAlternatives scopes each bucket's window to the models a request
+// spends it on. Two plans can give one model (ZCode Trust Build's and the
+// Start Plan's GLM-5.3-Flash), and the server picks the bucket — ZCode
+// sends no plan with a request — so a model counts on one bucket: a live
+// one before a spent one, the least used of those. A bucket that is no
+// model's stays on the card, Aside, so a spent one doesn't hold up the
+// model, or the account, another still has (ganlerk on Discord).
+func zcodeAlternatives(ws []QuotaWindow, bs []zcodeBucket) {
+	best := map[string]int{}
+	for i, b := range bs {
+		for _, m := range b.models {
+			k := strings.ToLower(m)
+			j, ok := best[k]
+			if !ok || bs[j].spent && !b.spent || bs[j].spent == b.spent && ws[i].Used < ws[j].Used {
+				best[k] = i
+			}
+		}
+	}
+	for i, b := range bs {
+		if len(b.models) == 0 {
+			continue
+		}
+		var mine []string
+		for _, m := range b.models {
+			if best[strings.ToLower(m)] == i {
+				mine = append(mine, m)
+			}
+		}
+		if len(mine) == 0 {
+			ws[i].Aside = true
+			continue
+		}
+		ws[i].matches = func(model string) bool {
+			for _, m := range mine {
+				if strings.EqualFold(m, model) {
+					return true
+				}
+			}
+			return false
+		}
+	}
+}
diff --git a/internal/provider/zcode_start_test.go b/internal/provider/zcode_start_test.go
index feb34b1b..6a741d98 100644
--- a/internal/provider/zcode_start_test.go
+++ b/internal/provider/zcode_start_test.go
@@ -303,3 +303,44 @@ func TestZCodeStartHTTP1(t *testing.T) {
 		t.Fatalf("sent:\n%s\nwant:\n%s", strings.Join(got, "\n"), strings.Join(want, "\n"))
 	}
 }
+
+// ganlerk (Discord): an account with ZCode Trust Build and the Start Plan,
+// both giving GLM-5.3-Flash, the Start Plan's all used and Trust Build's
+// 14.5%. The server spends whichever has some, so GLM-5.3-Flash counts on
+// Trust Build's bucket and the spent one is set aside: neither the model
+// nor the account reads as used up.
+func TestZCodeStartSpentSiblingAside(t *testing.T) {
+	signIn(t)
+	jwt := zcodeTestJWT(time.Now().Add(24 * time.Hour))
+	u := newZCodeStartUpstream(t, jwt)
+	now := time.Now()
+	u.balance = map[string]any{
+		"server_time": now.Unix(),
+		"plans": []any{
+			map[string]any{"plan_id": "zai-start-plan", "user_plan_id": "s1", "name": "ZCode Start Plan", "status": "active", "ends_at": now.Add(7 * 24 * time.Hour).Unix()},
+			map[string]any{"plan_id": "zai-trust-build", "user_plan_id": "t1", "name": "ZCode Trust Build", "status": "active", "ends_at": now.Add(24 * time.Hour).Unix()},
+		},
+		"balances": []any{
+			map[string]any{"plan_id": "zai-start-plan", "user_plan_id": "s1", "show_name": "GLM-5.3", "capabilities": []any{"model:GLM-5.3"},
+				"total_units": 3000000, "used_units": 0, "remaining_units": 3000000},
+			map[string]any{"plan_id": "zai-start-plan", "user_plan_id": "s1", "show_name": "GLM-5.3-Flash", "capabilities": []any{"model:GLM-5.3-Flash"},
+				"total_units": 5000000, "used_units": 5000000, "remaining_units": 0},
+			map[string]any{"plan_id": "zai-trust-build", "user_plan_id": "t1", "show_name": "GLM-5.3-Flash", "capabilities": []any{"model:GLM-5.3-Flash"},
+				"total_units": 100000000, "used_units": 14501196, "remaining_units": 85498804, "expires_at": now.Add(time.Hour).Unix()},
+		},
+	}
+	q := zcodeStartQuota(context.Background(), Login{User: "u@example.com"}, jwt)
+	if q.Error != "" || len(q.Windows) != 3 {
+		t.Fatalf("usage: %+v", q)
+	}
+	if w := q.Windows[1]; w.Used != 100 || !w.Aside {
+		t.Fatalf("the spent Start Plan bucket isn't set aside: %+v", w)
+	}
+	a := allowanceOf(q.Windows, now)
+	if used, _ := a.For("glm-5.3-flash", now); used < 14 || used > 15 {
+		t.Fatalf("GLM-5.3-Flash counts %v%% used, not Trust Build's 14.5%%", used)
+	}
+	if used, _ := a.For("glm-5.3", now); used != 0 {
+		t.Fatalf("GLM-5.3: %v", used)
+	}
+}