feat: Add rename cooldown field and cloudprov rename

admin/internal/cloudprov/cloudprov.go

@@ -202,3 +202,20 @@ func ProjectedUsers(ctx context.Context, hqUserID string) ([]sharedmodels.User,
 	}
 	return users, nil
 }
+
+// RenameInstance changes a cloud instance's name and moves it to the slug that
+// name derives to.
+//
+// It writes `instances` and nothing else, so admin's control-plane write
+// boundary is unchanged. It issues no licence: a licence binds the instance
+// UUID, which a rename never touches.
+func RenameInstance(ctx context.Context, instanceID, name string) (*sharedmodels.Instance, error) {
+	return provision.RenameInstance(ctx, db.ControlDB(), instanceID, name)
+}
+
+// RestoreInstanceIdentity puts an instance's previous name and slug back, for a
+// caller unwinding a rename whose admin-side write failed. Leaving the two
+// databases disagreeing would have HQ print a host that is not the host.
+func RestoreInstanceIdentity(ctx context.Context, instanceID, name, slug string) error {
+	return provision.RestoreInstanceIdentity(ctx, db.ControlDB(), instanceID, name, slug)
+}

admin/internal/models/models.go

@@ -111,6 +111,15 @@ const GracePeriod = 3 * 24 * time.Hour
 // second mechanism.
 const RenewWindow = 7 * 24 * time.Hour
 
+// RenameCooldown is how long a customer must wait between renames of one
+// instance.
+//
+// A rename moves the instance's DNS host and invalidates every saved link to it,
+// so this exists to make that a considered act rather than a slider. Staff are
+// not subject to it: a support conversation about a name is already a human
+// deciding.
+const RenameCooldown = 24 * time.Hour
+
 type Account struct {
 	ID               bson.ObjectID `bson:"_id,omitempty" json:"-"`
 	AccountID        string        `bson:"account_id" json:"account_id"`
@@ -137,6 +146,11 @@ type Instance struct {
 	Status         string        `bson:"status" json:"status"`
 	CurrentLicense string        `bson:"current_license,omitempty" json:"current_license,omitempty"`
 	RelinkCount    int           `bson:"relink_count" json:"relink_count"`
+	// RenamedAt is when this instance last changed name, and backs the customer
+	// rename cooldown. It is a pointer because absent means "never renamed"; a
+	// zero time.Time would read as year 1 — an inert cooldown, but only by
+	// accident. Staff renames deliberately leave it alone.
+	RenamedAt      *time.Time    `bson:"renamed_at,omitempty" json:"renamed_at,omitempty"`
 	InjectFailedAt *time.Time    `bson:"inject_failed_at,omitempty" json:"inject_failed_at,omitempty"`
 	// NoticesSent holds the lifecycle notice keys already emailed for the
 	// CURRENT term ("expiring", "expired", "delete_7", "delete_1"). Renewal