feat: add manual subscription date editing for admins (#7257)

diff --git a/BTCPayServer.Client/BTCPayServerClient.Subscriptions.cs b/BTCPayServer.Client/BTCPayServerClient.Subscriptions.cs
index f91424c..1333777 100644
--- a/BTCPayServer.Client/BTCPayServerClient.Subscriptions.cs
+++ b/BTCPayServer.Client/BTCPayServerClient.Subscriptions.cs
@@ -54,6 +54,10 @@ public partial class BTCPayServerClient
     public async Task<SubscriberModel> UnsuspendSubscriber(string storeId, string offeringId, string customerSelector, CancellationToken token = default)
         => await SendHttpRequest<SubscriberModel>($"api/v1/stores/{storeId}/offerings/{offeringId}/subscribers/{customerSelector}/unsuspend", null, HttpMethod.Post, token);
 
+    public async Task<SubscriberModel> UpdateSubscriberDates(string storeId, string offeringId, string customerSelector,
+        UpdateSubscriberDatesRequest request, CancellationToken token = default)
+        => await SendHttpRequest<SubscriberModel>($"api/v1/stores/{storeId}/offerings/{offeringId}/subscribers/{Uri.EscapeDataString(customerSelector)}/dates", request, HttpMethod.Put, token);
+
     public async Task<PortalSessionModel> CreatePortalSession(CreatePortalSessionRequest request, CancellationToken token = default)
         => await SendHttpRequest<PortalSessionModel>($"api/v1/subscriber-portal", request, HttpMethod.Post, token);
     public async Task<PortalSessionModel> GetPortalSession(string portalSessionId, CancellationToken token = default)
diff --git a/BTCPayServer.Client/Models/Subscriptions/UpdateSubscriberDatesRequest.cs b/BTCPayServer.Client/Models/Subscriptions/UpdateSubscriberDatesRequest.cs
new file mode 100644
index 0000000..4f0fbbf
--- /dev/null
+++ b/BTCPayServer.Client/Models/Subscriptions/UpdateSubscriberDatesRequest.cs
@@ -0,0 +1,13 @@
+using System;
+using Newtonsoft.Json;
+
+namespace BTCPayServer.Client.Models;
+
+public class UpdateSubscriberDatesRequest
+{
+    [JsonConverter(typeof(NBitcoin.JsonConverters.DateTimeToUnixTimeConverter))]
+    public DateTimeOffset? StartDate { get; set; }
+
+    [JsonConverter(typeof(NBitcoin.JsonConverters.DateTimeToUnixTimeConverter))]
+    public DateTimeOffset? ExpirationDate { get; set; }
+}
diff --git a/BTCPayServer.Tests/SubscriptionTests.cs b/BTCPayServer.Tests/SubscriptionTests.cs
index b78752a..aebc136 100644
--- a/BTCPayServer.Tests/SubscriptionTests.cs
+++ b/BTCPayServer.Tests/SubscriptionTests.cs
@@ -486,6 +486,24 @@ public class SubscriptionTests(ITestOutputHelper testOutputHelper) : UnitTestBas
         Assert.False(subscriber.IsSuspended);
         Assert.Null(subscriber.SuspensionReason);
 
+        var newExpiration = DateTimeOffset.UtcNow.AddDays(90);
+        subscriber = await client.UpdateSubscriberDates(user.StoreId, offering.Id,
+            planCheckout.Subscriber.Customer.Id,
+            new UpdateSubscriberDatesRequest { ExpirationDate = newExpiration });
+        Assert.Equal(newExpiration.ToUnixTimeSeconds(), subscriber.PeriodEnd!.Value.ToUnixTimeSeconds());
+        Assert.True(subscriber.IsActive);
+
+        await AssertEx.AssertApiError(400, "invalid-dates", () => client.UpdateSubscriberDates(
+            user.StoreId, offering.Id, planCheckout.Subscriber.Customer.Id,
+            new UpdateSubscriberDatesRequest
+            {
+                StartDate = DateTimeOffset.UtcNow.AddDays(10),
+                ExpirationDate = DateTimeOffset.UtcNow.AddDays(5)
+            }));
+        var noOpResult = await client.UpdateSubscriberDates(user.StoreId, offering.Id,
+            planCheckout.Subscriber.Customer.Id, new UpdateSubscriberDatesRequest());
+        Assert.Equal(newExpiration.ToUnixTimeSeconds(), noOpResult.PeriodEnd!.Value.ToUnixTimeSeconds());
+
         var session = await client.CreatePortalSession(new()
         {
             StoreId = user.StoreId,
diff --git a/BTCPayServer/Plugins/Subscriptions/Controllers/GreenfieldOfferingController.cs b/BTCPayServer/Plugins/Subscriptions/Controllers/GreenfieldOfferingController.cs
index 4de16b4..37f966a 100644
--- a/BTCPayServer/Plugins/Subscriptions/Controllers/GreenfieldOfferingController.cs
+++ b/BTCPayServer/Plugins/Subscriptions/Controllers/GreenfieldOfferingController.cs
@@ -255,6 +255,27 @@ namespace BTCPayServer.Plugins.Subscriptions.Controllers
             return await GetSubscriber(storeId, offeringId, customerSelector);
         }
 
+        [Authorize(AuthenticationSchemes = AuthenticationSchemes.Greenfield, Policy = SubscriptionsPolicies.CanManageSubscribers)]
+        [HttpPut("~/api/v1/stores/{storeId}/offerings/{offeringId}/subscribers/{customerSelector}/dates")]
+        public async Task<IActionResult> UpdateSubscriberDates(string storeId, string offeringId,
+            [ModelBinder<CustomerSelectorModelBinder>]
+            CustomerSelector customerSelector,
+            [FromBody] UpdateSubscriberDatesRequest? request)
+        {
+            var subscriber = await ctx.Subscribers.GetBySelector(offeringId, customerSelector, storeId);
+            if (subscriber is null)
+                return SubscriberNotFound();
+            if (request is null or { StartDate: null, ExpirationDate: null })
+                return await GetSubscriber(storeId, offeringId, customerSelector);
+            var startDate = (request.StartDate ?? subscriber.PlanStarted).ToUniversalTime();
+            var expirationDate = request.ExpirationDate?.ToUniversalTime();
+            if (expirationDate is { } exp && exp <= startDate)
+                return this.CreateAPIError(400, "invalid-dates", "Expiration date must be after the start date.");
+            await subscriptionHostedService.UpdateDates(subscriber.Id, startDate, expirationDate);
+            ctx.ChangeTracker.Clear();
+            return await GetSubscriber(storeId, offeringId, customerSelector);
+        }
+
         [AllowAnonymous]
         [HttpPost("~/api/v1/plan-checkout/{checkoutId}")]
         public async Task<IActionResult> ProceedPlanCheckout(string checkoutId, [FromQuery] string? email = null)
diff --git a/BTCPayServer/Plugins/Subscriptions/Controllers/UIOfferingController.cs b/BTCPayServer/Plugins/Subscriptions/Controllers/UIOfferingController.cs
index ade74cd..6c7a22b 100644
--- a/BTCPayServer/Plugins/Subscriptions/Controllers/UIOfferingController.cs
+++ b/BTCPayServer/Plugins/Subscriptions/Controllers/UIOfferingController.cs
@@ -100,7 +100,9 @@ public partial class UIOfferingController(
 
     [HttpPost("stores/{storeId}/offerings/{offeringId}/Subscribers")]
     public async Task<IActionResult> SubscriberSuspend(string storeId, string offeringId, string customerId, string? command = null,
-        string? suspensionReason = null, decimal? amount = null, string? description = null)
+        string? suspensionReason = null, decimal? amount = null, string? description = null,
+        DateOnly? startDate = null, DateOnly? expirationDate = null,
+        int? timezoneOffset = null, int? expirationTimezoneOffset = null)
     {
         await using var ctx = DbContextFactory.CreateContext();
         var sub = await ctx.Subscribers.GetByCustomerId(customerId, offeringId: offeringId, storeId: storeId);
@@ -156,6 +158,53 @@ public partial class UIOfferingController(
                 });
             TempData.SetStatusSuccess(message);
         }
+        else if (command is "edit-dates")
+        {
+            if (startDate is null)
+            {
+                TempData.SetStatusMessageModel(new()
+                {
+                    Severity = StatusMessageModel.StatusSeverity.Error,
+                    Html = StringLocalizer["Invalid start date provided."]
+                });
+                return GoToOffering(storeId, offeringId, SubscriptionSection.Subscribers);
+            }
+
+            var startOffsetMinutes = timezoneOffset ?? 0;
+            var expOffsetMinutes = expirationTimezoneOffset ?? startOffsetMinutes;
+            if (startOffsetMinutes < -840 || startOffsetMinutes > 840 ||
+                expOffsetMinutes < -840 || expOffsetMinutes > 840)
+            {
+                TempData.SetStatusMessageModel(new()
+                {
+                    Severity = StatusMessageModel.StatusSeverity.Error,
+                    Html = StringLocalizer["Invalid timezone offset."]
+                });
+                return GoToOffering(storeId, offeringId, SubscriptionSection.Subscribers);
+            }
+
+            var parsedStart = new DateTimeOffset(startDate.Value.ToDateTime(TimeOnly.MinValue),
+                TimeSpan.FromMinutes(-startOffsetMinutes)).ToUniversalTime();
+
+            DateTimeOffset? parsedExpiration = null;
+            if (expirationDate is not null)
+            {
+                parsedExpiration = new DateTimeOffset(expirationDate.Value.ToDateTime(TimeOnly.MinValue),
+                    TimeSpan.FromMinutes(-expOffsetMinutes)).ToUniversalTime();
+                if (parsedExpiration.Value <= parsedStart)
+                {
+                    TempData.SetStatusMessageModel(new()
+                    {
+                        Severity = StatusMessageModel.StatusSeverity.Error,
+                        Html = StringLocalizer["Expiration date must be after the start date."]
+                    });
+                    return GoToOffering(storeId, offeringId, SubscriptionSection.Subscribers);
+                }
+            }
+
+            await SubsService.UpdateDates(sub.Id, parsedStart, parsedExpiration);
+            TempData.SetStatusSuccess(StringLocalizer["Subscription dates updated for {0}", subName]);
+        }
 
         return GoToOffering(storeId, offeringId, SubscriptionSection.Subscribers);
     }
diff --git a/BTCPayServer/Plugins/Subscriptions/SubscriptionHostedService.cs b/BTCPayServer/Plugins/Subscriptions/SubscriptionHostedService.cs
index 4424912..2c009c3 100644
--- a/BTCPayServer/Plugins/Subscriptions/SubscriptionHostedService.cs
+++ b/BTCPayServer/Plugins/Subscriptions/SubscriptionHostedService.cs
@@ -134,8 +134,42 @@ public class SubscriptionHostedService(
             await ctx.SaveChangesAsync();
             await UpdateSubscriptionStates(subCtx, move.MemberSelector);
         }
+        else if (evt is UpdateDatesRequest datesRequest)
+        {
+            var ctx = subCtx.Context;
+            var sub = await ctx.Subscribers.IncludeAll().FirstOrDefaultAsync(s => s.Id == datesRequest.SubId, cancellationToken);
+            if (sub is null)
+                throw new InvalidOperationException("Subscriber not found");
+
+            sub.PlanStarted = datesRequest.StartDate;
+            sub.PaymentReminded = false;
+
+            if (datesRequest.ExpirationDate is { } expDate)
+            {
+                if (sub.TrialEnd is not null)
+                {
+                    sub.TrialEnd = expDate;
+                    sub.ReminderDate = expDate - TimeSpan.FromDays(sub.PaymentReminderDaysOrDefault);
+                }
+                else if (sub.Plan.RecurringType != PlanData.RecurringInterval.Lifetime)
+                {
+                    sub.PeriodEnd = expDate;
+                    sub.TrialEnd = null;
+                    sub.GracePeriodEnd = sub.Plan.GracePeriodDays > 0 ? expDate.AddDays(sub.Plan.GracePeriodDays) : (DateTimeOffset?)null;
+                    sub.ReminderDate = expDate - TimeSpan.FromDays(sub.PaymentReminderDaysOrDefault);
+                }
+            }
+
+            await ctx.SaveChangesAsync(cancellationToken);
+            await UpdateSubscriptionStates(subCtx, datesRequest.SubId);
+        }
     }
 
+    record UpdateDatesRequest(long SubId, DateTimeOffset StartDate, DateTimeOffset? ExpirationDate);
+
+    public Task UpdateDates(long subId, DateTimeOffset startDate, DateTimeOffset? expirationDate)
+        => RunEvent(new UpdateDatesRequest(subId, startDate, expirationDate));
+
     SubscriptionContext CreateContext() => CreateContext(CancellationToken);
 
     SubscriptionContext CreateContext(CancellationToken cancellationToken) =>
diff --git a/BTCPayServer/Plugins/Subscriptions/Views/UIOffering/EditDatesModal.cshtml b/BTCPayServer/Plugins/Subscriptions/Views/UIOffering/EditDatesModal.cshtml
new file mode 100644
index 0000000..1e86d75
--- /dev/null
+++ b/BTCPayServer/Plugins/Subscriptions/Views/UIOffering/EditDatesModal.cshtml
@@ -0,0 +1,109 @@
+<div class="modal fade" id="editDatesModal" tabindex="-1" aria-hidden="true">
+    <div class="modal-dialog modal-dialog-centered">
+        <div class="modal-content">
+            <div class="modal-header">
+                <h4 class="modal-title" text-translate="true">Edit Subscription Dates</h4>
+                <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="@StringLocalizer["Close"]">
+                    <vc:icon symbol="close" />
+                </button>
+            </div>
+            <form method="post">
+                <div class="modal-body">
+                    <div>
+                        <span text-translate="true">Editing dates for</span>
+                        <span class="edit-dates-subscriber-name fw-semibold"></span>
+                    </div>
+                </div>
+                <div class="modal-body pt-0">
+                    <input name="customerId" type="hidden" />
+                    <input name="timezoneOffset" type="hidden" class="edit-dates-tz" />
+                    <input name="expirationTimezoneOffset" type="hidden" class="edit-dates-expiry-tz" />
+
+                    <div class="mb-3">
+                        <label class="form-label" text-translate="true">Start Date</label>
+                        <input type="date" name="startDate" class="form-control edit-dates-start" required />
+                    </div>
+
+                    <div class="mb-3 edit-dates-expiration-group">
+                        <label class="form-label edit-dates-expiration-label"></label>
+                        <input type="date" name="expirationDate" class="form-control edit-dates-expiration" />
+                        <div class="form-text text-muted" text-translate="true">
+                            Grace period and reminder date are recalculated automatically from plan settings.
+                            Leave blank for lifetime plans.
+                        </div>
+                    </div>
+                    <div class="text-danger edit-dates-error" style="display:none"></div>
+                </div>
+                <div class="modal-footer">
+                    <button type="button" class="btn btn-secondary" data-bs-dismiss="modal" text-translate="true">Cancel</button>
+                    <button type="submit" class="btn btn-primary edit-dates-save" name="command" value="edit-dates" text-translate="true">Save</button>
+                </div>
+            </form>
+        </div>
+    </div>
+</div>
+
+<script>
+    document.addEventListener('DOMContentLoaded', function () {
+        const modalEl = document.getElementById('editDatesModal');
+        if (!modalEl) return;
+
+        const startInput = modalEl.querySelector('.edit-dates-start');
+        const expirationInput = modalEl.querySelector('.edit-dates-expiration');
+        const expirationLabel = modalEl.querySelector('.edit-dates-expiration-label');
+        const errorEl = modalEl.querySelector('.edit-dates-error');
+        const saveBtn = modalEl.querySelector('.edit-dates-save');
+        const tzInput = modalEl.querySelector('.edit-dates-tz');
+        const expiryTzInput = modalEl.querySelector('.edit-dates-expiry-tz');
+
+        function offsetForDate(dateString) {
+            return dateString
+                ? new Date(dateString + 'T00:00:00').getTimezoneOffset()
+                : new Date().getTimezoneOffset();
+        }
+
+        function validate() {
+            const start = startInput.value;
+            const expiration = expirationInput.value;
+            if (start && expiration && expiration <= start) {
+                errorEl.innerText = 'Expiration date must be after the start date.';
+                errorEl.style.display = '';
+                saveBtn.disabled = true;
+            } else {
+                errorEl.style.display = 'none';
+                saveBtn.disabled = false;
+            }
+        }
+
+        startInput.addEventListener('change', function () {
+            tzInput.value = offsetForDate(this.value);
+            validate();
+        });
+        expirationInput.addEventListener('change', function () {
+            expiryTzInput.value = offsetForDate(this.value);
+            validate();
+        });
+
+        modalEl.addEventListener('show.bs.modal', function (event) {
+            const trigger = event.relatedTarget;
+            if (!trigger) return;
+
+            const tr = trigger.closest('tr');
+            modalEl.querySelector('input[name="customerId"]').value = tr.getAttribute('data-subscriber-id') || '';
+            modalEl.querySelector('.edit-dates-subscriber-name').innerText = tr.getAttribute('data-subscriber-email') || '';
+
+            const startVal = tr.getAttribute('data-plan-started') || '';
+            const expVal = tr.getAttribute('data-expiration') || '';
+            startInput.value = startVal;
+            expirationInput.value = expVal;
+            tzInput.value = offsetForDate(startVal);
+            expiryTzInput.value = offsetForDate(expVal);
+
+            const isTrial = tr.getAttribute('data-is-trial') === 'true';
+            expirationLabel.innerText = isTrial ? 'Trial End Date' : 'Expiration Date';
+
+            errorEl.style.display = 'none';
+            saveBtn.disabled = false;
+        });
+    });
+</script>
diff --git a/BTCPayServer/Plugins/Subscriptions/Views/UIOffering/Offering.cshtml b/BTCPayServer/Plugins/Subscriptions/Views/UIOffering/Offering.cshtml
index 67a9c69..502238c 100644
--- a/BTCPayServer/Plugins/Subscriptions/Views/UIOffering/Offering.cshtml
+++ b/BTCPayServer/Plugins/Subscriptions/Views/UIOffering/Offering.cshtml
@@ -1,4 +1,4 @@
-@using BTCPayServer.Client
+@using BTCPayServer.Client
 @using BTCPayServer.Plugins.Emails
 @using BTCPayServer.Plugins.Subscriptions
 @using BTCPayServer.Plugins.Subscriptions.Controllers
@@ -203,6 +203,8 @@
                 <tr>
                     <th text-translate="true">User</th>
                     <th text-translate="true">Credits</th>
+                    <th text-translate="true">Start Date</th>
+                    <th text-translate="true">Expiration</th>
                     <th text-translate="true">Plan</th>
                     <th text-translate="true">Phase</th>
                     <th text-translate="true">Status</th>
@@ -217,7 +219,10 @@
                         <tr data-subscriber-email="@subscriber.Data.Customer.Email.Get()"
                             data-subscriber-id="@subscriber.Data.CustomerId"
                             data-currency="@subscriber.Data.Plan.Currency"
-                            data-current-credit-value="@subscriber.Data.GetCredit()">
+                            data-current-credit-value="@subscriber.Data.GetCredit()"
+                            data-plan-started="@subscriber.Data.PlanStarted.UtcDateTime.ToString("yyyy-MM-dd")"
+                            data-expiration="@((subscriber.Data.TrialEnd ?? subscriber.Data.PeriodEnd)?.UtcDateTime.ToString("yyyy-MM-dd") ?? "")"
+                            data-is-trial="@(subscriber.Data.TrialEnd.HasValue ? "true" : "false")">
                             <td class="fw-semibold text-nowrap d-flex align-items-center subscriber-email-col">
                                 @if (subscriber.Data.TestAccount)
                                 {
@@ -273,6 +278,36 @@
                                     @DisplayFormatter.Currency(subscriber.Data.GetCredit(), subscriber.Data.Plan.Currency, DisplayFormatter.CurrencyFormat.CodeAndSymbol)
                                 </span>
                             </td>
+                            <td class="text-nowrap">
+                                <a href="#"
+                                   class="edit-dates-link text-decoration-none"
+                                   data-bs-toggle="modal"
+                                   data-bs-target="#editDatesModal"
+                                   title="@StringLocalizer["Edit dates"]">
+                                    @subscriber.Data.PlanStarted.ToString("d")
+                                    <span class="ms-1 text-muted small">&#x270E;</span>
+                                </a>
+                            </td>
+                            <td class="text-nowrap">
+                                @{
+                                    var subExpiry = subscriber.Data.TrialEnd ?? subscriber.Data.PeriodEnd;
+                                }
+                                @if (subExpiry.HasValue)
+                                {
+                                    <a href="#"
+                                       class="edit-dates-link text-decoration-none"
+                                       data-bs-toggle="modal"
+                                       data-bs-target="#editDatesModal"
+                                       title="@StringLocalizer["Edit dates"]">
+                                        @subExpiry.Value.ToString("d")
+                                        <span class="ms-1 text-muted small">&#x270E;</span>
+                                    </a>
+                                }
+                                else
+                                {
+                                    <span class="text-muted">—</span>
+                                }
+                            </td>
                             <td class="text-nowrap">@subscriber.Data.Plan.Name</td>
                             <td>
                         <span class="subscriber-phase">
@@ -454,6 +489,7 @@
     <partial name="SuspendSubscriberModal" />
     <partial name="NewSubscriberModal" model="Model.SelectablePlans" />
     <partial name="ChangeCreditModal" />
+    <partial name="EditDatesModal" />
 </div>
 
 @section PageFootContent {
diff --git a/BTCPayServer/wwwroot/swagger/v1/swagger.template.subscriptions.json b/BTCPayServer/wwwroot/swagger/v1/swagger.template.subscriptions.json
index 427cb41..c69491a 100644
--- a/BTCPayServer/wwwroot/swagger/v1/swagger.template.subscriptions.json
+++ b/BTCPayServer/wwwroot/swagger/v1/swagger.template.subscriptions.json
@@ -481,6 +481,69 @@
                 }
             }
         },
+        "/api/v1/stores/{storeId}/offerings/{offeringId}/subscribers/{customerSelector}/dates": {
+            "put": {
+                "summary": "Update subscriber dates",
+                "description": "Manually overrides the subscription start date and/or expiration date for a subscriber.\n\nOmitting a field leaves the corresponding date unchanged. An empty body `{}` is a no-op and returns the subscriber unchanged.\n\nWhen `expirationDate` is provided, the grace period end and reminder date are recalculated automatically from the plan settings.",
+                "operationId": "UpdateSubscriberDates",
+                "tags": ["Subscriptions"],
+                "security": [
+                    {
+                        "API_Key": [
+                            "btcpay.store.canmanagesubscribers"
+                        ],
+                        "Basic": []
+                    }
+                ],
+                "parameters": [
+                    {
+                        "$ref": "#/components/parameters/StoreId"
+                    },
+                    {
+                        "$ref": "#/components/parameters/OfferingId"
+                    },
+                    {
+                        "$ref": "#/components/parameters/CustomerSelector"
+                    }
+                ],
+                "requestBody": {
+                    "required": true,
+                    "description": "Dates to update. All fields are optional — omitting a field leaves it unchanged.",
+                    "content": {
+                        "application/json": {
+                            "schema": {
+                                "$ref": "#/components/schemas/UpdateSubscriberDatesRequest"
+                            }
+                        }
+                    }
+                },
+                "responses": {
+                    "200": {
+                        "description": "Subscriber dates updated (or unchanged if no fields were provided).",
+                        "content": {
+                            "application/json": {
+                                "schema": {
+                                    "$ref": "#/components/schemas/SubscriberModel"
+                                }
+                            }
+                        }
+                    },
+                    "400": {
+                        "description": "Error code: `invalid-dates`. The expiration date must be after the start date.",
+                        "content": {
+                            "application/json": {
+                                "schema": {
+                                    "$ref": "#/components/schemas/ProblemDetails"
+                                }
+                            }
+                        }
+                    },
+                    "404": {
+                        "description": "Subscriber not found."
+                    }
+                }
+            }
+        },
         "/api/v1/plan-checkout/{checkoutId}": {
             "get": {
                 "summary": "Get a plan checkout",
@@ -920,6 +983,26 @@
                     }
                 }
             },
+            "UpdateSubscriberDatesRequest": {
+                "type": "object",
+                "description": "Request payload for updating subscriber dates. All fields are optional — omitting a field leaves the corresponding date unchanged.",
+                "properties": {
+                    "startDate": {
+                        "type": "integer",
+                        "format": "unix-time",
+                        "nullable": true,
+                        "description": "New subscription start date as a Unix timestamp. Omit to leave the current start date unchanged.",
+                        "example": 1710000000
+                    },
+                    "expirationDate": {
+                        "type": "integer",
+                        "format": "unix-time",
+                        "nullable": true,
+                        "description": "New expiration date as a Unix timestamp. Updates `trialEnd` if the subscriber is in a trial, otherwise updates `periodEnd`. Grace period end and reminder date are recalculated automatically. Omit to leave the current expiration date unchanged.",
+                        "example": 1712678400
+                    }
+                }
+            },
             "CustomerSelector": {
                 "type": "string",
                 "description": "Flexible identifier for selecting a customer. Supports: customer ID (e.g., `cust_abc123`), an email (e.g., `user@example.com`), or a key/value identity (e.g., `Email:user@example.com`).",