From 9858316b30468c06eb0e35e9fee68fe57dd992fb Mon Sep 17 00:00:00 2001
From: Jennie Robinson Faber <jennie@jenniefaber.com>
Date: Mon, 18 May 2026 17:56:17 +0100
Subject: [PATCH] fix(admin-events): preserve datetime on edit round-trip

Editing an event was pulling its UTC startDate/endDate, slicing off the
"Z" with toISOString().slice(0, 16), and then handing the bare digits to
a datetime-local input. The input reinterprets them as local time, so
each save shifted the time by the browser's UTC offset. Same pattern
for registrationDeadline and earlyBirdDeadline.

Format the value using local-time components instead so the round-trip
matches what the admin sees.
---
 app/pages/admin/events/create.vue | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/app/pages/admin/events/create.vue b/app/pages/admin/events/create.vue
index 07267e5..7f910fe 100644
--- a/app/pages/admin/events/create.vue
+++ b/app/pages/admin/events/create.vue
@@ -649,6 +649,16 @@ const eventForm = reactive({
   },
 });
 
+// Format a Date/ISO value into a datetime-local string using local-time components.
+// `toISOString().slice(0,16)` drifts by the browser's UTC offset on edit round-trip.
+const formatForDatetimeLocal = (value) => {
+  if (!value) return "";
+  const d = new Date(value);
+  if (isNaN(d.getTime())) return "";
+  const pad = (n) => String(n).padStart(2, "0");
+  return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}T${pad(d.getHours())}:${pad(d.getMinutes())}`;
+};
+
 // Agenda management functions
 const addAgendaItem = () => {
   eventForm.agenda.push("");
@@ -711,8 +721,8 @@ if (route.query.edit) {
         description: event.description,
         content: event.content || "",
         featureImage: event.featureImage || null,
-        startDate: new Date(event.startDate).toISOString().slice(0, 16),
-        endDate: new Date(event.endDate).toISOString().slice(0, 16),
+        startDate: formatForDatetimeLocal(event.startDate),
+        endDate: formatForDatetimeLocal(event.endDate),
         eventType: event.eventType,
         location: event.location || "",
         isOnline: event.isOnline,
@@ -723,9 +733,7 @@ if (route.query.edit) {
         tags: event.tags || [],
         maxAttendees: event.maxAttendees || "",
         registrationRequired: event.registrationRequired,
-        registrationDeadline: event.registrationDeadline
-          ? new Date(event.registrationDeadline).toISOString().slice(0, 16)
-          : "",
+        registrationDeadline: formatForDatetimeLocal(event.registrationDeadline),
         agenda: event.agenda || [],
         tickets: event.tickets || {
           enabled: false,
@@ -746,13 +754,10 @@ if (route.query.edit) {
           description: "",
         },
       });
-      // Handle early bird deadline formatting
       if (event.tickets?.public?.earlyBirdDeadline) {
-        eventForm.tickets.public.earlyBirdDeadline = new Date(
+        eventForm.tickets.public.earlyBirdDeadline = formatForDatetimeLocal(
           event.tickets.public.earlyBirdDeadline,
-        )
-          .toISOString()
-          .slice(0, 16);
+        );
       }
     }
   } catch (error) {