diff --git a/shared/src/datetime/datetime-normalize.ts b/shared/src/datetime/datetime-normalize.ts
index c21aaa1d8..a292cd90a 100644
--- a/shared/src/datetime/datetime-normalize.ts
+++ b/shared/src/datetime/datetime-normalize.ts
@@ -19,6 +19,7 @@
  */
 
 const MERIDIEM_CLOCK = /^(\d{1,2})(?::(\d{2}))?(?::\d{2})?\s*([ap])\.?\s?m\.?$/i;
+const LEADING_DATE = /^(\d{4}-\d{2}-\d{2})/;
 
 /**
  * '3:00 PM' / '02:30:00 pm' / '3 PM' → '15:00'.
@@ -27,34 +28,40 @@ const MERIDIEM_CLOCK = /^(\d{1,2})(?::(\d{2}))?(?::\d{2})?\s*([ap])\.?\s?m\.?$/i
  */
 export function parseMeridiemClock(value: string | null | undefined): string | null {
   const m = MERIDIEM_CLOCK.exec((value || '').trim());
-  if (!m) return null;
-  let hour = Number.parseInt(m[1], 10);
-  const minute = m[2] ? Number.parseInt(m[2], 10) : 0;
+  const rawHour = m?.[1];
+  const half = m?.[3];
+  if (!rawHour || !half) return null;
+
+  let hour = Number.parseInt(rawHour, 10);
+  const minute = Number.parseInt(m?.[2] ?? '0', 10);
   if (!Number.isFinite(hour) || hour > 12) return null;
-  const isPm = m[3].toLowerCase() === 'p';
+
+  const isPm = half.toLowerCase() === 'p';
   // 12 AM is midnight and 12 PM is noon: the hour does not shift at 12.
   if (hour === 12) hour = isPm ? 12 : 0;
   else if (isPm) hour += 12;
+
   return `${String(hour).padStart(2, '0')}:${String(Math.min(59, minute)).padStart(2, '0')}`;
 }
 
+/** The part after a leading `YYYY-MM-DD`, with its `T` or space removed. */
+function clockPart(value: string): string {
+  return value.slice(10).replace(/^[T\s]/, '').trim();
+}
+
 /** Split a naive date-time string into its date and its 24-hour clock. */
 export function splitLocalDateTime(value: string | null | undefined): { date: string | null; time: string | null } {
   const raw = (value || '').trim();
-  if (!raw) return { date: null, time: null };
+  const date = LEADING_DATE.exec(raw)?.[1];
+  if (!date) return { date: null, time: null };
 
-  const dateMatch = /^(\d{4}-\d{2}-\d{2})/.exec(raw);
-  if (!dateMatch) return { date: null, time: null };
-  const date = dateMatch[1];
-
-  const rest = raw.slice(10).replace(/^[T\s]/, '').trim();
+  const rest = clockPart(raw);
   if (!rest) return { date, time: null };
 
   const meridiem = parseMeridiemClock(rest);
   if (meridiem) return { date, time: meridiem };
 
-  const clock = /^(\d{2}:\d{2})/.exec(rest);
-  return { date, time: clock ? clock[1] : null };
+  return { date, time: /^(\d{2}:\d{2})/.exec(rest)?.[1] ?? null };
 }
 
 /**
@@ -64,17 +71,18 @@ export function splitLocalDateTime(value: string | null | undefined): { date: st
  */
 export function normalizeLocalDateTime(value: string): string {
   if (!value) return value;
-  const dateMatch = /^(\d{4}-\d{2}-\d{2})/.exec(value.trim());
-  if (!dateMatch) return value;
+  const trimmed = value.trim();
+  const date = LEADING_DATE.exec(trimmed)?.[1];
+  if (!date) return value;
 
   // Only a printed 12-hour clock is rewritten. Everything else comes back
   // untouched, which is what makes this safe to drop into the middle of the
   // mapper: a value carrying a UTC offset, a date-only value, or a shape this
   // does not know keeps whatever it meant before.
-  const rest = value.trim().slice(10).replace(/^[T\s]/, '').trim();
+  const rest = clockPart(trimmed);
   const clock = parseMeridiemClock(rest);
   if (!clock) return value;
 
-  const seconds = /^\d{1,2}:\d{2}:(\d{2})/.exec(rest);
-  return `${dateMatch[1]}T${clock}:${seconds ? seconds[1] : '00'}`;
+  const seconds = /^\d{1,2}:\d{2}:(\d{2})/.exec(rest)?.[1] ?? '00';
+  return `${date}T${clock}:${seconds}`;
 }