diff --git a/apps/edr-freight-api/src/modules/train-scheduling/batch-window.util.spec.ts b/apps/edr-freight-api/src/modules/train-scheduling/batch-window.util.spec.ts
index 797421fcc..25ee84b8c 100644
--- a/apps/edr-freight-api/src/modules/train-scheduling/batch-window.util.spec.ts
+++ b/apps/edr-freight-api/src/modules/train-scheduling/batch-window.util.spec.ts
@@ -110,10 +110,11 @@ describe('batch-window board windows (config-driven booking cycles)', () => {
       (w, i) => i > 0 && windows[i - 1].date !== w.date,
     );
     expect(crossesNight).toBe(true);
-    // Cycles run continuously from the window day up to departure.
-    expect(windows[windows.length - 1].end.getTime()).toBeLessThanOrEqual(
-      departure.getTime(),
-    );
+    // Cycles run continuously from the window day up to departure — the last one
+    // reaches departure, proving the runaway cap did not truncate the projection.
+    expect(windows[windows.length - 1].end.getTime()).toBe(departure.getTime());
+    // Spans the full lead (window day 05 Jun → departure 08 Jun).
+    expect(new Set(windows.map((w) => w.date)).size).toBeGreaterThanOrEqual(3);
   });
 
   it('export: single FCFS window exportBookingLeadHours before departure', () => {
diff --git a/apps/edr-freight-api/src/modules/train-scheduling/batch-window.util.ts b/apps/edr-freight-api/src/modules/train-scheduling/batch-window.util.ts
index a38d9e75f..442c21f95 100644
--- a/apps/edr-freight-api/src/modules/train-scheduling/batch-window.util.ts
+++ b/apps/edr-freight-api/src/modules/train-scheduling/batch-window.util.ts
@@ -164,6 +164,10 @@ export function isRoundTheClock(hours: OfficeHours): boolean {
  *
  * Returns `null` when the next open would fall on/after `departure` — the train
  * leaves before another cycle could run, so the window is done.
+ *
+ * Precondition: `windowCloseHour >= windowOpenHour` — the desk runs within a
+ * single EAT day and never wraps past midnight (enforced when global rules are
+ * saved). openHour === closeHour is the 24-hour desk, handled first.
  */
 export function nextCycleOpensAt(
   earliestNextOpen: Date,
@@ -179,7 +183,7 @@ export function nextCycleOpensAt(
     const openMinutes = hours.windowOpenHour * 60;
     const closeMinutes = hours.windowCloseHour * 60;
     if (readyMinutes < openMinutes) {
-      // Desk not open yet today (ready before opening) → open this morning.
+      // Ready before the desk opens on its own EAT calendar day → open this morning.
       opensAt = eatDayToUtc(eatDay(earliestNextOpen), hours.windowOpenHour);
     } else if (readyMinutes < closeMinutes) {
       // Inside office hours → open as soon as ready.
@@ -397,9 +401,16 @@ export function listConfigBookingWindows(
   const windowDay = shiftEatDay(eatDay(departure), -cfg.importWindowLeadDays);
 
   let opensAt: Date | null = anchorOpensAt ?? eatDayToUtc(windowDay, cfg.windowOpenHour);
-  // Reopen daily until the train departs; cap the projection so a tiny duration
-  // can't run away (spanning up to importWindowLeadDays of office days).
-  for (let cycle = 0; cycle < 200; cycle += 1) {
+  // The loop terminates naturally: every cycle advances opensAt by at least
+  // (duration + reopen) > 0, and nextCycleOpensAt returns null once opensAt would
+  // reach departure. maxCycles is a derived runaway backstop sized to the real
+  // span (first open → departure) over the smallest possible advance, so a
+  // legitimate config is never silently truncated — only a pathological
+  // zero-length one would hit it.
+  const spanMs = departure.getTime() - opensAt.getTime();
+  const minAdvanceMs = Math.max(durationMs + reopenMs, 60_000);
+  const maxCycles = Math.ceil(spanMs / minAdvanceMs) + 2;
+  for (let cycle = 0; cycle < maxCycles; cycle += 1) {
     if (opensAt.getTime() >= departure.getTime()) break;
     let closesAt = new Date(opensAt.getTime() + durationMs);
     if (closesAt.getTime() > departure.getTime()) closesAt = departure;
diff --git a/apps/edr-freight-api/src/modules/train-scheduling/train-scheduling.service.ts b/apps/edr-freight-api/src/modules/train-scheduling/train-scheduling.service.ts
index 6be4cd966..1f676f0f3 100644
--- a/apps/edr-freight-api/src/modules/train-scheduling/train-scheduling.service.ts
+++ b/apps/edr-freight-api/src/modules/train-scheduling/train-scheduling.service.ts
@@ -293,6 +293,17 @@ export class TrainSchedulingService {
     if (dto.paymentWindowMinutes != null) row.paymentWindowMinutes = dto.paymentWindowMinutes;
     if (dto.reopenDelayMinutes != null) row.reopenDelayMinutes = dto.reopenDelayMinutes;
 
+    // The daily booking desk runs [openHour, closeHour) within one EAT day, so
+    // the desk must not wrap past midnight. openHour === closeHour is the 24-hour
+    // desk; openHour > closeHour (an overnight range) is rejected — the reopen
+    // engine has no notion of a window that spans midnight.
+    if (row.windowCloseHour < row.windowOpenHour) {
+      throw new BadRequestException(
+        `Window close hour (${row.windowCloseHour}) must be on or after the open hour ` +
+          `(${row.windowOpenHour}); set them equal for a 24-hour desk.`,
+      );
+    }
+
     // Fields that change the STAMPED open/close times of a schedule. docReview/
     // payment/reopen are read live by the cron each tick, so they need no
     // re-stamp; only the four below feed computeImport/ExportWindowTimes.