diff --git a/frontend/src/pages/SessionHistoryPage.tsx b/frontend/src/pages/SessionHistoryPage.tsx
index e8d93aad..be1879a5 100644
--- a/frontend/src/pages/SessionHistoryPage.tsx
+++ b/frontend/src/pages/SessionHistoryPage.tsx
@@ -120,13 +120,16 @@ export function SessionHistoryPage() {
         if (filters.dateRange?.from) {
           const fromDate = filters.dateRange.from
           const toDate = filters.dateRange.to || filters.dateRange.from
+          // Set end-of-day on the "to" date so sessions created that day are included
+          const toDateEnd = new Date(toDate)
+          toDateEnd.setHours(23, 59, 59, 999)
 
           if (filters.dateType === 'started') {
             params.started_after = fromDate.toISOString()
-            params.started_before = toDate.toISOString()
+            params.started_before = toDateEnd.toISOString()
           } else {
             params.completed_after = fromDate.toISOString()
-            params.completed_before = toDate.toISOString()
+            params.completed_before = toDateEnd.toISOString()
           }
         }
 
@@ -176,7 +179,7 @@ export function SessionHistoryPage() {
           problem_domain: aiFilters.problem_domain || undefined,
           confidence_tier: aiFilters.confidence_tier || undefined,
           date_from: aiFilters.date_from || undefined,
-          date_to: aiFilters.date_to || undefined,
+          date_to: aiFilters.date_to ? `${aiFilters.date_to}T23:59:59.999Z` : undefined,
         })
         if (!cancelled) setAiSessions(data)
       } catch {