Preserve civil daypart clocks across DST

internal/report/period_test.go

@@ -43,6 +43,37 @@ func TestResolveDailyRequiresDate(t *testing.T) {
 	}
 }
 
+func TestDailyRunIDsDistinguishResolvedDates(t *testing.T) {
+	location := loadTestLocation(t)
+	now := parseTestTime("2026-05-29T17:45:00-05:00")
+	tests := []struct {
+		date     time.Time
+		wantDate string
+	}{
+		{date: time.Date(2026, time.May, 30, 12, 0, 0, 0, location), wantDate: "2026-05-30"},
+		{date: time.Date(2026, time.May, 31, 12, 0, 0, 0, location), wantDate: "2026-05-31"},
+	}
+
+	runIDs := make(map[string]struct{}, len(tests))
+	for _, tt := range tests {
+		resolved, err := Resolve(Daily, ResolveRequest{Now: now, Location: location, Date: tt.date})
+		if err != nil {
+			t.Fatalf("Resolve(Daily) error = %v", err)
+		}
+		runID := resolved.Metadata().RunID
+		if runID == "" {
+			t.Fatal("Daily RunID is empty")
+		}
+		if !strings.HasSuffix(runID, "_"+tt.wantDate) {
+			t.Fatalf("Daily RunID = %q, want resolved date %q", runID, tt.wantDate)
+		}
+		if _, exists := runIDs[runID]; exists {
+			t.Fatalf("duplicate Daily RunID %q", runID)
+		}
+		runIDs[runID] = struct{}{}
+	}
+}
+
 func TestRegistryContainsOnlyPromptBackedReports(t *testing.T) {
 	registry := DefaultRegistry()
 	definitions := registry.All()