diff --git a/internal/gateway/ui/index.html b/internal/gateway/ui/index.html
index 9bd187d..611d9a5 100644
--- a/internal/gateway/ui/index.html
+++ b/internal/gateway/ui/index.html
@@ -2016,16 +2016,41 @@ const pnote = $("#period-note");
           // like a bug unless the dates are on screen — so print them.
           const prange = $("#period-range");
           if (prange && st.period && st.period !== "all" && st.from) {
-            const d0 = new Date(st.from);
-            const d1 = st.buckets && st.buckets.length
-              ? new Date(st.buckets[st.buckets.length - 1].bucket + "T00:00:00Z")
-              : d0;
-            const f = (d) =>
-              d.toISOString().slice(0, 10);
-            prange.textContent =
-              t("periodRange") +
-              " " + f(d0) + " → " + f(d1) +
-              (st.buckets ? " (" + st.buckets.length + "d)" : "");
+            // Bucket labels are hourly for a day ("2026-10-03T09") and daily
+            // for a week or month ("2026-10-01"). Appending "T00:00:00Z" to
+            // the hourly form builds "2026-10-03T09T00:00:00Z", which Date
+            // rejects — toISOString() then throws and the whole assignment is
+            // lost, leaving the range line silently empty on the day view (the
+            // one people look at most).
+            const f = (d) => d.toISOString().slice(0, 10);
+            const label = st.buckets && st.buckets.length
+              ? st.buckets[st.buckets.length - 1].bucket
+              : "";
+            let endMs = 0;
+            if (/^\d{4}-\d{2}-\d{2}$/.test(label)) {
+              endMs = new Date(label + "T00:00:00Z").getTime();
+            } else if (/^\d{4}-\d{2}-\d{2}T\d{2}$/.test(label)) {
+              // An hourly bucket covers its hour, so the day it belongs to is
+              // what the range should end on.
+              endMs = new Date(label + ":00:00Z").getTime();
+            }
+            const from = new Date(st.from);
+            const end = endMs ? new Date(endMs) : from;
+            // The bucket count is not a day count: the day view buckets by
+            // HOUR, so "(5d)" for five hours of today was simply wrong. Days
+            // covered comes from the window itself, which is what the reader
+            // is trying to establish.
+            let days = 1;
+            if (endMs) {
+              days = Math.max(
+                1,
+                Math.round((endMs - from.getTime()) / 86400000) + 1,
+              );
+            }
+            const tail = " (" + days + "d)";
+            prange.textContent = endMs
+              ? t("periodRange") + " " + f(from) + " → " + f(end) + tail
+              : t("periodRange") + " " + f(from) + tail;
           } else if (prange) {
             prange.textContent = "";
           }
diff --git a/internal/gateway/ui_key_auto_test.go b/internal/gateway/ui_key_auto_test.go
index ba72a15..1caee4c 100644
--- a/internal/gateway/ui_key_auto_test.go
+++ b/internal/gateway/ui_key_auto_test.go
@@ -266,3 +266,24 @@ func TestUIKeyAutoEditsDoNotAutoPersist(t *testing.T) {
 		}
 	}
 }
+
+// The stats range line formats its end date from the LAST bucket label.
+// Bucket labels are hourly for the day view ("2026-10-03T09") and daily for
+// week/month ("2026-10-01"), so blindly appending "T00:00:00Z" to the hourly
+// form builds "2026-10-03T09T00:00:00Z" — Date rejects it, toISOString()
+// throws, and the assignment is lost. The symptom is an empty range line on
+// exactly the view people look at most, with no error anywhere.
+func TestUIStatsPeriodRangeHandlesHourlyBuckets(t *testing.T) {
+	src := uiSource(t)
+	el := readFuncBody(t, src, "paintStats")
+	// It must branch on the label shape instead of concatenating blindly.
+	if !strings.Contains(el, `T\d{2}$`) && !strings.Contains(el, `\d{2}-\d{2}T\d{2}`) {
+		t.Fatal("paintStats must recognise the hourly bucket label shape " +
+			"(YYYY-MM-DDTHH); concatenating a time onto it yields an invalid Date")
+	}
+	// And it must not contain the naive form that broke it.
+	if strings.Contains(el, `bucket + "T00:00:00Z"`) {
+		t.Fatal("paintStats still appends T00:00:00Z to the bucket label — " +
+			"this throws on the day view and leaves the range line empty")
+	}
+}