Load earlier calendar windows when editing historical dates

src/App.test.tsx

@@ -226,7 +226,7 @@ describe("homepage", () => {
 
   test("historical check-ins use the selected date's tracking method and preserve today", async () => {
     const f = connectAccount();
-    f.setTime("2026-09-03T12:00:00Z");
+    f.setTime("2026-01-03T12:00:00Z");
     const habit = await f.json("/habits", "POST", { name: "Reading", method: "manual" }, 201);
     f.setTime("2026-09-04T12:00:00Z");
     await f.json(`/habits/${habit.id}`, "PATCH", { method: "count", target: 10, unit: "pages" });
@@ -243,6 +243,14 @@ describe("homepage", () => {
     expect((await f.json(`/habits/${habit.id}/days/2026-09-03`)).complete).toBe(true);
     expect((await f.json(`/habits/${habit.id}/days/2026-09-04`)).value).toBe(0);
     expect(container.textContent).toContain("Saved check-in for 2026-09-03");
+    fetchMock.mockClear();
+    await act(async () => {
+      const input = container.querySelector<HTMLInputElement>('input[type="date"]')!;
+      Object.getOwnPropertyDescriptor(dom.HTMLInputElement.prototype, "value")!.set!.call(input, "2026-01-03");
+      input.dispatchEvent(new dom.Event("change", { bubbles: true }) as unknown as Event);
+    });
+    expect(container.querySelector('[aria-label^="2026-01-03:"]')).not.toBeNull();
+    expect(fetchMock.mock.calls.some(([url]) => String(url).includes("from=2025-11-01") && String(url).includes("compact=true"))).toBe(true);
   });
 
   test("signed-out visitors can try progress without calling private habit APIs", async () => {

src/components/HabitHistory.tsx

@@ -47,6 +47,14 @@ export function HabitHistory({
   const [historyLoading, setHistoryLoading] = useState(false);
   useEffect(() => { setRange(monthWindow(date, 3)); }, [date]);
   const [selectedDate, setSelectedDate] = useState<string>();
+  function selectDate(selected: string) {
+    setSelectedDate(selected);
+    const available = monthWindow(date, 12);
+    if (selected >= available.from && selected <= available.to && (selected < range.from || selected > range.to)) {
+      const requested = monthWindow(selected, 3);
+      setRange({ from: requested.from < available.from ? available.from : requested.from, to: requested.to });
+    }
+  }
   const [editingDay, setEditingDay] = useState(false);
   const [savingDay, setSavingDay] = useState(false);
   const [calendar, setCalendar] = useState<CalendarResponse | null>(null);
@@ -119,7 +127,7 @@ export function HabitHistory({
   ) : (
     <>
     <CalendarHeatmap
-      onSelectDate={setSelectedDate}
+      onSelectDate={selectDate}
       selectedDate={selectedDate}
       compact
       initialMonths={3}
@@ -132,7 +140,7 @@ export function HabitHistory({
       color={calendar.settings.mainColor}
       emptyColor={calendar.settings.emptyColor}
       days={days}
-      selectedDayAction={selected => <Button variant="secondary" disabled={disabled} aria-label="Edit selected check-in" aria-haspopup="dialog" onClick={() => { setSelectedDate(selected); setEditingDay(true); }}><Pencil size={16} aria-hidden="true" />Edit check-in</Button>}
+      selectedDayAction={selected => <Button variant="secondary" disabled={disabled} aria-label="Edit selected check-in" aria-haspopup="dialog" onClick={() => { selectDate(selected); setEditingDay(true); }}><Pencil size={16} aria-hidden="true" />Edit check-in</Button>}
       legend={
         <CalendarLegend
           label={`${habit.name} progress calendar`}
@@ -144,7 +152,7 @@ export function HabitHistory({
     />
     {editingDay && <Modal id={`check-in-${habit.habitId}`} title="Edit check-in" description={habit.name ?? "Habit"} closeLabel="Close check-in editor" onClose={() => setEditingDay(false)} busy={savingDay}>
     <div className="ds-history-editor">
-      <div className="ds-form-stack"><Field label="Check-in date">{id => <input id={id} type="date" disabled={savingDay} max={date} value={selectedDate ?? date} onChange={event => { if (event.target.value) setSelectedDate(event.target.value); }} />}</Field></div>
+      <div className="ds-form-stack"><Field label="Check-in date">{id => <input id={id} type="date" disabled={savingDay} max={date} value={selectedDate ?? date} onChange={event => { if (event.target.value) selectDate(event.target.value); }} />}</Field></div>
       <CheckInEditor key={`${habit.habitId}:${selectedDate ?? date}`} habitId={habit.habitId} date={selectedDate ?? date} disabled={disabled} onExpired={onExpired}
         onBusyChange={setSavingDay} onSaved={() => { setAttempt(value => value + 1); onHistorySaved?.(); }} />
     </div></Modal>}