Add longer battery ranges and a custom date-range picker

Extends the battery card's range beyond Today/3 days/This week to Last 30
days, Last 365 days, All time, and a user-picked custom start/end date.
Since battery telemetry is only ever captured on the live "today" poll and
never backfilled, a long or all-time range typically has real gaps -- the
card now shows how many of the requested days actually have battery data
rather than implying continuous history.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/api/usage.py

@@ -33,6 +33,27 @@ def _resolve_start(session, days: str, end: datetime) -> datetime:
     return end - timedelta(days=n)
 
 
+def _resolve_range(
+    session, days: str, start_date: str | None, end_date: str | None
+) -> tuple[datetime, datetime]:
+    """Either a `days`/"all" preset (relative to now), or an explicit
+    `start_date`/`end_date` pair ("YYYY-MM-DD", inclusive, interpreted as
+    whole Brisbane-local calendar days) for a user-picked custom range."""
+    if start_date or end_date:
+        if not start_date or not end_date:
+            raise HTTPException(400, "start_date and end_date must both be given for a custom range")
+        try:
+            start = datetime.strptime(start_date, "%Y-%m-%d").replace(tzinfo=BNE)
+            end = datetime.strptime(end_date, "%Y-%m-%d").replace(tzinfo=BNE) + timedelta(days=1)
+        except ValueError:
+            raise HTTPException(400, "start_date/end_date must be in YYYY-MM-DD format")
+        if end <= start:
+            raise HTTPException(400, "end_date must be on or after start_date")
+        return start, end
+    end = datetime.now(timezone.utc)
+    return _resolve_start(session, days, end), end
+
+
 def _bucket_key(local_date, granularity: str) -> str:
     if granularity == "month":
         return local_date.replace(day=1).isoformat()
@@ -163,19 +184,27 @@ def tou_breakdown(days: str = Query("1")) -> dict:
     }
 
 
+_MAX_BATTERY_CHART_POINTS = 2000
+
+
 @router.get("/battery_history")
-def battery_history(days: str = Query("1")) -> dict:
+def battery_history(
+    days: str = Query("1"), start_date: str | None = Query(None), end_date: str | None = Query(None)
+) -> dict:
     """SOC/charge/discharge curve for plants with a battery. Battery
     telemetry is only ever captured on the live "today" poll (see
     `IntervalReadingRow.battery_soc_percent`), never backfilled for
     historical rows, so a plant with no battery -- or one whose data
-    predates that feature -- simply returns no points here."""
-    end = datetime.now(timezone.utc)
+    predates that feature -- simply returns no points here. Over a long or
+    "all time" range, most of that range typically has no battery data at
+    all (e.g. it predates the battery being installed, or this feature
+    shipping) -- `days_with_data`/`range_days` let the UI say so plainly
+    rather than implying a full, continuous history."""
     with get_session() as session:
-        start = _resolve_start(session, days, end)
+        start, end = _resolve_range(session, days, start_date, end_date)
         rows = get_usage_series(session, start, end)
 
-    points = [
+    all_points = [
         {
             "ts": row.ts.isoformat(),
             "soc_percent": row.battery_soc_percent,
@@ -185,23 +214,41 @@ def battery_history(days: str = Query("1")) -> dict:
         for row in rows
         if row.battery_soc_percent is not None
     ]
-    return {"available": bool(points), "points": points}
+    days_with_data = len({row.ts.astimezone(BNE).date() for row in rows if row.battery_soc_percent is not None})
+    range_days = max(1, (end - start).days)
+
+    points = all_points
+    if len(points) > _MAX_BATTERY_CHART_POINTS:
+        # Long ranges (a year, "all time") can accumulate more points than a
+        # line chart can usefully render -- evenly subsample rather than
+        # truncating, so the shape of the whole range is still represented.
+        step = len(points) / _MAX_BATTERY_CHART_POINTS
+        points = [points[int(i * step)] for i in range(_MAX_BATTERY_CHART_POINTS)]
+
+    return {
+        "available": bool(all_points),
+        "points": points,
+        "days_with_data": days_with_data,
+        "range_days": range_days,
+    }
 
 
 @router.get("/battery_value")
-def battery_value(days: str = Query("1")) -> dict:
+def battery_value(
+    days: str = Query("1"), start_date: str | None = Query(None), end_date: str | None = Query(None)
+) -> dict:
     """What the battery actually saved you: discharged energy valued at the
     import rate it avoided, minus charged energy valued at the feed-in
     credit it gave up, both matched to the current plan's own TOU windows."""
-    end = datetime.now(timezone.utc)
     with get_session() as session:
-        start = _resolve_start(session, days, end)
+        start, end = _resolve_range(session, days, start_date, end_date)
         rows = get_usage_series(session, start, end)
         current_plan = get_current_plan(session)
 
+    range_days = max(1, (end - start).days)
     battery_rows = [r for r in rows if r.battery_charge_w is not None or r.battery_discharge_w is not None]
     if not battery_rows or current_plan is None:
-        return {"available": False}
+        return {"available": False, "range_days": range_days}
 
     battery_readings = []
     for row in battery_rows:
@@ -220,6 +267,7 @@ def battery_value(days: str = Query("1")) -> dict:
     return {
         "available": True,
         "days_with_data": result.days_with_data,
+        "range_days": range_days,
         "charged_kwh": round(result.charged_kwh, 2),
         "discharged_kwh": round(result.discharged_kwh, 2),
         "avoided_import_dollars": round(result.avoided_import_dollars, 2),

app/static/css/style.css

@@ -207,6 +207,15 @@ form.settings-form label.p-day-label input {
 .tou-bar-fill-credit { background: var(--good); }
 .tou-bar-amount { width: 130px; flex-shrink: 0; text-align: right; }
 
+select, input[type="date"] {
+  background: var(--card-bg);
+  color: var(--fg);
+  border: 1px solid var(--border);
+  border-radius: 4px;
+  padding: 0.35rem 0.5rem;
+  font-size: 0.9rem;
+}
+
 .pill-toggle { display: inline-flex; border: 1px solid var(--border); border-radius: 6px; overflow: hidden; }
 .pill-toggle button {
   margin: 0;

app/web/templates/dashboard.html

@@ -99,12 +99,25 @@
 <div class="card" id="battery-card" style="display:none;">
   <div style="display:flex; justify-content:space-between; align-items:center; flex-wrap:wrap; gap:0.5rem;">
     <h3 style="margin:0;">Battery</h3>
-    <div class="pill-toggle" id="battery-range-toggle">
-      <button data-days="1" class="active">Today</button>
-      <button data-days="3">Last 3 days</button>
-      <button data-days="7">This week</button>
+    <div style="display:flex; gap:0.5rem; align-items:center; flex-wrap:wrap;">
+      <select id="battery-range-select">
+        <option value="1" selected>Today</option>
+        <option value="3">Last 3 days</option>
+        <option value="7">This week</option>
+        <option value="30">Last 30 days</option>
+        <option value="365">Last 365 days</option>
+        <option value="all">All time</option>
+        <option value="custom">Custom range&hellip;</option>
+      </select>
+      <span id="battery-custom-range" style="display:none; gap:0.4rem; align-items:center;">
+        <input type="date" id="battery-start-date">
+        <span class="muted">to</span>
+        <input type="date" id="battery-end-date">
+        <button id="battery-apply-range" style="margin:0; padding:0.35rem 0.7rem; font-size:0.85rem;">Apply</button>
+      </span>
     </div>
   </div>
+  <div id="battery-coverage-note" class="muted" style="margin-top:0.4rem;"></div>
   <div class="chart-container" style="height:220px;">
     <canvas id="battery-soc-chart"></canvas>
   </div>
@@ -327,10 +340,17 @@ touToggle.addEventListener('click', (e) => {
   loadTouBreakdown(btn.dataset.days);
 });
 
-async function loadBatterySection(days) {
+function batteryQueryString(range) {
+  return range.startDate
+    ? `start_date=${range.startDate}&end_date=${range.endDate}`
+    : `days=${range.days}`;
+}
+
+async function loadBatterySection(range) {
+  const qs = batteryQueryString(range);
   const [history, value] = await Promise.all([
-    fetch(`/api/usage/battery_history?days=${days}`).then(r => r.json()),
-    fetch(`/api/usage/battery_value?days=${days}`).then(r => r.json()),
+    fetch(`/api/usage/battery_history?${qs}`).then(r => r.json()),
+    fetch(`/api/usage/battery_value?${qs}`).then(r => r.json()),
   ]);
 
   const card = document.getElementById('battery-card');
@@ -343,7 +363,24 @@ async function loadBatterySection(days) {
   }
   card.style.display = '';
 
-  const multiDay = days !== '1';
+  const coverageNote = document.getElementById('battery-coverage-note');
+  if (history.days_with_data < history.range_days) {
+    // Battery telemetry is only ever captured on the live "today" poll,
+    // never backfilled -- so a long or "all time" range will usually have
+    // real gaps (before the battery existed, before this feature shipped,
+    // or a day the system was offline). Say so plainly rather than let a
+    // sparse chart look like a data bug.
+    coverageNote.textContent = `${history.days_with_data} of ${history.range_days} day(s) in this range have battery data.`;
+  } else {
+    coverageNote.textContent = `${history.days_with_data} day(s) of battery data.`;
+  }
+
+  // Multi-day spans get a date in the label; a single day just gets the
+  // time -- based on what the data actually spans, not the range picked,
+  // since a long range with sparse data can still resolve to under a day.
+  const first = history.points[0] ? new Date(history.points[0].ts) : null;
+  const last = history.points.length ? new Date(history.points[history.points.length - 1].ts) : null;
+  const multiDay = first && last && (last - first) > 24 * 60 * 60 * 1000;
   const labels = history.points.map(p => {
     const d = new Date(p.ts);
     return d.toLocaleString('en-AU', {
@@ -391,7 +428,7 @@ async function loadBatterySection(days) {
   }
   const net = value.net_value_dollars;
   const approxNote = value.uses_tiered_feed_in_approximation
-    ? ' Export credit side is approximated: your plan\'s feed-in tariff depends on daily export volume, not time of day.'
+    ? '<div class="muted" style="margin-top:0.5rem;">Export credit side is approximated: your plan\'s feed-in tariff depends on daily export volume, not time of day.</div>'
     : '';
   valueBody.innerHTML = `
     <div style="display:flex; gap:2rem; flex-wrap:wrap;">
@@ -401,17 +438,36 @@ async function loadBatterySection(days) {
       <div title="What the charged energy would have earned as feed-in credit had it been exported instead"><div class="muted">Foregone export credit</div><strong class="savings-negative">-$${value.foregone_export_dollars.toFixed(2)}</strong></div>
       <div><div class="muted">Estimated battery value</div><strong class="${net >= 0 ? 'savings-positive' : 'savings-negative'}">${net >= 0 ? '+' : '-'}$${Math.abs(net).toFixed(2)}</strong></div>
     </div>
-    <div class="muted" style="margin-top:0.5rem;">Over ${value.days_with_data} day(s) with battery data.${approxNote}</div>
+    ${approxNote}
   `;
 }
 
-const batteryToggle = document.getElementById('battery-range-toggle');
-batteryToggle.addEventListener('click', (e) => {
-  const btn = e.target.closest('button');
-  if (!btn) return;
-  batteryToggle.querySelectorAll('button').forEach(b => b.classList.remove('active'));
-  btn.classList.add('active');
-  loadBatterySection(btn.dataset.days);
+const batteryRangeSelect = document.getElementById('battery-range-select');
+const batteryCustomRange = document.getElementById('battery-custom-range');
+const batteryStartDate = document.getElementById('battery-start-date');
+const batteryEndDate = document.getElementById('battery-end-date');
+const batteryApplyRange = document.getElementById('battery-apply-range');
+
+batteryRangeSelect.addEventListener('change', () => {
+  if (batteryRangeSelect.value === 'custom') {
+    batteryCustomRange.style.display = 'inline-flex';
+    // Default the pickers to a sensible starting point (last 30 days)
+    // rather than leaving them empty with nothing to Apply yet.
+    if (!batteryEndDate.value) {
+      const today = new Date();
+      const monthAgo = new Date(today.getTime() - 30 * 24 * 60 * 60 * 1000);
+      batteryEndDate.value = today.toISOString().slice(0, 10);
+      batteryStartDate.value = monthAgo.toISOString().slice(0, 10);
+    }
+    return;
+  }
+  batteryCustomRange.style.display = 'none';
+  loadBatterySection({ days: batteryRangeSelect.value });
+});
+
+batteryApplyRange.addEventListener('click', () => {
+  if (!batteryStartDate.value || !batteryEndDate.value) return;
+  loadBatterySection({ startDate: batteryStartDate.value, endDate: batteryEndDate.value });
 });
 
 const rangeSelect = document.getElementById('range-select');
@@ -419,7 +475,7 @@ rangeSelect.addEventListener('change', () => loadDashboard(rangeSelect.value));
 loadDashboard(rangeSelect.value);
 
 loadTouBreakdown(1);
-loadBatterySection(1);
+loadBatterySection({ days: '1' });
 loadLiveFlow();
 setInterval(loadLiveFlow, FLOW_REFRESH_MS);
 </script>