Add a Sleep trend chart: cumulative sleep today vs yesterday and the recent average

Answers "is the puppy behind on sleep right now?": cumulative hours
slept sampled at each hour boundary, today's line ending at the current
moment, with yesterday and the mean of the last N days as reference
curves. N follows the 7/14/30 chart-days picker, and days with no sleep
logged are skipped so a young log doesn't drag the average down.

src/app.js

@@ -1241,6 +1241,128 @@
     svg.innerHTML = parts.join("");
   }
 
+  // ---------- sleep trend ----------
+  // Cumulative hours slept as the day progresses: today's running total (up to
+  // now) against yesterday's full curve and the mean of the last N full days,
+  // where N follows the 7/14/30 chart-days picker.
+  // Each curve is a list of { x: hour-of-day 0..24, y: cumulative hours }.
+  function sleepTrendCurves(events) {
+    const HOUR = 3_600_000;
+    const windows = sleepWindows(events); // ongoing sleep already clipped to now
+    const sleptMs = (from, to) => {
+      let total = 0;
+      for (const w of windows) {
+        const s = Math.max(w.start, from);
+        const e = Math.min(w.end, to);
+        if (e > s) total += e - s;
+      }
+      return total;
+    };
+    const dayStartTs = (daysAgo) => {
+      const d = startOfDay(new Date());
+      d.setDate(d.getDate() - daysAgo);
+      return d.getTime();
+    };
+    // capTs (today only) truncates the curve at "now" with a final fractional
+    // point, so the line visibly ends where the day currently stands.
+    const curveFor = (start, capTs) => {
+      const pts = [];
+      for (let h = 0; h <= 24; h++) {
+        const to = start + h * HOUR;
+        if (capTs != null && to >= capTs) {
+          pts.push({ x: (capTs - start) / HOUR, y: sleptMs(start, capTs) / HOUR });
+          break;
+        }
+        pts.push({ x: h, y: sleptMs(start, to) / HOUR });
+      }
+      return pts;
+    };
+
+    const today = curveFor(dayStartTs(0), Date.now());
+
+    const yesterdayCurve = curveFor(dayStartTs(1));
+    const yesterday = yesterdayCurve[24].y > 0 ? yesterdayCurve : null;
+
+    // Mean of the last N full days, skipping days with no sleep at all so a
+    // young log (or a tracking gap) doesn't drag the average toward zero.
+    const avgDays = chartDays();
+    const dayCurves = [];
+    for (let i = 1; i <= avgDays; i++) {
+      const c = curveFor(dayStartTs(i));
+      if (c[24].y > 0) dayCurves.push(c);
+    }
+    let avg = null;
+    if (dayCurves.length > 0) {
+      avg = [];
+      for (let h = 0; h <= 24; h++) {
+        avg.push({ x: h, y: dayCurves.reduce((s, c) => s + c[h].y, 0) / dayCurves.length });
+      }
+    }
+
+    return { today, yesterday, avg, avgDays };
+  }
+
+  function drawSleepTrendChart(curves) {
+    const svg = document.getElementById("chart-sleep-trend");
+    if (!svg) return;
+    const W = 320, H = 160;
+    const ML = 26, MR = 8, MT = 10, MB = 22;
+    const innerW = W - ML - MR;
+    const innerH = H - MT - MB;
+
+    const series = [
+      // Reference lines first so today draws on top of them.
+      { pts: curves.avg,       cls: "trend-avg",       label: `${curves.avgDays}-day average` },
+      { pts: curves.yesterday, cls: "trend-yesterday", label: "Yesterday" },
+      { pts: curves.today,     cls: "trend-today",     label: "Today" },
+    ].filter(s => s.pts && s.pts.length > 1);
+
+    const rawMax = Math.max(...series.flatMap(s => s.pts.map(p => p.y)));
+    const { yMax, steps: ySteps } = niceAxisSleepHours(rawMax);
+
+    const xOf = (hour) => ML + (hour / 24) * innerW;
+    const yOf = (v) => MT + innerH * (1 - v / yMax);
+
+    const parts = [];
+    for (let i = 0; i <= ySteps; i++) {
+      const y = MT + innerH * (1 - i / ySteps);
+      const v = Math.round(yMax * i / ySteps * 10) / 10;
+      const vText = v % 1 === 0 ? v : v.toFixed(1);
+      parts.push(`<line class="grid" x1="${ML}" y1="${y}" x2="${W - MR}" y2="${y}"/>`);
+      parts.push(`<text x="${ML - 4}" y="${y + 3}" text-anchor="end">${vText}h</text>`);
+    }
+    for (const hr of [0, 6, 12, 18, 24]) {
+      const x = xOf(hr);
+      parts.push(`<line class="grid" x1="${x.toFixed(1)}" y1="${MT}" x2="${x.toFixed(1)}" y2="${MT + innerH}"/>`);
+      const anchor = hr === 0 ? "start" : hr === 24 ? "end" : "middle";
+      parts.push(`<text x="${x.toFixed(1)}" y="${H - MB + 14}" text-anchor="${anchor}">${pad2(hr)}</text>`);
+    }
+
+    for (const s of series) {
+      const d = s.pts
+        .map((p, i) => `${i === 0 ? "M" : "L"}${xOf(p.x).toFixed(1)} ${yOf(p.y).toFixed(1)}`)
+        .join(" ");
+      const last = s.pts[s.pts.length - 1];
+      const title = `${s.label} — ${last.y.toFixed(1)}h slept`;
+      parts.push(`<path class="${s.cls}" d="${d}"><title>${escapeText(title)}</title></path>`);
+    }
+
+    svg.innerHTML = parts.join("");
+  }
+
+  function renderSleepTrend(events) {
+    const curves = sleepTrendCurves(events);
+    drawSleepTrendChart(curves);
+    // Drop legend chips for missing reference lines (no data for them yet),
+    // and keep the average chip's label in step with the chart-days picker.
+    const yLegend = document.getElementById("legend-trend-yesterday");
+    const aLegend = document.getElementById("legend-trend-avg");
+    const aText   = document.getElementById("legend-trend-avg-text");
+    if (yLegend) yLegend.hidden = !curves.yesterday;
+    if (aLegend) aLegend.hidden = !curves.avg;
+    if (aText)   aText.textContent = `${curves.avgDays}-day avg`;
+  }
+
   // ---------- weight ----------
   // Pick a "nice" kg axis that frames the data with a little headroom rather
   // than forcing 0-based (a puppy going 5→8 kg would otherwise look flat).
@@ -1619,6 +1741,7 @@
     renderWakeWindows(events);
     renderWeekly(events);
     renderSleepTimeline(events);
+    renderSleepTrend(events);
     renderHourHeatmap(events);
     renderTraining(events);
     renderWeight(events);
@@ -2573,6 +2696,7 @@
       renderWakeWindows(evs);
       renderWeekly(evs);
       renderSleepTimeline(evs);
+      renderSleepTrend(evs);
       renderHourHeatmap(evs);
       renderTraining(evs);
       if (navigator.onLine && !syncing) setStatus();

src/changelog.json

@@ -1,4 +1,5 @@
 [
+  { "date": "2026-07-15", "text": "New Sleep trend chart: today's running sleep total through the day, against yesterday and the average over your chart window (7/14/30 days)" },
   { "date": "2026-07-15", "text": "Quick actions that don't fit right now are dimmed (asleep → everything but Sleep end; awake → Sleep end) — still tappable for corrections" },
   { "date": "2026-07-15", "text": "Editing an event no longer pops the date picker over the whole screen on iPhone" },
   { "date": "2026-07-15", "text": "Weight and amount fields no longer show up on events that don't use them (e.g. editing a pee)" },

src/index.html

@@ -220,6 +220,17 @@
         <p class="muted-note">Each row is a day, midnight to midnight; shaded = asleep. Tap a row to open that day.</p>
       </section>
 
+      <section class="patterns" data-panel="sleep-trend">
+        <h2>Sleep trend</h2>
+        <svg id="chart-sleep-trend" class="chart-svg" viewBox="0 0 320 160" role="img" aria-label="Cumulative sleep hours through the day: today, yesterday and the recent average"></svg>
+        <div class="legend">
+          <span class="lg trend-today"><span class="sw"></span>Today</span>
+          <span class="lg trend-yesterday" id="legend-trend-yesterday"><span class="sw"></span>Yesterday</span>
+          <span class="lg trend-avg" id="legend-trend-avg"><span class="sw"></span><span id="legend-trend-avg-text">7-day avg</span></span>
+        </div>
+        <p class="muted-note">Hours slept so far at each point of the day, against yesterday and the average over the picked chart window.</p>
+      </section>
+
       <section class="patterns" data-panel="hour-heatmap">
         <h2>By hour of day <span class="muted-note" data-chart-days-label>(last 7 days)</span></h2>
         <svg id="chart-hour-heatmap" class="chart-svg" viewBox="0 0 320 120" role="img" aria-label="Pee, poo and meal frequency by hour of day"></svg>

src/style.css

@@ -900,6 +900,33 @@ input.switch:checked::after { transform: translateX(18px); }
 .chart-svg .stl-hit { fill: transparent; cursor: pointer; }
 .chart-svg .stl-hit:hover { fill: var(--accent); fill-opacity: 0.08; }
 
+/* Sleep trend lines: today strongest, the reference curves lighter/dashed. */
+.chart-svg .trend-today {
+  stroke: var(--sleep);
+  stroke-width: 2.5;
+  stroke-linejoin: round;
+  fill: none;
+}
+.chart-svg .trend-yesterday {
+  stroke: var(--muted);
+  stroke-width: 1.5;
+  stroke-linejoin: round;
+  fill: none;
+  opacity: 0.75;
+}
+.chart-svg .trend-avg {
+  stroke: var(--sleep);
+  stroke-width: 1.5;
+  stroke-dasharray: 4 3;
+  stroke-linejoin: round;
+  fill: none;
+  opacity: 0.7;
+}
+.lg.trend-today .sw { background: var(--sleep); }
+.lg.trend-yesterday .sw { background: var(--muted); }
+.lg.trend-avg .sw { background: color-mix(in srgb, var(--sleep) 55%, var(--surface)); }
+.lg[hidden] { display: none; }
+
 .chart-svg .hm-cell { stroke: none; }
 .chart-svg .hm-pee { fill: var(--pee); }
 .chart-svg .hm-poo { fill: var(--poo); }