Fix VO2 max gauge: correct semicircle geometry, fixed 30-70 range, arrow pointer

Rewrote the SVG arc math — sweep=0 (counter-clockwise) correctly draws the
upper semicircle from left (30) over the top to right (70). The gauge now:
- Spans a fixed VO2 range of 30–70 across 180°
- Shows dimmed age/sex-specific ACSM category bands as background
- Fills a bright arc from 30 to the current value in the category colour
- Has a small triangular arrow pointer at the value position on the arc
- Shows the value number centred in the dome, coloured for its category

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/pages/HealthPage.jsx

@@ -55,70 +55,84 @@ function getVo2Category(value, age, sex) {
   return idx === -1 ? VO2_CATEGORIES[4] : VO2_CATEGORIES[idx]
 }
 
-function arcPath(cx, cy, r, startDeg, endDeg) {
-  const toRad = d => (d - 90) * Math.PI / 180
-  const x1 = cx + r * Math.cos(toRad(startDeg))
-  const y1 = cy + r * Math.sin(toRad(startDeg))
-  const x2 = cx + r * Math.cos(toRad(endDeg))
-  const y2 = cy + r * Math.sin(toRad(endDeg))
-  const large = endDeg - startDeg > 180 ? 1 : 0
-  return `M ${x1} ${y1} A ${r} ${r} 0 ${large} 1 ${x2} ${y2}`
-}
-
 function Vo2MaxGauge({ value, birthYear, biologicalSex }) {
+  // Fixed display range: 30–70 spans the full 180° semicircle
+  const MIN = 30, MAX = 70
+  const cx = 70, cy = 68, r = 50, sw = 12
+
   const age = birthYear ? new Date().getFullYear() - birthYear : 40
+
+  // Map a VO2 value to standard-math angle (PI=left/30, 0=right/70)
+  const toAngle = v => Math.PI * (1 - Math.max(0, Math.min(1, (v - MIN) / (MAX - MIN))))
+
+  // Map a VO2 value to SVG [x, y] on the arc.
+  // Uses sweep=0 (counter-clockwise) so the arc goes left→top→right.
+  const toXY = (v, radius = r) => {
+    const a = toAngle(v)
+    return [cx + radius * Math.cos(a), cy - radius * Math.sin(a)]
+  }
+
+  // SVG arc path from VO2 v1 to v2, sweep=0 (upper / counter-clockwise)
+  const seg = (v1, v2) => {
+    const [x1, y1] = toXY(v1)
+    const [x2, y2] = toXY(v2)
+    const large = (v2 - v1) / (MAX - MIN) > 0.5 ? 1 : 0
+    return `M ${x1.toFixed(2)} ${y1.toFixed(2)} A ${r} ${r} 0 ${large} 0 ${x2.toFixed(2)} ${y2.toFixed(2)}`
+  }
+
+  // Category segment boundaries from the age/sex ACSM table
+  const table = biologicalSex === 'female' ? VO2_FEMALE : VO2_MALE
+  const row = table.find(([maxAge]) => age <= maxAge) || table[table.length - 1]
+  const thresholds = row[1]
+  const bounds = [MIN, ...thresholds, MAX]   // 6 boundary values for 5 segments
+
   const cat = value != null ? getVo2Category(value, age, biologicalSex) : null
 
-  // Gauge spans 180° — from 180° (9 o'clock) to 360° (3 o'clock) across the top
+  // Triangular arrow pointer: tip points outward from arc, base sits inside track
-  const cx = 70, cy = 72, r = 52, sw = 14
+  const pointerPts = value != null ? (() => {
-  const startDeg = 180, totalDeg = 180
+    const a = toAngle(Math.max(MIN, Math.min(MAX, value)))
-  const segDeg = totalDeg / 5
+    const s = 0.13  // half-spread in radians (~7.5°)
-
+    const tipX  = cx + (r + 9)  * Math.cos(a), tipY  = cy - (r + 9)  * Math.sin(a)
-  // Compute value angle for needle
+    const baseX = r - 5
-  let needleAngle = null
+    const b1x = cx + baseX * Math.cos(a + s),  b1y = cy - baseX * Math.sin(a + s)
-  if (value != null) {
+    const b2x = cx + baseX * Math.cos(a - s),  b2y = cy - baseX * Math.sin(a - s)
-    const table = biologicalSex === 'female' ? VO2_FEMALE : VO2_MALE
+    return `${tipX.toFixed(1)},${tipY.toFixed(1)} ${b1x.toFixed(1)},${b1y.toFixed(1)} ${b2x.toFixed(1)},${b2y.toFixed(1)}`
-    const row = table.find(([maxAge]) => age <= maxAge) || table[table.length - 1]
+  })() : null
-    const thresholds = row[1]
-    const rangeMin = thresholds[0] - 8   // below Very Poor threshold
-    const rangeMax = thresholds[3] + 12  // above Good threshold (Excellent zone)
-    const pct = Math.max(0, Math.min(1, (value - rangeMin) / (rangeMax - rangeMin)))
-    needleAngle = startDeg + pct * totalDeg
-  }
 
   return (
     <div className="flex flex-col items-center">
-      <svg width="140" height="80" viewBox="0 0 140 80">
+      <svg width="140" height="85" viewBox="0 0 140 85">
-        {/* Background track */}
+        {/* Dark background track */}
-        <path d={arcPath(cx, cy, r, startDeg, startDeg + totalDeg)}
+        <path d={seg(MIN, MAX)} stroke="#374151" strokeWidth={sw + 2} fill="none" strokeLinecap="butt" />
-          stroke="#1f2937" strokeWidth={sw} fill="none" strokeLinecap="butt" />
+
-        {/* 5 coloured category segments */}
+        {/* Dimmed category colour bands */}
-        {VO2_CATEGORIES.map((c, i) => (
+        {VO2_CATEGORIES.map((c, i) => {
-          <path key={i}
+          const v1 = Math.max(bounds[i], MIN)
-            d={arcPath(cx, cy, r, startDeg + i * segDeg, startDeg + (i + 1) * segDeg)}
+          const v2 = Math.min(bounds[i + 1], MAX)
-            stroke={c.color} strokeWidth={sw} fill="none" strokeLinecap="butt"
+          if (v2 <= v1) return null
-            strokeOpacity={0.25}
+          return (
-          />
+            <path key={i} d={seg(v1, v2)}
-        ))}
+              stroke={c.color} strokeWidth={sw} fill="none" strokeLinecap="butt" strokeOpacity={0.3} />
-        {/* Filled arc up to current value */}
+          )
-        {needleAngle != null && needleAngle > startDeg && (
+        })}
-          <path d={arcPath(cx, cy, r, startDeg, needleAngle)}
+
-            stroke={cat?.color} strokeWidth={sw} fill="none" strokeLinecap="butt" />
+        {/* Bright filled arc from MIN to current value */}
+        {value != null && (
+          <path d={seg(MIN, Math.max(MIN + 0.1, Math.min(value, MAX)))}
+            stroke={cat.color} strokeWidth={sw} fill="none" strokeLinecap="butt" />
         )}
-        {/* Needle dot */}
+
-        {needleAngle != null && (() => {
+        {/* Arrow pointer */}
-          const toRad = d => (d - 90) * Math.PI / 180
+        {pointerPts && <polygon points={pointerPts} fill={cat.color} />}
-          const nx = cx + r * Math.cos(toRad(needleAngle))
+
-          const ny = cy + r * Math.sin(toRad(needleAngle))
+        {/* VO2 value — coloured to match category */}
-          return <circle cx={nx} cy={ny} r={5} fill={cat?.color} />
+        <text x={cx} y={cy - 8} textAnchor="middle" dominantBaseline="middle"
-        })()}
+          fontSize="21" fontWeight="700" fill={cat?.color ?? '#6b7280'}>
-        {/* Value */}
-        <text x={cx} y={cy - 6} textAnchor="middle" dominantBaseline="middle"
-          fontSize="22" fontWeight="700" fill={cat?.color ?? '#6b7280'}>
           {value != null ? value.toFixed(1) : '--'}
         </text>
+
         {/* Category label */}
-        <text x={cx} y={cy + 14} textAnchor="middle" dominantBaseline="middle"
+        <text x={cx} y={cy + 10} textAnchor="middle" dominantBaseline="middle"
           fontSize="9" fill="#9ca3af">
           {cat?.label ?? (biologicalSex ? '' : 'Set sex in profile')}
         </text>