feat: responsive charts with timestamp tooltips

Charts (LineChart, AreaChart, BarChart) now fill their container
width instead of using a fixed 400px default. SVGs use width=100%
with preserveAspectRatio=none.

LineChart and AreaChart tooltips now show the data point timestamp
when x-values are Date objects, displayed as a header row above
the series values.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@cameleer/design-system",
-  "version": "0.1.45",
+  "version": "0.1.46",
   "type": "module",
   "main": "./dist/index.es.js",
   "module": "./dist/index.es.js",

src/design-system/composites/AreaChart/AreaChart.module.css

@@ -1,8 +1,9 @@
 .wrapper {
   position: relative;
-  display: inline-flex;
+  display: flex;
   flex-direction: column;
   gap: 4px;
+  width: 100%;
 }
 
 .svg {
@@ -78,6 +79,15 @@
   white-space: nowrap;
 }
 
+.tooltipTime {
+  font-family: var(--font-mono);
+  font-size: 10px;
+  color: var(--text-muted);
+  margin-bottom: 4px;
+  padding-bottom: 3px;
+  border-bottom: 1px solid var(--border-subtle);
+}
+
 .tooltipRow {
   display: flex;
   align-items: center;

src/design-system/composites/AreaChart/AreaChart.tsx

@@ -45,6 +45,7 @@ export function AreaChart({
   const [tooltip, setTooltip] = useState<{
     x: number
     y: number
+    xLabel: string
     values: { label: string; value: number; color: string }[]
   } | null>(null)
 
@@ -84,6 +85,15 @@ export function AreaChart({
 
     // Find closest x value
     const pctX = (mx - dims.paddingLeft) / plotW
+    const firstS = series[0]
+    const idx0 = Math.max(0, Math.min(firstS.data.length - 1, Math.round(pctX * (firstS.data.length - 1))))
+    const xVal = firstS.data[idx0]?.x
+    const xLabel = xVal instanceof Date
+      ? xVal.toLocaleString([], { month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit', second: '2-digit' })
+      : typeof xVal === 'number' && xVal > 1e10
+        ? new Date(xVal).toLocaleString([], { month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit', second: '2-digit' })
+        : String(xVal ?? '')
+
     const values = series.map((s, i) => {
       const idx = Math.round(pctX * (s.data.length - 1))
       const clamped = Math.max(0, Math.min(s.data.length - 1, idx))
@@ -95,16 +105,17 @@ export function AreaChart({
       }
     })
 
-    setTooltip({ x: mx, y: my, values })
+    setTooltip({ x: mx, y: my, xLabel, values })
   }
 
   return (
     <div className={`${styles.wrapper} ${className ?? ''}`}>
       {yLabel && <div className={styles.yLabel}>{yLabel}</div>}
       <svg
-        width={width}
+        width="100%"
         height={height}
         viewBox={`0 0 ${width} ${height}`}
+        preserveAspectRatio="none"
         className={styles.svg}
         onMouseMove={handleMouseMove}
         onMouseLeave={() => setTooltip(null)}
@@ -223,6 +234,9 @@ export function AreaChart({
             top: tooltip.y,
           }}
         >
+          {tooltip.xLabel && (
+            <div className={styles.tooltipTime}>{tooltip.xLabel}</div>
+          )}
           {tooltip.values.map((v) => (
             <div key={v.label} className={styles.tooltipRow}>
               <span className={styles.tooltipDot} style={{ background: v.color }} />

src/design-system/composites/BarChart/BarChart.module.css

@@ -1,8 +1,9 @@
 .wrapper {
   position: relative;
-  display: inline-flex;
+  display: flex;
   flex-direction: column;
   gap: 4px;
+  width: 100%;
 }
 
 .svg {

src/design-system/composites/BarChart/BarChart.tsx

@@ -101,9 +101,10 @@ export function BarChart({
     <div className={`${styles.wrapper} ${className ?? ''}`}>
       {yLabel && <div className={styles.yLabel}>{yLabel}</div>}
       <svg
-        width={width}
+        width="100%"
         height={height}
         viewBox={`0 0 ${width} ${height}`}
+        preserveAspectRatio="none"
         className={styles.svg}
         onMouseLeave={() => setTooltip(null)}
         aria-label="Bar chart"

src/design-system/composites/LineChart/LineChart.module.css

@@ -1,8 +1,9 @@
 .wrapper {
   position: relative;
-  display: inline-flex;
+  display: flex;
   flex-direction: column;
   gap: 4px;
+  width: 100%;
 }
 
 .svg {
@@ -69,6 +70,15 @@
   white-space: nowrap;
 }
 
+.tooltipTime {
+  font-family: var(--font-mono);
+  font-size: 10px;
+  color: var(--text-muted);
+  margin-bottom: 4px;
+  padding-bottom: 3px;
+  border-bottom: 1px solid var(--border-subtle);
+}
+
 .tooltipRow {
   display: flex;
   align-items: center;

src/design-system/composites/LineChart/LineChart.tsx

@@ -44,6 +44,7 @@ export function LineChart({
   const [tooltip, setTooltip] = useState<{
     x: number
     y: number
+    xLabel: string
     values: { label: string; value: number; color: string }[]
   } | null>(null)
 
@@ -80,6 +81,15 @@ export function LineChart({
     const my = e.clientY - rect.top
     const pctX = (mx - dims.paddingLeft) / plotW
 
+    const firstS = series[0]
+    const idx0 = Math.max(0, Math.min(firstS.data.length - 1, Math.round(pctX * (firstS.data.length - 1))))
+    const xVal = firstS.data[idx0]?.x
+    const xLabel = xVal instanceof Date
+      ? xVal.toLocaleString([], { month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit', second: '2-digit' })
+      : typeof xVal === 'number' && xVal > 1e10
+        ? new Date(xVal).toLocaleString([], { month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit', second: '2-digit' })
+        : String(xVal ?? '')
+
     const values = series.map((s, i) => {
       const idx = Math.round(pctX * (s.data.length - 1))
       const clamped = Math.max(0, Math.min(s.data.length - 1, idx))
@@ -91,16 +101,17 @@ export function LineChart({
       }
     })
 
-    setTooltip({ x: mx, y: my, values })
+    setTooltip({ x: mx, y: my, xLabel, values })
   }
 
   return (
     <div className={`${styles.wrapper} ${className ?? ''}`}>
       {yLabel && <div className={styles.yLabel}>{yLabel}</div>}
       <svg
-        width={width}
+        width="100%"
         height={height}
         viewBox={`0 0 ${width} ${height}`}
+        preserveAspectRatio="none"
         className={styles.svg}
         onMouseMove={handleMouseMove}
         onMouseLeave={() => setTooltip(null)}
@@ -202,6 +213,9 @@ export function LineChart({
           className={styles.tooltip}
           style={{ left: tooltip.x + 12, top: tooltip.y }}
         >
+          {tooltip.xLabel && (
+            <div className={styles.tooltipTime}>{tooltip.xLabel}</div>
+          )}
           {tooltip.values.map((v) => (
             <div key={v.label} className={styles.tooltipRow}>
               <span className={styles.tooltipDot} style={{ background: v.color }} />