fix(api): keep candle open continuity

kustomize/base/api/server.mjs

@@ -786,6 +786,14 @@ function fillForwardCandles(candles, { bucketSeconds, limit, nowSec }) {
     if (hit) {
       const c = { ...hit };
       c.volume = Number.isFinite(c.volume) ? c.volume : 0;
+      // Keep continuity: next candle opens where previous candle closed.
+      // This avoids visual "gaps" when ticks are sparse.
+      if (prev && Number.isFinite(prev.close)) {
+        const prevClose = Number(prev.close);
+        c.open = prevClose;
+        c.high = Math.max(Number(c.high), prevClose, Number(c.close));
+        c.low = Math.min(Number(c.low), prevClose, Number(c.close));
+      }
       out[i] = c;
       prev = c;
       continue;