T16 review fixes: an unknown system zone stops instead of reading as UTC, the view window refits when data shrinks, the volume profile counts narrow and flat candles whole, Fibonacci labels stay in their pane, the DOM ladder shows its tick's decimals, the tape flashes on each new trade, typed numbers reach their owner before a press, and a smaller loss than expected reads as a beat

src/finance/candles.rs

@@ -162,14 +162,22 @@ pub(crate) fn profile(
     (low, high): (f64, f64),
     bands: usize,
 ) -> Vec<(f64, f64, f64)> {
+    assert!(bands > 0 && high > low, "a profile needs bands over a span");
     let step = (high - low) / bands as f64;
     let mut traded = vec![0.0; bands];
     for candle in candles {
-        let reach = (candle.high - candle.low).max(step);
+        let span = candle.high - candle.low;
+        if span <= 0.0 {
+            let band = ((candle.close - low) / step)
+                .floor()
+                .clamp(0.0, (bands - 1) as f64);
+            traded[band as usize] += candle.volume;
+            continue;
+        }
         for (band, volume) in traded.iter_mut().enumerate() {
             let (from, to) = (low + step * band as f64, low + step * (band + 1) as f64);
             let overlap = (to.min(candle.high) - from.max(candle.low)).max(0.0);
-            *volume += candle.volume * overlap / reach;
+            *volume += candle.volume * overlap / span;
         }
     }
     traded
@@ -250,4 +258,20 @@ mod tests {
         );
         assert_eq!((bands[3].0, bands[3].1), (13.0, 14.0));
     }
+
+    #[test]
+    fn narrow_and_flat_candles_count_all_their_volume() {
+        let narrow = Candle::new(Timestamp::UNIX_EPOCH, (10.2, 10.3, 10.1, 10.2), 100.0);
+        let flat = Candle::new(Timestamp::UNIX_EPOCH, (12.5, 12.5, 12.5, 12.5), 40.0);
+        let traded: Vec<f64> = profile(&[narrow, flat], (10.0, 14.0), 4)
+            .iter()
+            .map(|band| band.2)
+            .collect();
+        assert!(
+            (traded[0] - 100.0).abs() < 1e-9,
+            "{traded:?}: a narrow candle's whole volume"
+        );
+        assert_eq!(traded[2], 40.0, "a flat candle lands in its band");
+        assert!((traded.iter().sum::<f64>() - 140.0).abs() < 1e-9);
+    }
 }