Give every labelled y-axis value a tick in the fast charts

documentation/changelog.rst

@@ -24,7 +24,7 @@ New features
 * The flex-context editor now also shows the fields that scheduling the asset would inherit from parent assets — uneditable, with buttons to jump to the editor of the defining parent asset or to override the field on the asset itself [see `PR #2346 <https://www.github.com/FlexMeasures/flexmeasures/pull/2346>`_]
 * Show asset annotations in asset charts: a lightly shaded time band across all subcharts, darkening with a tooltip (showing the annotation text and source) when hovered in a subchart; alerts get a warning hue, and instant annotations render as a vertical rule with a top marker; also adds a ``GET /api/v3_0/assets/<id>/chart_annotations`` endpoint [see `PR #2312 <https://www.github.com/FlexMeasures/flexmeasures/pull/2312>`_]
 * Floor off-clock API datetimes to a non-instantaneous sensor's resolution by default when ingesting sensor data, uploading sensor data, and handling scheduler flex-model timed events; configurable with the ``floor_datetimes_to_resolution`` sensor attribute [see `PR #2146 <https://www.github.com/FlexMeasures/flexmeasures/pull/2146>`_ and `PR #2194 <https://www.github.com/FlexMeasures/flexmeasures/pull/2194>`_]
-* In the UI, asset and sensor charts now render with Apache ECharts (canvas) by default, for much faster drawing and interaction on dense time series, while staying visually and functionally equivalent to the previous Vega-Lite charts, which remain available as a fallback via a toggle [see `PR #2234 <https://www.github.com/FlexMeasures/flexmeasures/pull/2234>`_]
+* In the UI, asset and sensor charts now render with Apache ECharts (canvas) by default, for much faster drawing and interaction on dense time series, while staying visually and functionally equivalent to the previous Vega-Lite charts, which remain available as a fallback via a toggle [see `PR #2234 <https://www.github.com/FlexMeasures/flexmeasures/pull/2234>`_ and `PR #2399 <https://www.github.com/FlexMeasures/flexmeasures/pull/2399>`_]
 * Breaking behaviour change: the top-level flex-context's ``relax-constraints`` field now defaults to ``True`` (matching the default already used within each ``commodities`` entry), so constraint violations are softly penalized by default instead of being hard constraints, unless explicitly set to ``False`` [see `PR #2172 <https://www.github.com/FlexMeasures/flexmeasures/pull/2172>`_]
 * Support for creating new assets by using another asset as a template from the UI. [see `PR #2195 <https://www.github.com/FlexMeasures/flexmeasures/pull/2195>`_ and `PR #2268 <https://www.github.com/FlexMeasures/flexmeasures/pull/2268>`_
 * In the UI, asset and sensor lists can be filtered by ID prefix through API-backed search fields [see `PR #2231 <https://www.github.com/FlexMeasures/flexmeasures/pull/2231>`_]

flexmeasures/ui/static/js/fast-chart.js

@@ -1303,7 +1303,13 @@ function buildLineBarOption(elementId, groups, opts) {
       axisLabel: { fontSize: FONT_SIZE, color: "#222" },
       ...yAxisDomainOptions(group), // issue #2244 y-axis modes (zero / data / floor / strict)
       splitLine: { show: true, lineStyle: { opacity: 0.7 } },
-      // Finer gridlines between the major value lines, as in Vega-Lite.
+      // A tick mark next to each labelled value, as in Vega-Lite. ECharts would
+      // otherwise hide them ("auto" resolves to hidden for a value axis whose
+      // other axis is a time axis), leaving the labels floating next to the grid —
+      // with only the shorter minor ticks below, halfway between the labels.
+      axisTick: { show: true, lineStyle: { color: "#888" } },
+      // Finer gridlines between the major value lines, as in Vega-Lite, with
+      // shorter tick marks to match.
       minorTick: { show: true, splitNumber: 2 },
       minorSplitLine: { show: true, lineStyle: { color: "#e0e0e0", width: 1 } },
     });