fix(flet-charts): match axis labels with float tolerance

CHANGELOG.md

@@ -28,6 +28,7 @@
 * Fix `flet pack` desktop packaging so Windows and Linux bundles include the expected client archive, and Windows taskbar pins point to the packed app instead of the cached `flet.exe` ([#5151](https://github.com/flet-dev/flet/issues/5151), [#6403](https://github.com/flet-dev/flet/pull/6403)) by @ndonkoHenri.
 * Fix environment variable priority in `flet build` template: inherit from `Platform.environment` and use `putIfAbsent` for FLET_* variables so pre-set system env vars are not overwritten ([#6394](https://github.com/flet-dev/flet/pull/6394)) by @Bahtya.
 * Fix 3- and 4-digit hex color shorthand (e.g. `#c00`, `#fc00`) rendering as invisible by expanding them to their full 6/8-digit forms ([#6419](https://github.com/flet-dev/flet/issues/6419), [#6421](https://github.com/flet-dev/flet/pull/6421)) by @ndonkoHenri.
+* Fix `LineChart` (and other charts) silently dropping custom `ChartAxisLabel` entries whose `value` matched a tick only after floating-point rounding (e.g. `0.1`, `0.2`, `0.3`) by switching label lookup to a tolerance-based comparison scaled to the axis interval ([#6445](https://github.com/flet-dev/flet/issues/6445), [#6459](https://github.com/flet-dev/flet/pull/6459)) by @KangZhaoKui.
 
 ### Other changes
 

sdk/python/packages/flet-charts/src/flutter/flet_charts/lib/src/utils/charts.dart

@@ -156,8 +156,11 @@ AxisTitles parseAxisTitles(Control? control) {
         getTitlesWidget: labels.isEmpty
             ? defaultGetTitle
             : (double value, TitleMeta meta) {
-                var label = labels
-                    .firstWhereOrNull((l) => l.getDouble("value") == value);
+                final epsilon = meta.appliedInterval * 1e-3;
+                final label = labels.firstWhereOrNull((l) {
+                  final v = l.getDouble("value");
+                  return v != null && (v - value).abs() < epsilon;
+                });
                 return label?.buildTextOrWidget("label") ??
                     const SizedBox.shrink();
               },