fix(baseAxis): fix y-axis tick positioning (#7061)

packages/mermaid/src/diagrams/xychart/chartBuilder/components/axis/bandAxis.ts

@@ -17,6 +17,7 @@ export class BandAxis extends BaseAxis {
     textDimensionCalculator: TextDimensionCalculator
   ) {
     super(axisConfig, title, textDimensionCalculator, axisThemeConfig);
+    this.isBandAxis = true;
     this.categories = categories;
     this.scale = scaleBand().domain(this.categories).range(this.getRange());
   }

packages/mermaid/src/diagrams/xychart/chartBuilder/components/axis/baseAxis.ts

@@ -23,6 +23,7 @@ export abstract class BaseAxis implements Axis {
   protected outerPadding = 0;
   protected titleTextHeight = 0;
   protected labelTextHeight = 0;
+  public isBandAxis = false;
 
   constructor(
     protected axisConfig: XYChartAxisConfig,
@@ -46,7 +47,16 @@ export abstract class BaseAxis implements Axis {
   }
 
   getRange(): [number, number] {
-    return [this.range[0] + this.outerPadding, this.range[1] - this.outerPadding];
+    if (this.isBandAxis) {
+      return [this.range[0] + this.outerPadding, this.range[1] - this.outerPadding];
+    }
+    // This is a value axis
+    if (this.axisPosition === 'left' || this.axisPosition === 'right') {
+      // For vertical value axis, no padding at the bottom
+      return [this.range[0] + this.outerPadding, this.range[1]];
+    }
+    // For horizontal value axis, padding only at the end
+    return [this.range[0], this.range[1] - this.outerPadding];
   }
 
   setAxisPosition(axisPosition: AxisPosition): void {

packages/mermaid/src/diagrams/xychart/chartBuilder/components/axis/index.ts

@@ -19,6 +19,7 @@ export interface Axis extends ChartComponent {
   getTickDistance(): number;
   recalculateOuterPaddingToDrawBar(): void;
   setRange(range: [number, number]): void;
+  isBandAxis: boolean;
 }
 
 export function getAxis(

packages/mermaid/src/diagrams/xychart/chartBuilder/components/plot/barPlot.ts

@@ -19,11 +19,27 @@ export class BarPlot {
 
     const barPaddingPercent = 0.05;
 
-    const barWidth =
-      Math.min(this.xAxis.getAxisOuterPadding() * 2, this.xAxis.getTickDistance()) *
-      (1 - barPaddingPercent);
-    const barWidthHalf = barWidth / 2;
+    let barWidth: number;
+    let barWidthHalf: number;
 
+    // Axis at the bottom of the bar
+    let bandAxis: Axis;
+    if (this.yAxis.isBandAxis) {
+      bandAxis = this.yAxis;
+    } else {
+      bandAxis = this.xAxis;
+    }
+
+    if (bandAxis.isBandAxis) {
+      barWidth =
+        Math.min(bandAxis.getAxisOuterPadding() * 2, bandAxis.getTickDistance()) *
+        (1 - barPaddingPercent);
+      barWidthHalf = barWidth / 2;
+    } else {
+      // For value axis, keep bars aligned and adjust width for extra half bar
+      barWidth = Math.min(bandAxis.getAxisOuterPadding() * 2, bandAxis.getTickDistance()) * 0.5;
+      barWidthHalf = 0;
+    }
     if (this.orientation === 'horizontal') {
       return [
         {