feat: grid based movement for scatterplots

src/command/describe.ts

@@ -6,8 +6,8 @@ import type { BrailleViewModel } from '@state/viewModel/brailleViewModel';
 import type { TextViewModel } from '@state/viewModel/textViewModel';
 import type { BoxBrailleState, LineBrailleState, NonEmptyTraceState } from '@type/state';
 import type { Command } from './command';
-import { TraceType } from '@type/grammar';
 import { Scope } from '@type/event';
+import { TraceType } from '@type/grammar';
 
 /**
  * Abstract base class for describe commands.
@@ -417,6 +417,12 @@ export class AnnouncePositionCommand extends DescribeCommand {
       return;
     }
 
+    // Grid mode: announce axis ranges without points
+    if (state.text.gridPoints !== undefined && state.text.range && state.text.crossRange) {
+      this.announceGridPosition(state);
+      return;
+    }
+
     // Get position from audio.panning (contains x, y, rows, cols)
     const { panning } = state.audio;
     const { x, y, rows, cols } = panning;
@@ -491,6 +497,28 @@ export class AnnouncePositionCommand extends DescribeCommand {
     }
   }
 
+  /**
+   * Announces position for grid navigation mode.
+   * Shows axis ranges without the points list.
+   */
+  private announceGridPosition(state: NonEmptyTraceState): void {
+    const { text } = state;
+    const xRange = text.range!;
+    const yRange = text.crossRange!;
+
+    if (this.textService.isTerse()) {
+      this.textViewModel.update(
+        `${xRange.min} through ${xRange.max}, ${yRange.min} through ${yRange.max}`,
+      );
+    } else {
+      const xLabel = text.main.label || 'x';
+      const yLabel = text.cross.label || 'y';
+      this.textViewModel.update(
+        `${xLabel} is ${xRange.min} through ${xRange.max}, ${yLabel} is ${yRange.min} through ${yRange.max}`,
+      );
+    }
+  }
+
   /**
    * Announces position for boxplots with section information.
    * Uses braille state which normalizes box position regardless of orientation.

src/model/abstract.ts

@@ -15,6 +15,7 @@ import type {
 import type { Trace } from './plot';
 import { NavigationService } from '@service/navigation';
 import { TraceType } from '@type/grammar';
+import { Constant } from '@util/constant';
 
 const DEFAULT_SUBPLOT_TITLE = 'unavailable';
 
@@ -253,6 +254,68 @@ export abstract class AbstractPlot<State> implements Movable, Observable<State>,
   public moveToPoint(_x: number, _y: number): void {
     // implement basic stuff, assuming something like highlightValues that holds the points and boxes
   }
+
+  /**
+   * Sets whether grid navigation mode is active. Override in traces that support grid navigation.
+   */
+  /**
+   * Returns true if this trace supports compare (lower/higher value) navigation.
+   * Override to false for trace types that don't use compare modes (e.g., scatter).
+   */
+  public supportsCompareMode(): boolean {
+    return true;
+  }
+
+  /**
+   * Returns the display name for the default data navigation mode.
+   * Override to provide a trace-specific name (e.g., "ROW AND COLUMN NAVIGATION" for scatter).
+   */
+  public dataModeName(): string {
+    return Constant.DATA_MODE;
+  }
+
+  public setGridMode(_enabled: boolean): void {
+    // No-op for traces that don't support grid navigation.
+  }
+
+  /**
+   * Returns true if this trace supports grid navigation.
+   */
+  public supportsGridMode(): boolean {
+    return false;
+  }
+
+  /**
+   * Grid navigation: move up one cell. Returns false if at boundary.
+   */
+  public moveGridUp(): boolean {
+    this.notifyRotorBounds();
+    return false;
+  }
+
+  /**
+   * Grid navigation: move down one cell. Returns false if at boundary.
+   */
+  public moveGridDown(): boolean {
+    this.notifyRotorBounds();
+    return false;
+  }
+
+  /**
+   * Grid navigation: move left one cell. Returns false if at boundary.
+   */
+  public moveGridLeft(): boolean {
+    this.notifyRotorBounds();
+    return false;
+  }
+
+  /**
+   * Grid navigation: move right one cell. Returns false if at boundary.
+   */
+  public moveGridRight(): boolean {
+    this.notifyRotorBounds();
+    return false;
+  }
 }
 
 export abstract class AbstractTrace extends AbstractPlot<TraceState> implements Trace {
@@ -276,8 +339,10 @@ export abstract class AbstractTrace extends AbstractPlot<TraceState> implements
     this.type = layer.type;
     this.title = layer.title ?? DEFAULT_SUBPLOT_TITLE;
 
-    this.xAxis = layer.axes?.x ?? DEFAULT_X_AXIS;
-    this.yAxis = layer.axes?.y ?? DEFAULT_Y_AXIS;
+    const axisX = layer.axes?.x;
+    const axisY = layer.axes?.y;
+    this.xAxis = (typeof axisX === 'object' ? axisX.label : axisX) ?? DEFAULT_X_AXIS;
+    this.yAxis = (typeof axisY === 'object' ? axisY.label : axisY) ?? DEFAULT_Y_AXIS;
     this.fill = layer.axes?.fill ?? DEFAULT_FILL_AXIS;
   }