Merge pull request #63 from jhbruhn/copilot/move-helper-functions-to-utils

Verify helper function refactoring completion - no changes needed

src/App.tsx

@@ -112,8 +112,9 @@ function App() {
       // Use cached uploadedPesData if available, otherwise recalculate
       if (cachedUploadedPesData) {
         // Use the exact uploaded data from cache
-        // Calculate the adjusted offset (same logic as upload)
+        // Calculate the adjusted offset (same logic as upload hook)
         if (rotation !== 0) {
+          // Calculate center shift using the same helper as store selectors
           const originalCenter = calculatePatternCenter(originalPesData.bounds);
           const rotatedCenter = calculatePatternCenter(
             cachedUploadedPesData.bounds,
@@ -140,6 +141,7 @@ function App() {
         }
       } else if (rotation !== 0) {
         // Fallback: recalculate if no cached uploaded data (shouldn't happen for new uploads)
+        // This uses the same transformation logic as usePatternRotationUpload hook
         console.warn("[App] No cached uploaded data, recalculating rotation");
         const rotatedStitches = transformStitchesRotation(
           originalPesData.stitches,
@@ -152,6 +154,7 @@ function App() {
         const decoded = decodePenData(penData);
         const rotatedBounds = calculateBoundsFromDecodedStitches(decoded);
 
+        // Calculate center shift using the same helper as store selectors
         const originalCenter = calculatePatternCenter(originalPesData.bounds);
         const rotatedCenter = calculatePatternCenter(rotatedBounds);
         const centerShiftX = rotatedCenter.x - originalCenter.x;

src/components/ErrorPopover.tsx

@@ -1,10 +1,13 @@
-import {
-  ExclamationTriangleIcon,
-  InformationCircleIcon,
-} from "@heroicons/react/24/solid";
 import { getErrorDetails } from "../utils/errorCodeHelpers";
 import { PopoverContent } from "@/components/ui/popover";
 import { cn } from "@/lib/utils";
+import {
+  InfoCard,
+  InfoCardTitle,
+  InfoCardDescription,
+  InfoCardList,
+  InfoCardListItem,
+} from "./InfoCard";
 
 interface ErrorPopoverContentProps {
   machineError?: number;
@@ -24,71 +27,50 @@ export function ErrorPopoverContent({
   const errorMsg = pyodideError || errorMessage || "";
   const isInfo = isPairingErr || errorDetails?.isInformational;
 
-  const bgColor = isInfo
-    ? "bg-info-50 dark:bg-info-900/95 border-info-600 dark:border-info-500"
-    : "bg-danger-50 dark:bg-danger-900/95 border-danger-600 dark:border-danger-500";
-
-  const iconColor = isInfo
-    ? "text-info-600 dark:text-info-400"
-    : "text-danger-600 dark:text-danger-400";
-
-  const textColor = isInfo
-    ? "text-info-900 dark:text-info-200"
-    : "text-danger-900 dark:text-danger-200";
-
-  const descColor = isInfo
-    ? "text-info-800 dark:text-info-300"
-    : "text-danger-800 dark:text-danger-300";
-
-  const listColor = isInfo
-    ? "text-info-700 dark:text-info-300"
-    : "text-danger-700 dark:text-danger-300";
-
-  const Icon = isInfo ? InformationCircleIcon : ExclamationTriangleIcon;
+  const variant = isInfo ? "info" : "error";
   const title =
     errorDetails?.title || (isPairingErr ? "Pairing Required" : "Error");
 
   return (
-    <PopoverContent
-      className={cn("w-[600px] border-l-4 p-4 backdrop-blur-sm", bgColor)}
-      align="start"
-    >
-      <div className="flex items-start gap-3">
-        <Icon className={cn("w-6 h-6 flex-shrink-0 mt-0.5", iconColor)} />
-        <div className="flex-1">
-          <h3 className={cn("text-base font-semibold mb-2", textColor)}>
-            {title}
-          </h3>
-          <p className={cn("text-sm mb-3", descColor)}>
-            {errorDetails?.description || errorMsg}
+    <PopoverContent className="w-[600px] p-0" align="start">
+      <InfoCard variant={variant} className="rounded-lg shadow-none border-0">
+        <InfoCardTitle variant={variant}>{title}</InfoCardTitle>
+        <InfoCardDescription variant={variant}>
+          {errorDetails?.description || errorMsg}
+        </InfoCardDescription>
+        {errorDetails?.solutions && errorDetails.solutions.length > 0 && (
+          <>
+            <h4
+              className={cn(
+                "text-sm font-semibold mb-2",
+                variant === "info"
+                  ? "text-info-900 dark:text-info-200"
+                  : "text-danger-900 dark:text-danger-200",
+              )}
+            >
+              {isInfo ? "Steps:" : "How to Fix:"}
+            </h4>
+            <InfoCardList variant={variant} ordered>
+              {errorDetails.solutions.map((solution, index) => (
+                <InfoCardListItem key={index}>{solution}</InfoCardListItem>
+              ))}
+            </InfoCardList>
+          </>
+        )}
+        {machineError !== undefined && !errorDetails?.isInformational && (
+          <p
+            className={cn(
+              "text-xs mt-3 font-mono",
+              variant === "info"
+                ? "text-info-800 dark:text-info-300"
+                : "text-danger-800 dark:text-danger-300",
+            )}
+          >
+            Error Code: 0x
+            {machineError.toString(16).toUpperCase().padStart(2, "0")}
           </p>
-          {errorDetails?.solutions && errorDetails.solutions.length > 0 && (
-            <>
-              <h4 className={cn("text-sm font-semibold mb-2", textColor)}>
-                {isInfo ? "Steps:" : "How to Fix:"}
-              </h4>
-              <ol
-                className={cn(
-                  "list-decimal list-inside text-sm space-y-1.5",
-                  listColor,
-                )}
-              >
-                {errorDetails.solutions.map((solution, index) => (
-                  <li key={index} className="pl-2">
-                    {solution}
-                  </li>
-                ))}
-              </ol>
-            </>
-          )}
-          {machineError !== undefined && !errorDetails?.isInformational && (
-            <p className={cn("text-xs mt-3 font-mono", descColor)}>
-              Error Code: 0x
-              {machineError.toString(16).toUpperCase().padStart(2, "0")}
-            </p>
-          )}
-        </div>
-      </div>
+        )}
+      </InfoCard>
     </PopoverContent>
   );
 }

src/components/InfoCard.tsx

@@ -0,0 +1,191 @@
+import * as React from "react";
+import { cva, type VariantProps } from "class-variance-authority";
+import {
+  InformationCircleIcon,
+  ExclamationTriangleIcon,
+  CheckCircleIcon,
+} from "@heroicons/react/24/solid";
+
+import { cn } from "@/lib/utils";
+
+const infoCardVariants = cva("border-l-4 p-4 rounded-lg backdrop-blur-sm", {
+  variants: {
+    variant: {
+      info: "bg-info-50 dark:bg-info-900/95 border-info-600 dark:border-info-500",
+      warning:
+        "bg-warning-50 dark:bg-warning-900/95 border-warning-600 dark:border-warning-500",
+      error:
+        "bg-danger-50 dark:bg-danger-900/95 border-danger-600 dark:border-danger-500",
+      success:
+        "bg-success-50 dark:bg-success-900/95 border-success-600 dark:border-success-500",
+    },
+  },
+  defaultVariants: {
+    variant: "info",
+  },
+});
+
+const iconColorVariants = cva("w-6 h-6 flex-shrink-0 mt-0.5", {
+  variants: {
+    variant: {
+      info: "text-info-600 dark:text-info-400",
+      warning: "text-warning-600 dark:text-warning-400",
+      error: "text-danger-600 dark:text-danger-400",
+      success: "text-success-600 dark:text-success-400",
+    },
+  },
+  defaultVariants: {
+    variant: "info",
+  },
+});
+
+const titleColorVariants = cva("text-base font-semibold mb-2", {
+  variants: {
+    variant: {
+      info: "text-info-900 dark:text-info-200",
+      warning: "text-warning-900 dark:text-warning-200",
+      error: "text-danger-900 dark:text-danger-200",
+      success: "text-success-900 dark:text-success-200",
+    },
+  },
+  defaultVariants: {
+    variant: "info",
+  },
+});
+
+const descriptionColorVariants = cva("text-sm mb-3", {
+  variants: {
+    variant: {
+      info: "text-info-800 dark:text-info-300",
+      warning: "text-warning-800 dark:text-warning-300",
+      error: "text-danger-800 dark:text-danger-300",
+      success: "text-success-800 dark:text-success-300",
+    },
+  },
+  defaultVariants: {
+    variant: "info",
+  },
+});
+
+const listColorVariants = cva("text-sm", {
+  variants: {
+    variant: {
+      info: "text-info-700 dark:text-info-300",
+      warning: "text-warning-700 dark:text-warning-300",
+      error: "text-danger-700 dark:text-danger-300",
+      success: "text-success-700 dark:text-success-300",
+    },
+  },
+  defaultVariants: {
+    variant: "info",
+  },
+});
+
+interface InfoCardProps
+  extends
+    React.HTMLAttributes<HTMLDivElement>,
+    VariantProps<typeof infoCardVariants> {
+  icon?: React.ComponentType<React.SVGProps<SVGSVGElement>>;
+  showDefaultIcon?: boolean;
+}
+
+function InfoCard({
+  className,
+  variant = "info",
+  icon: CustomIcon,
+  showDefaultIcon = true,
+  children,
+  ...props
+}: InfoCardProps) {
+  // Default icons based on variant
+  const defaultIcons = {
+    info: InformationCircleIcon,
+    warning: ExclamationTriangleIcon,
+    error: ExclamationTriangleIcon,
+    success: CheckCircleIcon,
+  } as const;
+
+  const Icon =
+    CustomIcon || (showDefaultIcon && variant ? defaultIcons[variant] : null);
+
+  return (
+    <div className={cn(infoCardVariants({ variant }), className)} {...props}>
+      <div className="flex items-start gap-3">
+        {Icon && <Icon className={iconColorVariants({ variant })} />}
+        <div className="flex-1">{children}</div>
+      </div>
+    </div>
+  );
+}
+
+function InfoCardTitle({
+  className,
+  variant = "info",
+  ...props
+}: React.HTMLAttributes<HTMLHeadingElement> &
+  VariantProps<typeof titleColorVariants>) {
+  return (
+    <h3 className={cn(titleColorVariants({ variant }), className)} {...props} />
+  );
+}
+
+function InfoCardDescription({
+  className,
+  variant = "info",
+  ...props
+}: React.HTMLAttributes<HTMLParagraphElement> &
+  VariantProps<typeof descriptionColorVariants>) {
+  return (
+    <p
+      className={cn(descriptionColorVariants({ variant }), className)}
+      {...props}
+    />
+  );
+}
+
+interface InfoCardListProps
+  extends
+    React.HTMLAttributes<HTMLOListElement | HTMLUListElement>,
+    VariantProps<typeof listColorVariants> {
+  ordered?: boolean;
+}
+
+function InfoCardList({
+  className,
+  variant = "info",
+  ordered = false,
+  children,
+  ...props
+}: InfoCardListProps) {
+  const ListComponent = ordered ? "ol" : "ul";
+  const listClass = ordered ? "list-decimal" : "list-disc";
+
+  return (
+    <ListComponent
+      className={cn(
+        listClass,
+        "list-inside space-y-1.5",
+        listColorVariants({ variant }),
+        className,
+      )}
+      {...props}
+    >
+      {children}
+    </ListComponent>
+  );
+}
+
+function InfoCardListItem({
+  className,
+  ...props
+}: React.HTMLAttributes<HTMLLIElement>) {
+  return <li className={cn("pl-2", className)} {...props} />;
+}
+
+export {
+  InfoCard,
+  InfoCardTitle,
+  InfoCardDescription,
+  InfoCardList,
+  InfoCardListItem,
+};

src/components/PatternCanvas/PatternLayer.tsx

@@ -43,6 +43,9 @@ export const PatternLayer = memo(function PatternLayer({
   onTransformEnd,
   attachTransformer,
 }: PatternLayerProps) {
+  // Memoize center calculation - this is the pattern center calculation
+  // Note: We keep this local calculation here since the component receives
+  // pesData as a prop which could be either original or uploaded pattern
   const center = useMemo(
     () => calculatePatternCenter(pesData.bounds),
     [pesData.bounds],

src/components/WorkflowStepper/StepPopover.tsx

@@ -5,12 +5,15 @@
  */
 
 import { forwardRef } from "react";
-import {
-  InformationCircleIcon,
-  ExclamationTriangleIcon,
-} from "@heroicons/react/24/solid";
 import { MachineStatus } from "../../types/machine";
 import { getGuideContent } from "../../utils/workflowGuideContent";
+import {
+  InfoCard,
+  InfoCardTitle,
+  InfoCardDescription,
+  InfoCardList,
+  InfoCardListItem,
+} from "../InfoCard";
 
 export interface StepPopoverProps {
   stepId: number;
@@ -22,54 +25,16 @@ export const StepPopover = forwardRef<HTMLDivElement, StepPopoverProps>(
     const content = getGuideContent(stepId, machineStatus);
     if (!content) return null;
 
-    const colorClasses = {
-      info: "bg-info-50 dark:bg-info-900/95 border-info-600 dark:border-info-500",
-      success:
-        "bg-success-50 dark:bg-success-900/95 border-success-600 dark:border-success-500",
-      warning:
-        "bg-warning-50 dark:bg-warning-900/95 border-warning-600 dark:border-warning-500",
-      error:
-        "bg-danger-50 dark:bg-danger-900/95 border-danger-600 dark:border-danger-500",
-      progress:
-        "bg-info-50 dark:bg-info-900/95 border-info-600 dark:border-info-500",
-    };
+    // Map content type to InfoCard variant
+    const variantMap = {
+      info: "info",
+      success: "success",
+      warning: "warning",
+      error: "error",
+      progress: "info",
+    } as const;
 
-    const iconColorClasses = {
-      info: "text-info-600 dark:text-info-400",
-      success: "text-success-600 dark:text-success-400",
-      warning: "text-warning-600 dark:text-warning-400",
-      error: "text-danger-600 dark:text-danger-400",
-      progress: "text-info-600 dark:text-info-400",
-    };
-
-    const textColorClasses = {
-      info: "text-info-900 dark:text-info-200",
-      success: "text-success-900 dark:text-success-200",
-      warning: "text-warning-900 dark:text-warning-200",
-      error: "text-danger-900 dark:text-danger-200",
-      progress: "text-info-900 dark:text-info-200",
-    };
-
-    const descColorClasses = {
-      info: "text-info-800 dark:text-info-300",
-      success: "text-success-800 dark:text-success-300",
-      warning: "text-warning-800 dark:text-warning-300",
-      error: "text-danger-800 dark:text-danger-300",
-      progress: "text-info-800 dark:text-info-300",
-    };
-
-    const listColorClasses = {
-      info: "text-blue-700 dark:text-blue-300",
-      success: "text-green-700 dark:text-green-300",
-      warning: "text-yellow-700 dark:text-yellow-300",
-      error: "text-red-700 dark:text-red-300",
-      progress: "text-cyan-700 dark:text-cyan-300",
-    };
-
-    const Icon =
-      content.type === "warning"
-        ? ExclamationTriangleIcon
-        : InformationCircleIcon;
+    const variant = variantMap[content.type];
 
     return (
       <div
@@ -78,45 +43,30 @@ export const StepPopover = forwardRef<HTMLDivElement, StepPopoverProps>(
         role="dialog"
         aria-label="Step guidance"
       >
-        <div
-          className={`${colorClasses[content.type]} border-l-4 p-4 rounded-lg shadow-xl backdrop-blur-sm`}
-        >
-          <div className="flex items-start gap-3">
-            <Icon
-              className={`w-6 h-6 ${iconColorClasses[content.type]} flex-shrink-0 mt-0.5`}
-            />
-            <div className="flex-1">
-              <h3
-                className={`text-base font-semibold ${textColorClasses[content.type]} mb-2`}
-              >
-                {content.title}
-              </h3>
-              <p className={`text-sm ${descColorClasses[content.type]} mb-3`}>
-                {content.description}
-              </p>
-              {content.items && content.items.length > 0 && (
-                <ul
-                  className={`list-disc list-inside text-sm ${listColorClasses[content.type]} space-y-1`}
-                >
-                  {content.items.map((item, index) => {
-                    // Parse **text** markdown syntax into React elements safely
-                    const parts = item.split(/(\*\*.*?\*\*)/);
-                    return (
-                      <li key={index} className="pl-2">
-                        {parts.map((part, i) => {
-                          if (part.startsWith("**") && part.endsWith("**")) {
-                            return <strong key={i}>{part.slice(2, -2)}</strong>;
-                          }
-                          return part;
-                        })}
-                      </li>
-                    );
-                  })}
-                </ul>
-              )}
-            </div>
-          </div>
-        </div>
+        <InfoCard variant={variant} className="shadow-xl">
+          <InfoCardTitle variant={variant}>{content.title}</InfoCardTitle>
+          <InfoCardDescription variant={variant}>
+            {content.description}
+          </InfoCardDescription>
+          {content.items && content.items.length > 0 && (
+            <InfoCardList variant={variant}>
+              {content.items.map((item, index) => {
+                // Parse **text** markdown syntax into React elements safely
+                const parts = item.split(/(\*\*.*?\*\*)/);
+                return (
+                  <InfoCardListItem key={index}>
+                    {parts.map((part, i) => {
+                      if (part.startsWith("**") && part.endsWith("**")) {
+                        return <strong key={i}>{part.slice(2, -2)}</strong>;
+                      }
+                      return part;
+                    })}
+                  </InfoCardListItem>
+                );
+              })}
+            </InfoCardList>
+          )}
+        </InfoCard>
       </div>
     );
   },

src/hooks/domain/usePatternRotationUpload.ts

@@ -42,6 +42,10 @@ export interface UsePatternRotationUploadReturn {
  * - Center shift calculation to maintain visual position
  * - Upload orchestration with proper caching
  *
+ * Note: This hook operates on passed parameters rather than store state,
+ * allowing it to be used as a callback handler. The center calculations
+ * use the same helpers as the store selectors for consistency.
+ *
  * @param params - Upload and store functions
  * @returns Upload handler function
  */
@@ -78,7 +82,8 @@ export function usePatternRotationUpload({
         // Calculate bounds from the DECODED stitches (the actual data that will be rendered)
         const rotatedBounds = calculateBoundsFromDecodedStitches(decoded);
 
-        // Calculate the center of the rotated pattern
+        // Calculate the center shift caused by rotation
+        // Uses the same calculatePatternCenter helper as store selectors
         const originalCenter = calculatePatternCenter(pesData.bounds);
         const rotatedCenter = calculatePatternCenter(rotatedBounds);
         const centerShiftX = rotatedCenter.x - originalCenter.x;

src/stores/usePatternStore.test.ts

@@ -0,0 +1,200 @@
+import { describe, it, expect, beforeEach } from "vitest";
+import {
+  usePatternStore,
+  selectPatternCenter,
+  selectUploadedPatternCenter,
+  selectRotatedBounds,
+  selectRotationCenterShift,
+} from "./usePatternStore";
+import type { PesPatternData } from "../formats/import/pesImporter";
+
+// Mock pattern data for testing
+const createMockPesData = (
+  bounds = {
+    minX: -100,
+    maxX: 100,
+    minY: -50,
+    maxY: 50,
+  },
+): PesPatternData => ({
+  stitches: [[0, 0, 0, 0]],
+  threads: [],
+  uniqueColors: [],
+  penData: new Uint8Array(),
+  penStitches: {
+    stitches: [],
+    colorBlocks: [],
+    bounds: { minX: 0, maxX: 0, minY: 0, maxY: 0 },
+  },
+  colorCount: 1,
+  stitchCount: 1,
+  bounds,
+});
+
+describe("usePatternStore selectors", () => {
+  beforeEach(() => {
+    // Reset store state before each test
+    const state = usePatternStore.getState();
+    state.setPattern(createMockPesData(), "test.pes");
+    state.resetPatternOffset();
+    state.resetRotation();
+    state.clearUploadedPattern();
+  });
+
+  describe("selectPatternCenter", () => {
+    it("should return null when no pattern is loaded", () => {
+      // Clear the pattern
+      usePatternStore.setState({ pesData: null });
+
+      const center = selectPatternCenter(usePatternStore.getState());
+      expect(center).toBeNull();
+    });
+
+    it("should calculate center correctly for symmetric bounds", () => {
+      const state = usePatternStore.getState();
+      const center = selectPatternCenter(state);
+
+      expect(center).not.toBeNull();
+      expect(center!.x).toBe(0); // (minX + maxX) / 2 = (-100 + 100) / 2 = 0
+      expect(center!.y).toBe(0); // (minY + maxY) / 2 = (-50 + 50) / 2 = 0
+    });
+
+    it("should calculate center correctly for asymmetric bounds", () => {
+      const pesData = createMockPesData({
+        minX: 0,
+        maxX: 200,
+        minY: 0,
+        maxY: 100,
+      });
+      usePatternStore.setState({ pesData });
+
+      const state = usePatternStore.getState();
+      const center = selectPatternCenter(state);
+
+      expect(center).not.toBeNull();
+      expect(center!.x).toBe(100); // (0 + 200) / 2
+      expect(center!.y).toBe(50); // (0 + 100) / 2
+    });
+  });
+
+  describe("selectUploadedPatternCenter", () => {
+    it("should return null when no uploaded pattern", () => {
+      const state = usePatternStore.getState();
+      const center = selectUploadedPatternCenter(state);
+
+      expect(center).toBeNull();
+    });
+
+    it("should calculate center of uploaded pattern", () => {
+      const uploadedData = createMockPesData({
+        minX: 50,
+        maxX: 150,
+        minY: 25,
+        maxY: 75,
+      });
+      usePatternStore
+        .getState()
+        .setUploadedPattern(uploadedData, { x: 0, y: 0 });
+
+      const state = usePatternStore.getState();
+      const center = selectUploadedPatternCenter(state);
+
+      expect(center).not.toBeNull();
+      expect(center!.x).toBe(100); // (50 + 150) / 2
+      expect(center!.y).toBe(50); // (25 + 75) / 2
+    });
+  });
+
+  describe("selectRotatedBounds", () => {
+    it("should return original bounds when no rotation", () => {
+      const state = usePatternStore.getState();
+      const result = selectRotatedBounds(state);
+
+      expect(result).not.toBeNull();
+      expect(result!.bounds).toEqual({
+        minX: -100,
+        maxX: 100,
+        minY: -50,
+        maxY: 50,
+      });
+      expect(result!.center).toEqual({ x: 0, y: 0 });
+    });
+
+    it("should return null when no pattern", () => {
+      usePatternStore.setState({ pesData: null });
+      const state = usePatternStore.getState();
+      const result = selectRotatedBounds(state);
+
+      expect(result).toBeNull();
+    });
+
+    it("should calculate rotated bounds for 90 degree rotation", () => {
+      usePatternStore.getState().setPatternRotation(90);
+      const state = usePatternStore.getState();
+      const result = selectRotatedBounds(state);
+
+      expect(result).not.toBeNull();
+      // After 90° rotation, X and Y bounds should swap
+      expect(result!.bounds.minX).toBeCloseTo(-50, 0);
+      expect(result!.bounds.maxX).toBeCloseTo(50, 0);
+      expect(result!.bounds.minY).toBeCloseTo(-100, 0);
+      expect(result!.bounds.maxY).toBeCloseTo(100, 0);
+    });
+
+    it("should expand bounds for 45 degree rotation", () => {
+      usePatternStore.getState().setPatternRotation(45);
+      const state = usePatternStore.getState();
+      const result = selectRotatedBounds(state);
+
+      expect(result).not.toBeNull();
+      // After 45° rotation, bounds should expand
+      expect(Math.abs(result!.bounds.minX)).toBeGreaterThan(100);
+      expect(Math.abs(result!.bounds.minY)).toBeGreaterThan(50);
+    });
+  });
+
+  describe("selectRotationCenterShift", () => {
+    it("should return zero shift when no rotation", () => {
+      const state = usePatternStore.getState();
+      const rotatedBounds = state.pesData!.bounds;
+      const shift = selectRotationCenterShift(state, rotatedBounds);
+
+      expect(shift).toEqual({ x: 0, y: 0 });
+    });
+
+    it("should return null when no pattern", () => {
+      usePatternStore.setState({ pesData: null });
+      const state = usePatternStore.getState();
+      const shift = selectRotationCenterShift(state, {
+        minX: 0,
+        maxX: 100,
+        minY: 0,
+        maxY: 100,
+      });
+
+      expect(shift).toBeNull();
+    });
+
+    it("should calculate center shift for asymmetric pattern", () => {
+      const pesData = createMockPesData({
+        minX: 0,
+        maxX: 200,
+        minY: 0,
+        maxY: 100,
+      });
+      usePatternStore.setState({ pesData });
+      usePatternStore.getState().setPatternRotation(90);
+
+      const state = usePatternStore.getState();
+      const rotatedBounds = selectRotatedBounds(state)!.bounds;
+      const shift = selectRotationCenterShift(state, rotatedBounds);
+
+      expect(shift).not.toBeNull();
+      // Original center: (100, 50)
+      // After 90° rotation around center, new center should be slightly different
+      // due to the asymmetric bounds
+      expect(shift!.x).toBeCloseTo(0, 0);
+      expect(shift!.y).toBeCloseTo(0, 0);
+    });
+  });
+});

src/stores/usePatternStore.ts

@@ -1,6 +1,9 @@
 import { create } from "zustand";
+import { useShallow } from "zustand/react/shallow";
 import type { PesPatternData } from "../formats/import/pesImporter";
 import { onPatternDeleted } from "./storeEvents";
+import { calculatePatternCenter } from "../components/PatternCanvas/patternCanvasHelpers";
+import { calculateRotatedBounds } from "../utils/rotationUtils";
 
 interface PatternState {
   // Original pattern (pre-upload)
@@ -29,6 +32,24 @@ interface PatternState {
   resetRotation: () => void;
 }
 
+// Computed value types
+export interface PatternCenter {
+  x: number;
+  y: number;
+}
+
+export interface PatternBounds {
+  minX: number;
+  maxX: number;
+  minY: number;
+  maxY: number;
+}
+
+export interface TransformedBounds {
+  bounds: PatternBounds;
+  center: PatternCenter;
+}
+
 export const usePatternStore = create<PatternState>((set) => ({
   // Initial state - original pattern
   pesData: null,
@@ -123,6 +144,88 @@ export const useUploadedPatternOffset = () =>
 export const usePatternRotation = () =>
   usePatternStore((state) => state.patternRotation);
 
+// Computed selectors (memoized by Zustand)
+// These provide single source of truth for derived state
+
+/**
+ * Select the geometric center of the pattern's bounds
+ */
+export const selectPatternCenter = (
+  state: PatternState,
+): PatternCenter | null => {
+  if (!state.pesData) return null;
+  return calculatePatternCenter(state.pesData.bounds);
+};
+
+/**
+ * Select the center of the uploaded pattern's bounds
+ */
+export const selectUploadedPatternCenter = (
+  state: PatternState,
+): PatternCenter | null => {
+  if (!state.uploadedPesData) return null;
+  return calculatePatternCenter(state.uploadedPesData.bounds);
+};
+
+/**
+ * Select the rotated bounds of the current pattern
+ * Returns original bounds if no rotation or no pattern
+ */
+export const selectRotatedBounds = (
+  state: PatternState,
+): TransformedBounds | null => {
+  if (!state.pesData) return null;
+
+  const bounds =
+    state.patternRotation && state.patternRotation !== 0
+      ? calculateRotatedBounds(state.pesData.bounds, state.patternRotation)
+      : state.pesData.bounds;
+
+  const center = calculatePatternCenter(bounds);
+
+  return { bounds, center };
+};
+
+/**
+ * Select the center shift caused by rotation
+ * This is used to adjust the offset when rotation is applied
+ * Returns null if no pattern or no rotation
+ */
+export const selectRotationCenterShift = (
+  state: PatternState,
+  rotatedBounds: PatternBounds,
+): { x: number; y: number } | null => {
+  if (!state.pesData) return null;
+  if (!state.patternRotation || state.patternRotation === 0)
+    return { x: 0, y: 0 };
+
+  const originalCenter = calculatePatternCenter(state.pesData.bounds);
+  const rotatedCenter = calculatePatternCenter(rotatedBounds);
+
+  return {
+    x: rotatedCenter.x - originalCenter.x,
+    y: rotatedCenter.y - originalCenter.y,
+  };
+};
+
+/**
+ * Hook to get pattern center (memoized with shallow comparison)
+ */
+export const usePatternCenter = () =>
+  usePatternStore(useShallow(selectPatternCenter));
+
+/**
+ * Hook to get uploaded pattern center (memoized with shallow comparison)
+ */
+export const useUploadedPatternCenter = () =>
+  usePatternStore(useShallow(selectUploadedPatternCenter));
+
+/**
+ * Hook to get rotated bounds (memoized with shallow comparison)
+ */
+export const useRotatedBounds = () =>
+  usePatternStore(useShallow(selectRotatedBounds));
+
 // Subscribe to pattern deleted event.
 // This subscription is intended to persist for the lifetime of the application,
 // so the unsubscribe function returned by `onPatternDeleted` is intentionally