fix: Address Copilot review feedback on event subscriptions

Add error handling and documentation to event subscriptions based on
Copilot review feedback.

Changes:
- Added try-catch blocks to all event callbacks for graceful error handling
- Added comments documenting that subscriptions persist for app lifetime
- Improved JSDoc for onPatternDeleted function with lifecycle details
- Added error logging to help debug potential issues

Benefits:
- Prevents silent failures in event callbacks
- Clear documentation about subscription lifecycle
- Better developer experience with error messages

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/stores/storeEvents.ts

@@ -28,9 +28,17 @@ export const useEventStore = create<EventState>((set) => ({
 }));
 
 /**
- * Subscribe to pattern deleted event
+ * Subscribe to the pattern deleted event.
- * @param callback - Function to call when event is emitted
+ *
- * @returns Unsubscribe function
+ * The subscription remains active until the returned unsubscribe function is called.
+ * If the unsubscribe function is not called, the listener will persist for the
+ * lifetime of the event store (typically the lifetime of the application).
+ *
+ * Call the returned unsubscribe function when the listener is no longer needed,
+ * especially for short-lived components or non-module-level subscriptions.
+ *
+ * @param callback - Function to call when the event is emitted.
+ * @returns Unsubscribe function that removes the listener when invoked.
  */
 export const onPatternDeleted = (callback: () => void): (() => void) => {
   let prevCount = useEventStore.getState().patternDeletedCount;

src/stores/useMachineCacheStore.ts

@@ -194,7 +194,17 @@ export const useMachineCacheStore = create<MachineCacheState>((set, get) => ({
   },
 }));
 
-// Subscribe to pattern deleted event
+// 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
+// not stored or called.
 onPatternDeleted(() => {
+  try {
     useMachineCacheStore.getState().clearResumeState();
+  } catch (error) {
+    console.error(
+      "[MachineCacheStore] Failed to clear resume state on pattern deleted event:",
+      error,
+    );
+  }
 });

src/stores/useMachineUploadStore.ts

@@ -128,7 +128,17 @@ export const useMachineUploadStore = create<MachineUploadState>((set) => ({
   },
 }));
 
-// Subscribe to pattern deleted event
+// 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
+// not stored or called.
 onPatternDeleted(() => {
+  try {
     useMachineUploadStore.getState().reset();
+  } catch (error) {
+    console.error(
+      "[MachineUploadStore] Failed to reset on pattern deleted event:",
+      error,
+    );
+  }
 });

src/stores/usePatternStore.ts

@@ -123,7 +123,17 @@ export const useUploadedPatternOffset = () =>
 export const usePatternRotation = () =>
   usePatternStore((state) => state.patternRotation);
 
-// Subscribe to pattern deleted event
+// 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
+// not stored or called.
 onPatternDeleted(() => {
+  try {
     usePatternStore.getState().clearUploadedPattern();
+  } catch (error) {
+    console.error(
+      "[PatternStore] Failed to clear uploaded pattern on pattern deleted event:",
+      error,
+    );
+  }
 });