Frontend: Fix race condition

It resulted from yesterday's refactor c2681d4. Oops.

Author: vdavid

apps/desktop/src/lib/file-explorer/BriefList.svelte

@@ -10,6 +10,8 @@
         createParentEntry,
         getEntryAt as getEntryAtUtil,
         fetchVisibleRange as fetchVisibleRangeUtil,
+        calculateFetchRange,
+        isRangeCached,
         shouldResetCache,
     } from './file-list-utils'
 
@@ -87,18 +89,6 @@
         containerWidth > 0 ? Math.min(calculatedColumnWidth, containerWidth) : calculatedColumnWidth,
     )
 
-    // Debug logging
-    $effect(() => {
-        // eslint-disable-next-line no-console
-        console.log('[BRIEF] maxFilenameWidth:', {
-            backendMaxWidth,
-            containerWidth,
-            calculatedColumnWidth,
-            maxFilenameWidth,
-            COLUMN_PADDING,
-        })
-    })
-
     // Total number of columns needed
     const totalColumns = $derived(Math.ceil(totalCount / itemsPerColumn))
 
@@ -129,6 +119,13 @@
         const startItem = startCol * itemsPerColumn
         const endItem = Math.min(endCol * itemsPerColumn, totalCount)
 
+        // Check if range is already cached BEFORE setting isFetching
+        // This prevents blocking subsequent fetches when data is already available
+        const { fetchStart, fetchEnd } = calculateFetchRange({ startItem, endItem, hasParent, totalCount })
+        if (isRangeCached(fetchStart, fetchEnd, cachedRange)) {
+            return // Already cached
+        }
+
         isFetching = true
         try {
             const result = await fetchVisibleRangeUtil({

apps/desktop/src/lib/file-explorer/FullList.svelte

@@ -9,6 +9,8 @@
         createParentEntry,
         getEntryAt as getEntryAtUtil,
         fetchVisibleRange as fetchVisibleRangeUtil,
+        calculateFetchRange,
+        isRangeCached,
         shouldResetCache,
     } from './file-list-utils'
 
@@ -88,12 +90,22 @@
     async function fetchVisibleRange() {
         if (!listingId || isFetching) return
 
+        const startItem = virtualWindow.startIndex
+        const endItem = virtualWindow.endIndex
+
+        // Check if range is already cached BEFORE setting isFetching
+        // This prevents blocking subsequent fetches when data is already available
+        const { fetchStart, fetchEnd } = calculateFetchRange({ startItem, endItem, hasParent, totalCount })
+        if (isRangeCached(fetchStart, fetchEnd, cachedRange)) {
+            return // Already cached
+        }
+
         isFetching = true
         try {
             const result = await fetchVisibleRangeUtil({
                 listingId,
-                startItem: virtualWindow.startIndex,
-                endItem: virtualWindow.endIndex,
+                startItem,
+                endItem,
                 hasParent,
                 totalCount,
                 includeHidden,

apps/desktop/src/lib/file-explorer/file-list-utils.ts

@@ -85,10 +85,14 @@ export interface FetchRangeResult {
     range: { start: number; end: number }
 }
 
-/** Fetches entries for a visible range with prefetch buffer */
-export async function fetchVisibleRange(params: FetchRangeParams): Promise<FetchRangeResult | null> {
-    const { listingId, startItem, endItem, hasParent, totalCount, includeHidden, cachedRange, onSyncStatusRequest } =
-        params
+/** Calculates the fetch range for visible items with prefetch buffer */
+export function calculateFetchRange(params: {
+    startItem: number
+    endItem: number
+    hasParent: boolean
+    totalCount: number
+}): { fetchStart: number; fetchEnd: number } {
+    const { startItem, endItem, hasParent, totalCount } = params
 
     // Account for ".." entry
     let adjustedStart = startItem
@@ -102,8 +106,27 @@ export async function fetchVisibleRange(params: FetchRangeParams): Promise<Fetch
     const fetchStart = Math.max(0, adjustedStart - PREFETCH_BUFFER / 2)
     const fetchEnd = Math.min(hasParent ? totalCount - 1 : totalCount, adjustedEnd + PREFETCH_BUFFER / 2)
 
+    return { fetchStart, fetchEnd }
+}
+
+/** Checks if the needed range is already cached */
+export function isRangeCached(
+    fetchStart: number,
+    fetchEnd: number,
+    cachedRange: { start: number; end: number },
+): boolean {
+    return fetchStart >= cachedRange.start && fetchEnd <= cachedRange.end
+}
+
+/** Fetches entries for a visible range with prefetch buffer */
+export async function fetchVisibleRange(params: FetchRangeParams): Promise<FetchRangeResult | null> {
+    const { listingId, startItem, endItem, hasParent, totalCount, includeHidden, cachedRange, onSyncStatusRequest } =
+        params
+
+    const { fetchStart, fetchEnd } = calculateFetchRange({ startItem, endItem, hasParent, totalCount })
+
     // Only fetch if needed range isn't cached
-    if (fetchStart >= cachedRange.start && fetchEnd <= cachedRange.end) {
+    if (isRangeCached(fetchStart, fetchEnd, cachedRange)) {
         return null // Already cached
     }