fix(dav): Prevent race condition in useDAVFiles

Assisted-by: ClaudeCode:claude-fable-5
Signed-off-by: David Dreschner <david.dreschner@nextcloud.com>

Author: DerDreschner

lib/composables/dav.spec.ts

@@ -240,4 +240,53 @@ describe('dav composable', () => {
 		await waitRefLoaded(isLoading)
 		expect(abort).toBeCalledTimes(1)
 	})
+
+	it('a superseded (aborted) load does not clear the loading state of the newer load', async () => {
+		// Each getDirectoryContents call stays pending until resolved manually,
+		// and rejects with an AbortError when its signal is aborted — mirroring a
+		// real DAV request that is cancelled on fast navigation.
+		const pending: Array<{ resolve: () => void }> = []
+		const client = {
+			stat: vi.fn((v) => ({ data: { path: v } })),
+			getDirectoryContents: vi.fn((_path, opts) => new Promise((resolve, reject) => {
+				opts.signal?.addEventListener('abort', () => {
+					const error = new Error('aborted')
+					error.name = 'AbortError'
+					reject(error)
+				})
+				pending.push({ resolve: () => resolve({ data: [] }) })
+			})),
+		}
+		nextcloudFiles.getClient.mockImplementationOnce(() => client)
+		nextcloudFiles.resultToNode.mockImplementation((v) => v)
+
+		const view = ref<'files' | 'recent' | 'favorites'>('files')
+		const path = ref('/')
+		const { loadFiles, isLoading } = useDAVFiles(view, path)
+
+		// Load A is in flight
+		loadFiles()
+		await nextTick()
+		expect(pending).toHaveLength(1)
+		expect(isLoading.value).toBe(true)
+
+		// Load B supersedes A: navigating aborts A and starts B loading
+		path.value = '/subdir/'
+		await nextTick()
+		expect(pending).toHaveLength(2)
+
+		// Let A's aborted request reject and run its catch/finally
+		await nextTick()
+		await nextTick()
+
+		// Regression: A's finally must not flip isLoading to false while B is
+		// still loading — otherwise the FilePicker sees isLoading=false with a
+		// null folder and confirms an empty selection ("No nodes selected").
+		expect(isLoading.value).toBe(true)
+
+		// Completing B settles the loading state
+		pending[1].resolve()
+		await waitRefLoaded(isLoading)
+		expect(isLoading.value).toBe(false)
+	})
 })

lib/composables/dav.ts

@@ -68,20 +68,20 @@ export function useDAVFiles(
 	async function loadDAVFiles() {
 		if (abortController) {
 			abortController.abort()
-			abortController = undefined
 		}
 
-		abortController = new AbortController()
+		const thisAbortController = new AbortController()
+		abortController = thisAbortController
 		isLoading.value = true
 		try {
 			if (currentView.value === 'favorites') {
-				files.value = await getFavoriteNodes({ client, path: currentPath.value, signal: abortController.signal })
+				files.value = await getFavoriteNodes({ client, path: currentPath.value, signal: thisAbortController.signal })
 				folder.value = null
 			} else if (currentView.value === 'recent') {
-				files.value = await getRecentNodes({ client, signal: abortController.signal })
+				files.value = await getRecentNodes({ client, signal: thisAbortController.signal })
 				folder.value = null
 			} else {
-				const content = await getNodes({ client, path: currentPath.value, signal: abortController.signal })
+				const content = await getNodes({ client, path: currentPath.value, signal: thisAbortController.signal })
 				folder.value = content.folder
 				files.value = content.contents
 			}
@@ -92,8 +92,16 @@ export function useDAVFiles(
 			}
 			throw error
 		} finally {
-			abortController = undefined
-			isLoading.value = false
+			// Only clear the shared loading state if this invocation is still the
+			// current load. When a newer loadDAVFiles() has already aborted and
+			// superseded this one, resetting here would flip `isLoading` to false
+			// (and drop the newer abort controller) while the newer load is still
+			// in flight and `folder` is still null — which lets the FilePicker
+			// confirm with an empty selection and throw "No nodes selected".
+			if (abortController === thisAbortController) {
+				abortController = undefined
+				isLoading.value = false
+			}
 		}
 	}