fix: normalize recursive listing paths to forward slashes (#6003)

frontend/src/utils/__tests__/check-conflict.test.ts

@@ -220,4 +220,52 @@ describe("checkConflict", () => {
 
     expect(conflicts).toHaveLength(0);
   });
+
+  // Regression for #5980: a FileBrowser server running on Windows returns
+  // backslash-separated paths from the recursive listing. Without normalizing
+  // them, the prefix strip and key lookup never match, so the conflict modal is
+  // skipped and the backend returns a bare 409.
+  it("detects a conflict for backslash-separated server paths (Windows)", async () => {
+    vi.mocked(api.fetchAll).mockResolvedValue([
+      {
+        path: "\\target\\file.txt",
+        name: "file.txt",
+        size: 10,
+        modified: "2026-06-04T00:00:00Z",
+        isDir: false,
+      },
+    ]);
+
+    const conflicts = await checkConflict(
+      [moveItem("file.txt", "/files/target/")],
+      "/files/target/"
+    );
+
+    expect(conflicts).toHaveLength(1);
+  });
+
+  it("detects nested conflicts for backslash-separated server paths (Windows)", async () => {
+    vi.mocked(api.fetchAll).mockResolvedValue([
+      {
+        path: "\\target\\folder\\nested file.txt",
+        name: "nested file.txt",
+        size: 10,
+        modified: "2026-06-04T00:00:00Z",
+        isDir: false,
+      },
+    ]);
+
+    const files = [
+      {
+        name: "nested file.txt",
+        size: 12,
+        isDir: false,
+        fullPath: "folder/nested file.txt",
+      },
+    ];
+
+    const conflicts = await checkConflict(files, "/files/target/");
+
+    expect(conflicts).toHaveLength(1);
+  });
 });

frontend/src/utils/upload.ts

@@ -62,9 +62,10 @@ export async function checkConflict(
   const normBase = removePrefix(basePath).replace(/\/+$/, "");
   const serverMap = new Map<string, RecursiveEntry>();
   for (const entry of serverEntries) {
-    const rel = entry.path.startsWith(normBase)
-      ? entry.path.slice(normBase.length)
-      : entry.path;
+    // A Windows server may return OS-native backslash separators; normalize to
+    // forward slashes so the prefix strip and key lookup line up.
+    const path = entry.path.replace(/\\/g, "/");
+    const rel = path.startsWith(normBase) ? path.slice(normBase.length) : path;
     serverMap.set(rel.replace(/^\/+/, ""), entry);
   }
 

http/resource.go

@@ -424,7 +424,10 @@ var resourceGetRecursiveHandler = withUser(func(w http.ResponseWriter, r *http.R
 		}
 
 		entries = append(entries, RecursiveEntry{
-			Path:    fPath,
+			// afero.Walk joins paths with the OS separator, so on Windows fPath
+			// uses backslashes. The web API contract is forward slashes, so
+			// normalize it here (mirrors search/search.go).
+			Path:    filepath.ToSlash(fPath),
 			Name:    info.Name(),
 			Size:    info.Size(),
 			ModTime: info.ModTime(),