diff --git a/apps/desktop/package.json b/apps/desktop/package.json
index 8df63468f54..1d479b26a2d 100644
--- a/apps/desktop/package.json
+++ b/apps/desktop/package.json
@@ -72,6 +72,7 @@
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "cmdk": "^1.1.1",
+    "dnd-core": "^14.0.1",
     "hast-util-from-html-isomorphic": "^2.0.0",
     "hast-util-to-text": "^4.0.2",
     "ignore": "^7.0.5",
@@ -83,6 +84,7 @@
     "radix-ui": "^1.4.3",
     "react": "^19.2.5",
     "react-arborist": "^3.5.0",
+    "react-dnd-html5-backend": "^14.0.3",
     "react-dom": "^19.2.5",
     "react-router-dom": "^7.17.0",
     "react-shiki": "^0.9.3",
diff --git a/apps/desktop/src/app/right-sidebar/files/dnd-manager.ts b/apps/desktop/src/app/right-sidebar/files/dnd-manager.ts
new file mode 100644
index 00000000000..07f4d2f87fa
--- /dev/null
+++ b/apps/desktop/src/app/right-sidebar/files/dnd-manager.ts
@@ -0,0 +1,27 @@
+import { createDragDropManager, type DragDropManager } from 'dnd-core'
+import { HTML5Backend } from 'react-dnd-html5-backend'
+
+let manager: DragDropManager | null = null
+
+/**
+ * A single, app-lifetime react-dnd manager for the file tree.
+ *
+ * react-arborist mounts its own react-dnd `DndProvider` with `HTML5Backend`
+ * inside every `<Tree>`. react-dnd v14 stores that provider's manager on a
+ * global, ref-counted singleton context and nulls it when the count hits 0.
+ * On a keyed remount (cwd / collapse changes force a fresh `<Tree>`), the
+ * singleton can be torn down and recreated while the previous `HTML5Backend`
+ * still owns the `window.__isReactDndHtml5Backend` setup flag — so the new
+ * backend's `setup()` throws "Cannot have two HTML5 backends at the same
+ * time." and trips the file-tree error boundary (it never recovers, because
+ * "Try again" just remounts into the same race).
+ *
+ * Passing arborist a stable `dndManager` makes it skip the global-singleton
+ * path entirely and reuse one backend for the lifetime of the app, so the
+ * window flag is never double-claimed.
+ */
+export function getFileTreeDndManager(): DragDropManager {
+  manager ??= createDragDropManager(HTML5Backend)
+
+  return manager
+}
diff --git a/apps/desktop/src/app/right-sidebar/files/tree.tsx b/apps/desktop/src/app/right-sidebar/files/tree.tsx
index 49cd72a8d27..80ad1697cd5 100644
--- a/apps/desktop/src/app/right-sidebar/files/tree.tsx
+++ b/apps/desktop/src/app/right-sidebar/files/tree.tsx
@@ -7,6 +7,7 @@ import { useResizeObserver } from '@/hooks/use-resize-observer'
 import { useI18n } from '@/i18n'
 import { cn } from '@/lib/utils'
 
+import { getFileTreeDndManager } from './dnd-manager'
 import type { TreeNode } from './use-project-tree'
 
 const ROW_HEIGHT = 22
@@ -94,6 +95,7 @@ export function ProjectTree({
           disableDrag
           disableDrop
           disableEdit
+          dndManager={getFileTreeDndManager()}
           height={size.height}
           indent={INDENT}
           initialOpenState={openState}
diff --git a/nix/lib.nix b/nix/lib.nix
index 072f950462d..f4ce4c958e7 100644
--- a/nix/lib.nix
+++ b/nix/lib.nix
@@ -21,7 +21,7 @@ let
 
   # Single npm deps fetch from the workspace root lockfile.
   # All workspace packages share this derivation.
-  npmDepsHash = "sha256-mVWPJLIYa4EA0iNPiSVLAPzjjnWdky2HbG5mwApy1lo=";
+  npmDepsHash = "sha256-mYgKXE/FL4hnkrEvpVv+ULM/oeyIfO2AM9Ol8OrfWm0=";
 
   npmDeps = pkgs.fetchNpmDeps {
     inherit src;
diff --git a/package-lock.json b/package-lock.json
index a3a0f703de9..fb2afc5149b 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -102,6 +102,7 @@
         "class-variance-authority": "^0.7.1",
         "clsx": "^2.1.1",
         "cmdk": "^1.1.1",
+        "dnd-core": "^14.0.1",
         "hast-util-from-html-isomorphic": "^2.0.0",
         "hast-util-to-text": "^4.0.2",
         "ignore": "^7.0.5",
@@ -113,6 +114,7 @@
         "radix-ui": "^1.4.3",
         "react": "^19.2.5",
         "react-arborist": "^3.5.0",
+        "react-dnd-html5-backend": "^14.0.3",
         "react-dom": "^19.2.5",
         "react-router-dom": "^7.17.0",
         "react-shiki": "^0.9.3",