diff --git a/.changeset/fn-8232-task-detail-attachment-picker.md b/.changeset/fn-8232-task-detail-attachment-picker.md
new file mode 100644
index 0000000000..477ec8bd1b
--- /dev/null
+++ b/.changeset/fn-8232-task-detail-attachment-picker.md
@@ -0,0 +1,7 @@
+---
+"@runfusion/fusion": patch
+---
+
+summary: Fix the task-detail attach-file icon when the Definition tab is not open.
+category: fix
+dev: Keeps the shared fileInputRef input mounted outside tab-specific content.
diff --git a/packages/dashboard/app/components/TaskDetailModal.tsx b/packages/dashboard/app/components/TaskDetailModal.tsx
index cb237c81e8..f035b5f954 100644
--- a/packages/dashboard/app/components/TaskDetailModal.tsx
+++ b/packages/dashboard/app/components/TaskDetailModal.tsx
@@ -4490,6 +4490,19 @@ export function TaskDetailContent({
                     <Zap size={14} aria-hidden="true" />
                   </button>
                 </div>
+                {/*
+                FNXC:TaskDetailAttachments 2026-07-17-12:30:
+                FN-8232: keep the hidden file input mounted independently of activeTab.
+                The paperclip renders on every non-editing tab while task details default
+                to Activity or Summary; a Definition-only input made that control a no-op.
+                */}
+                <input
+                  className="detail-hidden-file-input"
+                  ref={fileInputRef}
+                  type="file"
+                  accept="image/*"
+                  onChange={handleUpload}
+                />
                 {overseerExplainOpen && (
                   <div className="detail-overseer-explain-panel" data-testid="detail-overseer-explain-panel" role="region" aria-live="polite">
                     {isLoadingOverseerExplain ? (
@@ -5892,13 +5905,6 @@ export function TaskDetailContent({
             ) : (
               <div className="detail-empty-inline">{t("taskDetail.attachments.none", "(no attachments)")}</div>
             )}
-            <input
-              className="detail-hidden-file-input"
-              ref={fileInputRef}
-              type="file"
-              accept="image/*"
-              onChange={handleUpload}
-            />
             <button
               className="btn btn-sm"
               onClick={() => fileInputRef.current?.click()}
diff --git a/packages/dashboard/app/components/__tests__/TaskDetailModal.inline-editing-and-integrations.test.tsx b/packages/dashboard/app/components/__tests__/TaskDetailModal.inline-editing-and-integrations.test.tsx
index a8f39a9dcb..fbc209a9a8 100644
--- a/packages/dashboard/app/components/__tests__/TaskDetailModal.inline-editing-and-integrations.test.tsx
+++ b/packages/dashboard/app/components/__tests__/TaskDetailModal.inline-editing-and-integrations.test.tsx
@@ -3372,6 +3372,29 @@ describe("TaskDetailModal inline action row parity (FN-8194)", () => {
     expect(fileInputClick).toHaveBeenCalledOnce();
   });
 
+  it("opens the shared file picker from Activity without rendering Definition", () => {
+    render(
+      <TaskDetailModal
+        initialTab="chat"
+        task={makeTask({ id: "FN-8232", column: "todo" })}
+        onClose={noop}
+        onMoveTask={noopMove}
+        onDeleteTask={noopDelete}
+        onMergeTask={noopMerge}
+        onOpenDetail={noopOpenDetail}
+        addToast={noop}
+      />,
+    );
+
+    const fileInputs = document.querySelectorAll<HTMLInputElement>('input[type="file"]');
+    expect(fileInputs).toHaveLength(1);
+    const fileInputClick = vi.spyOn(fileInputs[0], "click");
+
+    fireEvent.click(screen.getByTestId("detail-inline-attach"));
+
+    expect(fileInputClick).toHaveBeenCalledOnce();
+  });
+
   it("toggles GitHub tracking through the existing update path and reflects enabled state", async () => {
     const { updateTask } = await import("../../api");
     const mockUpdate = vi.mocked(updateTask);