Fix native chat drop ownership across session surfaces

src/renderer/src/components/native-chat/NativeChatPaneFileDropSurface.tsx

@@ -28,12 +28,13 @@ export function useNativeChatPaneFileDropClaim(claim: NativeChatPaneDropClaim):
   useLayoutEffect(() => {
     claimRef.current = claim
   })
-  const { scopeKey } = claim
+  const { scopeKey, disabled } = claim
   const registration = useMemo<NativeChatPaneDropRegistration>(
     () => ({ getClaim: () => claimRef.current, scopeKey }),
     [scopeKey]
   )
-  useLayoutEffect(() => register?.(registration), [register, registration])
+  // A guard transition ends the current hover before the next paint.
+  useLayoutEffect(() => register?.(registration), [disabled, register, registration])
 }
 
 export function NativeChatPaneFileDropSurface({
@@ -55,15 +56,13 @@ export function NativeChatPaneFileDropSurface({
     },
     []
   )
-  const registrationRef = useRef(registration)
-  registrationRef.current = registration
   const handlers = useMemo(
     () =>
       makeNativeChatPaneFileDropHandlers({
-        getClaim: () => registrationRef.current?.getClaim() ?? null,
+        getClaim: () => registration?.getClaim() ?? null,
         setDragActive: setIsDragActive
       }),
-    []
+    [registration]
   )
   // An OS drag never reaches React: the preload drop route consumes that event
   // before it leaves `document`. Its end is the only signal the overlay gets.

src/renderer/src/components/native-chat/NativeChatView.tsx

@@ -3,15 +3,21 @@ import { NativeChatStructuredSession } from './NativeChatStructuredSession'
 import { NativeChatResolvedView } from './NativeChatResolvedView'
 import { useNativeChatStatusEntry } from './use-native-chat-status-entry'
 import type { NativeChatViewProps } from './native-chat-view-types'
+import { NativeChatPaneFileDropSurface } from './NativeChatPaneFileDropSurface'
 
 export type { NativeChatViewProps } from './native-chat-view-types'
 
 /** Resolves an agent terminal into its native conversation and composer UI. */
 export default function NativeChatView(props: NativeChatViewProps): React.JSX.Element {
-  if (props.mode === 'structured') {
-    return <NativeChatStructuredSession key={props.sessionId} {...props} />
-  }
-  return <NativeChatBridgeView {...props} />
+  return (
+    <NativeChatPaneFileDropSurface className="relative flex h-full min-h-0 min-w-0 w-full">
+      {props.mode === 'structured' ? (
+        <NativeChatStructuredSession key={props.sessionId} {...props} />
+      ) : (
+        <NativeChatBridgeView {...props} />
+      )}
+    </NativeChatPaneFileDropSurface>
+  )
 }
 
 function NativeChatBridgeView({

src/renderer/src/components/native-chat/native-chat-pane-file-drop.test.tsx

@@ -152,6 +152,26 @@ describe('NativeChatPaneFileDropSurface', () => {
     expect(onDropCapture).not.toHaveBeenCalled()
   })
 
+  it('clears the active invitation when the composer becomes guarded', () => {
+    const pane = (disabled: boolean) => (
+      <NativeChatPaneFileDropSurface className="pane">
+        <ClaimingComposer disabled={disabled} />
+      </NativeChatPaneFileDropSurface>
+    )
+    const { container, rerender } = render(pane(false))
+    fireDrag(screen.getByTestId('composer'), 'dragover', workspaceDrag())
+    expect(container.querySelector(OVERLAY)).not.toBeNull()
+
+    rerender(pane(true))
+    expect(container.querySelector(OVERLAY)).toBeNull()
+    expect(container.querySelector('.pane')?.getAttribute('data-composer-scope-key')).toBe('pane:1')
+
+    rerender(pane(false))
+    expect(container.querySelector(OVERLAY)).toBeNull()
+    fireDrag(screen.getByTestId('composer'), 'dragover', workspaceDrag())
+    expect(container.querySelector(OVERLAY)).not.toBeNull()
+  })
+
   it('keeps the overlay up while the cursor crosses children, and drops it on exit', () => {
     const { transcript, container } = renderPane(<ClaimingComposer />)
     fireDrag(transcript, 'dragover', workspaceDrag())

src/renderer/src/components/native-chat/native-chat-view-file-drop.test.tsx

@@ -0,0 +1,55 @@
+// @vitest-environment happy-dom
+
+import { afterEach, expect, it, vi } from 'vitest'
+import { cleanup, fireEvent, render, screen } from '@testing-library/react'
+import { WORKSPACE_FILE_PATH_MIME } from '@/lib/workspace-file-drag'
+import NativeChatView from './NativeChatView'
+import { useNativeChatPaneFileDropClaim } from './NativeChatPaneFileDropSurface'
+
+const drop = vi.hoisted(() => ({ onDrop: vi.fn() }))
+
+vi.mock('@/i18n/i18n', () => ({ translate: (_key: string, fallback: string) => fallback }))
+vi.mock('./NativeChatSessionGate', () => ({ NativeChatSessionGate: () => null }))
+vi.mock('./NativeChatResolvedView', () => ({ NativeChatResolvedView: () => null }))
+vi.mock('./use-native-chat-status-entry', () => ({ useNativeChatStatusEntry: vi.fn() }))
+vi.mock('./NativeChatStructuredSession', () => ({
+  NativeChatStructuredSession: () => {
+    useNativeChatPaneFileDropClaim({
+      scopeKey: 'structured:session',
+      disabled: false,
+      onDragOverCapture: (event) => event.preventDefault(),
+      onDropCapture: drop.onDrop
+    })
+    return <div data-testid="transcript">Conversation above the composer</div>
+  }
+}))
+
+afterEach(cleanup)
+
+it('owns pane drops for standalone structured sessions without a terminal portal', () => {
+  const { container } = render(
+    <NativeChatView
+      mode="structured"
+      tabId="structured-tab"
+      sessionId="session"
+      agent="codex"
+      target={{ kind: 'local' }}
+      isVisible
+      isFocusedGroup
+    />
+  )
+  const transcript = screen.getByTestId('transcript')
+  const dataTransfer = { types: [WORKSPACE_FILE_PATH_MIME] }
+
+  fireEvent.dragOver(transcript, { dataTransfer })
+  expect(container.querySelector('[data-native-chat-drop-overlay]')).not.toBeNull()
+  expect(
+    transcript
+      .closest('[data-native-file-drop-target="composer"]')
+      ?.getAttribute('data-composer-scope-key')
+  ).toBe('structured:session')
+
+  fireEvent.drop(transcript, { dataTransfer })
+  expect(drop.onDrop).toHaveBeenCalledTimes(1)
+  expect(container.querySelector('[data-native-chat-drop-overlay]')).toBeNull()
+})

src/renderer/src/components/terminal-pane/TerminalPaneNativeChatPortal.tsx

@@ -1,6 +1,5 @@
 import { createPortal } from 'react-dom'
 import NativeChatView from '../native-chat/NativeChatView'
-import { NativeChatPaneFileDropSurface } from '../native-chat/NativeChatPaneFileDropSurface'
 import { makePaneKey } from '../../../../shared/stable-pane-id'
 import { canContinueAgentSessionInNewSession } from './terminal-agent-session-continuation'
 import type { TerminalPaneController } from './use-terminal-pane-controller'
@@ -69,7 +68,7 @@ export function TerminalPaneNativeChatPortal({
   }
 
   return createPortal(
-    <NativeChatPaneFileDropSurface className="native-chat-pane-shell absolute inset-0 z-10 flex min-h-0 min-w-0 bg-background">
+    <div className="native-chat-pane-shell absolute inset-0 z-10 flex min-h-0 min-w-0 bg-background">
       {structuredSessionId && structuredChatAgent ? (
         <NativeChatView
           mode="structured"
@@ -96,7 +95,7 @@ export function TerminalPaneNativeChatPortal({
           contextMenuActions={contextMenuActions}
         />
       )}
-    </NativeChatPaneFileDropSurface>,
+    </div>,
     chatPane.container,
     `native-chat-${tabId}-${chatPane.leafId}`
   )