fix(client): persist workspace drag order

packages/client/runtime/src/client/workspaces/manager.ts

@@ -173,10 +173,19 @@ export class WorkspaceManager {
     const frameGeneration = this.orderFrameGeneration
     const previousOrder = this.itemViews().map(workspace => workspace.workspaceId)
     this.installOrder(insertIdBefore(previousOrder, workspaceId, beforeWorkspaceId))
-    const { result } = await this.api.workspace.insertBefore({
-      workspaceId,
-      ...beforeWorkspaceId === undefined ? {} : { beforeWorkspaceId },
-    })
+    let result: RpcResult<{ workspaceIds: WorkspaceId[] }>
+    try {
+      ;({ result } = await this.api.workspace.insertBefore({
+        workspaceId,
+        ...beforeWorkspaceId === undefined ? {} : { beforeWorkspaceId },
+      }))
+    } catch (error) {
+      if (requestGeneration === this.orderRequestGeneration
+        && frameGeneration === this.orderFrameGeneration) {
+        this.installOrder(previousOrder)
+      }
+      throw error
+    }
     if (result.ok && requestGeneration === this.orderRequestGeneration
       && frameGeneration === this.orderFrameGeneration) {
       this.installOrder(result.value.workspaceIds)

packages/client/runtime/tests/workspaces-service.spec.ts

@@ -107,6 +107,12 @@ describe('WorkspaceManager', () => {
     expect(manager.getSnapshot().items.map(item => item.workspaceId)).toEqual(['one', 'two', 'three'])
     await expect(rejected).resolves.toMatchObject({ ok: false })
     expect(manager.getSnapshot().items.map(item => item.workspaceId)).toEqual(['one', 'three', 'two'])
+
+    api.onWorkspaceInsertBefore = () => Promise.reject(new Error('transport down'))
+    const disconnected = manager.insertBefore(wid('three'), wid('one'))
+    expect(manager.getSnapshot().items.map(item => item.workspaceId)).toEqual(['three', 'one', 'two'])
+    await expect(disconnected).rejects.toThrow('transport down')
+    expect(manager.getSnapshot().items.map(item => item.workspaceId)).toEqual(['one', 'three', 'two'])
   })
 
   it('replays removal over an in-flight baseline and ignores duplicate or late updates', async () => {

packages/client/ui-workspace/src/client/WorkspaceBrowser.tsx

@@ -200,9 +200,10 @@ function SessionTree({
   const [drag, setDrag] = useState<DragState | null>(null)
   const sessionDropCommitted = useRef(false)
   const [workspaceDrag, setWorkspaceDrag] = useState<WorkspaceDragState | null>(null)
-  const sessionDragging = drag !== null
+  const workspaceDropCommitted = useRef(false)
+  const nativeDragActive = drag !== null || workspaceDrag !== null
   useEffect(() => {
-    if (!sessionDragging) return
+    if (!nativeDragActive) return
     // Row hover still owns the insertion marker. Accept the native drag at
     // document level so releasing outside the list is not rendered as a
     // rejected drop before dragend commits that last marker.
@@ -217,7 +218,7 @@ function SessionTree({
       document.removeEventListener('dragover', acceptDrag)
       document.removeEventListener('drop', acceptDrop)
     }
-  }, [sessionDragging])
+  }, [nativeDragActive])
   const currentGroup = current === undefined
     ? undefined
     : (workspaces.find(w => w.sessionIds.includes(current))?.workspaceId as string | undefined)
@@ -310,6 +311,26 @@ function SessionTree({
       console.warn('session reorder rejected:', reason)
     })
   }
+  const commitWorkspaceDrag = (
+    activeDrag: WorkspaceDragState,
+    over: NonNullable<WorkspaceDragState['over']>,
+  ): void => {
+    if (workspaceDropCommitted.current) return
+    workspaceDropCommitted.current = true
+    setWorkspaceDrag(null)
+    const rowIndex = workspaces.findIndex(workspace => workspace.workspaceId === over.id)
+    if (rowIndex === -1) return
+    const anchor = over.half === 'before' ? over.id : workspaces[rowIndex + 1]?.workspaceId
+    if (anchor === activeDrag.workspaceId) return
+    const sourceIndex = workspaces.findIndex(workspace => workspace.workspaceId === activeDrag.workspaceId)
+    const anchorIndex = anchor === undefined
+      ? workspaces.length
+      : workspaces.findIndex(workspace => workspace.workspaceId === anchor)
+    if (sourceIndex !== -1 && (anchorIndex === sourceIndex || anchorIndex === sourceIndex + 1)) return
+    insertWorkspaceBefore(activeDrag.workspaceId, anchor).catch((reason: unknown) => {
+      console.warn('workspace reorder rejected:', reason)
+    })
+  }
 
   return (
     <div className={clsx(css.treeBody, css.wide)}>
@@ -323,8 +344,18 @@ function SessionTree({
             ? workspaceDrag.over.half
             : null
           const workspaceDragProps = workspaceId === undefined ? undefined : {
-            start: () => { setWorkspaceDrag({ workspaceId, over: null }) },
-            end: () => { setWorkspaceDrag(null) },
+            start: () => {
+              workspaceDropCommitted.current = false
+              setWorkspaceDrag({ workspaceId, over: null })
+            },
+            end: () => {
+              if (workspaceDrag?.over !== null && workspaceDrag?.over !== undefined) {
+                commitWorkspaceDrag(workspaceDrag, workspaceDrag.over)
+              } else {
+                setWorkspaceDrag(null)
+              }
+              workspaceDropCommitted.current = false
+            },
           }
           const hoverWorkspace = workspaceId === undefined
             ? undefined
@@ -337,18 +368,7 @@ function SessionTree({
             ? undefined
             : (half: 'before' | 'after') => {
               if (workspaceDrag === null) return
-              const rowIndex = workspaces.findIndex(workspace => workspace.workspaceId === workspaceId)
-              const anchor = half === 'before' ? workspaceId : workspaces[rowIndex + 1]?.workspaceId
-              setWorkspaceDrag(null)
-              if (anchor === workspaceDrag.workspaceId) return
-              const sourceIndex = workspaces.findIndex(workspace => workspace.workspaceId === workspaceDrag.workspaceId)
-              const anchorIndex = anchor === undefined
-                ? workspaces.length
-                : workspaces.findIndex(workspace => workspace.workspaceId === anchor)
-              if (sourceIndex !== -1 && (anchorIndex === sourceIndex || anchorIndex === sourceIndex + 1)) return
-              insertWorkspaceBefore(workspaceDrag.workspaceId, anchor).catch((reason: unknown) => {
-                console.warn('workspace reorder rejected:', reason)
-              })
+              commitWorkspaceDrag(workspaceDrag, { id: workspaceId, half })
             }
           return (
           // Group section: header row + expanded top-level session rows. The

packages/client/ui-workspace/tests/workspace-browser.spec.tsx

@@ -629,6 +629,34 @@ describe('WorkspaceBrowser', () => {
     expect(insertWorkspaceBefore).toHaveBeenCalledWith(wid('tail'), wid('beta'))
   })
 
+  it('accepts a document-level drop and commits the last Workspace marker on drag end', () => {
+    const insertWorkspaceBefore = vi.fn(async () => {})
+    mount({
+      useWorkspaces: hook(workspaceState([
+        workspace('alpha', []),
+        workspace('beta', []),
+        workspace('tail', []),
+      ])),
+      insertWorkspaceBefore,
+    })
+    const source = screen.getByText('tail').closest('[role="treeitem"]') as HTMLElement
+    let target = screen.getByText('beta').closest('[role="treeitem"]')?.parentElement as HTMLElement
+    while (target.parentElement?.getAttribute('role') !== 'tree') {
+      target = target.parentElement as HTMLElement
+    }
+    target.getBoundingClientRect = () => ({
+      top: 100, bottom: 134, left: 0, right: 200, width: 200, height: 34, x: 0, y: 100, toJSON: () => ({}),
+    })
+    fireEvent.dragStart(source, { dataTransfer: dragData() })
+    fireDrag(target, 'dragOver', 105)
+    const outsideDrop = createEvent.drop(document.body)
+    Object.defineProperty(outsideDrop, 'dataTransfer', { value: dragData() })
+    fireEvent(document.body, outsideDrop)
+    expect(outsideDrop.defaultPrevented).toBe(true)
+    fireEvent.dragEnd(source)
+    expect(insertWorkspaceBefore).toHaveBeenCalledWith(wid('tail'), wid('beta'))
+  })
+
   it('drag reorder reports the anchor to insertSessionBefore and skips no-op drops', () => {
     const insertSessionBefore = vi.fn(async () => {})
     const sessions = sessionState([summary('one', 3), summary('two', 2), summary('three', 1)])