fix: defer removeDraft until after switch succeeds

Moves removeDraft() call to after the switch/close logic completes,
preserving the draft if closeWorkflow returns false due to a failed
switch. Adds test coverage for draft preservation on switch failure.

Addresses review feedback:
https://github.com/Comfy-Org/ComfyUI_frontend/pull/11389#pullrequestreview-2960339131

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/platform/workflow/core/services/workflowService.test.ts

@@ -11,6 +11,7 @@ import { useSettingStore } from '@/platform/settings/settingStore'
 import { useToastStore } from '@/platform/updates/common/toastStore'
 import type { ComfyWorkflow } from '@/platform/workflow/management/stores/workflowStore'
 import { useWorkflowStore } from '@/platform/workflow/management/stores/workflowStore'
+import { useWorkflowDraftStore } from '@/platform/workflow/persistence/stores/workflowDraftStore'
 import { useWorkflowService } from '@/platform/workflow/core/services/workflowService'
 import { useMissingNodesErrorStore } from '@/platform/nodeReplacement/missingNodesErrorStore'
 import { useExecutionErrorStore } from '@/stores/executionErrorStore'
@@ -1292,6 +1293,21 @@ describe('useWorkflowService', () => {
       expect(workflowStore.isOpen(active)).toBe(true)
     })
 
+    it('does not remove draft when switch fails', async () => {
+      const draftStore = useWorkflowDraftStore()
+      const active = createAndRegister('workflows/active.json', 0)
+      createAndRegister('workflows/other.json', 1)
+      workflowStore.activeWorkflow = active as LoadedComfyWorkflow
+
+      vi.mocked(app.loadGraphData).mockRejectedValue(
+        new Error('configure failed')
+      )
+
+      await service.closeWorkflow(active, { warnIfUnsaved: false })
+
+      expect(draftStore.removeDraft).not.toHaveBeenCalled()
+    })
+
     it('falls back to default workflow when replacement throws', async () => {
       const active = createAndRegister('workflows/active.json', 0)
       createAndRegister('workflows/other.json', 1)

src/platform/workflow/core/services/workflowService.ts

@@ -324,8 +324,6 @@ export const useWorkflowService = () => {
       }
     }
 
-    workflowDraftStore.removeDraft(workflow.path)
-
     // If this is the last workflow, create a new default temporary workflow.
     // Route through trySwitch so a rejection from loadGraphData
     // (validation / extension hooks / node-replacement loading) keeps the tab
@@ -340,6 +338,10 @@ export const useWorkflowService = () => {
       if (!didSwitch) return false
     }
 
+    // Remove draft only after switch succeeds — keeps draft intact if close is
+    // aborted due to switch failure, so the tab retains its persisted state.
+    workflowDraftStore.removeDraft(workflow.path)
+
     await workflowStore.closeWorkflow(workflow)
     return true
   }