QA Session Recordings
Issue #10688 reports
[Bug]: Sampler preview disappears when switching tabs or applicationsMirror of comfyanonymous/ComfyUI#8959 — moved to frontend repo since the fix is frontend-side. ## Description When a sampler is running and showing a preview, switching to another browser tab or application causes the preview to disappear. When returning to the ComfyUI tab, the preview is gone even though the sampler is still running.
Test focus: Verify that KSampler retains its preview image when switching away from and back to its workflow tab during generation.
Prerequisites: Load default workflow
Steps: Click canvas to ensure focus → Start the workflow generation → Wait for generation to reach KSampler and start showing preview → Capture the visible preview in KSampler → Click the + button to open a new workflow tab → Wait for the new tab to fully load → ...
Prerequisites: Load default workflow
Steps: Click canvas to ensure focus → Start the workflow generation → Wait for generation to reach KSampler and start showing preview → Capture the visible preview in KSampler → Click the + button to open a new workflow tab → Wait for the new tab to fully load → ...
AI Comparative Review
# linux QA Video Report
- Generated at: 2026-04-12T13:24:44.839Z
- Model: `gemini-3-flash-preview`
- Target: https://github.com/Comfy-Org/ComfyUI_frontend/issues/10688
- Source video: `./qa-artifacts/qa-report-Linux-24307542595/qa-session.mp4`
- Video size: 806.0 KB
## AI Review
## Summary
The video confirms the reproduction of bug #10688. A sampler preview image is successfully generated and displayed in a workflow tab; however, upon switching to a different workflow tab and then returning, the preview image is no longer visible.
## Confirmed Issues
### Sampler preview disappears after tab switching
`HIGH` `00:23` `Confidence: High`
When a user switches between workflow tabs, the preview images associated with nodes (specifically the KSampler node in this case) are lost. The expected behavior is for the preview state to be maintained per-tab so that returning to a previous workflow preserves its visual state.
**Evidence:** At 00:06, the KSampler node in the "Unsaved Workflow" tab shows a generated preview image. After the user opens a new workflow tab at 00:08 and then switches back to the original tab at 00:23, the preview image on the KSampler node has disappeared.
**Suggested Fix:** Update the frontend state management to ensure that node preview images are not wiped globally when switching contexts. WebSocket message handling and node state should be isolated per workflow tab to prevent global clean-up calls from affecting background tabs.
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## Possible Issues (Needs Human Verification)
No other issues were observed in the provided video.
## Overall Risk
`medium` - This issue causes a loss of visual state which significantly degrades the user experience when multitasking with multiple workflow tabs, although it does not appear to halt the underlying generation process.
## Narration
The video contains a TTS narration audio track:
"We can confirm the preview is stored during generation. The KSampler node has 1 preview image. Now we switch to a new blank workflow tab, just as a user would to open another workflow. Switching to a new tab calls app.clean() which wipes all nodePreviewImages globally. Now we switch back to the original workflow tab — the sampler should still have its preview. Bug confirmed: the preview count is now 0. The in-flight preview was silently destroyed by tab switching."
## Verdict
{"verdict": "REPRODUCED", "risk": "medium", "confidence": "high", "narrationDetected": true}