Fix flow-view mount race (StrictMode double-fetch)#24
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useModelData's boot fetch had no cancellation, so React StrictMode's dev-mode mount->cleanup->mount double-invoke fired it twice; the first response still landed after its own effect cleaned up and reset flowDiagrams/model with a fresh reference, retriggering FlowsView's render effect while the prior mount was still settling. Two live React roots ended up writing into the same shared container, surfacing as "Cannot update an unmounted root" / "Attempted to synchronously unmount a root while React was already rendering" on flow-view mount. Guards the fetch effect with the standard ignore-flag cleanup pattern, and separately hardens FlowsView's renderDiagram against any instance whose owning effect was torn down while it awaited ELK layout.
damusix
marked this pull request as ready for review
July 15, 2026 05:13
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Summary
useModelData's boot fetch had no cancellation, so React StrictMode's dev-mode double-invoke fired it twice; the stale first response landed after its own effect cleaned up and resetflowDiagrams/modelwith a fresh reference, retriggering the flow renderer's mount effect while the prior mount was still settling — two live React roots ended up writing into the same shared container.disposedguard onFlowsView's asyncrenderDiagramso any orphaned continuation from a torn-down instance bails instead of racing for the container.What this solves
Console errors on flow-view mount in dev (
ignatius serve/bun run dev): "Cannot update an unmounted root" / "Attempted to synchronously unmount a root while React was already rendering." Reproduced live, fixed, and confirmed clean across repeated fresh loads.