fix: avoid false-positive batch invariant error#18246
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Thanks to #17940 (comment) I was finally able to isolate and reproduce a false-positive invariant error. I had a hunch this could happen and this shows it. Essentially, you can end up in situations where two batches are scheduled to run in the same microtask queue flush, and if the first rebases the second the invariant will throw, which is wrong. We can avoid this by checking if a decrement is queued.
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Rich-Harris
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May 20, 2026
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This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## svelte@5.55.9 ### Patch Changes - fix: don't unset batch when calling `{#await ...}` promise ([#18243](#18243)) - fix: promise-ify `{#await await ...}` expressions on the server and correctly hydrate them on the client ([#18243](#18243)) - fix: deduplicate dependencies that are added outside the init/update cycle ([#18243](#18243)) - fix: avoid false-positive batch invariant error ([#18246](#18246)) - fix: inline primitive constants in attribute values during SSR ([#18232](#18232)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
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Thanks to #17940 (comment) I was finally able to isolate and reproduce a false-positive invariant error. I had a hunch this could happen and this shows it. Essentially, you can end up in situations where two batches are scheduled to run in the same microtask queue flush, and if the first rebases the second the invariant will throw, which is wrong. We can avoid this by checking if a decrement is queued.