🎯 Changes

Fixes #11587.

A query created inside $effect.root stays subscribed after the root's disposer runs. The observer is never released, so the cache entry survives its gcTime, interval refetches keep firing, and a pending request that uses its AbortSignal is never aborted.

createBaseQuery subscribes eagerly, outside any effect, so that the subscription exists on the server and on suspended branches. Two things are meant to tear that subscription down later:

• the watchChanges effect on [isRestoring.current, observer], which returns a cleanup, but only from its second run, since the helper skips the first invocation
• onDestroy, which throws outside a component and is swallowed by the surrounding try

Inside $effect.root neither applies, so the first subscription has no teardown. This adds one effect whose only job is to unsubscribe on teardown, which the root disposer runs. In a component it is redundant with onDestroy, and unsubscribing twice is a no-op. It is in a try for the same reason as the onDestroy next to it: outside an effect context the call throws, and that should not become an error for callers. During SSR the effect does not run and onDestroy still handles cleanup.

Tests

packages/svelte-query/tests/createQuery/observer-cleanup.svelte.test.ts is the reproducer from the issue, written by @Osraka, included with their commit as the source. It covers createQuery and createInfiniteQuery in the success, error and disabled states, disposal before the first effect runs, signal abortion, interval refetches, and two controls that already passed: normal component unmount and disposal after switching clients.

• Before: 10 failed, 2 passed, matching the issue.
• After: 12 passed. Whole package: 24 files, 226 tests, no type errors.
• test:eslint, test:lib, test:types, test:build and build pass for @tanstack/svelte-query, and test:sherif, test:knip and test:docs pass for the repository. (pnpm run test:pr itself hung with no output on my machine before running anything, so I ran its targets directly.)

On #11542 and #11557: both branch from before #9810, so this reproducer passes there only because their base predates the regression. Neither merges onto current main without a conflict in this file, and both target different symptoms.

✅ Checklist

• I have followed the steps in the Contributing guide.
• I have tested code changes locally with pnpm run test:pr, or these tests do not apply to this pull request.
• I fully understand the code in this pull request, including any code generated with AI assistance.

🚀 Release Impact

• This change affects published code, and I have generated a changeset.
• This change is docs/CI/dev-only (no release).

Summary by CodeRabbit

• Bug Fixes

  • Query observers now unsubscribe when their effect root is disposed, including after successful, failed, or disabled queries.
  • Disposing a root also stops interval refetches and aborts requests that use cancellation signals. Cleanup continues to work on component unmount and when the client changes.

• Tests

  • Added coverage for observer cleanup, resource disposal, and garbage collection.