Problem

After logging out, the next in-app login (any method) hangs indefinitely on the auth page: the form submits but never progresses. Reliably reproduced via Google SSO → logout → email/password login → stuck, but the root cause is not SSO-specific — any logout → in-app re-login (without a page reload) hits it.

Root cause

MatrixService is a singleton. Its client-ready barrier #clientReadyDeferred is only ever fulfilled once, at boot inside loadSDK() — the sole call site of .fulfill().

Logout stays in-app (router.transitionTo, not a page reload), and its finally runs resetState(). resetState() recreates the matrix client synchronously but then replaces #clientReadyDeferred with a fresh, never-fulfilled Deferred. Nothing re-runs loadSDK(), so the new deferred stays pending for the life of the singleton.

The next login → realm auth → createRealmSession() does await this.#clientReadyDeferred.promise. That promise never resolves → start() never returns → the login task never settles → the auth page stays mounted.

Regression introduced in f3fb792bce ("Memory leak cleanup"): before it, resetState() left the deferred fulfilled. The cleanup recreated it to drop references but overlooked that it is only fulfilled once, at boot.

Fix

In resetState(), fulfill the freshly created #clientReadyDeferred when _client exists (the client is already recreated synchronously just above). This restores the invariant "the deferred is fulfilled whenever _client exists" while keeping the memory-cleanup intent of a stale-reference-free deferred. The _client guard covers the edge case where the SDK hasn't loaded yet.

Testing

New integration test matrix-service-relogin-test.ts asserts createRealmSession settles after a resetState() instead of hanging (raced against a timeout guard so a hang fails the test rather than stalling the suite).

Verified headless:

• Fails against pre-fix code — times out on the hang.
• Passes with the fix; full matrix-service integration filter is green (22/22).

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