Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/features/identity-setup/hooks/emailAddressRules.test.ts`:
- Line 242: Rewrite the changed test descriptions using plain-language “When …,
then …” behavior statements, without naming implementation symbols. In
src/features/identity-setup/hooks/emailAddressRules.test.ts lines 242-242,
replace the isEmailAddressFormatValid suite description; in
src/features/identity-setup/hooks/useEmailAddressValidation.test.ts lines
30-188, remove hook and callback names from the affected suite and test
descriptions while preserving their behavioral meaning.
- Around line 243-252: Update the affected tests around
isEmailAddressFormatValid to follow the AAA pattern: assign each input during
Arrange, call isEmailAddressFormatValid in a separate Act statement, then assert
the stored result. Add blank lines between the Arrange, Act, and Assert sections
while preserving the existing inputs and expected outcomes.

In `@src/features/identity-setup/hooks/useEmailAddressValidation.test.ts`:
- Line 30: Update the test descriptions within the useEmailAddressValidation
suite to use “When …, then …” wording focused on user-observable situations and
outcomes. Remove references to implementation names such as the hook,
validateAddress, and checkAvailability while preserving each test’s existing
behavior and assertions.
- Around line 161-175: Add a deferred-request test for checkAvailability that
starts with one username/domain, changes the current input before the
availability promise resolves, then resolves the old request successfully and
asserts its result cannot set canSubmit to true or authorize submission. Cover
the stale-result path in useEmailAddressValidation and include the rejection
behavior if the existing test utilities support it.
- Around line 31-39: Update the test setup around beforeEach and afterEach to
call vi.restoreAllMocks() at the start of beforeEach before configuring
checkAddressAvailability.mockResolvedValue. Remove the vi.clearAllMocks() call
from afterEach while preserving fake-timer setup and restoration.

In `@src/features/identity-setup/hooks/useEmailAddressValidation.ts`:
- Around line 56-65: Update checkAvailability in useEmailAddressValidation so
requests are invalidated immediately when the username or domain changes, and
ensure a request whose requestId no longer matches latestRequestIdRef.current
returns a non-success availability state instead of its stale result. Keep
lastCheck updates restricted to the current request, and preserve the existing
valid-result behavior when the request remains current.