1. I thought that it made the most sense to handle this check and serverRequest "once" in handleInitialClientSocketMessage. This is different than the check and request for MORE_ONE_TIME_KEYS which is handled within processClientResponses and gets "hit" every time the keyserver receives client responses. I concluded it was unnecessary to query the cookies table to check for signed_identity_keys every single time clientResponses are received and thought handleInitialClientSocketMessage would be a more appropriate place.

2. I concluded that we didn't need any client codeVersion checks here because [native/web]GetClientResponsesSelector will just ignore serverRequests that they're unable to handle (aka no branch to handle a given serverRequestType). It doesn't look like the keyserver holds onto any state regarding what requests have been sent to clients, so I concluded it was fine if the SIGNED_IDENTITY_KEYS_BLOB request was simply ignored by old clients.

3. I'm awaiting the call to isCookieMissingSignedIdentityKeysBlob separately from other async calls in handleInitialClientSocketMessage. I didn't think it made sense to group with the following:

because if, for example, there was a clientResponse to a SIGNED_IDENTITY_KEYS_BLOB request: there would be a race condition between

A. setting the signed_identity_keys column
B. checking if the signed_identity_keys column is NULL

As a result I decided to sequence the isCookieMissingSignedIdentityKeysBlob check AFTER the processClientResponses check to ensure that the result from isCookieMissingSignedIdentityKeysBlob is current and "up-to-date." It's not the end of the world if isCookieMissingSignedIdentityKeysBlob gives us a stale NULL since we'll just request it from the client again, but figured this approach was more correct.

I also didn't think it made sense to handle within the Promise.alls within the !sessionInitializationResult.sessionContinued block or the corresponding else block because we'd need to write the check out twice. There are definitely ways to pull promises={} outside of the conditional branches and "pull the common stuff out," but I thought it was simpler to just sequence isCookieMissingSignedIdentityKeysBlob after those blocks and concluded any overhead was minimal.

Okay, will remove. Thought it was necessary check because:

Will move