Comprehensive list of mechanisms that automatically send authentication information in browsers

I’m trying to come up with a list of built-in mechanisms that either automatically send authentication information or automatically prompt the user to provide them in browsers.

So far I have

  1. Cookies – sends cookies based on domain / expiration etc

  2. 401 WWW-Authenticate: Negotiate (SPNEGO/GSS-API) – for whitelisted domains (needs browsers configuration) usually for Kerberos / NTLM

  3. Client certificate

  4. FIDO U2F (in supported browsers) – requires users to perform an action when prompted for a challenge

  5. WebAuthn (still in development, similar to the above)

  6. And obviously also Basic authentication (401 WWW-Authenticate: Basic)

Are there any other mechanisms to add to the above? (I’m excluding SAML/OIDC/OAuth as they don’t have any native support or special treatment as far as I know)

Why do OS and DBMS have their own synchronisation mechanisms, when OS can alone do it and it sits at the bottom of DB?

I know that synchronization is important in the OS, but why do we need a separate topic synchronization and concurrency in the DBMS? The OS concentrates on program synchronization while the DBMS concentrates on data synchronization. Why can’t the OS take responsibility for data synchronization?

What are the mechanisms that allow you to do a cantrip as a bonus action? [closed]

I’m digging around the players handbook, and so far all I see is the eldritch knight ability, and thats not quite what I need.

I’m trying to bring hideous blow over from 3.x to 5e for warlocks, but make it not suck. I was thinking maybe I could just sidestep the issue and make a mechanism that allows you to just cast eldritch blast as a bonus action when making an attack, maybe through an item or invocation? I’d rather not make it an invocation, but if I did I’d make it require the crossbow expert feat and some other crap.

Are there any magic item or class features I missed that allow you to cantrip as a bonus action?