Re: Correct documentation for protocol version

On Sun, Feb 8, 2026 at 12:27 PM Jelte Fennema-Nio <postgres(at)jeltef(dot)nl> wrote:
> After Jacob made his changes to the "Protocol Versions" section in
> e3d37853ecd, now seemed a good moment to update this patch to do the
> proposed.

I'm more than happy to remove the v2 information -- though we may want
to keep the v2 error format somewhere, if it's not already in the
startup flow description -- and I agree we should document the
NegotiateProtocolVersion history. ("9.3.21 and later" is misleading,
though; see a60a10338 and its thread.)

The discussion of the sslnegotiation=direct changes needs refinement,
IMO. All we did there was add raw TLS support on the same port;
negotiation of the protocol version happens via TLS in that case. (To
put it another way: clients and servers don't have to support that in
order to claim protocol 3.0 compliance.)

We could instead document the fact that the initial TLS 1.x packets
can be disambiguated from StartupMessages on the wire, which is what
lets us run the two separate protocols on a single port. We could also
document our ALPN requirements for that mode, or link to the
"protocol-flow-ssl" id in the docs.

Thanks!
--Jacob