"I am THE weekend engineer assigned to your ticket" or "I am A weekend engineer assigned to your ticket" [closed]

I understand this question is very similar to hundreds of previously asked ones, but we still cannot come to an agreement, and maybe we'll be fighting each other soon.

Which version is correct?

"Hello, My name is <>, and I'm the weekend engineer assigned to your case"

"Hello, My name is <>, and I'm a weekend engineer assigned to your case"

This is the first line in an email. So we are talking here about a very specific engineer (that's why we might need to use "the") and at the same time it's the first time we're introducing an engineer, one out of entire team, chosen randomly (that's why we might need to use "a")

Your first sentence uses the definite article ("the"), while your second uses an indefinite article ("a" or "an").

Choose the indefinite or definite article to indicate the hearer's prior information about the topic. Use the definite article if the weekend engineer is being introduced or if there is only one. For example:

"I'm transferring you to level 3 support. Bill is the engineer who will be assigned your case." (Introducing the one and only Bill; use the definite article.)

"I'm transferring you to level 3 support. A weekend engineer will help you." (Speaker does not know which of the engineers will be assigned, and is indicating this to the hearer by using the indefinite article.)

"Make sure to take the Volvo key." (The hearer knows there is only one key, so use the definite article.)

"It'll rain, so take an umbrella." (The hearer knows that there are several umbrellas available; use the indefinite article.)

"It'll rain, so take the umbrella." (The hearer knows there is only one umbrella; use the definite article.)