Yes, it is clear as crystal that the angel of the Lord/Jesus Christ is identified as the Lord God in His pre-existence before His incarnation in the New Testament. In fact, by you quoting Genesis 22;15-16 you have given the best proof of all in the entire Bible IMO. I will be happy to explain why.
Genesis 22:15-17, "Then the angel of the Lord called to Abraham a second time from heaven." (At Genesis 22:11 was the first time the angel of the Lord called from heaven.) vs16, and said, "By Myself I have sworn, declares the Lord because you have done this thing, and not withheld your son, your only son, vs17, indeed I will greatly bless you and I will greatly multiply your seed as he stars of the heavens, and the sand which is on the seashore; and you seed shall possess the gate of his enemies."
Please notice from vs16 the words "and said." What did the angel of the Lord say? "By Myself I have sworn, declares the Lord etc." The following is from the book of Hebrews in the NT at Hebrews 6:13-16.
"For WHEN GOD made the promise to Abraham, since He could swear by no one greater, HE SWORE BY HIMSELF, vs14, saying, I will surely bless you, and I will surely multiply you." Vs15, And thus, having patiently waited, he obtained the promise. Vs16, For men swear by one greater than themselves, and with them/men an oath given as confirmation is an end of every dispute."
Now, it is true that that, "The Law of Agency deals with the status of a person (known as the agent) acting by direction of another (the principal), and thereby legally binding the principal in his connection with a third person.The information I just gave is from the Jewish Law of Agnecy/Shaliach found in the Jewish Encyclopedia, page 232.
However, from the Jewish Virtual Library the law of agency most if not all of the time deals with, "laws of mamonot (commercial law), or (heave offering), sacrifices, divorce, and betrothal etc. According to the Tosefta (Kid, 4:1), Bet Shammai and Bet Hillel agreed that a person appointed to carry out a specific mandate is disqualified from acting as a witness in a case involving such mandate. The agent/Shaliach is not regarded as the principal as himself since the agent is disqualified from testifying as a witness.
Swear means to state under oath. Swearing an oath is a matter of one's own conscience, therefore Angels cannot swear oaths on behalf of God Himself and Jesus Christ is not an angel but rather the "messenger of the Lord." Angels cannot multiply descendants but the angel of the Lord multiplied Hagars descendants at Genesis 16:10.
The angel of the Lord appeared in the burning bush at Exodus 3:2-6 and claimed to be God at vs6. He appeared to Joshua at Joshua 5:13-15 and said at Joshua 6:2, "And the Lord said to Joshua I have given you Jerico. At Judges 2:1, the3 angel of the Lord brought you up out of Egypt and led you into the land I HAVE SWORN to your fathers, and said I will never break My covenant."
To be sure, I could give many more references where the angel of the Lord intervened on behalf of Isarael and its people as a mediator. Lastly, there is Malachi 3:1, "Behold, I am going to send My messenger, and he will clear the way before Me, And the LORD whom you seek will suddenly come to His temple; and the messenger of the covenant, in whom you delight, behold, He is coming, says the Lord of hosts." Who do you think this is? Also read Luke 1:68-79. As a side note, the angel of the Lord never appears in the New Testament as the angel of the Lord, although He is mentioned by Stephen at Acts 7.
The Hebrew word for angel is "malak." It means "Messenger, Sent One, Angel. The context determines how it is used. At Malachi 3:1, God says, I am going to send My angel/messenger, and he will clear the way before Me" This is referring to John the Baptist and John is not an angel. Continuing on with the verse, "And the Lord whom you seek, will suddenly come to His temple;" This is the Lord Jesus Christ.
Continuing on. and the malak/angel/messenger of the covenant, in whom you delight, behold, He is coming, says the Lord of hosts." This is referring to "THE" angel of the Lord, the pre-incarnate Jesus Christ who is not an angel but the "messenger" of the Lord in the OT. As a side note, the prophet Malachi, (a human being) well his name is from the word "malak/messenger." Human prophets are messengers.
Now, the poster of this thread (SLM) immediately quoted Genesis 22:15-16 wanting to know, the identity of the angel of the Lord. When I address this issue, I use or post Genesis 22:15-16 last and then I quote Hebrews 6:13-17 which backs up the identity of the angel of the Lord as God. Why? Because it is God who swore the oath to Abraham and at Genesis it's the angel of the Lord who swore the oath, which means that the angel of the Lord is not an actual angel because it is proven from these text angels can't swear oaths on behalf of God. That's also why the text says God swore the oath, "By Myself."
Now, Anne ask a legitimate question from Genesis 22:15-16, but it was a question in isolation as it relates to the angel of the Lord. Personally, I always start this issue with Genesis 16:7. Why? Because this is the first mention of the angel of the Lord as the angel of the Lord.
He says to Hagar at Genesis 16:8, "Where have you come from and where are you going? At vs9, TAOL says, "Return to Sarai. Vs, TAOL says, "moreover, I will greatly multiply your descendants so that they shall be too many to count." At vs11, he says, "Behold, you are with child and describes the child as a wild donkey of a man. In today's context Ishmael is the progenitor of the Arabs.
At vs13 Hagar says, "Then she called the name of the Lord who spoke to her, "Thou are a God who sees; for she said, "Have I even remained alive here after seeing Him." Now watch this? Genesis 17:1-5, "Now when Abraham was ninety-nine years old, the Lord appeared to Abraham and said to him. (this was a physical appearance).
I am God Almighty; Walk before Me, and be blameless. Vs2, And I will establish My covenant between Me and you, And I will multiply you exceedingly. Vs3, "And Abraham fell on his face and God talked with him, saying, Vs4, "As for Me, behold My covenant is with you, And you shall the father of a multitude of nations. Vs5, No longer shall you name be called Abram, But your name shall be Abraham; For I will make you the Father of a multitude of nations."
So here's the question? Is the being that multiplied Hagar's descendants the same being who multiplied Abraham's descendants? The reason I know this was a physical appearance of God is from Genesis 17:22, "And when He finished talking with him/Abraham, God went up from Abraham."
The angel of the Lord also appeared (physically) again to Abraham at Genesis 18 along with two actual angels. All through Genesis 18 God and Abraham have an interesting conversation which you can read for yourselves. At Genesis 18:33, (the last verse) says, "And as soon as He had finished speaking to Abraham the Lord departed; and Abraham returned to his place. What about the two angels? Genesis 19:1, "Now the two angels came to Sodom in the evening etc."
So now we know who the angel of the Lord is and what he did at Genesis 22:15-18. And as stated earlier, the angel of the Lord makes numerous appearances in the OT.