Is 'to smoke' a complement or adjunct in this sentence?

As you will tell from my answers, I like to focus on readability. At the satisfaction of my readers. Always imagining that they could give me a star rating based on the enjoyment of my book or sentence.

So for me, I think you need to clarify for the reader what you're trying to say.

Are you just missing a comma? as in, "he stopped, to smoke." an infinitive-of-purpose adjunct?

IMO, "to smoke" should be a direct object of "stopped" which is derived from a noun clause "that he will/would smoke".

In a comment, John Lawler wrote:

To smoke is a purpose infinitive. Stop, unlike start, can take only gerund complements (He stopped smoking, he started smoking, he started to smoke), so any infinitive following it has to be an adjunct.