When the victim left his house to go shopping, he saw the trio stationed by his mailbox.
The woman, who cannot be named for legal reasons, allegedly set her two friends on him.
"There he is, guys. Get him."
Prosecutor Sergeant Chris George said there was clear premeditation involved.
"They waited for him to come outside ... then they lowered the boom on him," he said.
The 26-year-old man was first to wade in, subjecting the victim to a flurry of punches and knocking him to the ground.
While Kennedy's repeated kicks to the defenceless man's legs did not cause severe damage, the judge said he was jointly responsible for the outcome.
"What he was doing was facilitated by what you were doing and vice-versa," he said.
The beating lasted two minutes.
Since a kick or a punch took only a fraction of a second to deliver, Judge Rollo labelled it a "prolonged" attack.
When the men finally relented, the victim staggered off to a neighbouring property where he sought medical help.
Doctors discovered his nose was broken in two places and cuts and bruises covering his face and body were catalogued.
Kennedy was serving a court-imposed sentence of supervision at the time and the judge charted a growing criminal history.
In particular, he noted an aggravated robbery in 2018 which was similarly committed as part of a group.
Kennedy had been bailed in September to undertake a residential rehabilitation programme but had been asked to leave for breaching curfew amid allegations he was using again.
Counsel Andrew Dawson said his client had been the subject of threats at the facility and emphasised he was still keen to address his drug issues.
Judge Rollo convicted Kennedy of injuring with intent to injure and jailed him for 18 months but left the door open for conversion to home detention, should an appropriate programme become available.
He ordered the defendant pay the victim $500 to cover emotional harm and damage to the man's phone and clothes.
- rob.kidd@odt.co.nz
