Huddersfield defender Liam Ridehalgh has signed a new one-year contract at the John Smith's Stadium.
The 22-year-old left-back spent last season on loan at Chesterfield and Rotherham but Town boss Mark Robins wants him to challenge for a first-team spot next term.
"The next year is potentially very important for Liam's development and I'm looking forward to getting a close look at him during pre-season, as during my time he has been gaining experience through his most recent loan spell at Rotherham," Robins told the club's official website.
"We have very good competition for places at left-back thanks to the likes of Calum Woods, Paul Dixon and new recruit Jake Carroll and Liam's challenge is to come back to the club and put his marker down."
The midfielder will now focus his attention on finding a new club after helping Saints claim the final European place with a 2-0 win over Motherwell on Sunday.
Davidson said: "The only thing I know is that I won't be at St Johnstone next season.
"I've thoroughly enjoyed my time here, I've loved every minute but it's time to move on and I'm delighted they've got Europe to enjoy next year.
"I've not got anything 100 per cent sorted. I've been trying not to get too involved in it while the season has been going on.
"It's a long summer now and there is plenty of time to get a new club. It will probably be sooner rather than later but at the moment I'm not too sure where I'll be going.
"It's the perfect way to leave. It means so much to the people here.
"I'm delighted to help give them a present and give them something to look forward to over the summer."
Saints have continental football to savour for a second year running, after facing Turkish outfit Eskisehirspor last time.
Davidson added: "Even last year when we got into Europe, I was shocked by how much it meant to so many people.
"It wasn't just the players and people connected with the club, it was the whole of Perth that got involved and it was a massive thing.
"To do it this year again, with the size of the budget we've got, I think is an unbelievable achievement.
"As a group, we deserve massive credit and you can't take that away from us."
Inverness had been in the driving seat for third place - and a Europa League berth - heading into the final day of the season, but defeat to Highland rivals Ross County, combined with Saints' win over Motherwell, saw Steve Lomas' men come out on top.
Goals from Liam Craig and Nigel Hasselbaink sealed the three points for St Johnstone.
Davidson said: "It was good in a way because we knew we had to win. All we could do was fully concentrate on winning the game.
"It would have been sad if Ross County had done us a favour and we didn't do our job.
"If we had won, and Inverness had won, then they would have deserved it. But we've managed to pip them at the line and we have been excellent as a whole squad so I think it's deserved."
