The leader of Plaid Cymru has called a pact between his party and Welsh Labour a "down-payment on independence".
The Co-operation Agreement between the two parties covers 46 policy areas, including universal free school meals as a step towards "a shared ambition that no child should go hungry".
The two partners – the Welsh Government and the Plaid Cymru Senedd Group – will work together to jointly develop and oversee the delivery of the policies covered by the agreement over the coming three years.
Addressing his party’s Annual Virtual Conference, Plaid Cymru Leader Adam Price hailed the agreement as "representing a new kind of politics".
The Co-operation Agreement covers 46 "nation building" policy areas including free childcare, plans to introduce rent controls, free school meals for all primary school pupils, the creation of a national care service, replacing council tax, increasing the number of Senedd members and changing the way they're elected, measures to tackle second homes and steps to transfer power over broadcasting to Wales.
Mr Price told the conference: "This is a nation-building Programme for Government which will change the lives of thousands of people the length and breadth of our country for the better.
"All this entails Plaid Cymru transforming itself from a traditional Opposition party in the Westminster sense to something new and refreshingly different, a Co-opposition party, co-operating where possible, while continuing to oppose, and to scrutinise and criticise where necessary.
"There is no precedent for what we are about to embark upon in the politics of these islands.
"It is a unique Welsh Departure from the British Constitution – a down-payment if you like on independence - though similar arrangements have happened elsewhere – notably in Scandinavian countries such as Sweden, Denmark, and Norway; and in Commonwealth countries such as New Zealand. Small nations all breaking the mould of politics-as-usual."
First Minister Mark Drakeford said: “This agreement brings the Welsh Government and Plaid Cymru together to respond to some of the most pressing issues facing Wales today, such as climate change and the energy and cost-of-living crisis.
“We can achieve more for people in Wales by working together and the agreement is both a response to the external challenges we face and a chance to build on the opportunities in our future. It will also help us secure a stable Senedd over the next three years, capable of delivering radical change and reform.
“These commitments build on our shared values of social solidarity, a sustainable planet and a vibrant democracy.”
Plaid won 13 seats in this year's election, one more than in the previous Senedd poll in 2016. They were, however, leap frogged by the Conservatives who had their best result since the first Senedd election in 1999.
Adam Price believes May’s election confirmed Wales’s status as an indy-curious nation.
"A curiosity that will give birth - sooner than many think - to an independent Wales," he told the conference.
"For Wales to be free, we must first be united. And, that is what this Co-operation Agreement sets out to achieve.
"It launches us on a pathway to a united Wales, one that, sooner than we perhaps think, will find it both comfortable and natural, indeed essential, to join the world community of normal, independent nations.
"As I said this week on the Senedd steps, if passed tomorrow, the Co-Operation Agreement is set to start on the first day of winter.
"Through it we will plant together “the seed beneath the snow” of a new society, a new Wales, a new beginning."
The Conservatives have strongly criticised the agreement, saying it will inflict "despair" on Wales and cause "constitutional chaos."
Meanwhile, the Liberal Democrats have said they're "concerned" that the agreement does not include measures to tackle the "crisis" in healthcare provision in Wales.