[gooseus]

My thoughts are that we should send out robust seed organisms on probes with on-board AI that can do adequate scans for evidence of existing life before attempting to release the seed organisms.

A more advanced probe would have AI that could study the target planet as it approached and get more accurate readings on the environment. If no evidence of life is present then the AI could begin to rapidly evolve the seed organisms toward fitness for the detected target environment.

On arrival it could orbit the planet for a as long while continuing to evolve and release new generations of seed candidates and observing changes in the environment. Once evidence that life has taken hold is detected it could stop seeding and just continue monitoring. I'm assuming it would send progress reports home every once in awhile, even if nobody was still here to receive them.