The performer deeply understood the logic of the project and proposed a more serious and interesting approach. Firstly, he significantly reduced my future operating costs for the product: where my version required payment for two regular subscriptions, he deployed a completely independent and free architecture on my own server. Secondly, he brilliantly reworked the internal algorithms of the system (including prompts and data processing logic), making the final result of the highest quality. The product works perfectly.
A strange and pleasant realization: out of dozens of candidates on the site, I accidentally dug deeper and found a real gem. I am 99% sure that no one else would have implemented this project as elegantly.
I would also like to highlight personal qualities: the person possesses high goodwill, an honest and responsible approach, always understands the client's position, can record a video of the completed work and how to use the program, and can join a conference to personally explain everything and answer all questions (without abusing it). High intelligence, openness to new experiences, and creativity allow him to instantly generate ideas and solve non-standard tasks.
The main advice to future clients: give this person a little time and space for creativity, and he will implement your project in the best way possible. I definitely recommend collaborating!