google just used ai agents to formally verify the signal protocol. not a writeup of the design. the actual code that protects messages in signal and google messages. deepmind's alphaproof code agents, powered by gemini carbon, wrote over 6 million lines of lean. that's the language you use to mathematically prove code is correct. the verification took 4 weeks. deepmind says that kind of work has historically taken expert teams years. they even re-inserted 2 old, already-fixed bugs on purpose. the system proved both versions were insecure. signal's cto called it a major breakthrough. if you care about crypto, privacy, or agents you can actually trust, this is the story this week. is this formal verification going mainstream, or a one-off flex?e