How did the 2025 front of frontier models, such as Opus 4.5, enable true parallel AI development?

In the second half of 2025, frontier models made a collective leap in four directions: autonomous debugging, instruction following, Skill rules for engineering norms, and Computer Use. These improvements allowed mechanisms to replace deep human involvement in addressing the three bottlenecks—for example, Agents can now autonomously run tests, fix bugs, and follow structured Skill files. This shift from human-in-the-loop to rule-based acceptance means developers can launch multiple Agents in parallel without being the serial bottleneck.