Opus 4.5 does made mistakes but I've found that's more due to ambiguous/imprecise functional requirements on my end rather than an inherent flaw of the agent pipeline. Giving it more clear instructions to reduce said ambiguity almost always fixes it, so I do not consider Opus failing. One of the very few times Opus 4.5 got completely stuck was, after tracing, an issue in a dependency's library which inherently can't be fixed on my end.

I am someone who has spent a lot of time with Sonnet 4.5 before that and was a very outspoken skeptic of agentic coding (https://news.ycombinator.com/item?id=43897320) until I gave Opus 4.5 a fair shake.