Right, I am a daily user of agentic LLM tools and have this exact problem in one large project that has complex business logic externally dictated by real world requirements out of my control, and let's say, variable quality of legacy code.

I remember when Gemini Pro 3 was the latest hotness and I started to get FOMO seeing demos on X posted to HN showing it one shot-ing all sorts of impressive stuff. So I tried it out for a couple days in Gemini CLI/OpenCode and ran into the exact same pain points I was dealing with using CC/Codex.

Flashy one shot demos of greenfield prompts are a natural hype magnet so get lots of attention, but in my experience aren't particularly useful for evaluating value in complex, legacy projects with tightly bounded requirements that can't be easily reduced to a page or two of prose for a prompt.

To be fair, you're not supposed to be doing the "one shot" thing with LLMs in a mature codebase.

You have to supply it the right context with a well formed prompt, get a plan, then execute and do some cleanup.

LLMs are only as good as the engineers using them, you need to master the tool first before you can be productive with it.

I would be much more impressed with implementing new, long-requested features into existing software (that are open to later maintain LLM-generated code).