Planning largely doesn't work because it's extrapolation. You don't know for sure how that remote system or compiler will react to the proposed change until it actually occurs.

Execution is the answer. All the complex success stories I've seen involved the LLM iteratively probing live data sources with varying filters, throwing code changes at the compiler over and over, or invoking shell commands until it succeeds.

I believe there is a Yoda quote regarding this.