These are great. I had my own list of takeaways [0] after doing this for a couple years, though I wouldn't go so far as calling mine factors.

Like you, biggest one I didn't include but would now is to own the lowest level planning loop. It's fine to have some dynamic planning, but you should own an OODA loop (observe, orient, decide, act) and have heuristics for determining if you're converging on a solution (e.g. scoring), or else breaking out (e.g. max loops).

I would also potentially bake in a workflow engine. Then, have your model build a workflow specification that runs on that engine (where workflow steps may call back to the model) instead of trying to keep an implicit workflow valid/progressing through multiple turns in the model.

[0]: https://mg.dev/lessons-learned-building-ai-agents/