Today, you send such workflow definition to claude code or codex and ask it to delegate proper subagents to complete those tasks in order, it can do quite well. So, what's the unique value for this solution?

The workflow definition can span across multiple agents. Say you have 3 steps in your workflow - step 1 can be done by claude, step 2 by codex and maybe step 3 by gemini. Because different agents have different strengths (for e.g I think codex is better for planning swe tasks)

Good point.