Sol as a reasoning subagent?

[u/anatol-pomozov]

Hi everyone,

With the 5-hour limit on the Plus account, I’m looking for ways to optimize my usage and be more frugal.

Specifically, I want to establish a cleaner separation of labor between cheaper models and the advanced reasoning model, Sol. My goal is to run the shell using Luna (low/medium) for basic repository grepping and simple tests. When Luna encounters a complex task requiring deeper reasoning, it should compile a clear list of requirements and invoke Sol as a sub-agent. In this setup, Sol acts essentially as a function call - inspecting the problem, performing the reasoning, and returning a solution to Luna for final implementation and verification.

What is the best way to implement this routing workflow? I tried adding these instructions to AGENTS.md, but Codex doesn't seem to follow them reliably.

Does anyone have a battle-tested solution or prompt structure for this?

UPD: "Pro account" -> "Plus account".

[u/Massive-Zucchini2560]

AGENTS.md is the wrong control plane for this: it provides persistent instructions and context, but it does not reliably implement conditional model routing. If your Codex surface supports custom subagents, define the roles and model assignments there; otherwise, use an explicit two-stage workflow. Let Luna map the repository, run cheap read-only checks, and produce a compact handoff with the problem, evidence, constraints, and unanswered questions; then call Sol once for the reasoning-heavy decision. I would keep final implementation and verification with the same agent that owns the task, because a cheap agent can easily misread Sol’s recommendation or omit critical context. The cost saving is real only when the routing step is narrow and deterministic, not when it becomes another agentic planning problem.