Let Codex pick the plan apart before Claude writes any code.
I'd rather find a wrong turn in a plan than in a finished branch. So Claude writes its plan to a file, Codex reads that file with the repo open, and its objections come back into Claude's session as a message. Claude answers them or changes the plan, and you approve the version that's left.
Free and open sourceRuns on Mac and LinuxYour own Claude and Codex logins
Recorded on a demo machine: a Codex helper's reply lands in Claude's prompt, with the sender checked by Overvibe.
By the time you spot the gap, it's already in the code
Approve a plan with a hole in it and the hole gets built. Claude wrote that plan with the same assumptions it will code with, so asking it to double-check rarely turns the hole up. A model starting from the plan and the repo reads it without those assumptions.
One agent on its own
The planner checks its own plan
Gaps show up in the diff, after the work
Approving means trusting one model's read
Agents side by side in Overvibe
Codex reads the plan with the repo open
Objections arrive before any code is written
You approve a plan that already took pushback
One plan, two readers
You type
❯Write the plan to PLAN.md, then get a second opinion from Codex on it before you write any code.
1Claude writes the plan
Into PLAN.md, so Codex reads exactly what you would approve.
2Codex reads it cold
Started attached to Claude, told to read the plan and the code it touches and to change nothing.
3The objections come back
One message in Claude's prompt: what's missing, what's risky, what Codex would do instead.
4You approve what's left
Claude answers each point or rewrites the plan, then waits for your OK.
What Claude runs. One command. The review lands in Claude's prompt as a message from "app: plan review". Read the CLI reference
$ overvibe new --attach --tool codex --cwd . --name "app: plan review" \
--prompt "Read PLAN.md and the code it touches. List gaps, risks and better options. Do not edit files. When done, run: overvibe send \"$OVERVIBE_SESSION\" \"<review>\""
One agent is enough when
the change is small. A plan review for a two-line fix costs more than it saves, so read Claude's plan yourself and approve it. Bring Codex in when the plan touches data, money or a migration, where a wrong first step is expensive to undo.
Questions
Does this work with Claude Code's plan mode?
Yes, with one extra step. Plan mode is for reading and planning, and starting Codex is a command, so leave plan mode (shift+tab) before you ask Claude to save the plan and bring Codex in.
Why Codex and not a second Claude?
A second Claude is more likely to share the first one's blind spots. Codex comes from a different lab and misses different things. agy works the same way with --tool agy.
What if Codex is wrong?
Claude says so in its answer, and you decide. Both arguments are in front of you in one session.
