critic-pair

flowchart TD
    Input([Task input]) --> Proposer[Proposer agent]
    Proposer --> Challenger[Challenger agent]
    Challenger --> Judge[Judge agent]
    Judge --> Verdict{ACCEPTED?}
    Verdict -- yes --> Done([Return proposal])
    Verdict -- no --> Escalate([Escalate with critique])

Two agents play adversarial roles before a result is accepted. The proposer produces a solution; the challenger actively tries to break it. A judge makes the final call.

How it works

The proposer agent produces an implementation for the task.
The challenger agent receives the proposal and tries to find every flaw: bugs, edge cases, security issues, performance problems.
The judge agent evaluates both and responds with ACCEPTED or REJECTED. If rejected, the critique is returned as structured feedback.

When to use

High-stakes outputs where a single-pass reviewer misses adversarial cases (auth logic, data parsing, financial calculations).
Situations where you want explicit, structured critique rather than a yes/no review.

When not to use

Routine low-risk tasks — the overhead of three agents is rarely justified.
When the judge’s criteria are vague; judge and challenger will contradict each other without converging.

Trade-offs


Pro	Surfaces flaws that a non-adversarial reviewer skips
Pro	Produces a structured critique even when rejected — useful as input to a fix loop
Con	Three sequential agent calls; 3× latency and cost of a single-agent review
Con	All three roles run on the same model here: blind spots are correlated, and the challenger misses what the proposer missed. A different model or a stronger effort for the challenger buys real diversity, at a cost
Con	Challenger can hallucinate flaws that don’t exist, causing false rejections

Failure modes

Hallucinated critique — challenger invents flaws; judge rejects a correct proposal.
Sycophantic judge — judge always accepts to avoid conflict, defeating the adversarial purpose.
Infinite rejection — combine with a loop-with-guard if the proposer retries on rejection, otherwise the pipeline stalls.