Karvey Second Opinion

Karvey — Second Opinion (cross-model reviewer)

Purpose

This is a cross-cutting skill of the Karvey Method: a support layer, NOT a phase. It does not change spec.json:phase nor advance the method's flow. It can be invoked at any time without altering the state of the Karvey project.

The goal is to obtain an independent cross-model second opinion: asking an AI model different from the current one (for example Claude reviewing GPT/Codex/Gemini's work, or vice versa) to look at the same code with fresh eyes. Model diversity catches failures that a single model, due to its own biases and blind spots, cannot see on its own.

It is especially useful before releasing something sensitive: production changes, security logic, data handling, migrations, or anything high-impact where a single pair of eyes is not enough.

Inspired by gstack's /codex pattern: invoke an external reviewer to cross-check.

What this skill does NOT do

• It does NOT replace karvey-qa's safety gate. It is a complement. This skill's verdict alone does NOT approve anything for release.
• It does NOT advance the phase of the Karvey Method nor modify spec.json.
• It is NOT the final authority: it is one more input to the human decision.

Modes

Default mode if not specified: Review.

Steps

1. Identify the diff / files to review

Determine the exact scope of the review:

• If the user passed a file or path as an argument → that is the scope.
• If not, get the current diff of the work in progress:

  git diff
  git diff --staged
  git diff origin/dev...HEAD   # or the corresponding base branch
  

• Gather the minimal necessary context: the diff, the touched files, and the requirement/objective the code must meet (read spec.json or the Karvey task if it exists).

2. Invoke a model different from the current one

The key is model diversity. Detect what is available and degrade gracefully:

1. External CLI of another model (preferred). Detect whether it exists on the system:

   command -v codex   2>/dev/null && echo "codex disponible"
   command -v gemini  2>/dev/null && echo "gemini disponible"
   command -v llm     2>/dev/null && echo "llm disponible"
   

   If one is available, invoke it passing the diff/context and the prompt according to the mode. This gives a genuinely cross-model opinion.

2. Graceful degradation (fallback): if NO CLI of another model is accessible, use a subagent (Agent) with an explicit adversarial prompt that instructs it to act as an independent, skeptical reviewer — explicitly looking for what the original author overlooked. Make it clear in the report that this was an intra-model fallback (same model family), so the real diversity is lower.

The prompt to the external reviewer must include, according to the mode:

• Review: "You are an independent reviewer. Evaluate this change against the requirement. Deliver a PASS or FAIL verdict and prioritized findings (blocking / major / minor)."
• Challenge: "You are an adversarial reviewer. Your job is to try to break this solution: find edge cases, fragile assumptions, race conditions, security or data failures. Assume there is a bug and look for it."
• Consult: "Let's talk openly about this design. What trade-offs do you see? What alternatives would you consider?"

3. Consolidate and compare against the own review

• Take the external model's findings.
• Contrast them with the own review (the current model's).
• Classify each point into: agreements (both models see it), discrepancies (one yes, the other no), and new findings that only the external model raised.

4. Report

Deliver a clear report with:

• Mode used and which external model was invoked (or whether it was an intra-model fallback).
• Verdict (in Review/Challenge modes): PASS / FAIL — remembering it is NOT release approval on its own.
• Agreements: findings where both models concur (high confidence).
• Discrepancies: where the opinions differ, with the reasoning behind each position.
• New findings: what only the second model detected.
• Recommendation: what to bring back to karvey-qa's gate and to the human decision.

Final reminder

This skill complements, does not replace karvey-qa's safety gate. A favorable second opinion does not authorize a release: the QA gate and human approval remain mandatory. And this skill never advances the phase of the Karvey Method.

Part of the Karvey™ Method — © HainTech, by Mauricio Quezada Ibáñez · Apache 2.0 · see karvey/LICENSE and karvey/TRADEMARK.md.