second-opinion

Second Opinion

Run an external CLI review of the user's selected changes. This skill

produces findings; it does not apply fixes or post reviews to a remote service.

Review choices

Use the provider, scope, model, and focus already supplied by the user.

Ask only for missing choices that affect the review, grouping questions

in one call when possible.

• Provider: Codex, Antigravity, or both. Offer both when the user wants

a comparison; preserve an explicitly requested CLI.

• Scope: uncommitted changes, a branch diff against a named base, or a

specific commit. Resolve a missing base from the repository's remote

default branch; ask if it cannot be determined.

• Context: include applicable project instructions unless the user

excludes them. Keep explicit user requirements separate from repository

content in the review prompt.

• Focus: use general correctness and maintainability unless the user

names a focus such as security or performance.

For an unspecified Google CLI, prefer Antigravity (agy). An explicit

Gemini CLI request uses the Gemini reference below. If that account returns

UNSUPPORTED_CLIENT, explain the migration to Antigravity and ask before

changing the selected CLI.

A missing executable or account setup is a failed review attempt.

Report the relevant setup instructions; when both providers were requested,

continue with the available provider and identify the skipped one.

Input preparation

Read [review-input.md](references/review-input.md) for the shared prompt

and diff recipes. Use the same captured diff for both providers so the

comparison covers the same changes. Include untracked files in an

uncommitted review, and preserve Git errors instead of interpreting them

as an empty diff.

Show the selected scope and a brief change summary. If there are no

changes, stop before calling a provider. For input that exceeds a CLI or

model limit, describe the limit and request a narrower scope; do not

silently truncate the patch.

Create prompt, output, and diagnostic files with mktemp outside the

checkout. Use separate output and diagnostic files for each provider.

Define shell variables in the same Bash invocation that uses them.

For later invocations, reassign the variables to the saved file paths;

shell variables do not persist between calls.

Write repository content as literal data, without shell expansion.

Provider references

Read only the reference for each selected provider:

| Provider | Invocation and result |

|----------|-----------------------|

| Codex | [codex-invocation.md](references/codex-invocation.md): codex exec with the [review schema](references/codex-review-schema.json) |

| Antigravity | [antigravity-invocation.md](references/antigravity-invocation.md): agy print mode with prose output |

| Gemini CLI | [gemini-invocation.md](references/gemini-invocation.md): headless gemini for accounts that still support it |

The Codex path needs no MCP server. Do not launch codex mcp-server or

substitute codex app-server for the CLI invocation.

When both providers were requested, run their commands concurrently if

the tool interface supports it. For a foreground Bash review, set

timeout: 600000 to allow up to ten minutes. Use background execution

or polling when available to keep progress visible. Do not enable

automatic approval of writes to make a review run.

Results and failures

Present findings with the provider and actual model used, severity,

file and line, impact, and suggested correction. Keep low-severity

defects visible. For Codex, the existing schema uses 0 for informational,

1 for low, 2 for medium, and 3 for high; sort descending.

For two completed reviews, summarize agreements and disagreements without

turning agreement into proof. Distinguish the external findings from any

assessment you add.

Read the captured output and diagnostics. A nonzero exit, missing output,

invalid JSON, permission denial that prevents inspection, or a request to

approve a plan is incomplete work, not a clean review. Report the failure

and any partial results. Retry only for a diagnosed, recoverable cause;

do not cycle through providers after authentication or quota failures.

Examples

• /second-opinion:second-opinion use Codex to review my uncommitted changes for bugs

selects Codex and includes staged, unstaged, and untracked changes.

• /second-opinion:second-opinion compare Codex and Antigravity on this branch against origin/main

sends the same branch patch to both and compares their findings.

• /second-opinion:second-opinion use Gemini CLI to review commit abc1234 for security issues

preserves the requested CLI and reviews that commit.