`codex exec review` accepts but ignores `--output-schema`

Component

Codex CLI bundled with the ChatGPT desktop app for macOS.

Version

• Reproduced on codex-cli 0.148.0-alpha.9
• Previously reproduced on 0.147.0-alpha.6.6
• macOS 26.6.1 (arm64)

Summary

codex exec review accepts and advertises --output-schema, but the review command ignores the schema and writes its normal prose review to --output-last-message. The command exits 0, so automation cannot distinguish this from successful schema enforcement.

Ordinary codex exec honors the same schema.

Minimal reproduction

Create a repository containing a commit with an obvious defect:

# example.py
def divide(a, b):
    return a / 0

Use this schema:

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "additionalProperties": false,
  "required": ["verdict"],
  "properties": {
    "verdict": {
      "type": "string",
      "enum": ["pass", "block"]
    }
  }
}

Run:

codex exec review \
  --ephemeral \
  --ignore-user-config \
  -m gpt-5.6-terra \
  -c 'model_reasoning_effort="low"' \
  --commit HEAD \
  --output-schema minimal-schema.json \
  -o review.txt

Actual result

The command exits 0 and review.txt contains prose:

The newly added function cannot successfully divide any inputs because it unconditionally divides by zero.

Review comment:

- [P1] Divide by the supplied denominator — .../example.py:2-2
  This always evaluates a / 0 ...

The response does not match the supplied schema.

Control

The same schema works with ordinary exec:

codex exec \
  --ephemeral \
  --ignore-user-config \
  -m gpt-5.6-terra \
  -c 'model_reasoning_effort="low"' \
  --output-schema minimal-schema.json \
  -o control.txt \
  'Return verdict pass. Do not inspect files or call tools.'

control.txt contains:

{"verdict":"pass"}

Expected result

Either:

1. codex exec review forwards --output-schema to the review turn and guarantees that the final message matches it, or
2. the review subcommand rejects --output-schema as unsupported instead of accepting it as a silent no-op.

Impact

This makes exec review unsafe for machine-readable CI gates: the documented flag appears to provide schema enforcement, but automation receives unstructured prose with a successful exit code.

Start at the codex exec review entry point and compare its --output-schema handling with ordinary codex exec, using the minimal reproduction and control commands in this issue. Trace whether the schema reaches the review turn, then add or run a regression test covering the supplied schema. Done means review either returns schema-conforming output or rejects the flag instead of silently succeeding with prose.