codex

# Codex — the GPT-5.6 Execution Lane Run a benchmark-selected GPT-5.6 task through the Codex CLI (`codex exec`) and return the result. This is the OpenAI execution lane — the general-purpose lane for work the model-selection policy sends to GPT-5.6, and the **canonical owner of general `codex exec` mechanics** — when the CLI changes, update here first. GPT selections are reachable only through this CLI; the Agent tool's `model` parameter covers Claude models only. **Under Claude Code, this skill runs only on explicit invocation or cross-provider escalation, never as the automatic default.** The harness-native model lane under Claude Code is the Anthropic lane (Opus 5). This skill is a deliberate cross-provider tool — codex review as a second-opinion, codex exec for a GPT-specific constraint — not a routing default. Two flows keep their own specialized codex integration — route to them instead of re-implementing here: | Existing flow | Owns | Where | |---|---|---| ## Phase 1: DECIDE — does this task belong on GPT-5.6? Policy mirror — canonical copy: `/do` SKILL.md, Model Selection (edit there first, then here). Rankings, higher = better; cost = avg USD per task, written as a plain number (slash-command templating corrupts dollar-digit sequences in injected skill bodies), what the owner actually pays. | Task class | Model / effort | DeepSWE Pass@1 / cost / output tokens / steps | |---|---|---| | Low-risk assistance | `gpt-5.6-terra` / `high` | 54 / 1.13 / 22k / 34 | | St...