codex

$27

Quick Reference

Use case

Sandbox mode

Key flags

Read-only review or analysis

read-only

--sandbox read-only 2>/dev/null

Apply local edits

workspace-write

--sandbox workspace-write --full-auto 2>/dev/null

Permit network or broad access

danger-full-access

--sandbox danger-full-access --full-auto 2>/dev/null

Resume recent session

Inherited from original

echo "prompt" | codex exec --skip-git-repo-check resume --last 2>/dev/null (no flags allowed)

Run from another directory

Match task needs

-C <DIR> plus other flags 2>/dev/null

Model Options

Model

Best for

Context window

Key features

gpt-5.2-max

Max model: Ultra-complex reasoning, deep problem analysis

400K input / 128K output

76.3% SWE-bench, adaptive reasoning, $1.25/$10.00

gpt-5.2 ⭐

Flagship model: Software engineering, agentic coding workflows

400K input / 128K output

76.3% SWE-bench, adaptive reasoning, $1.25/$10.00

gpt-5.2-mini

Cost-efficient coding (4x more usage allowance)

400K input / 128K output

Near SOTA performance, $0.25/$2.00

gpt-5.1-thinking

Ultra-complex reasoning, deep problem analysis

400K input / 128K output

Adaptive thinking depth, runs 2x slower on hardest tasks

GPT-5.2 Advantages: 76.3% SWE-bench (vs 72.8% GPT-5), 30% faster on average tasks, better tool handling, reduced hallucinations, improved code quality. Knowledge cutoff: September 30, 2024.

Reasoning Effort Levels:

• xhigh - Ultra-complex tasks (deep problem analysis, complex reasoning, deep understanding of the problem)

• high - Complex tasks (refactoring, architecture, security analysis, performance optimization)

• medium - Standard tasks (refactoring, code organization, feature additions, bug fixes)

• low - Simple tasks (quick fixes, simple changes, code formatting, documentation)

Cached Input Discount: 90% off ($0.125/M tokens) for repeated context, cache lasts up to 24 hours.

Following Up

• After every codex command, immediately use AskUserQuestion to confirm next steps, collect clarifications, or decide whether to resume with codex exec resume --last.

• When resuming, pipe the new prompt via stdin: echo "new prompt" | codex exec resume --last 2>/dev/null. The resumed session automatically uses the same model, reasoning effort, and sandbox mode from the original session.

• Restate the chosen model, reasoning effort, and sandbox mode when proposing follow-up actions.

Error Handling

• Stop and report failures whenever codex --version or a codex exec command exits non-zero; request direction before retrying.

• Before you use high-impact flags (--full-auto, --sandbox danger-full-access, --skip-git-repo-check) ask the user for permission using AskUserQuestion unless it was already given.

• When output includes warnings or partial results, summarize them and ask how to adjust using AskUserQuestion.

CLI Version

Requires Codex CLI v0.57.0 or later for GPT-5.2 model support. The CLI defaults to gpt-5.2 on macOS/Linux and gpt-5.2 on Windows. Check version: codex --version

Use /model slash command within a Codex session to switch models, or configure default in ~/.codex/config.toml.