About codex
codex is a skill for running Codex on Go projects, with guidance for choosing profiles and models, executing tasks, and verifying changes. It distinguishes read-only analysis from edits and broader access, and emphasizes checking repository artifacts after execution.
Key features
- 01Guidance for profile and model selection
- 02Commands for analysis, edits, and resuming
- 03Background execution and output handling
- 04Verification through git diff --stat
- 05Worktree and project conventions
Use cases
- 01Run read-only analysis on a Go project
- 02Build or test with an edit profile
- 03Choose a model for an interactive task
- 04Review Codex changes for unintended edits
Install
Copy the command and run it in a terminal.
npx skills add https:/After installing, type/codexin Claude Code to confirm it loaded.
Details
From the project READMECodex
Profiles
- (no profile) — read-only analysis (no compilation, no tests)
--profile edit— local edits, build, or test (workspace-write, full-auto)--profile full— network or broad filesystem access (danger-full-access, full-auto)
Use --profile edit whenever the task involves go test, go build, or any command that writes build artifacts. The default read-only sandbox blocks all writes including compiler temp dirs.
For complex tasks, add --config model_reasoning_effort="xhigh".
Model Selection
Default to the project model in .codex/config.toml (gpt-5.4).
Use --model gpt-5.3-codex-spark for speed-first interactive work:
- tight back-and-forth iteration
- quick bug fixes and targeted edits
- small-to-medium refactors or UI tweaks
- rapid prototyping where frequent redirect/interrupt is expected
Stay on default gpt-5.4 for depth-first work:
- long autonomous runs
- broad multi-file changes with heavy reasoning
- test-heavy or verification-heavy tasks
- higher correctness/risk surfaces where deeper reasoning is worth the extra latency
If the user explicitly requests a model, follow the user's request.
Commands
Project defaults in .codex/config.toml. Always include --skip-git-repo-check and 2>/dev/null. Only override model when the user explicitly requests it, or when the task clearly fits the Spark speed-first criteria above.
| Use case | Command |
|---|---|
| Read-only analysis | codex exec --skip-git-repo-check -o "$CODEX_OUT" "prompt" 2>/dev/null |
| Speed-first interactive loop (Spark) | add --model gpt-5.3-codex-spark |
| Apply local edits | add --profile edit |
| Network / broad access | add --profile full |
| Resume session | echo "prompt" | codex exec --skip-git-repo-check -o "$CODEX_OUT" resume --last 2>/dev/null |
Create a temp file for output before running: CODEX_OUT=$(mktemp /tmp/codex-out.XXXXXX). Read the result from $CODEX_OUT after completion.
Run with Bash run_in_background: true. Monitor via TaskOutput with block: true, timeout: 600000 — do NOT use sleep commands to poll. Read the -o file for the final answer.
Resuming
Don't pass model/effort/sandbox flags when resuming — original session settings carry over. -o is safe to include.
Conventions
This is a Go project. Use go test, go build, go vet in prompts. Codex workers don't receive CLAUDE.md or hooks, so project conventions must be explicit.
Post-Execution Verification
Always verify Codex output via git diff --stat — never trust the worker's self-reported file list. Codex workers may make out-of-scope changes (deleting files, reverting unrelated code, removing test functions). The completion promise may list only intended files while omitting destructive side effects.
When other work exists in the same codebase, include explicit "DO NOT modify or delete" file lists in the prompt. The positive instruction ("only touch these files") is insufficient — Codex interprets "clean up" broadly.
Per [[principles/prove-it-works]]: trust artifacts, not self-reports.
Worktree Usage
With -C <worktree-dir>, the worktree has its own git index. .claude/ may symlink to .agents/ — use .agents/ paths for git operations.