Codex Implementation

Use Codex as a separate implementation agent for bounded code changes. Claude remains responsible for scoping the task, reviewing the diff, running or checking verification, and explaining the final result.

Use this when the user asks for Codex or delegation, or when a bounded task would benefit from a parallel implementation agent producing a patch. Do not let Codex commit, push, deploy, or edit global config unless the user explicitly asked for that.

Use the configured Codex model by default. Pin a model explicitly only when the task calls for that specific model. Do not report a model name unless verified for the run.

Workflow

1. Pin the current state with git status --short and note any user changes to preserve.
2. Define the implementation scope: files or behavior to change, files to avoid, and verification commands.
3. Create a temporary artifact directory for Codex's report.
4. Run codex exec with repo write access.
5. After Codex exits, inspect git status and git diff.
6. Run the cheapest reliable verification yourself when practical.
7. Report what Codex changed, what Claude verified, and any remaining risks.

Use this command shape:

ARTIFACT_DIR="$(mktemp -d "${TMPDIR:-/tmp}/codex-implementation.XXXXXX")"
REPORT="$ARTIFACT_DIR/report.md"
PROMPT="$ARTIFACT_DIR/prompt.md"

# Write a self-contained prompt to $PROMPT, then run:
codex exec \
  -C "$PWD" \
  -s workspace-write \
  - < "$PROMPT" > "$REPORT"

Prompt Requirements

The prompt must be self-contained. Tell Codex:

• The repository path and the artifact directory.
• The goal, acceptance criteria, and any files or areas to avoid.
• That it must preserve unrelated user changes.
• That it must not commit, push, deploy, or edit global config.
• Which verification commands to run, or to explain why they were skipped.
• To write a concise final report with files changed, verification, and unresolved issues.

Keep the task bounded. If the requested work bundles several substantial changes, split them into separate Codex runs or ask the user to choose the first scope.

Example Prompt

You are implementing a scoped change for Claude.

Repository: /absolute/path/to/repo
Artifact directory: /tmp/codex-implementation.xxxxxx

Goal:
- Add keyboard navigation to the command palette.

Acceptance criteria:
- Arrow keys move the selection; Enter activates the selected item.
- Existing mouse behavior is unchanged.

Constraints:
- Preserve unrelated user changes.
- Do not commit, push, deploy, or edit global config.

Verification:
- Run the project's typecheck and lint commands and include the results.

Report:
- Files changed
- Behavioral summary
- Verification run and result
- Anything blocked or uncertain

Review After Codex

Always inspect Codex's diff before telling the user the work is done. Revert only Codex-created mistakes when you are sure they are not user changes. If Codex leaves the repo in a worse state or changes unrelated files, stop and report the issue with the diff.

If codex is not installed or the command fails, report the error and offer to implement the change directly instead.