codex-implementation

name

codex-implementation

description

Ask Codex CLI (gpt-5.5) to implement scoped code changes in the current repository, then have Claude inspect the resulting diff and verification. This is how gpt-5.5 is invoked for implementation work. Use when the user asks Claude to delegate implementation to Codex or gpt-5.5, when the model-selection rubric routes the work to gpt-5.5, or when a bounded task would benefit from another coding agent producing a patch.

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.

Workflow

1. Pin the current state with git status --short and note any user changes already present.
2. Define the implementation scope: files or behavior to change, files to avoid, constraints, 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" \
  --add-dir "$ARTIFACT_DIR" \
  -s workspace-write \
  -o "$REPORT" \
  "$(cat "$PROMPT")"

Use -s workspace-write by default. Use -s danger-full-access only when the implementation truly needs access outside the repo, app launch automation, simulator work, package manager global state, or other machine-level operations.

Prompt Requirements

Tell Codex:

• The exact implementation goal and acceptance criteria.
• The repo path and current branch context if relevant.
• Which existing patterns, files, or tests to inspect first.
• Files or behavior that must not be changed.
• 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 questions.

Keep the task bounded. If the requested work bundles several substantial changes, split 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:
- ArrowUp and ArrowDown move the highlighted item
- Enter selects the highlighted item
- Escape closes the palette
- Existing mouse behavior keeps working.

Constraints:
- Follow existing component and test patterns.

Verification:
- Run the focused component tests if available.
- Otherwise run the nearest relevant typecheck or test command and explain the choice.

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 summary.

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