codex-implementation

A workflow for asking the Codex command-line agent to make a limited code change in the current repository, then reviewing the resulting changes. A repository is the project folder containing the code and its history.

In plain words
What is it for?
Delegating bounded implementation tasks, inspecting the changed files, checking the Git diff, and running suitable verification commands.
Why use it?
It separates implementation from review: Codex makes the scoped change, while the surrounding workflow checks the diff and verification results. It also keeps the delegated task from committing, pushing, or deploying unless explicitly requested.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/connorch/skills/codex-implementation
Any agent
npx skills add connorch/skills --skill codex-implementation
Clone the repo
git clone --depth 1 https://github.com/connorch/skills

Made for: Claude Code, Codex.

Per session 107 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 851 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00107 $0.00851
Opus 5 $0.00053 $0.00426
Sonnet 5 $0.00021 $0.00170
Haiku 4.5 $0.00011 $0.00085

Measured yesterday against content hash db3ca69ed9b6, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

codex-implementation scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/codex-implementation/SKILL.md · 91 lines

How it starts

The opening of the file, as written. The whole thing — 91 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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.

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

Prompt Requirements

Tell Codex:

  • The exact task and expected behavior.
  • The repo path and current branch context if relevant.
  • 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.

Read the full file on GitHub · 91 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 91 lines · 107 tokens per session scan A db3ca69ed9b6

Subscribe to this mod's changes

codex-implementation is a skill published in the GitHub repository connorch/skills (2 stars, last pushed 4d ago), licensed MIT. It adds 107 tokens to every session and 851 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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