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.
npx agentmods add skills/dzhng/duet-agent/implement-spec-with-codexnpx skills add dzhng/duet-agent --skill implement-spec-with-codexgit clone --depth 1 https://github.com/dzhng/duet-agentWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/dzhng/duet-agent/implement-spec-with-codex)<a href="https://agentmods.dev/skills/dzhng/duet-agent/implement-spec-with-codex"><img src="https://agentmods.dev/badge/skills/dzhng/duet-agent/implement-spec-with-codex.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00063 | $0.00494 |
| Opus 5 | $0.00032 | $0.00247 |
| Sonnet 5 | $0.00013 | $0.00099 |
| Haiku 4.5 | $0.00006 | $0.00049 |
Grade A, and why
implement-spec-with-codex 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 4d ago.
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.
This is a copy
100% identical to implement-spec-with-codex — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
What it actually says
Implement Spec with Codex
Run implement-spec exactly — same loop, same
gates, same maintenance checkpoints — but Codex writes the code. Invoking this
skill IS the explicit ask that authorizes codex exec delegation under the
codex skill.
Role split
- Codex implements — whenever possible. Default every implementation pass
to a
codex exec, sliced sharp and prompted per the codex skill (prompt blocks, sandbox choice, exec liveness). Run independent slices as concurrent execs in separate worktrees, exactly where implement-spec would fan out subagents. - You orchestrate and review. The spec loop stays yours: pick the next slice, reconcile plan with code, author each prompt end-to-end, integrate diffs, run the gates, review the merged tree, commit, update the handoff, run maintenance checkpoints. None of that delegates.
Keep a pass yourself only when slicing it sharply would cost more than doing it — tiny fixups, plan reconciliation, integration conflicts.
Rules
- You own every result: read the full diff and run the verification yourself. "Codex says it's done" is never done.
- Visual results carry implement-spec's two extra proofs (production-route pixel diff + unprimed critique) with double force here: a sandboxed Codex never saw its change render, so a pass that misses the production render path entirely arrives looking fully "verified".
- A sandboxed Codex ships code it never saw run — browser-verify every visual slice yourself and budget fix rounds. Send a red gate back as a resumed follow-up with the failing evidence; fix it yourself only when that's smaller than re-prompting.
- Commit hygiene stays yours: review the change list of the merged tree before every commit, exactly as implement-spec demands of the integrating reviewer.
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.
- 4d ago First seen · 43 lines · 63 tokens per session scan A 98dbe0b754df
implement-spec-with-codex is a skill published in the GitHub repository dzhng/duet-agent (42 stars, last pushed 2d ago), licensed Apache-2.0. It adds 63 tokens to every session and 494 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to implement-spec-with-codex, differing in 0 lines, and is treated as a copy.
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