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/tonydzi/second-brain-starter-kit/codex-mirrornpx skills add tonydzi/second-brain-starter-kit --skill codex-mirrorgit clone --depth 1 https://github.com/tonydzi/second-brain-starter-kitWrote 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/tonydzi/second-brain-starter-kit/codex-mirror)<a href="https://agentmods.dev/skills/tonydzi/second-brain-starter-kit/codex-mirror"><img src="https://agentmods.dev/badge/skills/tonydzi/second-brain-starter-kit/codex-mirror.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 | $0.00111 | $0.01726 |
| Opus 5 | $0.00056 | $0.00863 |
| Sonnet 5 | $0.00022 | $0.00345 |
| Haiku 4.5 | $0.00011 | $0.00173 |
Grade A, and why
codex-mirror 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.
How it starts
The opening of the file, as written. The whole thing — 81 lines — stays where its author put it; the contents beside it link to each section on GitHub.
codex-mirror — the shared-canon mirror for Codex
The pain (found 2026-07-25): CLAUDE.md went through a v2 revision on 07-22, while ~/.codex/AGENTS.md quietly stayed on its June version — Codex worked off stale rules for a month, and the drift checker of that era was blind to the very same revision. The cure: the mirror is version-based (we compare versions, not shape), a watchdog shouts at night, and this skill is the cheap "rebuild" button so that the shouting doesn't turn into evening manual labour.
Roles (AK-47): the script moves the bytes and checks everything; I only write the text of the new rules. Do not retype the file by hand and do not eyeball the byte count.
Engine: python %USERPROFILE%\.claude\scripts\codex_mirror.py <check|backup|stamp|publish|selftest>
Step 0 — RECALL + the frame
- Memory: [[canon-versioning-and-drift-watchdog]] (the class "the watchdog died silently together with the thing it watched"), [[codex-cli-install]], [[any-llm-vault-actor]], [[claude-md-compression-contract]].
- The mirror = a canon edit → only the owner's machine in a live session; followers are receive-only ([[machine-governance-leader-follower]]).
- The 32 KiB cap is hard (DR 06-29: "lost in the middle" — a bloated file is WORSE than an empty one). The mirror = a distillation + pointers, NOT a copy of CLAUDE.md.
Step 1 — What exactly is stale
python %USERPROFILE%\.claude\scripts\codex_mirror.py check
Prints both versions, the headroom left before the cap and the delta from CLAUDE.CHANGELOG.md — exactly the entries that appeared after the mirror's version. That is the work list; you don't need to read all of CLAUDE.md.
VERDICT: OK→ leave, nothing to do.PATCH lag only→ green by design; write it in only if the micro-edit changes BEHAVIOUR (thresholds, gates), not wording.REBUILD→ carry on.
Step 2 — The safety net
python %USERPROFILE%\.claude\scripts\codex_mirror.py backup
Snapshot into ~/.codex/_backup/AGENTS.md.pre-<version>-<date-time>. Rollback = copy it back.
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 · 81 lines · 111 tokens per session scan A 899b85e5c4d8
codex-mirror is a skill published in the GitHub repository tonydzi/second-brain-starter-kit (5 stars, last pushed 5d ago), licensed MIT. It adds 111 tokens to every session and 1,726 once invoked, about $0.0006 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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