formax: Skill for Codex

.codex/skills/formax-system-prompt-workflow/SKILL.md

formax-system-prompt-workflow is a skill for Codex from yusifeng/formax. It costs 58 tokens per session (890 once invoked), scanned A, original, MIT.

Development guidance for changing how Formax builds prompts, adds system reminders, exposes deferred tools, and presents skills.

In plain words
What is it for?
Use it when designing, refactoring, or debugging Formax prompt assembly, system-reminder injection, deferred tool exposure, or skills presentation.
Why use it?
It helps keep prompt behavior consistent across requests and prevents temporary helper instructions from being saved as permanent conversation history.

Skill for Codex

Written for Codex: agents/openai.yaml present.

This is yusifeng/formax's own configuration. It tells Codex how to work on formax itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything formax configures →

Reuse

Borrowing it

Nothing to install: this file belongs to yusifeng/formax. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/yusifeng/formax/main/.codex/skills/formax-system-prompt-workflow/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/yusifeng/formax

Made for: Codex.

Wrote 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.

agentmods badge for formax-system-prompt-workflow

README.md
[![agentmods](https://agentmods.dev/badge/skills/yusifeng/formax/formax-system-prompt-workflow/github.svg)](https://agentmods.dev/skills/yusifeng/formax/formax-system-prompt-workflow)
Your own site
<a href="https://agentmods.dev/skills/yusifeng/formax/formax-system-prompt-workflow"><img src="https://agentmods.dev/badge/skills/yusifeng/formax/formax-system-prompt-workflow/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for formax-system-prompt-workflow

Your own site · 80×15
<a href="https://agentmods.dev/skills/yusifeng/formax/formax-system-prompt-workflow"><img src="https://agentmods.dev/badge/skills/yusifeng/formax/formax-system-prompt-workflow.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 58 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 890 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 5.1 $0.00058 $0.00890
Opus 5 $0.00029 $0.00445
Sonnet 5 $0.00012 $0.00178
Haiku 4.5 $0.00006 $0.00089

Measured 10d ago against content hash 89e7da8fe2ad, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

formax-system-prompt-workflow 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 10d 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.

.codex/skills/formax-system-prompt-workflow/SKILL.md · 76 lines

How it starts

The opening of the file, as written. The whole thing — 76 lines — stays where its author put it; the contents beside it link to each section on GitHub.

formax-system-prompt-workflow

Goal

Use this skill when changing system prompt assembly, reminder injection, deferred tool exposure, or skills prompt presentation.

Read First

  • docs/contracts/prompt-tool-exposure-contract.md
  • docs/contracts/skills-contract.md
  • docs/contracts/semantics-contract.md when request-scoped helper blocks affect replay or transcript semantics

Optional working notes:

  • references/parity-checklist.md
  • references/parity-evidence-template.md

These docs are canonical. If stable behavior changes, update them before or with code.

Invariants

  1. Keep a single prompt-profile path.
    • do not reintroduce promptProfile, lite, or similar profile branches
  2. Treat FORMAX_DEFERRED_TOOL_EXPOSURE as a linked behavior bundle.
    • prompt variant, tools exposure style, and skills presentation must stay aligned
  3. Keep helper blocks request-scoped and ephemeral.
    • injected <system-reminder> blocks and deferred helper blocks must not pollute persisted long-term history
  4. Only claim capabilities that Formax runtime actually implements.
    • do not add CC-like capability prose before the runtime supports it

Code Map

  • packages/core/src/prompts/system.ts: system prompt text, variant selection, capability gates
  • packages/core/src/features/repl/controller/send/sendMainTurn.ts: per-turn injected block order and REPL assembly
  • packages/core/src/tools/runtime/deferredToolExposureResolver.ts: deferred tools exposure and helper-block content
  • packages/core/src/tools/modules/skill/index.ts: skill tool description shaping and skills reminder text
  • packages/core/src/chat/engine.ts: request assembly and injected-block persistence boundaries
  • Cross-entrypoint mirrors when semantics move:
    • packages/core/src/app-server/turnRunner.ts
    • packages/core/src/sdk/query/runner.ts
  • scripts/repl-request-preview.ts: quick dry-run payload preview without live network calls

Deferred Exposure Checklist (FORMAX_DEFERRED_TOOL_EXPOSURE=1)

Read the full file on GitHub · 76 lines

Files

What ships with it

3 files 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. 10d ago First seen · 76 lines · 58 tokens per session scan A 89e7da8fe2ad

Subscribe to this mod's changes

formax-system-prompt-workflow is a skill published in the GitHub repository yusifeng/formax (193 stars, last pushed 1mo ago), licensed MIT. It adds 58 tokens to every session and 890 once invoked, about $0.0003 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 2026-08-30.