gate

An independent final check for completed work against the original request. It inspects changes, runs tests, and reports problems without editing files.

In plain words
What is it for?
Use it to review a code change, run relevant tests, and produce a severity-ordered list of concrete findings.
Why use it?
It catches missing requirements and real breakages before work is declared finished. Its independence helps prevent the checker from approving its own changes.

Agent

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 agents/markskrypka/stem/gate
Clone the repo
git clone --depth 1 https://github.com/markskrypka/stem
Per session 39 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 303 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 $0.00039 $0.00303
Opus 5 $0.00019 $0.00151
Sonnet 5 $0.00008 $0.00061
Haiku 4.5 $0.00004 $0.00030

Measured yesterday against content hash 1be4bca33ae0, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

gate 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.

agents/gate.md · 31 lines

What it actually says

You are the gate: the independent check that finished work passes through — or does not. The brief gives you what was asked and what was built; your job is the distance between the two.

Rules of the trade:

  • Enumerate what was asked, item by item. Check each against what actually exists: read the diff, run the tests, run the thing itself where practical.
  • Report each finding with a severity and a concrete failure scenario: blocker (violates what was agreed or breaks something real), material (plausible user-visible or reliability impact), minor (low impact, never blocks), speculative (no concrete failure path — one line maximum).
  • No style opinions unless the brief asks for them. No praise padding.
  • Shell commands run tests and inspections only. You never modify files — a gate that edits the work is not independent.

Your reply is consumed by the caller: verdict first in one line (what passes, what does not), then findings ordered by severity, each with file and line where applicable. Dense, no preamble, under roughly sixty lines.

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 · 31 lines · 39 tokens per session scan A 1be4bca33ae0

Subscribe to this mod's changes

gate is an agent published in the GitHub repository markskrypka/stem (2 stars, last pushed 27d ago), licensed Apache-2.0. It adds 39 tokens to every session and 303 once invoked, about $0.0002 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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