os-evolution-verifier

os-evolution-verifier is a skill for Claude Code, Codex from richfrem/agent-plugins-skills. It costs 91 tokens per session (3,603 once invoked), scanned A, original, MIT.

A verification tool that tests whether an agent-ecosystem change produced the expected files or handoff records, rather than trusting the agent's explanation.

In plain words
What is it for?
Use it to verify no-op decisions, new skills, update plans, evaluation-lab setup, handoff fields, and responses to unclear requests.
Why use it?
It provides concrete evidence that an orchestration process actually completed its work and followed the required output format.

Skill for Claude CodeCodex

Part of the agent-agentic-os plugin — 20 skills, 4 commands, 2 agents, 3 hooks shipped together

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/richfrem/agent-plugins-skills/os-evolution-verifier
Any agent
npx skills add richfrem/agent-plugins-skills --skill os-evolution-verifier
Clone the repo
git clone --depth 1 https://github.com/richfrem/agent-plugins-skills

Made for: Claude Code, Codex.

Or install agent-agentic-os, the plugin that ships this one along with the rest of its 20 skills, 4 commands, 2 agents, 3 hooks.

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 os-evolution-verifier

README.md
[![agentmods](https://agentmods.dev/badge/skills/richfrem/agent-plugins-skills/os-evolution-verifier.svg)](https://agentmods.dev/skills/richfrem/agent-plugins-skills/os-evolution-verifier)
Your own site
<a href="https://agentmods.dev/skills/richfrem/agent-plugins-skills/os-evolution-verifier"><img src="https://agentmods.dev/badge/skills/richfrem/agent-plugins-skills/os-evolution-verifier.svg" alt="Measured on agentmods" height="20"></a>
Per session 91 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,603 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 5.1 $0.00091 $0.03603
Opus 5 $0.00046 $0.01801
Sonnet 5 $0.00018 $0.00721
Haiku 4.5 $0.00009 $0.00360

Measured 2d ago against content hash 89bb2da724be, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

os-evolution-verifier 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 2d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/experiment_log.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

plugins/agent-agentic-os/skills/os-evolution-verifier/SKILL.md · 352 lines

How it starts

The opening of the file, as written. The whole thing — 352 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Overview

After evolving os-architect or its downstream agents, you need proof that the changes actually work. This skill dispatches os-architect in single-shot simulation mode for each test scenario and verifies artifact presence — not by reading the transcript, but by checking that expected files exist or expected content appears in output.

Evolution is verified by artifact presence, not by transcript review.


Artifact Verification Table

Evolution Type What to Check
Path C (Gap Fill) SKILL.md present at expected path
Path B (Update) tasks/todo/<slug>-plan.md AND tasks/todo/copilot_prompt_<slug>.md written
Path A+ (No-op) No new files written; HANDOFF_BLOCK contains STATUS: complete
Category 3 (Lab Setup) improvement/run-config.json written AND HANDOFF_BLOCK emitted
HANDOFF_BLOCK integrity All 7 fields present: INTENT, TARGET, PATH, DISPATCH, STATUS, OUTPUTS, NEXT_ACTION
Confidence model Low confidence prompt → clarifying question appears before Phase 2 audit
Evolution Integrity Gate When logic in plugins/ changes, references/map-debt.md or evolution-log.md is updated, or Evolution-Check: none is present

Phase 1 — Resolve Test Inputs

If invoked with all, find test scenarios:

ls temp/os-evolution-verifier/scenarios/*.json 2>/dev/null | sort

If invoked with a specific file, verify it exists and is valid JSON with required fields:

python3 -c "
import json, sys
d = json.load(open('$SCENARIO_FILE'))
required = ['id', 'name', 'path', 'prompt', 'expected_artifact', 'artifact_check']
missing = [f for f in required if f not in d]
if missing:
    print(f'SCHEMA ERROR: missing fields: {missing}'); sys.exit(1)
print(f'Scenario: {d[\"id\"]} — {d[\"name\"]}')
"

If no scenarios found and no file given, report:

"No test scenarios found. Create scenario JSON files in temp/os-evolution-verifier/scenarios/ or run context-bundler (red-team mode) to generate them from os-architect-agent.md."

Read the full file on GitHub · 352 lines

Files

What ships with it

5 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. 2d ago Changed · +2 lines 89bb2da724be
  2. 5d ago First seen · 350 lines · 91 tokens per session scan A e5f7818bbd80

Subscribe to this mod's changes

os-evolution-verifier is a skill published in the GitHub repository richfrem/agent-plugins-skills (6 stars, last pushed yesterday), licensed MIT. It adds 91 tokens to every session and 3,603 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.