runtime-simulation-validation

runtime-simulation-validation is a skill for Claude Code, Codex from paruff/uFawkesAI. It costs 27 tokens per session (706 once invoked), scanned A, original, MIT.

A check that runs build output in a local or simulated deployment environment.

In plain words
What is it for?
It helps test health endpoints, readiness and liveness checks, logs, metrics, and graceful shutdown behavior.
Why use it?
It finds startup failures, runtime errors, unhealthy services, crash loops, memory kills, and problematic logs before deployment.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions Claude Code; installed under .agents/ (shared by several agents); mentions Codex.

Good fit It helps test health endpoints, readiness and liveness checks, logs, metrics, and graceful shutdown behavior.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/paruff/ufawkesai/runtime-simulation-validation
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.

Any agent
npx skills add paruff/uFawkesAI --skill runtime-simulation-validation
Clone the repo
git clone --depth 1 https://github.com/paruff/uFawkesAI

Made for: Claude Code, 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 runtime-simulation-validation

README.md
[![agentmods](https://agentmods.dev/badge/skills/paruff/ufawkesai/runtime-simulation-validation/github.svg)](https://agentmods.dev/skills/paruff/ufawkesai/runtime-simulation-validation)
Your own site
<a href="https://agentmods.dev/skills/paruff/ufawkesai/runtime-simulation-validation"><img src="https://agentmods.dev/badge/skills/paruff/ufawkesai/runtime-simulation-validation/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 runtime-simulation-validation

Your own site · 80×15
<a href="https://agentmods.dev/skills/paruff/ufawkesai/runtime-simulation-validation"><img src="https://agentmods.dev/badge/skills/paruff/ufawkesai/runtime-simulation-validation.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 706 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
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 $0.00027 $0.00706
Opus 5 $0.00014 $0.00353
Sonnet 5 $0.00005 $0.00141
Haiku 4.5 $0.00003 $0.00071

Measured 8d ago against content hash 9d5a924e8ca5, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

runtime-simulation-validation scanned grade A with 1 finding 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 8d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- `curl` / HTTP client for health check validation
.agents/skills/test-execution/runtime-simulation-validation/SKILL.md · 118 lines

How it starts

The opening of the file, as written. The whole thing — 118 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill: Runtime Simulation Validation

Load trigger: "load runtime-simulation-validation skill" > DORA: Cap 5 (Small Batches / Shift Left on Quality) Token cost: Low

Purpose

Validate runtime behavior in a simulated environment.

Responsibilities

  • Deploy build output to local/simulated environment
  • Validate readiness and liveness probes
  • Validate logs and metrics
  • Detect runtime errors

Inputs

  • Build output (code, manifests)
  • Simulation environment (kind, minikube, Docker Compose, local server)

Outputs

  • runtime-simulation.json
  • runtime-errors.txt

Validation Rules

Startup

  • Application starts without errors
  • Startup completes within timeout
  • Liveness probe responds
  • Readiness probe responds

Runtime

  • No crash loops or restarts
  • No OOM kills
  • No unhandled exceptions in logs
  • Graceful shutdown works

Logs

  • No ERROR or FATAL messages in logs
  • No stack traces in logs
  • No sensitive data in logs
  • Logging format consistent

Health Endpoints

  • /healthz returns 200
  • /readyz returns 200 (or 503 when not ready)
  • /metrics returns valid Prometheus format (if applicable)

Simulation Environments

Environment Tool Use When
Kubernetes (local) kind / minikube K8s manifests to validate
Docker Docker Compose Multi-container apps
Standalone Direct execution Simple services
Mock server WireMock / MockServer External dependency simulation

Tools

  • kubectl for K8s simulation
  • docker-compose for multi-container simulation
  • curl / HTTP client for health check validation
  • Log aggregator for log analysis

Output Format

{
  "skill": "runtime-simulation-validation",
  "status": "pass | fail",
  "startup": {
    "starts_successfully": true,
    "startup_time_ms": 1200,
    "liveness_probe": "healthy",
    "readiness_probe": "ready"
  },
  "runtime": {
    "crash_loops": 0,
    "oom_kills": 0,
    "unhandled_exceptions": 0
  },
  "logs": {
    "error_count": 0,
    "fatal_count": 0,
    "sensitive_data_found": false
  },
  "health_endpoints": {
    "/healthz": 200,
    "/readyz": 200
  },
  "errors": []
}

Read the full file on GitHub · 118 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. 8d ago First seen · 118 lines · 27 tokens per session scan A 9d5a924e8ca5

Subscribe to this mod's changes

runtime-simulation-validation is a skill published in the GitHub repository paruff/uFawkesAI (2 stars, last pushed 19d ago), licensed MIT. It adds 27 tokens to every session and 706 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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