vibecode-pro-max-kit: Skill for Claude Code

.claude/skills/vc-feasibility-test/SKILL.md

vc-feasibility-test is a skill for Claude Code from withkynam/vibecode-pro-max-kit. It costs 61 tokens per session (2,405 once invoked), scanned A, original, MIT.

A one-time test for checking whether an unverified runtime, library, or external mechanism works as a proposed design expects.

In plain words
What is it for?
It is for running a focused probe and recording a viable, not viable, or inconclusive result.
Why use it?
It helps decide whether an approach is workable before committing to it in a specification or plan.

Skill for Claude Code

Written for Claude Code: argument-hint in frontmatter.

This is withkynam/vibecode-pro-max-kit's own configuration. It tells Claude Code how to work on vibecode-pro-max-kit 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 vibecode-pro-max-kit configures →

About the project

vibecode-pro-max-kit is a set of instructions, agents, skills, hooks, and settings that gives AI coding agents a plan-first software development workflow. It is designed for developers, product owners, and other builders using agents such as Claude Code, Codex, Cursor, Windsurf, or Copilot across different technology stacks. The catalogue entries are the kit's own workflow components.

withkynam/vibecode-pro-max-kit · 1,116 stars · on GitHub

Reuse

Borrowing it

Nothing to install: this file belongs to withkynam/vibecode-pro-max-kit. 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/withkynam/vibecode-pro-max-kit/main/.claude/skills/vc-feasibility-test/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/withkynam/vibecode-pro-max-kit

Made for: Claude Code.

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 vc-feasibility-test

README.md
[![agentmods](https://agentmods.dev/badge/skills/withkynam/vibecode-pro-max-kit/vc-feasibility-test.svg)](https://agentmods.dev/skills/withkynam/vibecode-pro-max-kit/vc-feasibility-test)
Your own site
<a href="https://agentmods.dev/skills/withkynam/vibecode-pro-max-kit/vc-feasibility-test"><img src="https://agentmods.dev/badge/skills/withkynam/vibecode-pro-max-kit/vc-feasibility-test.svg" alt="Measured on agentmods" height="20"></a>
Per session 61 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,405 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00061 $0.02405
Opus 5 $0.00030 $0.01203
Sonnet 5 $0.00012 $0.00481
Haiku 4.5 $0.00006 $0.00241

Measured 7d ago against content hash c2f20ce23fad, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

vc-feasibility-test 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 7d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/validate-feasibility-verdict.mjs), 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.

Makes network callslowCapability

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

| 5 | **Container exec / internal-port curl** | in-container service behavior, proxy injection, file-server, supervisord | `docker exec … curl http://localhost:{port}` on a **disposable** container | **needs-container**
.claude/skills/vc-feasibility-test/SKILL.md · 179 lines

How it starts

The opening of the file, as written. The whole thing — 179 lines — stays where its author put it; the contents beside it link to each section on GitHub.

vc-feasibility-test

Output style: Follow process/development-protocols/communication-standards.md — answer-first, plain language, no unexplained jargon, TL;DR on long responses.

One-shot empirical probe skill. Used when SPEC or INNOVATE encounters an approach hinging on an unverified external/runtime/library mechanism — the question is "does this mechanism actually work the way the design assumes?", asked before the decision locks.

Boundary vs vc-test-coverage-plan

These two skills are complementary and must not be confused:

  • vc-feasibility-test (this skill) = PRE-decision. "Does the mechanism work at all?" Run before SPEC/INNOVATE locks an approach, when the answer is unknown. Output: a one-shot VERDICT artifact.
  • vc-test-coverage-plan = POST-plan. "How do I cover this blast radius across the 4 test tiers?" Run after a plan exists, when the design is already chosen. Output: a per-area tier table.

If the approach is already decided and you are assigning test tiers → use vc-test-coverage-plan. If you cannot decide because a mechanism is unverified → use this skill first.

When To Invoke

  • When vc-spec-agent, vc-innovate-agent, or a vc-validate-agent Layer 2 dimension agent emits VC-FEASIBILITY-PROBE-NEEDED
  • When a mechanism cannot be verified from source code alone
  • One-shot: not an iterative loop (use vc-autoresearch for iteration)

Skill Executor

Always executed by vc-debugger (via the VC-FEASIBILITY-PROBE-NEEDED signal routing in orchestration.md). SPEC, INNOVATE, and VALIDATE Layer 2 agents do not run probes themselves.

Probe-Method Taxonomy (pick one family)

Every probe belongs to one of these 8 families. Name the chosen family in the VERDICT. Each family has a default cost/safety class (see next section) — the probe inherits it.

# Family What it probes Typical method Default cost class
1 Local process / Node script pure library/runtime behavior in isolation run a .mjs/Bun script, regex/parse check, call the lib fn directly cheap-local
2 Unit/integration test harness behavior under the project's own test runner pnpm --filter … test (Vitest) or bun test on a scratch case cheap-local
3 tRPC / Prisma / DB query route shape, query behavior, index/constraint semantics hit a tRPC route or run a Prisma/raw-SQL query against a test DB needs-container (only if it needs the live app DB) / else cheap-local
4 External API shape capture real response shape/behavior of a 3rd-party API one live request to OpenRouter / Stripe / Composio / Clerk / Bright Data needs-live-provider
5 Container exec / internal-port curl in-container service behavior, proxy injection, file-server, supervisord docker exec … curl http://localhost:{port} on a disposable container needs-container
6 Browser / CDP capture anti-detect quirks, CDP events, SPA nav, popup behavior Playwright/CDP client, page.on(...), snapshot needs-browser
7 WS / SSE handshake & timing gateway WS framing, SSE delivery/reconnect, JSONL shape raw ws/EventSource client + frame/timing capture needs-container (if against in-container service) / else cheap-local
8 Cloudflare worker runtime KV staleness, step-replay/idempotency, edge JWT verify wrangler dev + curl, deploy a throwaway worker needs-cf

Read the full file on GitHub · 179 lines

Files

What ships with it

4 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. 7d ago First seen · 179 lines · 61 tokens per session scan A c2f20ce23fad

Subscribe to this mod's changes

vc-feasibility-test is a skill published in the GitHub repository withkynam/vibecode-pro-max-kit (1,116 stars, last pushed 2mo ago), licensed MIT. It adds 61 tokens to every session and 2,405 once invoked, about $0.0003 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 2026-08-30.