z-spec-dev

A command that compares an existing test suite with constraints written in Z, a mathematical notation for describing software states and rules. It looks for tests covering those rules, including conditions, effects, and limits.

In plain words
What is it for?
Use it with a Z specification and an optional test directory, with results shown as a table or JSON.
Why use it?
It shows which specified behaviors are not represented in the tests. This helps reveal gaps that ordinary test-coverage percentages may miss.

Plugin for Claude Code

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.

Claude Code
/plugin marketplace add punt-labs/z-spec
agentmods
npx agentmods add plugins/punt-labs/z-spec/plugin
Clone the repo
git clone --depth 1 https://github.com/punt-labs/z-spec

Made for: Claude Code.

Per session not measured What this adds to a session before it is invoked.
When invoked not measured Not applicable: nothing here is loaded into a session.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Security

Grade A, and why

z-spec-dev 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.

plugin/.claude-plugin/plugin.json · 27 lines

What it actually says

{
  "name": "z-spec-dev",
  "description": "Create, validate, and test formal Z specifications for stateful systems using fuzz and probcli",
  "version": "0.20.4",
  "author": {
    "name": "Punt Labs",
    "email": "[email protected]"
  },
  "mcpServers": {
    "zspec": {
      "type": "stdio",
      "command": "uv",
      "args": [
        "run",
        "--directory",
        "${CLAUDE_PLUGIN_ROOT}",
        "z-spec",
        "mcp"
      ],
      "env": {
        "ZSPEC_PLUGIN_ROOT": "${CLAUDE_PLUGIN_ROOT}",
        "CLAUDE_PROJECT_DIR": "${CLAUDE_PROJECT_DIR}"
      }
    }
  }
}
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 · 27 lines scan A c20b5f703b87

Subscribe to this mod's changes

z-spec-dev is a plugin published in the GitHub repository punt-labs/z-spec (5 stars, last pushed yesterday), licensed MIT. Its token cost is not measured: this kind of file is read by the harness, not the model. 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.