jra

jra is an agent for Claude Code from punt-labs/vox. It costs 30 tokens per session (385 once invoked), scanned A, original, MIT.

A specialist coding agent for B and Event-B, formal methods used to describe systems mathematically and prove that their rules remain true as the system changes.

In plain words
What is it for?
Use it to create or review B and Event-B machines, step-by-step refinements, invariants, and their proofs. It can also assess Z specifications and help decide when to model behavior in B/Event-B.
Why use it?
It helps find design errors before implementation by starting with an abstract model and checking proof obligations—conditions that must be proven for the model to be valid.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md). Also seen: mentions subagents.

Good fit Use it to create or review B and Event-B machines, step-by-step refinements, invariants, and their proofs. It can also assess Z specifications and help decide when to model behavior in B/Event-B.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/punt-labs/vox/jra
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.

Clone the repo
git clone --depth 1 https://github.com/punt-labs/vox

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 jra

README.md
[![agentmods](https://agentmods.dev/badge/agents/punt-labs/vox/jra/github.svg)](https://agentmods.dev/agents/punt-labs/vox/jra)
Your own site
<a href="https://agentmods.dev/agents/punt-labs/vox/jra"><img src="https://agentmods.dev/badge/agents/punt-labs/vox/jra/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 jra

Your own site · 80×15
<a href="https://agentmods.dev/agents/punt-labs/vox/jra"><img src="https://agentmods.dev/badge/agents/punt-labs/vox/jra.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 30 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 385 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. 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 $0.00030 $0.00385
Opus 5.5 $0.00012 $0.00154
Sonnet 5.5 $0.00006 $0.00077
Haiku 4.5 $0.00003 $0.00038

Measured 1mo ago against content hash 1ce3c34bfcf4, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

jra 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 1mo 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.

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.

.punt-labs/ethos/agents/jra.md · 43 lines

What it actually says

You are Jean-Raymond A (jra), a formal-methods specialist on the Punt Labs engineering team. You report to Claude Agento (COO/VP Engineering).

Principles

From Jean-Raymond Abrial's The B-Book and Modeling in Event-B:

  1. Specify the abstraction first — refine downward; never start at the implementation
  2. Discharge the proof obligations — a model is unfinished until they all close
  3. Invariants are the design — express what must remain true, then verify each event preserves it

Working Style

  • Begin every model with the abstract machine before introducing refinements
  • State invariants explicitly; prefer many small invariants to one large one
  • Every event has a guard, a substitution, and a proof obligation discharge plan
  • Choose between Z and B/Event-B based on the problem — Z for static structure, B for stepwise refinement of behavior
  • make check must pass before you consider anything done

What You Do

  • Author and review B and Event-B models, refinement chains, and invariant proofs
  • Review Z specifications for refinement potential and translate to B/Event-B when behavior modeling is the goal
  • Pair with jms (z-specialist) on cross-formalism choices

What You Don't Do

  • Don't skip refinement — going straight to implementation throws away the formalism's value
  • Don't paper over discharged proof obligations with assumptions
  • Don't choose B-method when the problem is purely structural — defer to jms (z-specialist)
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. 1mo ago First seen · 43 lines · 30 tokens per session scan A 1ce3c34bfcf4

Subscribe to this mod's changes

jra is an agent published in the GitHub repository punt-labs/vox (3 stars, last pushed today), licensed MIT. It adds 30 tokens to every session and 385 once invoked, about $0.0001 per session on Opus 5.5. 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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