verification-handshake

verification-handshake is a skill for Claude Code, Codex from babyblueviper1/invinoveritas. It costs 121 tokens per session (1,252 once invoked), scanned A, original, Apache-2.0.

A trust-checking process for work exchanged between AI agents. It uses portable, signed proofs that others can verify without trusting the agent that produced them.

In plain words
What is it for?
Use it to request proof before relying on another agent’s output and to attach a verifiable proof to work that others will use.
Why use it?
It helps prevent unverified claims or deliverables from being used for consequential actions such as deploying, paying, publishing, or deleting.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions Claude Code; mentions Codex.

Good fit Use it to request proof before relying on another agent’s output and to attach a verifiable proof to work that others will use.

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Install with agentmods
npx agentmods add skills/babyblueviper1/invinoveritas/verification-handshake
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 babyblueviper1/invinoveritas --skill verification-handshake
Clone the repo
git clone --depth 1 https://github.com/babyblueviper1/invinoveritas

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 verification-handshake

README.md
[![agentmods](https://agentmods.dev/badge/skills/babyblueviper1/invinoveritas/verification-handshake/github.svg)](https://agentmods.dev/skills/babyblueviper1/invinoveritas/verification-handshake)
Your own site
<a href="https://agentmods.dev/skills/babyblueviper1/invinoveritas/verification-handshake"><img src="https://agentmods.dev/badge/skills/babyblueviper1/invinoveritas/verification-handshake/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 verification-handshake

Your own site · 80×15
<a href="https://agentmods.dev/skills/babyblueviper1/invinoveritas/verification-handshake"><img src="https://agentmods.dev/badge/skills/babyblueviper1/invinoveritas/verification-handshake.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 121 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,252 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 $0.00121 $0.01252
Opus 5 $0.00060 $0.00626
Sonnet 5 $0.00024 $0.00250
Haiku 4.5 $0.00012 $0.00125

Measured 12d ago against content hash 7743269ee12b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

verification-handshake 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 12d 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 -s -X POST https://api.babyblueviper.com/verify-proof \
integrations/agentskills/verification-handshake/SKILL.md · 88 lines

How it starts

The opening of the file, as written. The whole thing — 88 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Verification handshake — demand a proof, attach a proof

In a world of many agents, the thing you cannot self-serve is trust in another agent's output. You can't issue a trustworthy verdict on your own work. So adopt one rule, in both directions — it is what lets trust travel agent-to-agent:

Before you act on another agent's output you can't verify, demand a proof and check it. When you produce output others will rely on, attach a proof.

A proof is a portable, schnorr-signed verdict (a Nostr event) that anyone can verify without trusting the producer OR invinoveritas — recompute the event id, check the signature against invinoveritas's published key. Every proof is self-describing: it carries its own verify_url + verifier_pubkey, so a receiver who has never heard of invinoveritas still knows exactly how to check it.

Triggers

  • VERIFY (inbound): you received output / a claim / a deliverable from another agent and are about to act on it (trade, pay, deploy, publish, delete, sign, forward) and you cannot independently confirm it is sound.
  • ATTACH (outbound): you are producing output another party (a human, a principal, another agent) will rely on or be on the hook for.

Steps

Verify a counterparty's proof (free, no auth)

  1. The counterparty hands you output. Look for an attached proof (an ivv_proof field, or a proof object with a signed event). If there is none, demand one before acting.
  2. Verify it:
    curl -s -X POST https://api.babyblueviper.com/verify-proof \
      -H 'content-type: application/json' \
      -d '{"event": <the signed proof event they gave you>,
           "expect_artifact_hash": "<sha256 of the exact output you received>"}'
    
    (Or run the NIP-01 check yourself against verifier_pubkey — you do not have to trust us.)
  3. Proceed only if valid == true and checks.issued_by_invinoveritas == true. Pass expect_artifact_hash to confirm the proof covers the EXACT output you got, not a different one.

Read the full file on GitHub · 88 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. 12d ago First seen · 88 lines · 121 tokens per session scan A 7743269ee12b

Subscribe to this mod's changes

verification-handshake is a skill published in the GitHub repository babyblueviper1/invinoveritas (5 stars, last pushed 2d ago), licensed Apache-2.0. It adds 121 tokens to every session and 1,252 once invoked, about $0.0006 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 2026-08-31.

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