Receipt — sign an agent's work, verify it offline

Name: Receipt — sign an agent's work, verify it offline
Author: ecstatica

by ecstaticaversion 1.1.0i★ –iComputer or cloud

Registry nameio.github.ecstatica/ggbank-receipt

Install

Overview

Description from the maker (original English)

Ed25519 receipts over work artifacts: issue and verify offline, no account, no chain, no network.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi3 of 3 passedChecked from public information; code not scanned yet
UsageiNot measured yet★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Computer or cloud
Transport: stdio, Streamable HTTP
Category: Other

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 3 of 3 passed
Runs on the maker’s server: what you ask it goes through their server.
Can do 2 things (tools) issue_receipt, verify_receipt
The registry lists no key to fill in.

You need

Runs in the cloudNothing to install; it connects over the internet

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Works in Claude on the web, desktop and mobile:

Open Settings → Connectors
Press Add custom connector
Paste the address below and press Add
If it asks you to sign in, sign in with the maker

https://receipt.whirlwindcorp.com/mcp

Download the maker’s .mcpb file

The link goes to the maker’s own file; we do not host or repackage it. Open the file and Claude Desktop installs it.

Run this in your terminal

claude mcp add --transport http ggbank-receipt https://receipt.whirlwindcorp.com/mcp

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "ggbank-receipt": {
      "url": "https://receipt.whirlwindcorp.com/mcp"
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "ggbank-receipt": {
      "type": "http",
      "url": "https://receipt.whirlwindcorp.com/mcp"
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

ChatGPT connects only to servers on the internet:

Open ChatGPT on the web → Settings → Connectors (Apps)
Press Create or Add (some plans need Developer mode under Advanced first)
Paste the address below, give it a name and save
If it asks you to sign in, sign in with the maker

https://receipt.whirlwindcorp.com/mcp

Menu names can differ slightly by plan and over time.

Your choice stays on this device in a cookie; no account needed.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Tool names and descriptions exactly as the server reported them on Nov 7, 2026. The maker wrote them, not us; we show them as plain text.

issue_receipt
Sign an artifact with an Ed25519 receipt. Returns the receipt JSON: artifact hash, agent, task, amount and a signature anyone can verify offline.
verify_receipt
Verify a receipt offline: signature, every field, and optionally the artifact hash. Returns ok=false with the failing reason when anything has changed.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 7, 2026

✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account ecstatica, which owns the repo
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
✓ Pass
Endpoint responds
Responded in 576 ms (HTTP 200)
– Not applicable
Sign-in with OAuth
No sign-in needed
✓ Pass
No hidden instructions in tool descriptions
Read 2 tool descriptions and found no hidden instructions to the AI

Compared with others in Otheri

More stars than 0% of the other 18329 servers in this category
Published to the registry more recently than 82% of the other 18329 servers in this category
Basic checks equal to or better than 100% of the other 18329 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is Receipt — sign an agent's work, verify it offline safe?

It passed 3 of 3 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

Either way works: install it on your computer or connect to the cloud version.

Is it still maintained?

The GitHub repo last changed –, and the latest version (1.1.0) reached the registry 9 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. It connects by URL, so apps that accept remote MCP servers work too, such as ChatGPT in developer mode.

What can I use instead?

In the same category: Spec Driven Development, Remote Desktop Commander, Excaliself

Alternatives

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Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

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Runs on your computer★ 440MITUpdated 14 months ago

Install

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Runs in the cloud★ 211Updated 2 days ago

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Excaliself

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Runs in the cloudUpdated today

Install

README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

receipt

Sign the work your agent did. Let anyone verify it offline.

A receipt binds an agent, a task and a file with an Ed25519 signature. Verification needs no account, no chain, no network and no permission from us. Change one character of the file or one field of the receipt, and verification fails.

This is the smallest useful thing in the agent economy: the payment rails arrived before the proof rails. x402 passed 138 million payments while most agent jobs remain unfunded and unevaluated by anyone independent.

Install

git clone https://github.com/ecstatica/ggbank-receipt

cd ggbank-receipt python3 -m pip install --user cryptography

No dependency beyond cryptography. Python 3.10+.

Use

# 1. your agent's key (Ed25519, private key mode 0600)

python3 receipt.py keygen --out ~/.agent.key

2. sign a receipt over the artifact the agent delivered

python3 receipt.py issue \ --key ~/.agent.key \ --artifact report.pdf \ --task q-1042 \ --agent VOID-9 \ --amount 25 \ --out q-1042.receipt.json

3. anyone can verify it, offline

python3 receipt.py verify --receipt q-1042.receipt.json --artifact report.pdf

OK signature valid · issuer QRs56MmYfzwtOAih… OK artifact matches 04002a7e5527bbad… deliver · VOID-9 · task q-1042 · 25.0 GG · 2026-10-25T11:56:24Z

Send the receipt with the file. The buyer runs one command and knows the file is the one that agent produced and has not changed since.

What it proves, and what it does not

Proves: this key signed this artifact hash with these fields at this time, and nothing has changed since.

Does not prove: that the work is good, or that the key belongs to a particular human. Quality is a separate judgement; identity is a separate claim.

Use it as an MCP server (what agents actually call)

mcp_server.py speaks JSON-RPC over stdio — the protocol Claude Code, Cursor, Codex, Hermes and most agent frameworks already speak. Two tools: issue_receipt, verify_receipt. No network, no dependencies beyond cryptography.

{"mcpServers": {"receipt": {"command": "python3", "args": ["/abs/path/mcp_server.py"]}}}

{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"issue_receipt",

"arguments":{"artifact_path":"/tmp/report.pdf","agent":"VOID-9","task":"q-1042","amount_gg":25}}} → {"ok": true, "receipt": {...}}

Verified round trip: issue_receipt → verify_receipt returns ok: true; change the amount and it returns ok: false, reason: "signature: InvalidSignature".

What a receipt contains

"spec": "ggbank.receipt/1", "verb": "deliver", "agent": "VOID-9", "task": "q-1042", "artifact": {"name": "report.pdf", "sha256": "04002a7e…", "bytes": 18422}, "amount_gg": "25.000000", "fee_gg": "0.125000", "issued_at": "2026-10-25T11:56:24Z", "issuer": " ", "nonce": "…", "signature": " " }

Canonical JSON (sorted keys, no whitespace) is signed, so the signed bytes are reproducible in any language. Money fields are decimal strings, never floats.

Tamper detection, tested

python3 receipt.py verify --receipt tampered.json     # FAIL signature: InvalidSignature

python3 receipt.py verify --receipt good.json --artifact edited.pdf

FAIL artifact: hash mismatch

Licence

MIT.

Receipt — sign an agent's work, verify it offline

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Otheri

Common questions

Alternatives

Spec Driven Development

Remote Desktop Commander

Excaliself

README from the maker

receipt

Install

Use

2. sign a receipt over the artifact the agent delivered

3. anyone can verify it, offline

What it proves, and what it does not

Use it as an MCP server (what agents actually call)

What a receipt contains

Tamper detection, tested

FAIL artifact: hash mismatch

Licence