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POPCORN MCP

Verify signed time, SHA-256 task digests, schedule checkpoints, and historical receipts through MCP.

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Install POPCORN MCP

Pick your client, then add it in one click or paste the config.

STDIONode.js
~/Library/Application Support/Claude/claude_desktop_config.json
claude_desktop_config.json
{
  "mcpServers": {
    "popcorn-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@violetclaire/popcorn-mcp@0.1.3"
      ]
    }
  }
}

Settings → Developer → Edit Config, merge this into mcpServers, then fully quit and reopen Claude Desktop.

Automated check passed— started and listed 6 tools correctly (1d ago).

Overview

POPCORN MCP connects agents to Briarwood AI’s POPCORN service at 767-2676.com for signed time evidence and SHA-256 witness receipts. It includes a local `popcorn_sample` evaluation that verifies bundled production receipts and detects one-byte tampering without a wallet or network call. Use it when an agent needs portable evidence for a deadline, authorization window, handoff, or exact task-state version. Paid live receipts use x402 v2 and return signed evidence while the agent retains the original task data.

Use cases

  • Verify whether a task fell within a signed deadline window
  • Record a portable checkpoint for one exact task version
  • Link handoff receipts across agent sessions
  • Detect tampering in saved schedules and signed receipts

Key features

  • Signed time evidence
  • SHA-256 payload witnesses
  • ES256 compact JWS receipts
  • Offline receipt and tamper verification
  • Optional predecessor receipt linkage
  • x402 v2 payments on Base

Tools6

What POPCORN MCP lets your agent do. Expand a tool for its parameters.

Verified live~1.2k tokens of context

Security & health

What it can reach and how reliably it runs — from our own checks, not the maintainer’s claims.

ActiveLast checked 1d ago

Recent health check succeeded.

7/7 checks healthy over the last 45d

What it can do

From the 6 tools this server returned when we ran it; 6 declare their own safety hints.

Can delete or modify data · 2Makes network requests · 5Read-only tools · 4
Network at startup3 connections
Files written at startupNone
Install scriptsNone
npm provenanceNot published
Package age60 days
Maintainers1

Observed 2026-11-03 in an isolated sandbox. A description of reach, not a security audit.

Supply-chain signal

No high-severity advisories surfaced by our automated scan.

Critical 0High 0Medium 0Low 0

Scanned 3d ago via OSV.dev · @violetclaire/popcorn-mcp@0.1.3 (npm)

Adoption & maintenance

Factual signals from GitHub, npm, and our automated checks — not a rating.

npm downloads453Package downloads in the last 30 days.
Last commit6d agoMost recent push to the default branch.
Availability100%Our rolling endpoint + install checks that succeeded.
Install checkPassedOur sandbox started it and listed its tools.
Tools exposed6Callable tools this server registers over MCP.

How POPCORN MCP works

What POPCORN MCP does

POPCORN MCP gives agents access to signed temporal evidence and payload-bound task checkpoints. The underlying POPCORN service can provide signed time for deadlines, expiration windows, execution windows, and handoffs. It can also witness the SHA-256 digest of one exact payload, allowing a later verifier to check that the payload is unchanged and determine when its commitment was witnessed.

The connector includes a local sample tool named popcorn_sample. That evaluation checks two bundled historical production receipts and confirms that their one-byte tamper controls are rejected. It runs without a wallet, payment, or network request.

The service is intentionally limited to evidence. It does not schedule work, reserve resources, authorize actions, store private task state, or decide what an agent should do next.

How it works

For a live task checkpoint, the agent hashes the exact payload bytes locally and sends the resulting SHA-256 digest to POPCORN. The request also includes a new 32-byte nonce and may include the digest of the preceding receipt’s exact signed payload bytes. POPCORN returns a signed receipt containing those values and a bounded witness interval.

The live endpoints are GET /v1/time for signed time and POST /v2/receipt for a paid schedule or task checkpoint. Existing integrations can continue using POST /v1/receipt. The service charges $0.001 USDC on Base mainnet through x402 v2. Receipts use ES256 compact JWS and can be checked against the service’s public JWKS.

An agent carries the original payload and the signed receipt together. A verifier can then compare the payload digest, inspect the witness interval, and check an optional predecessor relationship. The receipt cannot reconstruct or retrieve the payload, prove caller identity or delivery, establish that an action executed, prevent replay, or establish authorization.

Setup and configuration

The repository connector requires Node.js 20 or newer. From the repository, install dependencies, build the connector, and start its sample mode:

bash
git clone https://github.com/violetclaire/popcorn-temporal-anchor.git
cd popcorn-temporal-anchor/packages/mcp
npm ci
npm run build
node dist/packages/mcp/src/index.js --sample

The published package can be evaluated with:

Terminal
npx -y @violetclaire/popcorn-mcp@0.1.3 --sample

After connecting an MCP client, call popcorn_sample with an empty object to run the same local verification. The repository also provides a separate offline verification command for the checked-in STOP packet; it performs no network or payment operation.

Tools and capabilities

  • Run the bundled historical receipt verification and tamper checks locally.
  • Obtain signed time evidence for deadlines, expirations, execution windows, and handoffs.
  • Request a signed SHA-256 checkpoint for one exact task or schedule payload.
  • Link a new receipt to the digest of a preceding receipt’s signed payload.
  • Verify payload integrity and the interval in which a commitment was witnessed.

Limitations and notes

POPCORN evidence describes a signed observation or commitment, not current authorization or execution. The service keeps the raw task and schedule with the agent rather than storing them. Live requests require an x402 v2 payment of $0.001 USDC on Base mainnet, while the bundled sample and verification checks are offline and free. Historical receipts remain verifiable, but their results describe the recorded evidence and local policy at that time.

Read the full README View source on GitHub

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Frequently Asked Questions about POPCORN MCP

POPCORN MCP is an MCP server that connects agents to the POPCORN service at 767-2676.com for signed time and SHA-256 witness receipts. Its main tools support local sample verification plus evidence workflows for deadlines, task versions, and handoffs. Live receipts use x402 v2 payments, while bundled checks run offline.

Install it from the repository with Node.js 20 or newer by running `npm ci`, `npm run build`, and the built MCP entry point. The documented sample command is `node dist/packages/mcp/src/index.js --sample`; the published package can also be run with `npx`.

Yes, POPCORN MCP includes offline verification. Run its sample mode or call `popcorn_sample` with `{}` to check the bundled historical receipts and their one-byte tamper controls without a wallet, payment, or network request.

A live receipt costs $0.001 USDC on Base mainnet through x402 v2. The paid endpoints provide signed time or a signed checkpoint for a SHA-256 payload digest, while local sample verification remains free.

It proves that a specific payload digest reached the POPCORN witness within a signed time interval. It can also commit to a preceding receipt when that digest is supplied. It does not prove caller identity, delivery, action execution, replay prevention, or authorization.

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