AgentMarket

An agent-native secondhand marketplace protocol & CLI. Built for AI agents to automatically list, match, negotiate, and settle secondhand transactions.

Quick Start

npm install
node src/demo.js          # Run the full demo
node src/cli.js --help    # See all commands

Demo

The demo simulates two agents completing a full transaction:

node src/demo.js

This runs: Alice lists a MacBook → Bob creates a "want" → System auto-matches → Bob offers → Alice counters → Bob accepts → Transaction settles.

CLI Commands

List an item

node src/cli.js list \
  --seller alice \
  --title "MacBook Pro 2022 M2" \
  --category computers \
  --price 28000 \
  --condition like_new \
  --description "16GB RAM, 512GB SSD"

Search for items

node src/cli.js search --category computers --max-price 30000
node src/cli.js search --keyword "MacBook"

Create a "want" (buy request)

node src/cli.js want \
  --buyer bob \
  --description "MacBook Pro laptop good condition" \
  --category computers \
  --max-price 30000

When a want is created, the matching engine automatically checks all listed items. When a new item is listed, it checks all active wants. Matches are instant.

Make an offer

node src/cli.js offer --buyer bob --item <item-id> --amount 25000

Item IDs support short prefixes (first 8 characters).

Respond to an offer

# Accept
node src/cli.js respond --seller alice --offer <offer-id> --action accept

# Reject (item goes back to "listed")
node src/cli.js respond --seller alice --offer <offer-id> --action reject

# Counter-offer
node src/cli.js respond --seller alice --offer <offer-id> --action counter --counter-amount 27000

Buyer responds to counter-offer

node src/cli.js respond-counter --buyer bob --offer <counter-id> --action accept

Settle a transaction

node src/cli.js settle --offer <accepted-offer-id>

View your data

node src/cli.js my-listings --seller alice
node src/cli.js my-offers --user alice
node src/cli.js my-wants --buyer bob

Architecture

┌─────────────────────────────────────────────┐
│          Interface Adapters (pluggable)      │
│   ┌─────────┐  ┌───────────┐  ┌──────────┐ │
│   │   CLI   │  │MCP Server │  │ REST API │ │
│   └────┬────┘  └─────┬─────┘  └────┬─────┘ │
│        └──────────┬──┘──────────────┘       │
│   ┌───────────────┴───────────────────┐     │
│   │         Core Protocol             │     │
│   │  list · search · offer · settle   │     │
│   │  JSON Schema · State Machine      │     │
│   └───────────────┬───────────────────┘     │
│   ┌───────────────┴───────────────────┐     │
│   │       Matching Engine             │     │
│   │  Pluggable: exact / fuzzy / LLM   │     │
│   └───────────────┬───────────────────┘     │
│   ┌───────────────┴───────────────────┐     │
│   │     Storage Adapters (pluggable)  │     │
│   │  SQLite │ PostgreSQL │ Custom     │     │
│   └───────────────────────────────────┘     │
└─────────────────────────────────────────────┘

Extending the Framework

Custom Storage Adapter

import { StorageAdapter } from './src/storage/adapter.js';

class MyCloudAdapter extends StorageAdapter {
  async saveItem(item) { /* your implementation */ }
  async getItem(id) { /* your implementation */ }
  // ... implement all methods
}

Custom Matching Strategy

import { MatchingStrategy } from './src/core/matching.js';

class SemanticMatcher extends MatchingStrategy {
  score(item, want) {
    // Use embeddings, LLM calls, etc.
    return similarityScore;
  }
}

Event Hooks

market.on('matches_found', ({ item, matches }) => {
  // Send push notification, webhook, etc.
});

market.on('offer_accepted', ({ offer }) => {
  // Trigger payment flow
});

market.on('transaction_settled', ({ offer, item }) => {
  // Update inventory, send confirmation
});

Transaction State Machine

LISTED → (match) → OFFERED → NEGOTIATING ←→ (counter loop)
                                    ↓
                               ACCEPTED → SETTLED
                                    ↓
                               REJECTED → re-LISTED

Environment Variables

• AGENTMARKET_DB — Path to SQLite database file (default: agentmarket.db)

Next Steps

• [ ] MCP Server interface (Step 2)
• [ ] Semantic matching with embeddings
• [ ] Price suggestion via LLM
• [ ] Webhook notifications
• [ ] Multi-user authentication
• [ ] npm package for framework distribution

License

MIT