projectstate

Persistent project memory for AI agents, paid per call in USDC over x402. No account, no API key.

https://projectstate.online/mcp — an MCP server (Streamable HTTP) that remembers, per project, what was decided, what was tried and failed, and what is still open, and hands an agent back the three facts it needs instead of the whole history.

Why

Every agent already has "memory". What it does not have is project state that survives across tools and sessions: Claude Code, Cursor, a CI agent and a script all working on the same repo, sharing one ranked, compact record of decisions and dead ends. That is what this is. Retrieval is the point: recall returns at most a few lines inside a character budget, ranked so superseded decisions sink and active ones float.

Related MCP server: engrams

Tools

Failed calls are free. Identical retries (or any call with the same idempotency_key) are never billed twice. Prices are published per tool in tools/list under _meta.priceUsd.

plan_check

The tool to call before starting something non-trivial:

plan_check(project="my-app", intent="switch the session cache to Redis", files=["src/cache.py"])

Plan check for 'my-app': 'switch the session cache to Redis'
Prior failures (1):
  #8 attempt/failed (2026-09-12): Tried Redis for the session cache — connection pool exhausted under load
Active decisions that constrain this (1):
  #9 decision/active (2026-09-12): Cache with SQLite instead of Redis — one less service to run
Open tasks that overlap (1):
  #10 task/open (2026-09-12): Benchmark the cache options

Three targeted searches in one call, returning only what would change the plan. A clean plan answers "Nothing on record matches this plan" so the agent can proceed without a second lookup.

How paying works

1. Call a tool. Without credit the result is isError: true with an x402 v2 PaymentRequired in structuredContent (scheme exact, USDC on Base, the amount, the pay-to address).

2. Sign the USDC payment and retry the same call with the payload in _meta["x402/payment"].

3. The result carries the settlement receipt in _meta["x402/payment-response"] and a credit token in _meta["projectstate/x402-credit"].

4. One payment buys credit ($0.10 on a session-based connection, $0.01 minimum per call without one). Later calls draw from it automatically on a session, or by sending the credit token as Authorization: Bearer xc_…. Unused credit stays on your wallet address.

Works with any x402-capable client: x402-mcp (withPayment()) for the Vercel AI SDK, the x402 Python package, or the 30-line handshake in scripts/x402_agent_demo.py.

from eth_account import Account
from mcp import Client
from x402 import x402Client
from x402.mechanisms.evm.exact import register_exact_evm_client
from x402.mechanisms.evm.signers import EthAccountSigner
from x402.schemas import PaymentRequired

x = x402Client(); register_exact_evm_client(x, EthAccountSigner(Account.from_key(KEY)))
async with Client("https://projectstate.online/mcp") as mcp:
    r = await mcp.call_tool("project_open", {"project": "my-app"})       # -> PaymentRequired
    pay = (await x.create_payment_payload(PaymentRequired(**r.structured_content))).model_dump(by_alias=True, exclude_none=True)
    r = await mcp.call_tool("project_open", {"project": "my-app"}, meta={"x402/payment": pay})
    token = r.meta["projectstate/x402-credit"]                          # reuse on later calls

What is under the hood

Python 3.12, the official MCP Python SDK (v2), SQLite + FTS5 (bm25, no vectors), the official x402 package against the Coinbase facilitator on Base mainnet. One process, one SQLite file, an admin dashboard with per-tool latency, error messages, a full audit ledger and a retrieval-quality meter (zero-hit and re-query rates) that says when keyword search stops being enough.

Docs: https://projectstate.online/docs · Registry: online.projectstate/projectstate · License: MIT

Run your own

deploy/install.sh sets up systemd, nginx, fail2ban, hourly SQLite backups and unattended upgrades on a small Ubuntu VPS; deploy/env.example lists every setting; deploy/x402_live_setup.sh switches the x402 rail to Base mainnet with Coinbase CDP keys. pytest tests/ runs 33 tests including a mock x402 facilitator that verifies real EIP-712 signatures.