Open-source local runner

Run commit-safe database MCP without a Synapsor Cloud account.

Synapsor Runner is a local-first MCP and database safety runtime. It exposes reviewed semantic tools, stores proposals, evidence, and replay locally, and applies approved Postgres/MySQL changes through guarded writeback in your environment.

Repository link hidden until publicLocal Docker demo Read the MCP model

Architecture

MCP calls a semantic tool; the runner creates a proposal or applies an approved job.

MCP server

semantic tools

Local runner

proposal and guarded transaction

Postgres/MySQL

source of truth

Synapsor replay

result recorded

Security invariants

The runner exposes semantic tools, not arbitrary SQL.

Write credentials stay in the customer environment.
MCP tools are reviewed capabilities such as billing.propose_late_fee_waiver, not execute_sql.
Proposal payloads contain target table, primary key, tenant guard, allowed columns, patch, conflict guard, and idempotency key.
The runner generates parameterized SQL inside the Postgres/MySQL adapter.
One approved job can update at most one row.
Applied, conflict, failed, or canceled is stored for proposal state and replay.

v0.1 scope

Small surface, clear non-goals.

Supported

stdio MCP server
Semantic read/proposal tools
Local SQLite proposals/evidence/replay
Postgres single-row UPDATE
MySQL single-row UPDATE
Conflict result reporting

Not supported

Arbitrary SQL tools
Model-callable approve/commit tools
INSERT or DELETE
DDL
Multi-row updates
Self-hosted Synapsor Cloud

Local demo

Run the full Docker demo with one command.

The local demo needs no Synapsor Cloud account. It starts disposable Postgres/MySQL containers, exposes semantic MCP tools, creates a proposal, proves the source database stays unchanged before approval, applies guarded writeback, retries idempotently, then proves stale-row conflict.

bash

# After cloning the future public runner repository:
./scripts/demo-docker.sh

# Optional contributor path if Node/Corepack is already installed:
corepack pnpm demo:local

This is not the whole Synapsor DBMS.

The open-source runner is the local MCP and trusted-writeback boundary. It does not make the hosted Synapsor control plane or Synapsor DBMS self-hostable. Synapsor Cloud adds team approvals, RBAC, managed policy, runner fleet status, hosted evidence and replay search, retention, and audit visibility.

Run local Docker demo Read runner docs