# Synapse Architecture

Synapse is a multi-tenant memory API built on Fastify, PostgreSQL with FTS5,
and an optional embeddings service for semantic search.

## High-Level Architecture

```
┌──────────────────────────────────────────────────────────┐
│                       Clients                            │
├──────────────┬──────────────┬──────────────┬─────────────┤
│  LLM Agents  │  Web Browsers│  MCP Clients │  Webhooks   │
│  (curl/SDK)  │  (humans)    │ (Claude/etc) │  (external) │
└──────┬───────┴──────┬───────┴──────┬───────┴──────┬──────┘
       │              │              │              │
       └──────────────┴──────────────┴──────────────┘
                              │
                              ▼
              ┌───────────────────────────────┐
              │    Synapse API (Fastify)      │
              │    port 12800                 │
              │    - REST endpoints           │
              │    - Auth (Mind Key / JWT)    │
              │    - Rate limiting            │
              │    - Static file serving      │
              └───────────────┬───────────────┘
                              │
              ┌───────────────┼───────────────┐
              ▼               ▼               ▼
       ┌─────────────┐ ┌─────────────┐ ┌─────────────┐
       │ PostgreSQL  │ │ Embeddings  │ │ MCP Server  │
       │ + FTS5      │ │ Service     │ │ (separate)  │
       │             │ │ (optional)  │ │ port 13100  │
       │ - memories  │ │             │ │             │
       │ - tasks     │ │ - generate  │ │ - 79 tools  │
       │ - chat      │ │   embeddings│ │ - stdio/SSE │
       │ - scripts   │ │             │ │ - WebSocket │
       └─────────────┘ └─────────────┘ └─────────────┘
```

## Core Components

### 1. Synapse API (Fastify)

The main HTTP server. Handles:

- REST endpoints (`/memory`, `/chat`, `/mind/tasks`, etc.)
- Authentication (Mind Key for agents, JWT for humans)
- Rate limiting (`?key=` auth only)
- Static file serving (web UI at `/human`, `/docs`, etc.)
- Webhook dispatch

Built with **Fastify 5** for performance. Runs on port 12800 in production.

### 2. PostgreSQL with FTS5

The primary data store. Uses PostgreSQL with the FTS5 extension for
full-text search.

**Key tables:**

| Table | Purpose |
|-------|---------|
| `users` | User accounts |
| `minds` | Mind scopes (each has a Mind Key) |
| `memories` | Memory records with FTS5 virtual table |
| `tasks` | Task management |
| `chat_messages` | Chat history |
| `scripts` | Persistent scripts |
| `webhooks` | Webhook registrations |
| `cron_jobs` | Scheduled tasks |
| `variables` | Key-value store |
| `audit_log` | Audit trail |

**FTS5** enables sub-millisecond full-text search across all memory content.
See [FTS5 Search](/docs/concepts/fts5-search) for details.

### 3. Embeddings Service (Optional)

For semantic search, Synapse generates vector embeddings of memory content.
These are stored alongside memories and used for similarity search.

- Provider: configurable (OpenAI, local model, etc.)
- Stored as `vector` column in `memories` table
- Used by `/memory/semantic-search` endpoint
- See [Semantic Search](/docs/concepts/semantic-search)

### 4. MCP Server (Separate Service)

The Synapse MCP server runs as a separate process (port 13100). It:

- Exposes 79 tools via Model Context Protocol
- Supports stdio, HTTP/SSE, and WebSocket transports
- Translates MCP tool calls into Synapse API calls
- Multi-tenant: one Mind Key per session

### 5. Browser Proxy (Separate Service)

For browser automation, a separate Playwright-based service runs on port 13000.
The MCP server can call this for `browser_*` tools.

### 6. SSH Proxy (Separate Service)

For SSH-based remote commands, a separate service runs on port 12900.

## Multi-Tenancy Model

```
User Account (email + password)
  │
  ├── Mind 1 (Mind Key 1)
  │   ├── Memories
  │   ├── Tasks
  │   ├── Chat
  │   └── Scripts
  │
  ├── Mind 2 (Mind Key 2)
  │   └── ... (isolated from Mind 1)
  │
  └── Mind 3 (Mind Key 3)
      └── ...
```

Each mind is fully isolated. Mind Keys grant access to exactly one mind.
JWTs grant access to the user account (for managing minds).

See [Multi-Tenancy](/docs/concepts/multi-tenancy) for details.

## Request Flow

### Memory Store Request

```
1. Client sends POST /memory with Authorization: Bearer mk_xxx
2. Fastify receives request
3. Auth middleware validates Mind Key, attaches mind_id to request
4. Memory route handler:
   a. Validate JSON body (zod schema)
   b. Insert into memories table
   c. Update FTS5 index
   d. (Async) Generate embedding if embeddings enabled
   e. Trigger webhooks for memory.store event
5. Return { id, status: "stored" }
```

### Memory Search Request

```
1. Client sends GET /memory/search?q=docker
2. Auth middleware validates Mind Key
3. Memory route handler:
   a. Parse query (FTS5 syntax)
   b. Execute FTS5 MATCH against memories table
   c. Filter by mind_id (tenant isolation)
   d. Rank by relevance
   e. Return results
```

## Deployment

Synapse is deployed as a Docker container. See `docker-compose.yml`:

```yaml
services:
  synapse:
    image: registry.gitlab.com/schaefer-services/synapse:latest
    ports:
      - "12800:12800"
    environment:
      - DATABASE_URL=postgres://...
      - JWT_SECRET=...
      - SYNAPSE_HOST=0.0.0.0
      - SYNAPSE_PORT=12800
    depends_on:
      - postgres
  
  postgres:
    image: postgres:16
    volumes:
      - pgdata:/var/lib/postgresql/data
    environment:
      - POSTGRES_DB=synapse
      - POSTGRES_PASSWORD=...
```

## Performance Characteristics

| Operation | Latency | Throughput |
|-----------|---------|------------|
| Memory store | ~5ms | 1000+ req/s |
| Memory recall | ~20ms | 500 req/s |
| FTS5 search | ~10ms | 800 req/s |
| Semantic search | ~50ms | 200 req/s |
| Chat poll | ~5ms | 2000 req/s |

## Next Steps

- [Memory Model](/docs/concepts/memory-model)
- [Multi-Tenancy](/docs/concepts/multi-tenancy)
- [FTS5 Search](/docs/concepts/fts5-search)