Skip to main content

Build a Persistent LLM Agent

Step-by-step guide to building an LLM agent that remembers across sessions using Synapse.


Overview

This guide walks through building an LLM agent that persists context across sessions using Synapse. By the end, your agent will:

  • Recall past context at session start
  • Store new learnings as they happen
  • Track multi-step tasks across sessions
  • Communicate with humans via async chat

Architecture

┌──────────────┐   recall/store   ┌──────────┐
│  LLM Agent   │ ◀──────────────▶ │ Synapse  │
│ (your code)  │                  │   API    │
└──────────────┘                  └──────────┘
       │
       │ poll/reply
       ▼
┌──────────────┐
│    Human     │ (browser or chat UI)
└──────────────┘

Step 1: Set Up Mind Key

# Register and get JWT
JWT=$(curl -s -X POST https://synapse.schaefer.zone/register \
  -H "Content-Type: application/json" \
  -d '{"email":"agent@example.com","password":"secret"}' | jq -r .jwt)

# Create mind and get Mind Key
MIND_KEY=$(curl -s -X POST https://synapse.schaefer.zone/minds \
  -H "Authorization: Bearer $JWT" \
  -H "Content-Type: application/json" \
  -d '{"name":"persistent-agent","description":"My persistent agent"}' | jq -r .mind_key)

echo "Save this: $MIND_KEY"

Step 2: Session Start Protocol

At the beginning of every session, recall all memories:

import os
import requests

MIND_KEY = os.environ["SYNAPSE_MIND_KEY"]
URL = "https://synapse.schaefer.zone"

def session_start():
    """Call this at the start of every session."""
    # 1. Recall all memories
    r = requests.get(
        f"{URL}/memory/recall",
        headers={"Authorization": f"Bearer {MIND_KEY}"}
    )
    memories = r.text  # plain text summary
    
    # 2. Check for unread chat messages
    r = requests.get(
        f"{URL}/chat/poll",
        headers={"Authorization": f"Bearer {MIND_KEY}"}
    )
    messages = r.json().get("messages", [])
    
    # 3. Check in-progress tasks
    r = requests.get(
        f"{URL}/mind/tasks?status=in_progress",
        headers={"Authorization": f"Bearer {MIND_KEY}"}
    )
    tasks = r.json().get("tasks", [])
    
    return {
        "memories": memories,
        "unread_messages": messages,
        "active_tasks": tasks,
    }

context = session_start()
# Build system prompt with this context

Step 3: Store New Learnings

Whenever the agent learns something worth remembering:

def remember(category, key, content, tags=None, priority="normal"):
    """Store a memory."""
    requests.post(
        f"{URL}/memory",
        headers={
            "Authorization": f"Bearer {MIND_KEY}",
            "Content-Type": "application/json",
        },
        json={
            "category": category,
            "key": key,
            "content": content,
            "tags": tags or [],
            "priority": priority,
        }
    )

# Examples
remember("identity", "user_name", "User is Michael Schäfer", 
         tags=["person"], priority="critical")
remember("preference", "communication_style", 
         "User prefers concise technical responses",
         tags=["communication"])
remember("project", "current_project", 
         "Building Synapse v1.6.0 with docs system",
         tags=["synapse", "docs"], priority="high")
remember("mistake", "npm_version_bump", 
         "Always bump package.json version after changes",
         tags=["npm", "ci"], priority="high")

Step 4: Task Management

Track multi-step work across sessions:

def create_task(title, description="", priority="normal"):
    r = requests.post(
        f"{URL}/mind/task",
        headers={"Authorization": f"Bearer {MIND_KEY}",
                 "Content-Type": "application/json"},
        json={"title": title, "description": description, "priority": priority}
    )
    return r.json()["id"]

def update_task(task_id, status=None, description=None):
    payload = {}
    if status: payload["status"] = status
    if description: payload["description"] = description
    requests.put(
        f"{URL}/mind/task/{task_id}",
        headers={"Authorization": f"Bearer {MIND_KEY}",
                 "Content-Type": "application/json"},
        json=payload
    )

# Multi-session workflow
task_id = create_task("Deploy v1.6.0", "Push docs system to production", "high")
update_task(task_id, status="in_progress")
# ... work across multiple sessions ...
update_task(task_id, status="done")

Step 5: Async Chat with Humans

Poll for messages between tool calls:

import time

def poll_messages():
    r = requests.get(
        f"{URL}/chat/poll",
        headers={"Authorization": f"Bearer {MIND_KEY}"}
    )
    return r.json().get("messages", [])

def reply(content):
    requests.post(
        f"{URL}/chat/reply",
        headers={"Authorization": f"Bearer {MIND_KEY}",
                 "Content-Type": "application/json"},
        json={"content": content}
    )

# Main loop
while working:
    # Poll for human messages
    for msg in poll_messages():
        print(f"Human: {msg['content']}")
        reply(f"Got it: {msg['content']}. Working on it.")
    
    # Do one unit of work
    do_work()
    
    time.sleep(30)  # don't poll too frequently

Step 6: Session End Protocol

At session end, store final context:

def session_end():
    """Call this before terminating the session."""
    # Store what we accomplished
    remember("context", "last_session_summary",
             f"Session ended at {time.now()}. Accomplished: ...",
             tags=["session"], priority="normal")
    
    # Update task statuses
    for task in get_active_tasks():
        if task_in_progress(task):
            update_task(task["id"], description=f"In progress: {current_step}")

session_end()

Complete Pattern

class PersistentAgent:
    def __init__(self):
        self.mind_key = os.environ["SYNAPSE_MIND_KEY"]
        self.url = "https://synapse.schaefer.zone"
    
    def run(self):
        # 1. Recall context
        context = self.session_start()
        
        # 2. Process unread messages
        for msg in context["unread_messages"]:
            self.handle_message(msg)
        
        # 3. Resume active tasks
        for task in context["active_tasks"]:
            self.continue_task(task)
        
        # 4. Do new work
        self.do_work()
        
        # 5. Persist state
        self.session_end()

Best Practices

Next Steps