[Feature] Pluggable persistent memory backend — self-hosted decay-weighted recall via Dakera

Problem

Chainlit stores conversation messages in a database (via chainlit.data abstraction), but there's no semantic memory layer that persists what matters across conversations. Each new chat thread with the same user starts cold — the assistant has no recollection of prior interactions or user preferences unless the developer manually implements retrieval.

Two distinct needs:

1. Within a session: Chainlit handles this well with message history
2. Cross-session persistence: Storing semantic context so future conversations can recall relevant past interactions

Proposed: Dakera as a pluggable memory backend

Dakera is a self-hosted vector memory server with decay weighting — recent memories rank higher, stale ones fade naturally. It would plug into Chainlit's lifecycle hooks:

import chainlit as cl
from dakera import DakeraClient

memory = DakeraClient(base_url="http://localhost:3300", api_key="demo")

@cl.on_chat_start
async def on_start():
    user_id = cl.user_session.get("user").identifier
    # Inject up to 5 relevant memories from prior sessions
    history = memory.recall(agent_id=user_id, query="user preferences and context", top_k=5)
    if history.memories:
        context = "\n".join(f"- {m.content}" for m in history.memories)
        await cl.Message(content=f"**Recalled from prior sessions:**\n{context}").send()

@cl.on_message
async def on_message(message: cl.Message):
    user_id = cl.user_session.get("user").identifier
    
    # ... run your LLM logic ...
    response = run_llm(message.content)
    
    # Store the exchange in Dakera for future sessions
    memory.store_memory(
        agent_id=user_id,
        content=f"User: {message.content}\nAssistant: {response}",
        session_id=cl.context.session.id,
    )
    await cl.Message(content=response).send()

Why not just use Chainlit's data layer?

Chainlit's SQLAlchemyDataLayer stores raw conversation threads — great for audit/history. Dakera adds semantic recall: instead of replaying the last N messages, it surfaces the 5 most relevant past exchanges based on the current query, with temporal decay so stale context doesn't pollute new conversations.

Broader pattern

This could be exposed as a DakeraMemoryStore that implements Chainlit's BaseStorageClient or BaseDataLayer interface, allowing users to configure it via config.toml:

[project]
enable_telemetry = false

[memory]
backend = "dakera"
url = "http://localhost:3300"
api_key = "demo"

Setup

docker run -d -p 3300:3300 -e DAKERA_API_KEY=demo ghcr.io/dakera-ai/dakera:latest
pip install dakera

Fully self-hosted — no data leaves your infrastructure. Happy to prototype as a PR.