# FluctlightDB — questions ## What is FluctlightDB? FluctlightDB is an open-source, embedded memory database for AI agents. An agent writes what happened with experience(), recalls it from a cue with activate(), and makes it durable with checkpoint(). It has a Rust core and a Python-first API, runs inside your process, and stores one brain directory per agent. ## How do I give an AI agent long-term memory with FluctlightDB? Install it with pip install "fluctlightdb[native]", open a brain with connect_embedded("./my-agent-brain"), write memories with brain.experience(text, context=..., salience=...), recall with brain.activate(cue), and call brain.checkpoint() when a unit of work completes. There is no server to start and nothing to configure first. ## How do I install FluctlightDB? Install it with pip install "fluctlightdb[native]". Open a brain with connect_embedded("./my-agent-brain"), write with experience(), recall with activate(), and call checkpoint() so the directory survives a restart. The steps are on /install. ## Is FluctlightDB a vector database? No. A vector database answers "what is nearest?"; FluctlightDB answers "what should this cue bring back?". One activate() call fuses full-text search, vector neighbours and graph spreading activation, and ranks verified memories with a source above ones the agent was merely told. It stores engrams with context, salience and provenance rather than bare vectors. ## How is FluctlightDB different from Chroma? Chroma and Qdrant answer what is nearest, and FluctlightDB answers what this cue should bring back by fusing full-text search, vector neighbours and graph spreading activation inside one activate() call. See /compare/vector-databases. ## How is FluctlightDB different from Mem0? A Mem0-style layer stores facts scraped from chat, and FluctlightDB stores engrams with provenance that the agent records with experience() and recalls with activate(). See /compare/mem0. ## Does FluctlightDB need a server or a cloud account? No. It is embedded: the engine runs in your Python process and a brain is a directory on disk, like SQLite for agent memory. An HTTP server (fluctlight-serve) and a Docker image exist for when you want to reach a brain from another process or language, but they are optional. ## Does FluctlightDB need an API key? No. The canonical sample calls connect_embedded(), experience(), activate() and checkpoint(), and neither that sample nor pip install "fluctlightdb[native]" takes an API key. ## Does FluctlightDB do semantic search out of the box? No. No embedder ships with the engine, so offline recall is lexical: a cue has to share tokens with what was stored. For paraphrase recall, pass a semantic_vector from an embedding model you choose, on both the experience() write and the activate() cue. ## Does FluctlightDB work with LangChain, LlamaIndex, the OpenAI Agents SDK or MCP? Yes. The project ships a LangChain memory and chat history (FluctlightMemory), a LlamaIndex memory (FluctlightLlamaMemory), remember and search handlers for the OpenAI Agents SDK, and an MCP server for Cursor, Claude and Codex, each installed as a pip extra such as fluctlightdb[langchain] or fluctlightdb[mcp]. TypeScript and other languages reach a brain over HTTP (the @fluctlightdb/agent client talks to fluctlight-serve), and there is a Docker image at ghcr.io/voxmastery/fluctlightdb. ## Can Claude, Cursor or Codex use FluctlightDB as persistent memory? Yes, through its MCP server (pip install "fluctlightdb[mcp]"), which exposes tools such as memory_remember and memory_recall. Each assistant session writes to and recalls from a brain directory on your own machine, so memory persists across sessions without sending it to a hosted service. ## Which Python versions and platforms does FluctlightDB support? The native package ships abi3 wheels for Python 3.9 to 3.13 on Linux, macOS and Windows, on x86-64 and arm64. Without the [native] extra you get a pure-Python fallback, which is slower and is not what the measurements were taken on. ## Is my agent’s memory safe if the process crashes? Writes go to a write-ahead log, and checkpoint() writes a whole new generation before atomically advancing a CURRENT pointer, so a process killed mid-write leaves the previous generation intact. Crash recovery is exercised in CI with SIGKILL mid-write and torn log tails. Nothing is durable until checkpoint() returns. ## What is the difference between activate() and recall()? They are two calls with two different return shapes. activate() returns {recalls, active_neurons, hops, myelinated}; recall() returns {hits, lanes_used, mode}. Start with activate() — it is the documented recall path. ## Can several agents share one FluctlightDB brain? They can, but they should not. When many agents share one brain the project’s own paper measures provenance separation at only 18% top-1, and that is unaddressed in code. Give each agent its own brain directory, or pass agent_id on every call. ## How accurate is FluctlightDB’s recall? On the maintainer’s own frozen July 2026 runs: 72.6% LoCoMo evidence recall at k=5, 96.8% at k=150, and 97.6% LongMemEval-S session recall at k=8. These are maintainer-reported with open harnesses and have not been independently reproduced. An earlier LoCoMo headline was retracted because its protocol counted turns the engine never retrieved. ## Is FluctlightDB production-ready? Not yet, and it says so. It is beta software with one active maintainer, production readiness defaults to false, and there has been no third-party security audit or penetration test. The core API — connect_embedded(), experience(), activate(), checkpoint(), recall() and the on-disk format — is marked stable; everything else is experimental. ## How many memories can one brain hold? Approximate nearest-neighbour search has not been evaluated beyond 100,000 memories. That is not a documented limit, it is an absence of measurement. ## Is FluctlightDB free and open source? Yes. It is dual-licensed MIT or Apache-2.0, the source is on GitHub, and the package is on PyPI as fluctlightdb. ## Is FluctlightDB related to Sword Art Online? No. FluctlightDB is an independent open-source database for AI agent memory. It borrows a word from fiction for its name and is not affiliated with Sword Art Online or its rights holders. ## How do I cite FluctlightDB? Ganesh S, “FluctlightDB: A Memory Model of Data for AI Agents”, 2026. Preprint arXiv:2608.12365, archived at doi:10.5281/zenodo.20949890. ## Still deciding? - [How it compares](/compare) - [Install](/install) - [Benchmarks](/benchmarks) - [Paper](/paper) - [Playground](/playground) - [Mistakes against this API](/docs#mistakes)