EverOS is a local-first, markdown-based memory framework for AI agents and chat applications. It ingests conversational sessions via a FastAPI REST API, extracts structured memories (episodes, atomic facts, agent cases, skills, user profiles) using LLMs, persists them as version-controllable Markdown files, and maintains derived search indexes in LanceDB (vector + BM25) and SQLite. The system provides a rich retrieval layer with keyword, vector, hybrid (RRF), and agentic (LLM-guided multi-round) search methods, plus a knowledge wiki feature. An Offline Memory Engine (OME) runs background strategies (reflection, clustering, extraction) on cron/idle/immediate triggers, and a cascade daemon watches the Markdown filesystem to reconcile indexes. The architecture is a layered monolith (entrypoints → service → memory → infrastructure) with cross-cutting components for LLM, embedding, rerank, tokenizer, and config. It ships with a CLI (Typer), a TUI demo (Textual), and extensive integration tests. While primarily an application, it includes a benchmark harness (LoCoMo, LongMemEval, EverMemBench) and evaluation fixtures, giving it a hybrid character with a strong research-oriented testing pipeline.