NexusOS

A local-first AI assistant platform. Runs entirely on your machine — a Python/FastAPI backend, a bundled Ollama instance for inference, a persistent memory service, and a React frontend. No external AI provider is called.

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What it is

NexusOS ("Nexus") is a self-hosted assistant you actually own. All inference runs through a locally bundled Ollama on localhost; conversations, facts, and settings live in local SQLite. It ships with desktop branding (XFCE theme, icons, boot splash) so it can be run as a full assistant environment on Linux, not just a web app.

Chat with vision and voice, persistent memory, tool-using playbooks, document RAG scoped to Projects, gated action tools, and full model management — see Flagship features below for what each of those actually does. Rounding it out: full conversation history (persist, search, edit, export) and a browser tail of the service logs.

Flagship features

Chat, vision & voice

Streaming responses over SSE, with stop/regenerate/edit-and-resend so a bad reply doesn't mean retyping the whole message. Attach images and route them to a multimodal Ollama model for vision. Dictate with local Whisper STT instead of typing, and have replies read back aloud. A per-message extended-thinking toggle lets a reasoning model show its work without a round-trip to Settings.

Persistent memory

A dedicated microservice reads every exchange and decides, via its own Ollama prompt, whether it contains a durable fact worth keeping — a preference, a name, a standing instruction. Saved facts get layered back into the system prompt on every future chat, so Nexus remembers you across conversations without you re-explaining yourself.

Playbooks

Ordered YAML system-prompt records instead of one static prompt. The first playbook is the active persona; the rest are automatically routed in as reference context when relevant. Each playbook can pin its own chat model and its own tool allowlist, so "coding assistant" and "creative writing partner" can be genuinely different setups, not just different wording.

Documents & RAG

Upload PDF, DOCX, TXT, or Markdown; NexusOS chunks and embeds it into a sqlite-vec index and cites the matching passages back into chat answers. Projects scope this per workspace — switch projects and the model only draws on that project's documents (or none, in the unscoped "All" view).

Action tools with an approval gate

Beyond read-only tools (search memory/history/documents, list models, get the time), Nexus can search the web, fetch a URL, or save a fact on its own initiative — but each of those three is gated behind an explicit approval prompt in the chat UI before it runs. Nothing reaches out to the network or writes to memory without you seeing the request first.

Model management

List, pull, and delete Ollama models from the UI or ncp, with hardware-aware recommendations (GPU detection via Vulkan) so a small-VRAM box isn't offered a model it can't run.

Quick start

NexusOS runs single-process: the backend on :8000 serves the built web UI itself, so there's no separate frontend server at runtime. Ollama is started manually from the app (Start AI in the sidebar), not at boot.

Linux

Nexus was built using an Apple T2 computer running Linux Mint XFCE. The desktop branding (theme, icons, boot splash) could hypothetically be adapted to any Linux distro, but I only support the Ubuntu/Linux Mint package base.

# 1. Build everything: venv (auto-selects AMD/NVIDIA/CPU), web UI, memory DB,
#    system packages, Ollama binary and the XFCE desktop wiring.
./install.sh

# 2. Launch (memory :8001, backend :8000 — backend also serves the built UI)
#    The install symlinks ncp into /usr/local/bin (sudo); open a new shell first.
ncp web

Python deps are layered: requirements-base.txt (GPU-agnostic core) plus one GPU overlay — requirements-amd.txt (ROCm) or requirements-nvidia.txt (CUDA). requirements-windows.txt is the standalone CPU-only runtime (no base overlay). bin/sync.py picks the right one for the host.

./install.sh is also the update path — re-run it any time to pull the latest and rebuild. --check dry-runs it; --no-desktop skips the XFCE panel/theme wiring (that stage is auto-skipped off XFCE anyway). It's a thin wrapper over bin/sync.py restore, the same code the Windows box runs.

Windows

# 0. Allow scripts to run (PowerShell blocks unsigned scripts by default, which
#    stops Nexus's CLI from working). Process scope covers only this window;
#    LocalMachine makes it permanent so ncp works from every future shell (run
#    PowerShell as Administrator for the LocalMachine line).
Set-ExecutionPolicy -Scope Process       -ExecutionPolicy Bypass -Force
Set-ExecutionPolicy -Scope LocalMachine  -ExecutionPolicy RemoteSigned -Force

# 1. Install Git, then clone (public repo, no account/token needed):
winget install Git.Git
# open a NEW PowerShell window, then:
git clone https://git.enderofwings.com/enderofwings/NexusOS.git nexus-core
cd nexus-core

# 2. Native install — winget Python/Node/Ollama, venv, pip, web build, desktop icon
powershell -ExecutionPolicy Bypass -File .\install-windows.ps1

Then double-click the NexusOS desktop icon, or launch from a new shell (PATH is read at process start, so already-open windows won't have ncp yet):

ncp web

The app opens at :8000; click Start AI to launch Ollama. The installer uses requirements-windows.txt (CPU-only, pure-Python — no ML stack, since Ollama does all inference over HTTP).

Individual services

source Promethean/bin/activate

uvicorn synapse.main:sio_app          --host 0.0.0.0 --port 8000 --reload   # backend (serves the UI too)
uvicorn synapse.memory.service:app    --host 0.0.0.0 --port 8001 --reload   # memory

# Frontend dev server (hot-reload) — only needed when editing the UI;
# production serves the built dist/ from the backend at :8000.
cd interface/web && npm run dev

Promethean

The name for the Python virtual environment all backend code runs in — keeps Nexus's dependencies out of the system Python. To add a package, activate it and pip install as usual:

# Linux
source Promethean/bin/activate
pip install <package>

# Windows — needs the RemoteSigned policy from step 0 above, since
# Activate.ps1 is a script PowerShell would otherwise refuse to run
Promethean\Scripts\Activate.ps1
pip install <package>

On Linux, the installer also registers a promethean alias in ~/.bashrc (and an optional "Promethean Terminal" desktop launcher) that drops you straight into an activated shell. There's no equivalent on Windows yet — use Activate.ps1 above, or call Promethean\Scripts\python.exe -m pip install <package> directly without activating at all.

CLI (ncp)

ncp stands for Nexus Control Panel. This was the original method of accessing the frontend and backend power switches before the UI was implemented. The CLI itself is the same Python script on both platforms and behaves identically either way — the exception is ncp panel (the tkinter GUI), which was tuned for Linux/XFCE and looks noticeably more dated on Windows.

Start/stop services and drive the same features as the web UI over the REST API:

ncp start        # backend + frontend (--backend|--frontend|--memory)
ncp stop

ncp chat "<message>"                   # stream a reply
ncp memory list | add <text> | rm <id>
ncp playbook list | show <id>          # first playbook (*) = active system prompt
ncp history [query]                    # recent conversations
ncp doctor [--fix]                     # diagnostics: venv, Node, imports, Ollama, status
ncp help                               # see complete help tree

Architecture

Component	Location	Role
Promethean (venv)	Promethean/	The Python venv all backend code runs in — source Promethean/bin/activate (Linux) / Promethean\Scripts\python.exe (Windows). Keeps deps out of the system Python.
Synapse (backend)	synapse/	FastAPI app: /chat/stream (+ /chat/approve for gated tool calls), /playbooks, /memory, /models, /documents, /projects, /conversations, /stt, /logs, /settings, /ollama, /frontend, /icons. Assembles the system prompt: active playbook → reference playbooks → memory facts → relevant past snippets → matching documents → web search results.
Memory service	synapse/memory/	Separate FastAPI app (:8001). /memories/extract uses an Ollama prompt to decide what to persist. Shares the SQLite DB with the backend.
Documents / RAG	synapse/memory/store.py	PDF/DOCX/TXT/MD ingest, chunked and embedded, retrieved via a sqlite-vec index; scoped per Project workspace.
Action tools	synapse/tools.py, synapse/search.py	Read-only tools (search memory/history/documents, list models, get time) run automatically; web_search, fetch_url, and remember require per-call approval from the chat UI.
Playbooks	synapse/playbooks/ + data/playbooks/	Ordered {id}.yaml records managed by PlaybookManager; each can pin a chat model and a tool list.
Ollama	ollama/bin/ollama	Bundled binary; OllamaManager handles lifecycle + model selection (Vulkan GPU detection). HTTP API at 127.0.0.1:11434.
Frontend	interface/web/	React 19 + Vite. Built to dist/ and served by the backend at :8000 (single-process). Pages: Chat, Playbooks, Models, Memory, Documents, Logs, Settings.

Storage

Most data lives in synapse/memory/memory.db (SQLite, WAL) — facts, conversations, messages, settings, and the document/vector index. Playbooks are the exception (YAML files in data/playbooks/). All paths are defined in synapse/nexus_config.py.

Layout

synapse/          FastAPI backend + memory service + playbook/ollama managers
interface/web/    React + Vite frontend
management/       nexus-cli.sh, ncp API client, control panel, desktop theme
bin/              install, backup/restore, panel + provisioning scripts
assets/           branding: icons, boot splash, XFCE/GTK theme
data/playbooks/   active playbook YAML
Promethean/       Python venv (gitignored, built by the installer)

Configuration

Concern	Location
Ollama host	OLLAMA_HOST env (default http://127.0.0.1:11434)
Filesystem paths	synapse/nexus_config.py
Frontend API base URL	interface/web/src/config.js
Python deps	requirements-base.txt + amd/nvidia GPU overlay; requirements-windows.txt = standalone CPU runtime

Issues and feature requests

Planned work and feature requests now live in NexusOS-requests instead of here. Click the link or hit the tab at the top of the repo.

Issues can be submitted in the Issues section as normal.

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_{NexusOS · local AI, self-hosted on GitNexus}