hearth for Windows

There is no download yet

Hearth has never been released. There is no installer to download and no signed binary anywhere: release/trust.json points at releases.hearth.invalid, a reserved name that cannot resolve, because an updater aimed at a real host nobody controls is worse than one aimed at a host that cannot exist.

Building it yourself takes about twenty minutes, most of it waiting. The install page walks through it from an empty folder.

Start here

Install and first run Build tools, clone, build, run, pick a model, and a first task worth trying. In order, with no steps assumed.

The full guide What Hearth is, the four permission modes, the workspace boundary, .hearthignore, undo, and what survives a restart.

Limitations The honest page. What a local model on your hardware will and will not do well, and where the boundaries are thinner than they look.

What it is

It brings its own engine

The installer carries a pinned CPython and llama.cpp’s llama-server. Nothing to install first, and no Ollama required. It borrows the WebView2 runtime Windows already ships rather than bundling a second browser.

It asks before it acts

Four permission modes. The default reads freely and stops before every file write and every shell command. Underneath, each run carries a fixed list of tools it may touch at all, enforced even in bypass mode.

It knows what fits

The model shop measures your RAM and VRAM and computes whether a given quantisation actually fits, KV cache included, rather than recommending something that will swap to disk and feel broken.

It stays inside the folder

Every file tool passes a containment check: path traversal, absolute paths, reserved device names, alternate data streams and NTFS junctions are all rejected, so a confused agent cannot reach outside the directory you named.

How it is built

Packaging and the installer One command builds it. Why the shell moved from Electron to Tauri, and the measurement that decided it: 364 MB of Chromium next to a 70 MB payload.

Threat model What the boundaries are on Windows, what they are not, and which protections are weaker here than on the NixOS system.

Signed updates An Ed25519 key built into the application, which protects users on an unsigned build and keeps protecting them after a certificate is bought.

Privacy Every destination Hearth contacts, and why each one is on the list.

Two projects, one name

This is Hearth for Windows: a desktop application, Apache-2.0, in its own repository.

There is also hearth, a security-first NixOS system for running local LLMs and sandboxed agents. Same name, same author, different thing. That one is orange and this one is blue, which is the fastest way to tell which set of docs you are reading.

Built by Eric Catalano. See About for the project, its licence, and how to report a problem.