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 - **Ubuntu / Debian**: `.deb` from GitHub Releases
 - **Fedora / RHEL**: `.rpm` from GitHub Releases
 
+**NixOS (flakes):**
+- Install guide (including Cachix setup): [`nixos-install.md`](./nixos-install.md)
+
 ### 🍎 macOS
 
 - **macOS**: `.dmg` (Universal or Apple Silicon)
diff --git a/nixos-install.md b/nixos-install.md
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+# Installing Psysonic on NixOS (flake)
+
+This guide is for **NixOS** users who want **Psysonic from the upstream Git flake** (`github:Psychotoxical/psysonic`). Supported systems match the flake: **`x86_64-linux`** and **`aarch64-linux`**.
+
+## Prerequisites
+
+**Flakes** enabled (e.g. in `configuration.nix`):
+
+```nix
+nix.settings.experimental-features = [ "nix-command" "flakes" ];
+```
+
+## Binary cache (Cachix)
+
+The project publishes store paths to a public Cachix cache so you can **substitute** binaries instead of compiling Psysonic locally on every machine.
+
+- **Cache page:** [psysonic.cachix.org](https://psysonic.cachix.org)
+- **Substituter URL:** `https://psysonic.cachix.org`
+- **Public key** (trust this only if it matches what you expect from the cache owners):
+
+  ```text
+  psysonic.cachix.org-1:M9cQyQ7tgvUWOQ5Pyt8ozlMoPLtOZir6MfRuTH9/VYA=
+  ```
+
+### NixOS (`configuration.nix` or a flake module)
+
+Add the substituter **and** its signing key under `nix.settings`. Keep `cache.nixos.org` in the list so ordinary `nixpkgs` binaries still resolve:
+
+```nix
+{
+  nix.settings = {
+    substituters = [
+      "https://psysonic.cachix.org"
+      "https://cache.nixos.org/"
+    ];
+    trusted-public-keys = [
+      "psysonic.cachix.org-1:M9cQyQ7tgvUWOQ5Pyt8ozlMoPLtOZir6MfRuTH9/VYA="
+      "cache.nixos.org-1:6NCHdSuAYQQOxGEKTGXLN9WWRXoSBT8GRiSnR6IdfGW="
+    ];
+  };
+}
+```
+
+After `nixos-rebuild switch`, builds that hit the cache will download from Cachix. More background: [Cachix — Getting started](https://docs.cachix.org/getting-started).
+
+## Install on NixOS (flake configuration)
+
+Add the repo as an **input**, then reference **`packages.<system>.psysonic`** (or **`default`**, which is the same package).
+
+### Example: top-level `flake.nix` + `nixosConfigurations`
+
+```nix
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    psysonic.url = "github:Psychotoxical/psysonic";
+  };
+
+  outputs = { self, nixpkgs, ... }@inputs: let
+    system = "x86_64-linux";
+  in {
+    nixosConfigurations.my-host = nixpkgs.lib.nixosSystem {
+      inherit system;
+      modules = [
+        ./configuration.nix
+        {
+          environment.systemPackages = [
+            inputs.psysonic.packages.${system}.psysonic
+          ];
+        }
+      ];
+    };
+  };
+}
+```
+
+Inside a **module** where you already have `pkgs` and flake `inputs` in scope, a common pattern is:
+
+```nix
+environment.systemPackages = with pkgs; [
+  # …
+  inputs.psysonic.packages.${pkgs.stdenv.hostPlatform.system}.psysonic
+];
+```
+
+### Pinning a revision or tag
+
+Follow **`main`** (above) to track the moving branch, or pin for reproducibility:
+
+```nix
+psysonic.url = "github:Psychotoxical/psysonic?ref=app-v1.34.13";  # example: release tag
+```
+
+Use a tag or commit SHA that exists on GitHub; the release workflow keeps **`flake.lock`** and **`nix/upstream-sources.json`** (`npmDepsHash`) in sync on tagged releases.
+
+### Apply configuration
+
+- **NixOS flake host**
+
+  ```bash
+  sudo nixos-rebuild switch --flake .#my-host
+  ```
+
+- **Home Manager** (if used separately)
+
+  ```bash
+  home-manager switch --flake .#my-user@my-host
+  ```
+
+## Home Manager
+
+If you manage packages with [Home Manager](https://github.com/nix-community/home-manager), add the same package to `home.packages`:
+
+```nix
+home.packages = [
+  inputs.psysonic.packages.${pkgs.stdenv.hostPlatform.system}.psysonic
+];
+```
+
+(Adjust how `inputs` / `pkgs` are passed into your Home Manager module.)
+
+## Desktop entry
+
+The flake package installs a **`.desktop`** file and icon via `copyDesktopItems`; after `nixos-rebuild switch` (or a Home Manager activation that includes the package), Psysonic should appear in your application launcher like any other desktop app.
+
+## Troubleshooting (Linux / WebKit)
+
+Some GPU / compositor setups show a black window or broken scrolling under Wayland/EGL. The upstream Help / FAQ documents workarounds (e.g. running under **X11** and compositor-related env vars). Those apply to the Nix-built binary as well as other Linux builds.
+
+## More detail in-repo
+
+- **`flake.nix`** — package outputs, `devShell`, supported systems (see comments there for `nix build` / `nix develop`).
+- **`nix/psysonic.nix`** — how the app is built from this source tree.
+- **`.github/workflows/release.yml`** — `verify-nix` job: refreshes lock/npm hash and pushes store paths to Cachix on release tags.