puppy-tracker

A tiny offline-first PWA for tracking your puppy's sleep, meals, pees, and poos. The browser is the primary client; a small Go server provides a shared source-of-truth and sync between devices.

How sync works

Each event has a UUID and an updatedAt timestamp.
Mutations (add / edit / delete) happen against localStorage first, so the app keeps working when offline. Deletes are recorded as tombstones so they can propagate.
On app load, on online, on every mutation (debounced), and every 60 s, the client POSTs its full event list to /api/events/sync. The server merges it with its own copy using last-write-wins on updatedAt and returns the merged set.
Service worker bypasses cache for /api/* so writes always hit the server when online; static assets are still cached for offline use.

A status pill in the header shows syncing… / synced 2m ago / pending / sync error / offline. Tap it to force-sync.

Layout

puppy-tracker/
├── flake.nix         # packages (server, static, default), devShell, nixosModule
├── module.nix        # systemd unit, StateDirectory, hardening
├── server/
│   ├── go.mod
│   └── main.go       # JSON-file store, LWW sync, static file serving
└── src/              # the web app
    ├── index.html
    ├── app.js
    ├── style.css
    ├── sw.js
    ├── manifest.json
    └── icon.svg

Run locally

nix run                       # http://localhost:8080, data in $XDG_DATA_HOME/puppy-tracker
PUPPY_ADDR=:9000 nix run      # custom port

# Hot-iterate (data in /tmp):
nix develop -c sh -c 'cd server && go run . -static ../src -data /tmp/puppy-events.json'

Use it on NixOS

In your system flake:

{
  inputs.puppy-tracker.url = "path:/path/to/puppy-tracker";

  outputs = { self, nixpkgs, puppy-tracker, ... }: {
    nixosConfigurations.my-host = nixpkgs.lib.nixosSystem {
      system = "x86_64-linux";
      modules = [
        puppy-tracker.nixosModules.default
        {
          services.puppy-tracker = {
            enable = true;
            port = 8080;
            openFirewall = true;
          };
        }
      ];
    };
  };
}

The server runs as a DynamicUser systemd unit. Data is stored at /var/lib/puppy-tracker/events.json via StateDirectory.

Notes

No auth. Intended for a home LAN. If exposing publicly, terminate TLS and authenticate with a reverse proxy in front (Caddy / nginx / Tailscale Funnel).

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