# Patzer v7.19: the tactic trainer that shows your move and explains why the better one wins

> Source: <https://dev.to/sikamikanikobg/patzer-v719-the-tactic-trainer-that-shows-your-move-and-explains-why-the-better-one-wins-50jn>
> Published: 2026-10-19 08:06:43+00:00

Last week I wrote about Patzer — a self-hosted Chess.com alternative that runs in one Docker container ([the original post](https://dev.to/sikamikanikobg/i-built-my-family-a-private-chesscom-one-docker-container-stockfish-plus-your-own-llm-184n)). Since then, the feature I've been most proud of shipped: a tactic trainer that explains your own mistakes.

The classic puzzle trainer — Lichess puzzles, Chess.com tactics — gives you a position and asks for the best move. Miss it, and you see the solution. But you never see *why* yours was wrong: why the engine's move wins and your move loses. You memorize that Qh5 is the move, not that Qd3 leaves your queen hanging to a fork.

v7.19.0 closes that gap.

**Your move, on the board.** In Train → From your games, Patzer builds puzzles from your actual Chess.com or Lichess games. The move you played in that game is now drawn as a red arrow on the puzzle position, so you no longer have to work out from "you played Qd3" which move that was.

**The coach explains the difference.** Once the puzzle is over — solved, or the solution shown, never before — your AI coach explains in plain words why the engine's move beats the one you played. It's the same engine-checked explanation as in Game Review, in your language, pitched at your audience setting.

The design decision from the original post is what makes this cheap to run: the LLM never analyses. The server works out the facts — what each move allows, hangs or wins, the opponent's best answer — and the model only turns that into coaching. A small local model (Ollama or vLLM) is enough, and a hallucinated piece is impossible.

**Puzzles come back.** A puzzle you don't solve at the first try comes back the next day, marked *Review* — the same simple daily queue as the opening trainer. Solved at the first try on a later day, it's done; missed again, it's back tomorrow.

**Puzzle of the day, with a streak.** One puzzle from the Lichess set near your puzzle rating, the same one all day, with a plain counter of the days in a row you did it.

**Play from here.** In Game Review, every move now has a "Play from here against Patzer" button. You play your own colour, pick the bot's strength and the clock, and the game is saved like any bot game — your own games become training positions.

Full list in the release notes, including a fix for the saved AI model dropdown when the model isn't on the server:

Still one container:

```
docker run -d -p 8800:8800 -v patzer-data:/app/data --name patzer ghcr.io/SikamikanikoBG/patzer:latest
```

MIT licensed, English-first with Bulgarian, Spanish, German and Russian out of the box. If you're running Patzer, pull the latest tag and try the trainer on your own games — that's the part I'd want you to try first.