I built my husband a vim trainer with a Gemma coach that runs in the browser

Description and use

The hjkl app teaches Vim through short drills, leveraging real Vim behavior and a local Gemma AI coach, enabling sustained learning without external motivation.

Problem

My husband struggled to learn vim because of too many commands to memorize and slow, awkward experience.

Outcome

The app enabled sustained engagement with vim drills, providing real-time feedback and AI-generated content, leading to continued learning without external motivation.

Workflow

• 1. Create lessons with a small set of commands and a cheat sheet.
• 2. Design drills with a goal, a reference solution, and a par length.
• 3. Run tests against real vim to validate solutions and par.
• 4. Implement AI coach using Gemma 4 E2B on WebGPU via Transformers.js.
• 5. Provide feedback after over-par solves and hints.
• 6. Generate new drills with Gemma and validate them.
• 7. Deploy as a static site on Cloudflare Workers.

Evidence

My husband has wanted to learn vim for a long time. He's tried a bunch of times, and it always ends the same way: he gives up.

Source

Each drill gives you a small buffer, a goal, and a keystroke "par" to beat. You solve it in a real vim editor, not a simulation.

Source

The AI coach is optional and off by default. When you turn it on, it downloads Gemma 4 E2B once and runs it in a Web Worker on WebGPU with Transformers.js.

Source

The app supplies the keys by reusing the key patterns from that lesson's hand‑written drills on the new text. Then it plays them in real vim to get the goal and par.

Source