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

Description and use

The author built a browser-based Vim trainer with a local Gemma AI coach, enabling real Vim practice, instant feedback, and AI-generated drills, all running offline without external APIs.

Problem

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

Outcome

The app enabled sustained engagement with Vim drills, provided real-time feedback via a local AI coach, and demonstrated that open-weight models can run entirely in the browser for personalized learning.

Workflow

• 1. Design lessons with limited commands and cheat sheet.
• 2. Implement real Vim editor using CodeMirror 6 and @replit/codemirror-vim.
• 3. Create drills with reference solutions and par checks via test suite.
• 4. Add AI coach using Gemma 4 E2B on WebGPU with Transformers.js.
• 5. Implement feedback and hint mechanisms.
• 6. Generate additional drills with Gemma and validate them.
• 7. Deploy static site on Cloudflare Workers.
• 8. Provide live demo and documentation.

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

On my machine, Gemma 4 E2B writes about 6 to 7 tokens a second, so a one-sentence explanation takes a few seconds.

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