typemind - Chrome AI Text Completion Extension

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  typemind demo

Inspiration

TypeMind draws on the fluid in-editor suggestions of tools like Cursor and GitHub Copilot, aiming to deliver that same focus-preserving flow directly inside Chrome while keeping user data local.

What I Learned

I became proficient with Chrome AI’s Prompt API, including session lifecycle management and guardrail handling.

How I Built It

I collaborated closely with the Codex CLI to iterate on implementation plans, validate the architecture, and assemble the build. The extension is split into a Vite-powered background service worker, a React + Tailwind popup, and an IIFE content script that injects a Shadow DOM overlay into editable surfaces—all coordinated through a session-aware completion engine under src/core.

Challenges Faced

I optimized prompts to shorten the path from keystroke to suggestion, avoiding the slowdown caused by sending excessive context to the Prompt API. By reusing Prompt API sessions, I balanced freshness with responsiveness for sustained performance gains. Supporting both textareas and rich contenteditable fields required carefully tracking selection state so users’ text was never overwritten.

Built With

• gemini
• react
• typescript
• vite