Cobrowser

An embedded, agent-controllable browser inside your editor — co-driven by you and your AI agent. A small companion app renders one isolated browser per workspace offscreen and streams it into a webview panel in VS Code / Cursor. You drive it (frames + input); your agent drives the same tabs over MCP (Claude Code, Cursor, or VS Code’s agent). Log into a site once — the session persists and the agent acts as you, sandboxed from your daily-driver browser.

Status: in daily use on macOS. What it deliberately does not do is under Limits.

Install

Search for Cobrowser in your editor’s Extensions view and install it; the editor keeps it up to date. VS Code installs it from the Visual Studio Marketplace; Cursor, VSCodium and other editors from Open VSX. Both list the macOS builds only.

Each release’s .vsix is also on GitHub, for installing by hand: cobrowser-darwin-arm64-.vsix on Apple silicon, cobrowser-darwin-x64-.vsix on Intel, with code --install-extension or the Extensions: Install from VSIX… command.

After installing, run Cobrowser: Open Browser from the Command Palette. After an update, restart extensions when the editor offers to (or reload the window); the browser app and the daemon replace themselves with the new version, and windows still on the old one keep working with them.

No browser setup required — the companion app (a pinned Electron, ~120 MB) downloads on first run (see Requirements).

Why

• Agent acts as you, but isolated. Each workspace gets its own browser profile inside the app, separate from your everyday Chrome or Firefox and outside the repo working tree. Manual logins persist there; the agent inherits them. (If you want the agent in your own browser instead, the bridge does that, one tab group or container at a time, when you turn it on.)
• No floating browser windows. Tabs render offscreen — there is no OS window at all — and appear as editor tabs next to your code.
• Consistent tool surface. MCP tool names mirror chrome-devtools-mcp (navigate_page, take_snapshot, click, fill, …).

Architecture

┌──────── cobrowser app (Electron, menu-bar icon; one per machine) ────────┐
│  workspace A ─ partition persist:A ─ tab ─ tab      (offscreen webContents)│
│  workspace B ─ partition persist:B ─ tab                                   │
│  paints → JPEG frames over a local WebSocket   ·   protocol relay          │
└───────────────┬──────────────────────────────────────────┬────────────────┘
                │ frames / resize / open / close            │ CDP over the same socket