From "I Can't Click" to a Full Testing Harness: How We Built Playwright for the Terminal

I'm building TTT -- a terminal text editor and IDE written in Go. Single binary, zero config, runs anywhere. Think VS Code but in your terminal. It has syntax highlighting, LSP integration, a plugin system, an integrated terminal, git integration, etc... The source is on GitHub and I develop it with Claude Code as my pair programmer. This is the story of how a frustrating limitation turned into something genuinely useful: a built-in scripted interaction system that lets AI agents (or anyone) drive the editor like Playwright drives a browser. The problem I was deep in revamping the widget system and building out a Lua plugin API. Phases of work stacking up -- widget rendering, panel support, tree views, input fields, command registration, keybinding hooks. The kind of work where you need to see what's happening. Click a tree node, check if it expands. Open a panel, verify focus moves correctly. Run a plugin, confirm the dialog appears. Here's the thing: Claude Code can run shell commands and read files. It cannot interact with a live TUI session. The editor launches, takes over the terminal, and that's it -- Claude is blind. Step 1: tui-use (what we had) The project already had functional tests using tui-use , a JavaScript library that drives a real terminal binary. It can type, press keys, wait for text to appear, and take snapshots: const tui = await start ( " bin/ttt " , [ " test-file.go " ]); await tui . waitFor ( " test-file.go " ); await tui . exec ( " editor.joinLines " ); const screen = await tui . snapshot (); expect ( screen ). toContain ( " joined line " ); This works. But it's slow -- each test spawns the binary, waits for screen renders, polls with timeouts, and parses terminal escape codes. And critically, it can't click . Mouse events aren't supported. For a widget system with tree views, buttons, and split panels, that's a dealbreaker. Step 2: Debug commands (the workaround) So we added a Debug: Simulate Click command to the editor itself. Open the co