Architecture Overview

High-Level Architecture

graph TD
    CLI[src/cli.ts<br/>Entry Point] --> CMD[src/commands/<br/>11 Commands]
    CMD --> PA[src/platform/<br/>Platform Adapters]
    CMD --> BC[src/bridge/<br/>Bridge Client]
    PA --> X11[X11 Adapter<br/>xdotool + import]
    PA --> WL[Wayland Adapter<br/>swaymsg + grim]
    PA --> MAC[macOS Adapter<br/>screencapture + osascript]
    BC --> TD[Token Discovery<br/>/tmp/*.token]
    BC --> BR[Tauri Bridge<br/>HTTP POST /eval]
    BR --> WV[Webview<br/>DOM + JS]
    CMD --> IMG[src/util/<br/>Image Pipeline]
    IMG --> IM[ImageMagick<br/>convert]

Module System

• ESM with "type": "module" in package.json
• NodeNext module resolution — all imports use .js extensions
• TypeScript compiles to dist/ with declarations

Entry Point

src/cli.ts creates the commander program and registers all 11 commands. It also manages:

• Platform adapter creation via getAdapter() — lazy initialization with tool checking
• Display server detection — delegates to detectDisplayServer() in src/platform/detect.ts

Command Pattern

Each command file exports a registerXxx(program, ...) function:

• Platform-dependent commands (screenshot, info, wait, list-windows) receive getAdapter as a parameter
• Bridge-dependent commands (dom, eval, ipc-monitor, console-monitor, storage, page-state) use resolveBridge() from shared.ts
• Both (screenshot with --selector, wait) use both adapter and bridge

src/commands/shared.ts provides two utilities:

• addBridgeOptions(cmd) — adds --port and --token options to a command
• resolveBridge(opts) — auto-discovers or uses explicit bridge config, returns BridgeClient

Platform Adapter Interface

All adapters implement the PlatformAdapter interface from src/types.ts:

interface PlatformAdapter {
  findWindow(title: string): Promise<string>;
  captureWindow(windowId: string, format: ImageFormat): Promise<Buffer>;
  getWindowGeometry(windowId: string): Promise<WindowInfo>;
  getWindowName(windowId: string): Promise<string>;
  listWindows(): Promise<WindowInfo[]>;
}

Adapters are in src/platform/:

Bridge Client

src/bridge/client.ts provides the BridgeClient class:

• eval(js, timeout?) — evaluate JS in the webview via HTTP POST
• getElementRect(selector) — get getBoundingClientRect() for an element
• getViewportSize() — get window.innerWidth/innerHeight
• getDocumentTitle() — get document.title
• getAccessibilityTree(selector, depth) — walk the accessibility tree
• ping() — check if the bridge is reachable

Token Discovery

src/bridge/tokenDiscovery.ts handles bridge auto-discovery:

1. Scan /tmp/ for files matching tauri-dev-bridge-*.token
2. Parse each as JSON: { port, token, pid }
3. Check PID liveness via process.kill(pid, 0)
4. Remove stale token files from dead processes
5. Return the first live bridge config

Also exports discoverBridgesByPid() for list-windows to map PIDs to bridge configs.

Image Pipeline

src/util/image.ts handles image processing:

• cropImage(buffer, rect, format) — crops via convert stdin/stdout
• resizeImage(buffer, maxWidth, format) — resizes via convert stdin/stdout
• computeCropRect(elementRect, viewport, windowGeometry) — computes the crop region accounting for window decorations

src/util/exec.ts provides the secure exec() wrapper:

• Uses execFile() with array arguments (never shell strings)
• validateWindowId() enforces /^\d+$/ pattern
• 100MB max buffer for large screenshots

Key Source Locations