---

name: frontend-dev description: Manages local web server lifecycle and enables web page development with Playwright MCP. Use when developing HTML/CSS/JS, building web pages, viewing web pages, testing UI interactions, verifying renders, debugging frontend issues, or iterating on web design. Covers build, startup, shutdown, and browser-based testing workflows.

Frontend Development

Toolkit for frontend development in the SpeedReader codebase. Handles server lifecycle and delegates browser-based testing to Playwright MCP.

Setup

Run setup first:

Copyuv run .claude/skills/frontend-dev/scripts/setup.py

Outputs:

• READY - Proceed with usage
• RESTART_REQUIRED - Ask user to restart Claude Code, then stop and wait

Development Loop

All scripts must be run with uv run, not python3.

1. Edit code

Make changes to frontend code in src/Frontend/.

2. Reload

Copyuv run .claude/skills/frontend-dev/scripts/reload.py

This builds SpeedReader, starts the server, and waits for health. The server runs in the background with a 15-minute auto-shutdown.

reload.py is fast. Claude should never attempt to short-circuit it.

reload.py does a complete, fresh build of the frontend. It is not necessary to run any build steps manually.

SpeedReader does not hot reload. Run reload.py after every code change.

3. Interact with Playwright MCP

Use Playwright MCP tools to interact with the page at http://localhost:5050/demo.

For visual regression testing, use ?hideProcessingTime=true to hide dynamic content:

Copyhttp://localhost:5050/demo?hideProcessingTime=true

Snapshot vs Screenshot:

• Use browser_snapshot for interaction (getting element refs) and existence checks
• Use browser_take_screenshot for visual verification - things that look fine in a snapshot are often revealed to be broken when viewed as a screenshot

As a general rule, use snapshots for interaction and screenshots for verification and validation.

Important: when looking at screenshots, be careful. It's very easy to say "this is fine" when the screenshot is close to the expected result, but different in a visually similar but semantically different way. Example: a rectangle with pointed corners vs rounded corners, small adjustments to the position of an item, the levels of indentation in a list. For cases like this, identify the area of interest, look very carefully at it, and try to identify physically small yet semantically distinctive features.

4. Repeat

Edit code -> reload -> verify with Playwright -> repeat until done.

Actions

Actions are reusable JS scripts. Call them via browser_run_code:

Copybrowser_run_code: code="@demo_upload"
browser_run_code: code="@demo_upload?file=test.png"
browser_run_code: code="@toggle_layers?a_rect=true;r_rect=false;polygon=false;text=true"

Syntax: @action or @action?key=value;key2=value2

Available actions:

• demo_upload - Upload image and wait for OCR. Args: file
• toggle_layers - Set visualization layer visibility. Args: a_rect, r_rect, polygon, text (all optional, true/false)

Writing Actions

Actions are JavaScript files in scripts/actions/. Each is an async function receiving page and args:

Copyasync (page, args) => {
  const file = args.file || 'hello.png';
  await page.locator('#file-input').setInputFiles(file);
  await page.waitForSelector('.stats-bar', { timeout: 60000 });
}

Create or edit actions as needed.

Fixes

Screenshots timing out

If browser_take_screenshot hangs or times out repeatedly, close and reopen the browser:

Copybrowser_close
browser_navigate: url="http://localhost:5050/demo"

This resets the browser state and typically resolves the issue.