browser

Argument: $ARGUMENTS

Command	Behavior
{url}	Navigate to URL, capture screenshot and ARIA snapshot
explore	Interactive exploration - navigate, inspect, understand UI
verify {description}	Verify specific UI behavior or state
extract {description}	Extract specific data from the frontend

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Choosing Your Approach

• Local/source-available sites: Read source code first to write selectors directly
• Unknown layouts: Use getAISnapshot() for element discovery and selectSnapshotRef() for interactions
• Visual feedback: Take screenshots to observe results

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Setup

Start the browser server before running scripts:

node skills/otto/lib/browser/server.js &

Wait for "Ready" message, then connect:

import { connect, waitForPageLoad } from 'skills/otto/lib/browser/client.js'

const client = await connect({ headless: true })

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Writing Scripts

Run scripts using npx tsx with heredocs for inline execution.

Key Principles:

1. Small scripts doing one action each
2. Evaluate state at completion
3. Use descriptive page names
4. Call await client.disconnect() to exit (pages persist)
5. Use plain JavaScript in page.evaluate() (no TypeScript syntax)

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Workflow Loop

1. Write script performing one action
2. Run and observe output
3. Evaluate results and current state
4. Decide: complete or need another script?
5. Repeat until task complete

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Navigate & Capture

Determine the dev server URL from package.json scripts, running processes, or project config.

const page = await client.page('main')
await page.goto(url)  // e.g., http://localhost:5173
await waitForPageLoad(page)

// Screenshot
await page.screenshot({ path: '.otto/screenshots/page.png' })

// ARIA snapshot
const snapshot = await client.getAISnapshot('main')
console.log(snapshot)

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Interact

// Click by ref
const btn = await client.selectSnapshotRef('main', 'e3')
await btn.click()

// Fill input by ref
const input = await client.selectSnapshotRef('main', 'e5')
await input.fill('user@example.com')

// Re-capture after interaction
await waitForPageLoad(page)
const newSnapshot = await client.getAISnapshot('main')

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Waiting

await waitForPageLoad(page)
await page.waitForSelector('.results')
await page.waitForURL('**/success')

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No TypeScript in Browser Context

Code in page.evaluate() runs in browser context without TypeScript support. Use plain JavaScript only—type annotations break at runtime.

// ✓ Correct
await page.evaluate(() => {
  const items = document.querySelectorAll('.item')
  return items.length
})

// ✗ Wrong - TypeScript syntax fails
await page.evaluate(() => {
  const items: NodeListOf<Element> = document.querySelectorAll('.item')
  return items.length
})

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Cleanup

await client.disconnect()

After completing the workflow, remove screenshots:

rm -rf .otto/screenshots

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ARIA Snapshot Format

- banner:
  - link "Home" [ref=e1]
- main:
  - heading "Welcome" [ref=e2]
  - form:
    - textbox "Email" [ref=e3]
    - button "Submit" [disabled] [ref=e4]

Use [ref=eN] values with selectSnapshotRef() to interact.

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Error Recovery

Page state persists after failures. Debug using screenshots and state inspection to evaluate current conditions before next action.

// After an error, reconnect and inspect
const client = await connect({ headless: true })
const snapshot = await client.getAISnapshot('main')
await client.page('main').then(p => p.screenshot({ path: '.otto/screenshots/debug.png' }))

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Scraping Data

For large datasets, intercept and replay network requests rather than scrolling the DOM. See references/scraping.md for the complete guide covering request capture, schema discovery, and paginated API replay.