Agent Browser

Browser Automation with agent-browser

When a dev server is running or the user asks to verify, test, or interact with a web page, use agent-browser to automate the browser.

Core Workflow

Every browser automation follows this pattern:

1. Navigate: agent-browser open <url>
2. Snapshot: agent-browser snapshot -i (get element refs like @e1, @e2)
3. Interact: Use refs to click, fill, select
4. Re-snapshot: After navigation or DOM changes, get fresh refs

agent-browser open http://localhost:3000
agent-browser wait --load networkidle
agent-browser snapshot -i

Dev Server Verification

When a dev server starts, use agent-browser to verify it's working:

# After starting a dev server (next dev, vite, etc.)
agent-browser open http://localhost:3000
agent-browser wait --load networkidle
agent-browser screenshot dev-check.png
agent-browser snapshot -i

Command Chaining

Commands can be chained with &&. The browser persists between commands via a background daemon.

agent-browser open http://localhost:3000 && agent-browser wait --load networkidle && agent-browser snapshot -i

Essential Commands

# Navigation
agent-browser open <url>              # Navigate (aliases: goto, navigate)
agent-browser close                   # Close browser

# Snapshot
agent-browser snapshot -i             # Interactive elements with refs
agent-browser snapshot -i -C          # Include cursor-interactive elements
agent-browser snapshot -s "#selector" # Scope to CSS selector

# Interaction (use @refs from snapshot)
agent-browser click @e1               # Click element
agent-browser fill @e2 "text"         # Clear and type text
agent-browser type @e2 "text"         # Type without clearing
agent-browser select @e1 "option"     # Select dropdown option
agent-browser check @e1               # Check checkbox
agent-browser press Enter             # Press key
agent-browser scroll down 500         # Scroll page

# Get information
agent-browser get text @e1            # Get element text
agent-browser get url                 # Get current URL
agent-browser get title               # Get page title

# Wait
agent-browser wait @e1                # Wait for element
agent-browser wait --load networkidle # Wait for network idle
agent-browser wait --url "**/page"    # Wait for URL pattern
agent-browser wait 2000               # Wait milliseconds

# Capture
agent-browser screenshot              # Screenshot to temp dir
agent-browser screenshot --full       # Full page screenshot
agent-browser screenshot --annotate   # Annotated screenshot with numbered labels
agent-browser pdf output.pdf          # Save as PDF

# Diff (compare page states)
agent-browser diff snapshot           # Compare current vs last snapshot
agent-browser diff screenshot --baseline before.png  # Visual pixel diff

Common Patterns

Form Submission

agent-browser open http://localhost:3000/signup
agent-browser snapshot -i
agent-browser fill @e1 "Jane Doe"
agent-browser fill @e2 "jane@example.com"
agent-browser click @e5
agent-browser wait --load networkidle

Authentication with State Persistence

# Login once and save state
agent-browser open http://localhost:3000/login
agent-browser snapshot -i
agent-browser fill @e1 "$USERNAME"
agent-browser fill @e2 "$PASSWORD"
agent-browser click @e3
agent-browser wait --url "**/dashboard"
agent-browser state save auth.json

# Reuse in future sessions
agent-browser state load auth.json
agent-browser open http://localhost:3000/dashboard

Data Extraction

agent-browser open http://localhost:3000/products
agent-browser snapshot -i
agent-browser get text @e5
agent-browser get text body > page.txt

Visual Debugging

agent-browser --headed open http://localhost:3000
agent-browser highlight @e1
agent-browser record start demo.webm

Ref Lifecycle (Important)

Refs (@e1, @e2, etc.) are invalidated when the page changes. Always re-snapshot after:

• Clicking links or buttons that navigate
• Form submissions
• Dynamic content loading (dropdowns, modals)

agent-browser click @e5              # Navigates to new page
agent-browser snapshot -i            # MUST re-snapshot
agent-browser click @e1              # Use new refs

Annotated Screenshots (Vision Mode)

Use --annotate for screenshots with numbered labels on interactive elements:

agent-browser screenshot --annotate
# Output: [1] @e1 button "Submit", [2] @e2 link "Home", ...
agent-browser click @e2

Semantic Locators (Alternative to Refs)

agent-browser find text "Sign In" click
agent-browser find label "Email" fill "user@test.com"
agent-browser find role button click --name "Submit"

JavaScript Evaluation

# Simple expressions
agent-browser eval 'document.title'

# Complex JS: use --stdin with heredoc
agent-browser eval --stdin <<'EVALEOF'
JSON.stringify(
  Array.from(document.querySelectorAll("img"))
    .filter(i => !i.alt)
    .map(i => ({ src: i.src.split("/").pop(), width: i.width }))
)
EVALEOF

Session Management

agent-browser --session site1 open http://localhost:3000
agent-browser --session site2 open http://localhost:3001
agent-browser session list
agent-browser close  # Always close when done

Timeouts and Slow Pages

agent-browser wait --load networkidle  # Best for slow pages
agent-browser wait "#content"          # Wait for specific element
agent-browser wait --url "**/dashboard"  # Wait for URL pattern
agent-browser wait 5000                # Fixed wait (last resort)