Stealth Browser Skill

Tool-agnostic anti-detection behavioral rules for browser automation. Applies regardless of browser engine (Camoufox, Playwright, future tools).

Load this skill when: The browser_navigate tool is used with the default Camoufox (anti-detection) mode. The tool's docstring directs you here.

Core Principle

Bot detection systems look for behavioral signals, not just fingerprints. A perfect fingerprint with robotic behavior is still detectable. The browser engine handles fingerprinting. This skill handles behavior.

Always-Headed Mode

Camoufox always launches headed on VNC display :99. This means:

• Human can always observe the browser via noVNC
• CAPTCHA/Turnstile escalation doesn't require browser restart
• browser_collaborate(True) speeds up timing (human watching)
• browser_collaborate(False) restores stealth timing (nobody watching)

Layer 1: Current Infrastructure (use now)

These rules work with the existing browser tools. The tools already implement human-like delays automatically — this section covers what YOU (the LLM session) must do on top.

Profile Pre-Warming

Before navigating to a target form (especially ATS job applications), browse the company's public careers page first. This builds browsing history and cookie trail in the persistent profile. A cold browser going straight to an application form is a bot signal.

Page Load Warm-Up

After browser_navigate, wait before interacting. Read the page snapshot, plan your actions. Do NOT immediately call browser_fill or browser_click. A human would look at the page first. 1-3 seconds minimum.

Honeypot Detection

Before filling ANY form field, check the accessibility snapshot for hidden fields. Do NOT fill fields that appear to be:

• display: none or visibility: hidden in the snapshot
• Zero-dimension elements
• Fields with names like url, website, fax that aren't expected for the form type (common honeypot names)
• Fields positioned off-screen

Filling a honeypot = instant bot detection. When in doubt, skip the field.

Form Filling Order

Fill fields in visual top-to-bottom order, matching how a human would tab through the form. Do NOT fill them in an arbitrary order.

Pre-Submit Validation

Before clicking submit:

1. Take a browser_screenshot()
2. Review the screenshot to verify all fields are filled correctly
3. Only then click submit
4. Take another screenshot after submit to capture confirmation

Error Recovery

If a form fill or click fails:

• Do NOT immediately retry — wait 2-5 seconds
• Take a screenshot to understand the current state
• Try an alternative selector
• If the page has changed (redirect, modal), re-read the snapshot

Per-Site Escalation

Before engaging high-detection sites, check references/per-site/ for site-specific rules. High-detection sites include:

• ATS systems: Ashby, Greenhouse, Lever
• Social platforms: Reddit, X/Twitter, LinkedIn
• Search engines: Google
• Tech communities: Hacker News, Stack Overflow

If no per-site reference exists, conduct a research pass first to understand the site's detection patterns before automating.

Layer 2: Active Infrastructure

These features are now implemented in the browser tools.

Per-Keystroke Typing (active)

browser_fill now types character-by-character with randomized inter-key intervals (50-200ms) when Camoufox is active. This fires the full keydown→keypress/input→keyup event chain per character. Atomic fill() only fires a single input event — trivially detectable.

Note for phone fields with input masks: The per-keystroke typing interacts with auto-formatting. If a phone field adds characters mid-type (e.g., "(123) 456-..."), let the field format naturally — the typing engine handles this. If the result looks wrong, retry with browser_fill after clearing the field manually.

Stealth Click (active)

browser_click now uses hover→mousemove trail→position jitter→realistic mousedown/mouseup gap when Camoufox is active. Clicks land within the central 60% of elements, not dead center. The Camoufox humanize=2.5 setting provides native Bézier cursor movement at the browser level.

Turnstile/CAPTCHA Auto-Resolution (active)

After browser_navigate, Turnstile is automatically detected and resolved. The resolution cascade runs without any manual intervention:

1. Auto-resolve (15s) — trusted browsers with cf_clearance clear instantly
2. Widget click — finds challenge container via DOM selectors and clicks with Camoufox's native Juggler input. This is the primary solver.
3. playwright-captcha — Shadow DOM traversal fallback
4. VNC click — real X11 input events via vncdotool (last resort)

You do NOT need to:

• Manually find or click Turnstile elements
• Use VNC/vncdotool yourself
• Write any challenge-bypass code
• Escalate to the user

Simply call browser_navigate(url) and check the response. If turnstile.status == "resolved", the page is ready. If "blocked", a Telegram alert was already sent.

Layer 3: VNC Trusted Input Bridge (automatic fallback)

VNC click is the LAST fallback in the automated cascade (Phase 2 in _wait_for_turnstile). You should almost never need to invoke it manually — browser_navigate handles it automatically after the widget click and playwright-captcha both fail.

This section documents the mechanism for debugging only. The VNC protocol injects real input events, bypassing detection of synthetic events (XTest, CDP, Playwright mouse).

Why It Works

x11vnc injects input through the VNC protocol, adding network-realistic timing and event sequencing patterns. While the underlying X11 mechanism is similar to xdotool, the VNC protocol layer produces timing closer to real human input (variable latency, natural event gaps). Playwright uses CDP protocol which Cloudflare directly fingerprints. The practical result: VNC-injected clicks pass Turnstile where xdotool and Playwright fail.

When to Use

• Turnstile checkbox doesn't auto-resolve after 15 seconds
• reCAPTCHA v2 checkbox needs a human-like click
• Any anti-bot system that rejects automated clicks

Prerequisites

• genesis-vnc.service running (x11vnc on port 5900, systemd auto-start)
• vncdotool installed (pip install vncdotool)
• If the VNC service uses password auth, start a temporary no-auth instance for programmatic use: x11vnc -display :99 -forever -nopw -quiet -bg -rfbport 5999

Steps

1. Find the element — use browser_run_js to get the target element's bounding rect:

   document.querySelector('[style*="display: grid"]').getBoundingClientRect()
   

2. Get window geometry — the browser window position on the Xvfb display:

   DISPLAY=:99 xdotool getwindowgeometry $(DISPLAY=:99 xdotool search --name "Camoufox")
   

3. Calculate screen coordinates:

   • screen_x = window_x + page_element_x
   • screen_y = window_y + browser_chrome_height + page_element_y
   • Chrome height is ~34px for Camoufox (viewport = window - 34)

4. Send human-like mouse movement — move through 1-2 intermediate points with 200-300ms pauses, then click:

   vncdo -s localhost::5999 move {start_x} {start_y}
   # pause 300ms
   vncdo -s localhost::5999 move {mid_x} {mid_y}
   # pause 200ms
   vncdo -s localhost::5999 move {target_x} {target_y} click 1
   

5. Wait and verify — allow 5-8 seconds for server-side verification, then check if the page title changed from "Just a moment..." to the actual page title.

Notes

• The cf_clearance cookie persists for days/weeks after clearing Turnstile. Subsequent page loads won't trigger the challenge.
• If verification fails (checkbox reappears), wait 10 seconds and retry once. Cloudflare rate-limits rapid attempts.
• This technique works for ANY browser on Xvfb, not just Camoufox.

Timing Profiles

The browser tools implement automatic delays. These are the profiles:

The delay fires automatically before browser_fill, browser_click, and browser_upload. You do NOT need to add manual sleeps.

Anti-Detection Services

See references/services.md for external services that supplement the browser's built-in anti-detection:

• 2Captcha: Programmatic CAPTCHA solving ($0.00145/solve)
• Browserbase: Cloud browser with real hardware ($0.002/session)
• Residential proxies: IP reputation improvement

Advanced Behavioral Rules

These rules address detection surfaces beyond basic timing and clicks. Apply them in all Camoufox sessions unless site-specific guidance overrides.

Idle Mouse Micro-Jitter

Real hands produce ±1-3px tremor while "still." Between actions (any dwell period >2s), the cursor must not be dead-still.

• Emit 1-3 mousemove events every 1-2s during all dwell periods
• Displacement: ±1-3px from current position (random, not oscillating)
• Do NOT jitter during active movement (only during stillness)
• Implemented in _idle_jitter() in browser.py

Keystroke Hold Time (keydown-to-keyup gap)

Real keys are held briefly before release. Each keypress fires keyboard.down(char) → hold → keyboard.up(char).

• Hold time per key: sample from log-normal distribution
• Calibration: median ~86ms (p5=48ms, p95=149ms) per CMU Keystroke dataset
• Vary per keystroke -- NOT uniform across all keys
• Flight time (key-up to next key-down): existing 50-200ms IKI still applies
• Implemented in _human_type() in browser.py

Navigation Graph Depth

Arriving directly at a form/auth page with no prior navigation is a strong bot signal regardless of per-page behavior.

• For ANY target that is a form, login, checkout, or data-heavy endpoint: navigate through at least 2 prior pages on the same domain
• Dwell 2-5s on each prior page before proceeding
• This generalizes the existing "visit careers page" rule to all targets
• Referrer chain must be organic (not cold-start direct navigation)

Tab Visibility Switch

Sessions maintaining continuous focus for >15s are atypical for humans.

• For pages with >15s dwell before form interaction: simulate one visibilitychange event (tab hidden + visible) before submission
• Use browser_run_js to dispatch: document.dispatchEvent(new Event('visibilitychange'))
• Or use actual tab switching if available

Scroll Patterns

Real scrolling decelerates, occasionally goes backwards, and pauses at content boundaries.

• Include at least one upward scroll segment per page (probability 0.2)
• Decelerate scroll to zero over 200-400ms at end of each gesture
• Add "scroll past then back" pattern when targeting form fields (p=0.3)
• Scroll delta variance: 20-100px per event (never constant)
• Implemented in _human_scroll() in browser.py

Pre-Form Element Interaction

Direct-to-form behavior (first interaction is a form field) scores -0.1 to -0.3 on reCAPTCHA v3.

• Before filling the first form field: move cursor to 1-2 non-form elements (nav link, header, image), dwell 0.3-1.5s each
• Then move to the first form field
• This produces an interaction graph that doesn't start at the form target

Typo and Self-Correction (long text fields only)

Real typists make errors at ~2% rate and correct them.

• For text fields >20 characters: introduce one typo per ~50 chars
• Type 1-2 wrong characters, pause 200-500ms, backspace, type correct
• Do NOT apply to short fields (names, emails, passwords)
• This is LLM-guided behavior, not auto-enforced in code

What This Skill Does NOT Cover

• Browser fingerprinting (handled by Camoufox at C++ level)
• Proxy/IP management (see references/services.md)
• Account management (login sessions, credential storage)