[Bug]: enable_stealth=True is a silent no-op — StealthAdapter imports symbols that don't exist in playwright-stealth 2.x

[NaabZer]

crawl4ai version

0.8.6 (also reproducible on main @ 1debe5f)

Expected Behavior

BrowserConfig(enable_stealth=True) should apply playwright-stealth evasions to crawled pages — masking navigator.webdriver, populating navigator.plugins, etc. — as documented in docs/md_v2/advanced/advanced-features.md and docs/examples/stealth_mode_example.py.

Current Behavior

No stealth shim is ever applied, even with enable_stealth=True, and no exception is thrown. navigator.webdriver stays true, navigator.plugins.length stays 0, and the resulting fingerprint is indistinguishable from a vanilla headless Chromium.

Root cause: StealthAdapter._check_stealth_availability() in crawl4ai/browser_adapter.py:158-171 imports stealth_async / stealth_sync from playwright_stealth. These symbols existed in tf-playwright-stealth 1.x but not in playwright-stealth 2.x (the current declared dep, set by #1714). Both ImportErrors are swallowed → _stealth_function = None → apply_stealth(page) short-circuits silently. playwright-stealth 2.0.3 exposes Stealth (with apply_stealth_async(page_or_context)), but the adapter never reaches for it.

Likely regression history

• feat(StealthAdapter): fix stealth features for Playwright integration #1501 (merged 2025-09-18) introduced StealthAdapter using the lowercase function imports — worked because the dep was still tf-playwright-stealth>=1.1.0.
• fix: Replace tf-playwright-stealth with playwright-stealth dependency (#1553) #1714 (merged 2026-02-01) swapped the dep to playwright-stealth>=2.0.0 to fix [Bug]: Wrong dependency declared: tf-playwright-stealth only exports lowercase stealth, stealth_async, StealthConfig #1553, but did not update the import sites in browser_adapter.py. Stealth has been silently broken on main since.

Is this reproducible?

Yes

Inputs Causing the Bug

- URL(s): https://bot.sannysoft.com/ (or any fingerprinting test page)
- Settings: BrowserConfig(enable_stealth=True, headless=True)
- Versions: crawl4ai==0.8.6, playwright-stealth==2.0.3

Steps to Reproduce

1. pip install crawl4ai==0.8.6  # pulls playwright-stealth>=2.0.0
2. Confirm the missing symbols:
   python -c "from playwright_stealth import stealth_async"
   # ImportError: cannot import name 'stealth_async' from 'playwright_stealth'
3. Run the snippet below.
4. Inspect the result — navigator.webdriver is still "true",
   navigator.plugins.length is 0. No stealth was applied.

Code snippets

import asyncio
from crawl4ai import AsyncWebCrawler, BrowserConfig, CrawlerRunConfig

async def main():
    browser_config = BrowserConfig(enable_stealth=True, headless=True)
    async with AsyncWebCrawler(config=browser_config) as crawler:
        result = await crawler.arun(
            url="https://bot.sannysoft.com/",
            config=CrawlerRunConfig(screenshot=True),
        )
        print(result.html[:2000])

asyncio.run(main())

Supporting Information

OS: Linux (Ubuntu 24.04)
Python version: 3.12
Browser: Chromium (bundled by Playwright)
Browser version: N/A

Error logs & Screenshots (if applicable)

No exception is raised — the failure is silent. The only signal is the unmasked navigator.webdriver / plugin-count rows on bot.sannysoft.com.