Claude + Playwright agent tackles CAPTCHA-heavy signups with adaptive reasoning

Henry Knight argues that most browser automation tutorials ignore the real challenge: modern bot-protection systems like PerimeterX, DataDome, and Cloudflare fingerprint browsers before a CAPTCHA ever appears. The fingerprinting happens at the JavaScript, TLS, and mouse-movement layers — meaning a solved CAPTCHA still results in a block if the automation signature was already flagged. His core architectural insight is to treat Claude as the reasoning layer rather than the execution layer: instead of hardcoded conditional logic, the agent captures a structured DOM snapshot (URL, title, body text, and a list of visible inputs) and passes it to `claude-sonnet-4-6`, which responds with a JSON action object containing the action, selector, value, and reasoning. This loop keeps Claude's role lightweight and fast, avoiding the cost of screenshot-based vision.

The source text is truncated before the full architecture is described.

For fingerprint evasion, the post shows a stealth init script injected via Playwright's `addInitScript` that removes the `navigator.webdriver` flag, restores `window.chrome` runtime properties, fakes a realistic browser plugin list, and locks `navigator.languages` to `['en-US', 'en']`. For CAPTCHA handling, a `handle_captcha` function maps challenge types — `recaptcha_v2`, `recaptcha_v3`, `hcaptcha`, `perimeterx`, `cloudflare` — to ordered lists of strategies (e.g., `solve_2captcha`, `rotate_fingerprint`, `wait_5min_retry`, `request_manual`). Each strategy attempt is logged to a SQLite `browser_memory` table, and on subsequent runs against the same domain the agent reads this history to skip strategies that previously failed, giving the system cross-session learning. The source text is truncated before the full architecture is described.

Key facts

1. 01Author Henry Knight spent two months building the AI-powered browser agent described in the post.
2. 02Modern bot-protection systems (PerimeterX, DataDome, Cloudflare) fingerprint browsers via canvas fingerprinting, TLS mismatch, CDP detection, mouse movement analysis, and request timing — before any CAPTCHA is shown.
3. 03Claude (`claude-sonnet-4-6`) acts as the reasoning layer, receiving a structured DOM snapshot and returning a JSON action object with action, selector, value, and reasoning fields.
4. 04A stealth init script patches `navigator.webdriver`, `window.chrome`, `navigator.plugins`, and `navigator.languages` to reduce browser fingerprint detection.
5. 05A `handle_captcha` function maps five challenge types (`recaptcha_v2`, `recaptcha_v3`, `hcaptcha`, `perimeterx`, `cloudflare`) to prioritized lists of solver strategies.
6. 06Strategy outcomes are logged to a SQLite `browser_memory` table, allowing the agent to skip known-failing strategies on future runs against the same domain.

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