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Agent LighthouseAgent Lighthouse

    Searches the text of every published page. The evidence sources themselves are not in this index — search all of them on the trusted sources page.

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    operability-safety/no-blocking-captcha

    Forms don't use blocking CAPTCHA

    What it checks

    Blocking CAPTCHAs like reCAPTCHA and hCaptcha prevent AI agents from completing forms on behalf of users. When someone asks an AI assistant to “fill out the contact form on Example.com,” the CAPTCHA blocks the action entirely. Use honeypot fields or invisible server-side validation instead.

    Why it matters

    An interactive CAPTCHA can gate a form: a reCAPTCHA v2 checkbox or challenge, an hCaptcha visual challenge, or Cloudflare Turnstile in managed or interactive mode. It stops an autonomous browsing agent from submitting that form on its own. The agent must hand control back to a human.

    Evidence

    • OpenAI’s computer-use agent guide lists “Solving CAPTCHA challenges” among the actions that require explicit user confirmation immediately before execution, and treats bypassing a site’s safety barrier as requiring full human takeover — developers.openai.com/…/tools-computer-use (verified 2026-08-21)
    • hCaptcha states it “helps to protect your sites and apps from bots, spam, and other automated abuse” — its purpose is to deny non-human clients — docs.hcaptcha.com (verified 2026-08-21)
    • reCAPTCHA v2 gates the g-recaptcha-response token on the user submitting a successful response; without that interaction there is no token to post with the form — developers.google.com/…/display (verified 2026-08-21)
    • Anthropic’s browser use tool documents no CAPTCHA-handling path at all: it acts on the accessibility tree and screenshots and assumes it can reach the page — platform.claude.com/…/browser-use-tool (verified 2026-08-21)

    Limits

    The blocking property belongs to the interactive variants only. Every vendor documents a frictionless mode that agents pass without noticing. reCAPTCHA v3 “returns a score for each request without user friction”, and “will never interrupt your users” (developers.google.com/…/v3, verified 2026-08-21). Turnstile ships managed, non-interactive and invisible widget types, and is marketed as a “CAPTCHA-free” alternative (developers.cloudflare.com/turnstile, verified 2026-08-21). hCaptcha offers “nearly passive ‘No-CAPTCHA’ modes” (docs.hcaptcha.com, verified 2026-08-21). The mechanism is therefore proven for the interactive case and false for the invisible case — which is exactly the distinction this audit’s whole-body substring scan cannot make, and which its own remediation text recommends adopting.

    How it scores

    OpenAI’s computer-use guide names “Solving CAPTCHA challenges” as an action the agent must not perform unattended. The CAPTCHA vendors document that their interactive modes exist precisely to require a human response. The blocking path is documented consumer behavior, not inference.

    Sources