Correlating What a Browser Agent Saw, What It Actually Clicked, the Requests That Followed and the External Effect That Occurred

Browser and computer-use agents act on screenshots, DOM snapshots and accessibility trees. Between the moment an agent sees a “Save” button and the moment an external system changes, many things can differ: an overlay or layout shift can send the click to another element; the element may sit in a third-party iframe with a different origin; a redirect can change the destination or method; a service worker or timer can emit requests no one clicked; a delayed submission can carry a changed form value;an HTTP 200 or a success banner may not mean the remote transaction committed; and a retry after an uncertain result can duplicate a payment. This disclosure describes a vendor-neutral, non-actuating method for correlating an original authorized task with the browser evidence and the external effect it actually produced. Each task carries a stable identity, principal, allowed effect and approval generation. Observations are qualified by DOM generation, viewport and focus; the intended control is requalified by a fresh hit-test against the actual event recipient. Frame identity, origin, navigation and redirect chains are reconstructed so that page membership never confers authority. All effect-producing operations — including worker-, timer- and API-originated ones — are tied to the original lineage, and the actual method, destination, payload and idempotency key are compared with what was approved under current authority and path coverage. External completion is established only from authoritative evidence, and retries are permitted only when prior effect status is proven. Twelve expected-versus-actual comparisons and further mandatory predicates are combined in three-valued logic: a contradiction yields INCONSISTENT and is never cancelled by missing evidence, full support yields CONSISTENT, and gaps yield UNRESOLVED.The document provides a 48-stage, six-phase engineering workflow with flowcharts, 48 technical invariants, six detailed embodiments, 43 formal relations with conditional proofs, 40 engineering checkpoints, a comparison with existing approaches (WebDriver/CDP automation, Playwright actionability checks, DOM and accessibility APIs, browser same-origin and sandbox policies, CSP and Fetch Metadata, HTTP idempotency keys, saga and outbox patterns, and agent guardrails) and a non-actuating reference evaluator in Python, JavaScript and Go with 74 shared synthetic vectors, all passing. It is not a browser engine or an interception product; the laboratory is synthetic, self-authored and not peer reviewed. The author is open to acquihire or strategic collaboration. Keywords: AI safety; browser agents; computer-use agents; browser automation; DOM; accessibility tree; hit testing; TOCTOU; iframes; same-origin policy; redirects; service workers; form submission; idempotency; retry safety; external effect verification; prompt injection; three-valued logic; WebDriver BiDi; Chrome DevTools Protocol