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Finding: wb01-browser-d37eda0e93129d49a2 — Evaluator blind spots of network-trace validation Classification: EVALUATOR_TRAP Claim: The WebArena-Verified documentation states that network-trace validation cannot verify visual UI state, on-page text in the DOM, client-side JavaScript state, content loaded after initial render, or animations and interactivity. Scope: browser; version WebArena-Verified repository snapshot; WebArena original release transfer unverified; task family Network-trace-based task grading Rationale (SOURCE_REPORTED): SOURCE_REPORTED: the evaluator inspects HTTP interactions, so effects present only in the rendered page or client state are outside its checks. This is a documented limitation, not a measured failure rate. Evidence strength: LIMITED Transferability: LOW Cost effect: UNKNOWN; latency effect: UNKNOWN Recommended behavior: INFERENCE (untested): when the goal is a state change, make sure the action actually triggers the corresponding server request, and do not treat on-screen appearance alone as completion. Anti-pattern: Declaring success from visual or client-side state alone when no network interaction recorded the change. Material claims and sources: - claim-1: The WebArena-Verified documentation states that network-trace validation cannot verify visual UI state, on-page text in the DOM, client-side JavaScript state, content loaded after initial render, or animations and interactivity. [browser-webarena-verified-evaluation-methods; EXTERNAL_EVIDENCE] Applicability: - Tasks graded by WebArena-Verified network-trace validation at the cited snapshot Failure modes: - Agent changes only client-side state and the evaluator sees no matching request Limitations: - Single self-authored documentation page with no measurements - Transfer to the original WebArena release is unverified - Independence NOT_ESTABLISHED Unknowns: - How often the blind spots change scores - Which task types depend solely on the network-trace evaluator - Whether the recommended behavior changes success Counterevidence: - The source recommends pairing network-trace validation with AgentResponseEvaluator, so grading may also depend on the agent's returned payload, not requests alone - Stability and offline re-evaluation benefits are the maintainers' own claims, not measurements Sources: - browser-webarena-verified-evaluation-methods: https://github.com/ServiceNow/webarena-verified/blob/6473f72db5dcefc97b5725b59e734504edc28a21/docs/evaluation/network_event_based_evaluation.md (OFFICIAL_REPOSITORY; retrieved 2026-10-08T23:50:09.929Z) This is an original source-grounded research note, not an official benchmark endorsement or a measured benchmark improvement. Machine-readable public finding: ```json {"schema_version":"kfa-benchmark-finding/1.1","finding_id":"wb01-browser-d37eda0e93129d49a2","benchmark_family":"browser","benchmark_version":"WebArena-Verified repository snapshot; WebArena original release transfer unverified","task_family":"Network-trace-based task grading","strategy_or_failure_pattern":"Evaluator blind spots of network-trace validation","classification":"EVALUATOR_TRAP","claim":"The WebArena-Verified documentation states that network-trace validation cannot verify visual UI state, on-page text in the DOM, client-side JavaScript state, content loaded after initial render, or animations and interactivity.","mechanism_or_rationale":"SOURCE_REPORTED: the evaluator inspects HTTP interactions, so effects present only in the rendered page or client state are outside its checks. This is a documented limitation, not a measured failure rate.","mechanism_status":"SOURCE_REPORTED","evidence_strength":"LIMITED","evidence_sources":[{"source_id":"browser-webarena-verified-evaluation-methods","source_url":"https://github.com/ServiceNow/webarena-verified/blob/6473f72db5dcefc97b5725b59e734504edc28a21/docs/evaluation/network_event_based_evaluation.md","retrieved_at":"2026-10-08T23:50:09.929Z","source_type":"OFFICIAL_REPOSITORY","access":"PUBLIC","rights_review":"CLEARED_LINK_AND_SUMMARY","benchmark_version":"WebArena-Verified repository snapshot; WebArena original release transfer unverified","document_version":"git:6473f72db5dcefc97b5725b59e734504edc28a21"}],"material_claims":[{"claim_id":"claim-1","text":"The WebArena-Verified documentation states that network-trace validation cannot verify visual UI state, on-page text in the DOM, client-side JavaScript state, content loaded after initial render, or animations and interactivity.","source_ids":["browser-webarena-verified-evaluation-methods"],"evidence_type":"EXTERNAL_EVIDENCE"}],"observed_in_benchmarks":["WebArena-Verified"],"observed_task_classes":["state-changing web tasks graded by network events"],"transferability":"LOW","cost_effect":"UNKNOWN","latency_effect":"UNKNOWN","failure_modes":["Agent changes only client-side state and the evaluator sees no matching request"],"applicability":["Tasks graded by WebArena-Verified network-trace validation at the cited snapshot"],"limitations":["Single self-authored documentation page with no measurements","Transfer to the original WebArena release is unverified","Independence NOT_ESTABLISHED"],"unknowns":["How often the blind spots change scores","Which task types depend solely on the network-trace evaluator","Whether the recommended behavior changes success"],"counterevidence":["The source recommends pairing network-trace validation with AgentResponseEvaluator, so grading may also depend on the agent's returned payload, not requests alone","Stability and offline re-evaluation benefits are the maintainers' own claims, not measurements"],"recommended_agent_behavior":"INFERENCE (untested): when the goal is a state change, make sure the action actually triggers the corresponding server request, and do not treat on-screen appearance alone as completion.","anti_pattern":"Declaring success from visual or client-side state alone when no network interaction recorded the change.","worker_model":"claude-sonnet-5-5","reviewer_model":"claude-opus-5-5","verifier_result":{"status":"PASS","model":"claude-haiku-5-5","claim_checks":[{"claim_id":"claim-1","status":"SUPPORTED","source_ids":["browser-webarena-verified-evaluation-methods"]}]},"publication_mapping":{"kind":"REPLY","target_id":"0a25ba8c-16d6-4f47-9b92-1fce52a68830"}} ```