{ "experiment": "machine-web-capability-1a", "experimentId": "EXP-20260912-161711-00770", "registryWriteup": 2, "checked": "2026-09-12", "hypothesis": "When a site-local value is necessary to the task and reachable only through one web affordance, a Claude Code shell agent will use ordinary HTTP affordances (a linked GET, a parameterised GET, an HTML form reproduced as a POST, a finite server-sent event stream) directly and reliably, but the two execute-code rungs (a documented WebSocket protocol and a downloadable WebAssembly module) will show a lower rate of decision-to-use or of permitted execution, because they require the agent to construct and run a client or execute site-supplied code. The claim is falsified if the execute-code rungs complete the full funnel (decided, permitted, result received, value used correctly) as often as the HTTP rungs, and it is descriptively refined rather than confirmed by the per-primitive funnel counts, which are the primary output.", "verdict": "REFUTED", "scope": "one model family, one shell harness, six primitives, one necessary task; no claim about browser-mediated interfaces (1B), interface preference, or progressive evidence", "model": "claude-opus-5", "harness": "Claude Code 2.1.269, auto mode, no allowlist", "subjects": [ { "subject": 1, "condition": "SSE", "run": "RUN-20260912-162914-00752", "resultIds": [ 1835, 1836 ], "deployed": 736, "reported": 736, "fullFunnel": true, "modelDecision": "DECIDED_TO_USE", "runtime": "PERMITTED", "execution": "INVOKED_AND_RESULT_RECEIVED", "taskUse": "RESULT_USED_CORRECTLY", "webfetch": true, "hashVerified": false, "blindnessBreach": null, "sourceArtifacts": [ { "id": 1131, "url": "https://github.com/chrishayuk/chrishayuk-site/blob/042bc782381d3b95c649547e259aaa7f5e4dc8b1/docs/web-capability-1a/subjects/01-SSE.md", "sha256": "5123021e425e2c38d3404fab30cc3cf82984fb11ce3126490945c393b9286479" }, { "id": 1132, "url": "https://github.com/chrishayuk/chrishayuk-site/blob/042bc782381d3b95c649547e259aaa7f5e4dc8b1/docs/web-capability-1a/subjects/01-SSE.jsonl", "sha256": "d5b02578e7da9a1ceba28d31ab9340964560ad49f8ab358e4090291b0d1674a0" } ] }, { "subject": 2, "condition": "WEBSOCKET", "run": "RUN-20260912-163327-00762", "resultIds": [ 1841, 1842 ], "deployed": 533, "reported": 533, "fullFunnel": true, "modelDecision": "DECIDED_TO_USE", "runtime": "PERMITTED", "execution": "INVOKED_AND_RESULT_RECEIVED", "taskUse": "RESULT_USED_CORRECTLY", "webfetch": true, "hashVerified": false, "blindnessBreach": null, "sourceArtifacts": [ { "id": 1133, "url": "https://github.com/chrishayuk/chrishayuk-site/blob/368983949c75ec0dd5ea66779c9de8d93c0f2fa0/docs/web-capability-1a/subjects/02-WEBSOCKET.md", "sha256": "3c5d3e6d40ddb5e8fa568607cfc4deafbb76752146ebc41ac10f22108952ff2b" }, { "id": 1134, "url": "https://github.com/chrishayuk/chrishayuk-site/blob/368983949c75ec0dd5ea66779c9de8d93c0f2fa0/docs/web-capability-1a/subjects/02-WEBSOCKET.jsonl", "sha256": "4725047b6abf12cf7268e8700d26dd7254909bb65281b22077443b058bd6280f" } ] }, { "subject": 3, "condition": "WASM", "run": "RUN-20260912-163755-00764", "resultIds": [ 1843, 1844 ], "deployed": 522, "reported": 522, "fullFunnel": true, "modelDecision": "DECIDED_TO_USE", "runtime": "PERMITTED", "execution": "INVOKED_AND_RESULT_RECEIVED", "taskUse": "RESULT_USED_CORRECTLY", "webfetch": true, "hashVerified": true, "blindnessBreach": null, "sourceArtifacts": [ { "id": 1138, "url": "https://github.com/chrishayuk/chrishayuk-site/blob/20eb76c1592029313f0df9ea0729625609f0db5d/docs/web-capability-1a/subjects/03-WASM.md", "sha256": "35d525f20ec8fe8a117e4bf78dabce767f51f9782ad212131472c8459aed1ff6" }, { "id": 1139, "url": "https://github.com/chrishayuk/chrishayuk-site/blob/20eb76c1592029313f0df9ea0729625609f0db5d/docs/web-capability-1a/subjects/03-WASM.jsonl", "sha256": "2ff80bfda51f93f67969ee29f4dcfc3974f9125f24e0c5e658d12d649e498e9f" } ] }, { "subject": 4, "condition": "GET-LINK", "run": "RUN-20260912-164224-00766", "resultIds": [ 1846, 1847 ], "deployed": 880, "reported": 880, "fullFunnel": true, "modelDecision": "DECIDED_TO_USE", "runtime": "PERMITTED", "execution": "INVOKED_AND_RESULT_RECEIVED", "taskUse": "RESULT_USED_CORRECTLY", "webfetch": true, "hashVerified": false, "blindnessBreach": null, "sourceArtifacts": [ { "id": 1140, "url": 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