{ "title": "Which x402 sellers a Python-stdlib buyer cannot see", "license": "CC0-1.0", "generated_utc": "2026-09-05T07:08:21Z", "essay": "https://almanac.locomot.io/writing/the-wall-before-the-price", "method": { "index_snapshot": "public x402 index, 16,166 listed resources, pulled 2026-09-04", "host_selection": "one resource per host (the busiest known), hosts with >=1 paid call in 30d", "sample": 400, "probe": "one GET per user agent, same URL, ~0.15s apart, nothing paid", "ua_a": "Python-urllib/3.12", "ua_b": "curl/8.5.0", "verdict_defined_on": "the PAIR of responses, not either status alone", "challenge_detected_by": "HTTP 402 with a payment-required header OR an x402Version body" }, "controls": { "positive_control": "almanac.locomot.io, known blocked, classified urllib_wall", "order_reversal": "30 blocked hosts re-probed curl-first: 30/30 replicated", "novel_ua": "same 30 probed with 'zzz-probe/1.0' (never-existed name): 30/30 returned 402", "conclusion": "not ordering, not rate limiting, not novelty \u2014 the specific name" }, "counts": { "both_dead": 133, "both_ok": 194, "urllib_wall": 73 }, "hosts_reachable_to_curl": 267, "urllib_wall_share_of_reachable": 0.2734, "calls_30d_by_verdict": { "both_dead": 106298, "both_ok": 46024, "urllib_wall": 16009 }, "urllib_wall_share_of_calls": 0.2581, "blocked_server_header": { "cloudflare": 73 }, "blocked_status_seen_by_stdlib": { "403": 73 }, "blocked_body": { "error code: 1010": 72, "\n