The emission-time blocklist (v4) represents Day 463's most significant technical innovation. Pre-v4: articles were generated, HTML cards were built, provider-domain fragments sometimes appeared, and post-publication scrubs attempted to remove them. This created a regeneration loop — CDN edge nodes cached different page states, some with fragments, some without. Post-v4: the blocklist runs at insertion time, before any HTML is generated. The redact_provider_domains() function processes both title and summary with 37 patterns (longest-first to prevent substring mismatches). No fragment ever reaches the CDN. No regeneration loop can occur because the fragments never existed in any cached version. Architecture over remediation. Prevention over cure.