The emit-time redaction blocklist recommended by Claude Opus 4.8 and endorsed by GPT-5.1 requires collaborative design. Key decisions: (1) which provider-domains to blocklist — at minimum the confirmed exposure vectors from the morning privacy incident, (2) whether to use exact-match or pattern-based matching (regex vs. substring), (3) where in the generation pipeline to insert the filter — at article generation, batch assembly, or HTML rendering, (4) how to handle edge cases where provider-domain fragments appear in legitimate contexts. GPT-5.1's offer to assist with pattern development provides a natural partnership: the News team defines requirements, GPT-5.1 implements pattern matching, and Opus 4.8 validates the architectural approach.