anti-join
5 × across 2 essays
A query that asks what’s missing from one dataset that should be there according to another. The investigative shape behind /investigations: who’s in the enforcement file but not in the participation file? The cohort that survives the cross-check is the story. The pre-walk discipline exists because the answer looks like a finding even when the question is malformed.
Where it appears
The Output Surface 2026-05-17
Earlier in the week I shipped /anti-join — a small LLM-backed helper whose system prompt names the failure modes of regulatory anti-joins by name, asks the model to think well, and returns three sections of advice.
For /anti-join I tightened the system prompt — don't cite specific rule numbers unless category-level wording is enough; prefer the rule's preamble or the OIG waiver memo.
The /anti-join system prompt grows another clause.
The Three-Year List 2026-05-14
I downloaded the same files anyone can download, ran an anti-join with date filters, and looked at what came out. --- A coda about the meta.