.build_series_break_refs() matches `fin_code IN (<codes in the result>)`. No row's item_code is ever the literal "ALL", so the four corpus-wide entries could never match and reached no user: SB085 1977 dollar precision across the 1976/1977 boundary SB087 2002 imputation exclusion FY2002-2006 SB194 2012 dense -> sparse representation change SB086 2017 government id scheme change SB194 is why this matters now. cog_pipeline#64 DoD 4 was "series_breaks.csv carries an ALL @ 2012 entry describing the representation change, SO cog_explain() surfaces it". The entry shipped; the reader dropped it. A query spanning FY2011 -> FY2012 crosses the boundary where an absent cell stops meaning "Census published $0" and starts meaning "not reported", and nothing said so. Provenance gains `corpus_break_refs`, built by .build_corpus_break_refs() on the break_year window alone -- which codes a result happens to contain is irrelevant to a caveat about the corpus. A separate field rather than more entries in series_break_refs, because an ALL caveat qualifies the whole result and folding the two together invites reading it as a caveat about one series; .build_series_break_refs() now excludes 'ALL' explicitly so the two stay disjoint by construction. cog_explain() prints them under their own "Corpus-wide caveats" heading, and cog-api passes provenance through verbatim, so the field reaches the API with no change there. On the year rule: all four entries are BOUNDARY caveats -- their own join_advice speaks of crossing 1976/1977, of FY2002-2006, of absence not being comparable across FY2012, of pre- vs post-2017 ids -- so the same `break_year BETWEEN min(years) AND max(years)` rule the code-specific path uses is the right one, and matches the issue's DoD 1. The issue's DoD 3 also asks that a FY2011 query surface SB085; that cannot hold under DoD 1 and does not hold under any reading of SB085's text, whose boundary is 1976/1977. Tested with a range that actually spans it, and flagged on the issue. Stacked on fix/regen-fixture-corpus-18: SB194 does not exist in main's bundled fixture, which predates the break being catalogued. Suite: 606 pass / 0 fail / 6 skip (was 594/0/6). cog-api 357 / 0 / 8, unchanged.